Abstracts



100 years of photosensitivity in optical glasses

Raman Kashyap

Ecole Polytechnique de Montréal (Canada)

 


Fundamentals of photosensitivity

B.Poumellec

Université de Paris Sud, Orsay, France

Abstract:
I will describe photosensitivity in glasses with specificity for silica based ones. The term photosensitivity means firstly that at least the first step of mechanism leading to some changes in physical properties, is a one or multiphoton absorption, secondly that the lifetimes of these changes are much longer than the one of the usual luminescence. From that, there are a lot of various effects depending on the chemical composition of the glass, but also, for a given glass, depending on the laser wavelength, power density or type (CW pulsed). I will describe a classification with some examples. Lastly, I will show complex mechanisms combining several effects.


Are stresses and stress changes in optical fibres the key to understanding the phenomenon of photosensitivity

H.G.Limberger

Institute of Imaging and Applied Optics - EPFL (Switzerland)

Abstract:
Residual stresses in optical fibre contribute to the overall refractive index distribution via the photoelastic effect. Absorption of laser light triggers stress changes and leads to refractive index modifications. This process may relax residual stresses in the glass network and thus explain the observed photosensitivity in optical fibres. However, the 'stress relief model' proposed by M.Sceats et al. failed to explain photosensitivity. Nevertheless, it triggered the investigation of light induced stress changes in optical fibres. They depend on core dopants, fibre drawing, pre-sensitization, and irradiation conditions. The photoelastic contribution can be correlated to total index changes. Thus conclusions about other dominant mechanisms, like compaction or colour centre changes may be drawn. Stress measurements in optical fibre and the role of light induced photoelastic index changes are presented.


UV-written Bragg gratings

Morten Ibsen

ORC, University of Southampton (UK)

Abstract:
It is no understatement to claim, that the Bragg grating [1,2] is the most significant fibre-optic invention since the erbium-doped fibre amplifier (EDFA). Unquestionably, it is the most versatile optical-fibre filter that exists and it has, hand-in-hand with the EDFA, facilitated dense wavelength division multiplexing (DWDM) in telecommunications, providing better processing of densely packed optical frequencies and easily out-performing any other available filter-technology. Further studies into the design, fabrication and applications of fibre Bragg gratings therefore are of major interest for future communication-systems, besides a diverse range of other applications including sensing, and short pulse fibre lasers. A Bragg grating is a periodic or almost-periodic structure, consisting of a variation of for example the refractive index with a typical period of ~0.5μm along the length of a waveguide and is typically formed within this waveguide using side-exposure to intense ultra-violet light [2]. By phase-matching the individual small reflections generated by the high-low, low-high index regions of difference ~10-4 along the waveguide, strong overall reflection of light incident on the grating is obtained within a well-defined spectral pass-band. Therefore, a Bragg grating can act as a band-rejection filter passing the wavelengths that are not in resonance with the grating and strongly reflecting wavelengths that satisfy the Bragg condition. The technology of Bragg gratings has matured significantly over the past years and with the recent advances in manufacturing capabilities of these obviously there will develop a demand for filters of even higher complexity to perform very specific filtering tasks. Currently it is often the imagination that sets the limits for what can be achieved experimentally. Of particular practical significance is the possibility to alter and control both the amplitude and phase of light reflected and/or transmitted through a grating. This possibility has been exploited in the past for a range of optical signal processing function including, for example, static chromatic dispersion compensation in optical fibre links [3], and the design and fabrication of Bragg grating filters for complex phase and amplitude coding applications similar to those used in microwave code-division multiple access (CDMA) communication systems [4]. These and many other recent new applications [5] of fibre Bragg gratings together with an overview of Bragg grating design-and fabrication-techniques will be taught in this lecture.

References:
[1] K.O.Hill et al., Appl. Phys. Lett., 32, p.647, 1978.
[2] G.Meltz et al., Optics Lett., 14, p.823, 1989.
[3] D.Garthe et al., IEE Electron. Lett, 30, p.2159, 1994.
[4] P.C.Teh et al., in proceedings to OFC'OO, PD9, 2000.
[5] M.Ibsen and R.Feced, Optics Lett., 28, p.980, 2003.


Fibre gratings in sensing applications

David Webb

Aston University (UK)

Abstract:
This lecture will focus on the applications of fibre grating devices mainly in sensing but also briefly in telecommunications. For sensing applications it is necessary to determine the measurand induced shift in Bragg wavelength. Many techniques for carrying this out have been demonstrated in research laboratories and there are now several commercial systems available, some of which will be reviewed. The lecture will cover applications of grating sensors in the fields of civil engineering, aerospace and medicine. Long period gratings will be introduced and their properties contrasted with those of Bragg gratings. Applications making use of some of the unique features of long period gratings will be presented.


Poling of glass

Walter Margulis

ACREO (Sweden)

Abstract:
Glass materials used in optical fibres and planar waveguides do not exhibit second order optical nonlinearity. However, through poling it is possible to record a strong nearly permanent electric field in the glass, thus breaking the intrinsic symmetry and inducing nonlinear phenomena, such as frequency doubling and the linear electrooptic (Pockels) effect. The nonlinearity induced in poled fibres and planar waveguides is sufficient to find practical applications in switches, modulators and frequency converters. In this lecture, the technology and some of the basic mechanisms of poling will be presented.


New directions and the future of UV-written technologies

Marc Douay

Universite des Sciences et Technologies de Lille (France)

Abstract:
The presentation concerns the various techniques used for inscriptions of components using glass photosensitivity. Gratings inscriptions (slanted, apodized, chirped) and UV patterning will be exposed for components written in fibers and/or planar waveguides. Concatenations, reductions of polarisation dispersion losses and polarisation modal dispersion will be exposed for gain equalisation in optical amplifiers. Presentations will be also exposed within the framework of the European contract Platon (Planar Technologies for Optical Networks). The aim of PLATON project is to study, develop and assess photosensitive planar technology in a system context, through key devices for future optical metropolitan networks.


Advances in ultrashort pulse lasers

Peter G.Kryukov

Fiber, Russian Academy of Sciences (Russia)

Abstract:
The main tendency of modern electronics including quantum electronics is miniaturization. Ultrashort-pulse lasers and fibre optics are examples of this tendency. The development of ultrashort-pulse lasers resulted in the fabrication of compact systems capable of emitting pulses of duration as short as a few cycles of a light wave with extremely high peak powers. A unique feature of femtosecond lasers is that they can generate radiation whose temporal coherency can be varied by 15 orders of magnitude. In fact, if a single pulse is selected from a continuous train of pulses, the temporal coherence of radiation cannot be grater than the pulse duration. At the same time, the spectrum of the train consists of an equidistant comb of narrow, as small as a few hertz, lines. This feature allows the use of femtosecond lasers both in optical coherent tomography, where an ultimately low temporal coherence is required, and in high-precision optical-frequency metrology, which requires extremely narrow laser lines. The union of femtosecond lasers and fibre optics is rather fruitful. Special fibres, for example, of the photonic-crystal type, provide a considerable increase in the comb spectrum until more than an octave, which is very important for metrological applications. The Er- and Yb-doped femtosecond fibre lasers are more compact and less expensive than Ti:sapphire lasers (working horse of femtosecond science and technology). Femtosecond laser pulses are successfully used for manufacturing important elements of fibre optics. The fabrication of long-period and Bragg fibre gratings and writing of waveguide structures in transparent materials with the help of femtosecond pulses were demonstrated. The results of studies of femtosecond fibre lasers and fabrication of fibre gratings with help of femtosecond pulses performed at FORC RAS are presented.


Breaking the limits in glass: From quantum interference to fs nanostructuring

Peter Kazansky

University of Southampton (UK)

Abstract:
Optical glass fibres and waveguides dominate optical communications. The development of linear electrooptic modulators/switches and parametric frequency converters directly integrated into optical glass waveguide structures technologically is very attractive. However such components require a second-order optical nonlinearity - a χ(2) which is normally absent in glass owing to its inversion symmetry. Thus, when self-organized frequency doubling was first discovered wide-ranging studies ensued into the mechanism and properties of this unexpected phenomenon. The mystery of self-organized χ(2) gratings was finally solved on the basis of a new physical phenomenon - the coherent photogalvanic effect, consisting in quantum interference between light fields at two different frequencies, ω and 2ω, which excites a phase dependent current (coherent photocurrent). Coherent photocurrent creates quasi-phase matching χ(2) gratings. Moreover in the experiments on electric-field second harmonic generation in optical fibres the first evidence of phase dependent modulation of a total cross-section of ionization due to quantum interference (coherent photoconductivity) in solid state materials has been obtained [1]. Another interesting field demonstrating unusual light-matter  interactions and properties of materials is modification of index of refraction and direct writing of photonic structures by. ultrashort light pulses in glass. A critical advantage of using femtosecond pulses relative to longer pulses for optical writing and data storage is that such pulses can rapidly and precisely deposit energy in solids. This is the principle of femtosecond photosensitivity and 3D direct writing of photonic structures ranging from 3D waveguides to embedded Fresnel zone plates. This research has led to demonstration of new phenomena - anomalous anisotropic light scattering and form birefringence in glass [2]. The anisotropic phenomena have been interpreted in terms of self-induced index nano-gratings in glass and self-organized form birefringence, which is a new manifestation of self-organization under intense irradiation. The observed self-organized periodic structures are the smallest (20 nm width) and the strongest (-0.2 index change) ever created by light in transparent materials. Moreover these are the first gratings created by light-matter (electron plasma) interference [3]. In the talk I review properties and potential applications of glass and optical fibres modified by strong fields and related new phenomena.

References:
[1] Phys. Rev. Let. 78, 2956 (1997)
[2] Phys. Rev. Lett. 82, 2199 (1999)
[3] Phys. Rev. Lett. 91, 247405 (2003)


Laser engineering in nano-structured glasses

Gerhard Seifert

Martin-Luther-University Halle (Germany)

Abstract:
The linear and nonlinear optical properties of nano-structured materials on the basis of glass can be designed within a very broad range of parameters to meet the needs of optical and optoelectronic applications. In particular glass containing metal or semiconductor nanoparticles can be engineered by modifying shape and spatial distribution of the nanoparticles using ultrashort laser pulses. In this lecture, the physics of the laser-induced particle modification and the optical characteristics of the structures produced will be discussed as well as the potential applications of this laser engineering of the nanostructure of composite glasses.


Raman fiber lasers: breakthrough in laser physics

E.M.Dianov, A.M.Prokhorov

General Physics Institute RAS (Russia)

Abstract:
The growing applications of lasers in various fields of contemporary technology, in medicine, for scientific research demand new laser frequencies in UV, visible and IR regions. The efficiency, compactness, flexibility in wavelength selection and high quality of the output beam of lasers are essential for many applications. Raman fiber lasers, a triumphal advent of which is connected with striking success in fiber optics technology meet these requirements. The lecture will focus on recent results in the development of new Raman fibers and in the creation of the family of Raman fiber lasers with practically any wavelength in the spectral region of 1-2 μm and beyond.


High-power ultrafast fiber lasers: new horizons and applications

Anatoly Grudinin

FIANIUM LTD., (UK)

Abstract:
In this lecture we first consider fundamental principles and effects of nonlinear fibre optics and in particular effect of nonlinear pulse propagation in optical fibres. Then a detailed description of ultrashort fibre laser will be given with special emphasis on properties and features of soliton fibre lasers operating in a wide spectral range. The second part of the lecture is focused on approaches to generate high average power and ultra-high peak power in all-fibre systems. Particular attention will be paid to novel technologies to maintain integrity and high fidelity of ultrashort pulses and potential applications of such systems.


Extreme Nonlinear Optics: Multiphoton X-Ray Photonics and Applications

Emily Gibson, Ariel Paul, Ron Tobey, Nick Wagner, Tim Lei, Ivan Christov, John Gland, Thomas Feurer, Keith Nelson, Henry Kapteyn, Margaret Murnane

JlLA University of Colorado at Boulder (USA)

Abstract:
In this lecture, the physical processes involved in the generation and optimisation of extreme-ultraviolet and soft x-ray light though the process of high-order harmonic generation will be discussed. Using concepts from visible wavelength photonics, it is now possible to extend nonlinear optics well into the x-ray region of the spectrum. We show that by manipulating the dynamics of this process using optimised waveguide structures and pulse shapes, we can control the energy of the emitted photons, as well as phase-matching the conversion process. Use of optimised structures can also improve the spatial and temporal coherence of the light. Finally, applications of ultra-fast x-rays in monitoring molecular dynamics on surfaces will also be discussed.

References:
[1] Nature 406, 164 (2000)
[2] Science 297, 376 (2002)
[3] Science 302, 95 (2003)


Quantum information and Wavelength Scale Structures

Prof John G.Rarity

Bristol University (UK)

Abstract:
Coding data bits in the phase or polarisation state of single photons allows us to exploit wave particle duality for novel computing and communication protocols. The first practical applications are the fibre and free-space quantum cryptography apparatus used for secure exchange of keys [1,2]. Further developments such as quantum relays and other few qubit applications require that pairs of qubits interact. To avoid the inevitably weak non-linear interactions between photons conditional linear optics logic has been developed to demonstrate CNOT operation albeit with limited efficiency [3,4]. Optical quantum logic schemes thus require high efficiency sources and detectors of single photons. However, in the future we would also want non-linearity at the single photon level. These components in the quantum logic toolbox could be realised by exploiting wavelength scale engineering of optical structures. The strong modification of mode density within periodic dielectric structures can drastically modify spontaneous emission from two-level systems. This can manifest as changes in spectral content, changes in lifetime and in low power saturation (non-linear) effects. Suitable two-level systems could be colour centres in crystals, quantum dots in semiconductors and transition metals in glassy materials. Of interest to the field of quantum information are single two- level systems coupled to a strong resonant mode. Such a system could form the basis of a single photon source, a single photon detector and single photon non-linear element. This talk will explore these ideas in the context of micro-structured materials.

References:
[1] N.Gisin, G.Ribordy, W.Tittel and H.Zbinden Rev. Mod. Phys. 74, 145 (2002).
[2] C.Kurtsiefer et al, Nature 419, 450 (2002).
[3] J.G.Rarity, Roy. Soc. Phil. Trans. 361, 2003, 1507-18
[4] J.L.O'Brien et al, Nature 426, 264 (2003).


Aspects of the quantum theory of near-field optics.

Ole Keller

Aalborg University Centre (Denmark) .

Abstract:
The classical macroscopic theory of near-field optical interactions is briefly reviewed paying particular attention to the role of evanescent fields. Starting from the electromagnetic field of a point dipole multiple near-field scattering is discussed. Studies of mescoscopic objects - such as quantum dots, wires and wells - necessitate that the near-field particle-particle interaction is treated on the basis of quantum mechanics. In the final part of the lecture I discuss in a field-unquantized setting the quantum approach to near-field optics starting from a description of the interaction between two atoms (molecules) in near-field contact. Near-field optics is of importance not only for applied optics, but also in theoretical physics because it helps us to unify the description of certain basic physical phenomena usually studied separately. Starting from near-field optical concepts I discuss (i) the space-time generation of single-photon wave packets in first quantization, (ii) the spatial resolution problem in optics, (iii) photon tunnelling, (iii) photon embryos, and (iv) causality.


Quantum Computing using Electron Spin in Group IV Semiconductors

Eli Yablonovitch

UCLA Electrical Engineering Department (USA)

Abstract:
This Lecture will present a systems analysis for a Quantum Factorisation Engine built in Si-Ge technology. This will be a review of the types of devices and system architectures that will be needed in order to make a quantum information processor in the Ge-Si material system. Attention will be paid to the required elementary operations; single spin measurement, single spin rotation, and two spin interaction. The UCLA group has recently measured a single electron spin inside a conventional Silicon integrated circuit. The fidelity requirement of the gate operations for quantum error correction represents the principal technical challenge, among many others


The atom chip

Ron Folman

Ben-Gurion University (Israel)

Abstract:
Quantum Technology deals small systems which can be isolated long enough to be useful as quantum systems. One example is the ultra cold neutral atom. An overview of the field of matter wave optics will be presented. We will then discuss the combination with integrated photonics on the atom chip, as a way of realizing quantum technology, through trapping, guiding, manipulating and measuring atoms.


Experimental nano-optics: principles and applications

Anatoly V.Zayats

The Queen's University of Belfast (UK)

Abstract:
The recent developments in scanning near-field optical microscopy (SNOM) have provided the possibility to visualise optical processes on the subwavelength scales with an optical resolution inaccessible by traditional far-field approaches which are limited by diffraction effects. This has opened up a new research field of nano-optics concerned with studies and applications of nano-scale optical effects and nanoscopic light sources. In this talk we will discuss the principles of nano-optics and scanning near-field optical microscopy and their applications in nano-photonics. After reviewing experimental approaches to near-field optical studies, we will focus on the examples of nonlinear nano-optics and surface plasmon photonics. A conventional aperture-based SNOM makes use of a small aperture which is scanned at a fixed distance in near-field proximity above the sample surface. In an apertureless SNOM, a nanoscopic scatterer is employed to probe the near-field distribution. Using a SNOM one can image, simultaneously, the surface topography and the optical field above the surface that allows correlation of the observed optical response to specific surface features. Nano-local absorption, reflection and fluorescence have been' successfully studied with SNOM. Nonlinear approaches to SNOM, particularly second-harmonic generation, have significantly improved optical resolution of the technique due to the electromagnetic field enhancement effects at the probe tip. Associated field confinement provides an opportunity to achieve strongly localised light sources. Near-field second-harmonic generation combines the extremely high surface sensitivity of second-harmonic generation with the high spatial resolution of SNOM and can lead to the development of new tools for imaging, local optical studies and modification of materials as well as novel nonlinear photonic devices on the subwavelength-scale. Only with near-field microscopy the direct studies of surface plasmons whose electromagnetic field is confined to the surface, have become possible. In turn surface plasmon effects facilitate nonlinear optical processes due to the associated with them field enhancement. It is the surface polaritons that determine the majority of linear and non-linear optical properties of metallic nanostructures. Surface plasmon polaritons are emerging as a new information carrier that enables manipulation and control of optical signals in a subwavelength photonic circuitry. Numerous applications can be envisaged in optical information processing and optical communications.

Further reading:
1. "Nano-optics and near-field microscopy," D.Richards and A.Zayats, Eds., Phil. Trans. Royal Soc. A, vol. 362, 2004, pp. 699-919.
2. A.V.Zayats and I.I.Smolyaninov, "Near-field second-harmonic generation," Phil. Trans. Royal Soc. A, vol. 362, 2004, pp. 843460.
3. A.V.Zayats and I.I.Smolyaninov, "Near-field photonics: surface plasmon polaritons and localised surface plasmons," J. Opt. A: Pure Appl. Opt., vol. 5, 2003, pp. 516-550.


Optical trapping/tweezing of microscopic objects and atoms

Kishan Dholakia

University of St. Andrews (UK)

Abstract:
Optical forces can dramatically influence the kinetic motion of objects ranging from the microscopic or cellular size right down to the atomic scale. In this lecture I will discuss the optical forces and show they may be used to tweeze particles and also cool atoms and guide both cold atoms and quantum degenerate gases. An overview of the state-of the art on optical micromanipulation will be given showing new areas of science that are emerging including the use of new and multiple beam shapes, optical sorting and optical transport including guiding along photonic crystal fibres. At the atomic scale I will give an overview of atom guiding and manipulation including applications for atom lithography and nano-positioning of atomic ensembles including Bose-Einstein condensates.


Supercontinuum Generation in Photonic Crystal Fibre

John Dudley

Universite de Franche-Comte (France)

Abstract:
Supercontinuum generation in photonic crystal fibre has now been reported under many different experimental conditions. This paper reviews supercontinuum generation over the full range of experimentally-reported parameters from the nanosecond to the femtosecond regime, and discusses the dominant frequency conversion mechanisms in each case. Despite apparent visual similarities between supercontinua generated under different conditions, it is shown that the intensity, phase and stability of the supercontinua can vary significantly. This paper will provide an overview of the underlying spectral broadening mechanisms and supercontinuum properties that should allow the optimization of supercontinuum sources tailored to particular application needs.


Negative refraction opens new doors in optics

John Pendry

Imperial College London (UK)

Abstract:
Materials with μ < 0 and ε < 0 were christened 'left handed' by Veselago because the wave vector and Poynting vector lie in opposite directions. It was later suggested that they could also be described by a negative refractive index, n < 0, an although this was disputed by some there are now several reliable experiments and computer simulations which show that this is indeed the case. In this talk I shall describe how the negative attribute goes even deeper. Regions of space with n < 0 can be thought of as optically cancelling or negating neighbouring positive regions. The simplest instance is a slab of n = -1 material of thickness d which cancels an equivalent thickness of vacuum and therefore acts as a lens: objects are brought into focus as an image a distance 2d along the normal to the slab. Other more complex instances of negative space will be discussed in the talk.


Direct UV-written waveguides in tin-doped multicomponent silicate glass

Frank Knappe1, Yvonne Menke2, Fabrice Grézaud1, Hagen Renner1, Monica Ferraris2, Ernst Brinkmeyer1

1. Technische Universitat Hamburg-Harburg, Optical Communication Technology, Eißendorfer Str. 40, D-21073 Hamburg, Germany
2. Politecnico di Torino, Dipartimento di Scienza dei Materiali e Ingeneria Chimica, Corso Duca degli Abruzzi, 24 10129 Torino, Italy Tel.: ++49 40 42878 3437, Fax: ++49 40 42878 2860, Knappe@tu-harburg.de

Abstract:
In this paper, the fabrication of waveguides by direct ultraviolet (UV) writing into a bulk tin-doped multicomponent silicate glass is presented. Refractive index increases in non-hydrogen-loaded samples of up to 5 × 10−3 were measured.


Physical Asymmetry of Defects Induced by Femtosecond Laser Irradiation in Silica

François Busque, Suzanne Lacroix, Raman Kashyap, Michel Meunier

Ecole polytechnique, Montréal, Canada

Abstract:
We are interested in the study of linear defects induced in silica by femtosecond laser irradiation. Its cross-section, revealed by cleaving the silica sample, presents a granular region at the input and a discontinuous tail.


Waveguide fabrication in bismuthate glasses using femtosecond laser pulses

Weijia Yang, Erica Bricchi and Peter G.Kazansky

Optoelectronics Research Centre , University of Southampton, Southampton SO17 1BJ, UK Tel. +44(0)-23-8059 2086, Fax: +44(0)-23-8059 3142, e-mail: wey@orc.soton.ac.uk

Abstract:
Femtosecond direct written waveguides in bismuthate glasses are reported. This is the first demonstration of direct written guiding channels in bismuthate glass which show an index of refractive change as high as 3 x 10-3


Extraordinary stability of femtosecond direct written structures

Erica Bricchi and Peter G.Kazansky

Optoelectronics Research Centre, University of Southampton, Southampton SO17 1BJ, UK Tel.: +44 023 8059 3142, +44 023 8059 3143, erb@orc.soton.ac.uk

Abstract:
We report novel results on the stability of femtosecond direct written structures: a silica sample previously irradiated with ultrashort pulses was annealed at increasing temperatures till 1400o C where it crystallized. Our results show that the birefringent direct written structures are stable till a temperature close to the glass transition of silica. After annealing at a temperature as high as 1100o C the form birefringence of the structures is still present, proving that the nature of the laser induced anisotropy is related to a structural change.


Fiber Optics for Quantum Computers

S.Helsby, H.F.Powell, P.Horak, B.G.Klappauf, M.Ibsen and P.Kazansky

Optoelectronics Research Centre, University of Southampton, Southampton, SO17 1BJ. hfp@orc.soton.ac.uk

Abstract:
We describe schemes for the integration of miniature optical components onto Atom Chips, for the manipulation and detection of ultra-cold atoms. Our intention is to build detectors sensitive enough to accurately detect single atoms. Two approaches . are discussed: simple fluorescence detection and the use of a resonant cavity. Theory predicts that cavities with F > 100 should be sufficient to obtain signal to noise ratios high enough to detect single atoms. The first micro cavities were demonstrated using mirrors formed by cleaved fiber ends coated with a stick-on dielectric coating to give F ~100. A more successful approach involves the full integration of the mirrors and fibers by using Bragg gratings written into the fiber core: it has been possible to form gap cavities with F ~ 150.


Investigation into the Photosensitivity of germanium-free antimony codoped alumino-silicate optical fibres

N.Y.Voo, J.K.Sahu, M.R.Mokhtar, D.N.Payne and M.Ibsen

Optoelectronics Research Centre, University of Southampton, SO17 1BJ, Southampton, UK E-mail nvv@orc.soton.ac.uk, jks@orc.soton.ac.uk

Abstract:
Photosensitivity of different concentrations of antimony (Sb) codoped alumino-silicate optical fibres are analysed. Bragg gratings with index modulations of ~3 x 10-4 are reported. The temperature stability of the gratings is tested and those in higher concentration fibres are found to be more temperature-resistant.


All solid photonic band-gap fibres

Feng Luan, Alan M.George, P.E.Hedley, D.M.Bird, J.C.Knight and P.St.J.Russell

Optoelectronics Group, Department of Physics, Univ. of Bath, Bath, BA2 7AY, United Kingdom pypfl@bath.ac.uk

Abstract:
We describe the design and fabrication of a photonic bandgap fibre formed using two different glasses. Light is guided in a low-index core region at wavelengths corresponding to the anti-resonances of the high-index strands in the fibre cladding.


Hypersensitisation in germanosilicate optical fibres

Albert Canagasabey1,2 John Canning1

1. Optical Fibre Technology Centre, University of Sydney, Australia, which is a member of the Australian Photonics Cooperative Research Centre.
2. Now at Optoelectronics Research Centre, University of Southampton, UK  Phone:4423-8059-4527; fax: 4423-8059-3 142; e-mail: asc@orc.soton.ac.uk

Abstract:
The process of hypersensitisation has been demonstrated with a number of ultra-violet wavelengths, the most recent being with a far-UV wavelength which is transmissive through the polymer coating. These results are presented. A further advancement in hypersensitisation through the use of a low-power UV lamp source is also demonstrated.


Second harmonic generation from coupled surface plasmon resonances of Au@SiO2 nanoparticles self-assembled on glass

Tomokatsu Hayakawa, Yoshitaka Usui, Yang Yong, and Masayuki Nogami

Department of Materials Science and Engineering, Nagoya Institute of Technology, Gokiso, Showa, Nagoya 466-8555, Japan, TEl/FAX: +81-52-735-5110, E-mail: hayatomo@nitech.ac.jp

Abstract:
Self-assembling fabrication of 2-dimensional gold (Au) nanoparticles array on aminopropyltrimethoxysilane-terminated glass substrate with various immersion times into Au sol provided a uniform Au nanoparticles monolayer for the immersion time of 1 hour and it was revealed that excess immersion times gave rise to the formation of colloidal domain structures of Au nanoparticles which, however, induced a second-order nonlinear - polarization generating a light in double frequency of Nd:YAG laser.


Design of Photonic Crystal Fibers for Optical Parametric Amplification

Gabriele Bolognini

National Excellence Center for Photonic Networks, Scuola Superiore Sant'Anna, 56127 Pisa, Italy E-mail: gabriele.boloanini@cnit.it, tel.: +39 050 9719 013.

Abstract:
The possibility of achieving broadband, high-gain optical parametric amplifiers with photonic crystal fibers is investigated. Simulations point out that it is possible to obtain broadband parametric gain by designing optimal fiber chromatic second and fourth order dispersion. The influence of fiber parameters on parametric amplification is discussed.


Extruded tellurite photonic crystal fibre

A.Wang, V.V.Ravi Kanth Kumar, Alan K.George, J.C.Knight, P.St.J.Russell

Optoelectronics Group, Department of Physics, University of Bath, BA2 7AY, U.K. Tel: +44(0) 1225-385007, Fax: +44(0) 1225-386110, ernail: pypaw@bath.ac.uk

Abstract:
We report the fabrication and properties of extruded tellurite photonic crystal fibres (PCFs). The spectral attenuation curve and dispersion curve of the solid-core tellurite PCFs are provided here. We also describe possible applications of tellurite PCFs in infra-red supercontinuum generation and in new forms of hollow-core fibres.


Electron Paramagnetic Resonance and optical absorption characterization of E'ă centers in silica

G.Buscarino, S.Agnello, R.Boscaino, F.M.Gelardi

INFM and Department of Physical and Astronomical Sciences, University of Palermo, Via Archirafi 36, 90123 Palermo, Italy  Tel: +39 0916234218; fax: +39 0916162461; e-mail: buscarin@fisica.unipa.it

Abstract:
We report an experimental study of the modifications of Electron Paramagnetic Resonance (EPR) and optical spectra of the E'ă center in silica induced by room temperature gamma irradiation and by subsequent thermal treatment. Our data show that the EPR signal of this center changes on increasing the irradiation dose from an almost axial symmetric line shape to an orthorhombic one in all but the synthetic wet silica materials, where only the orthorhombic line shape is found. The changes in EPR signature occurs together with a red shift of the peak position of the absorption band around 5.8 eV attributed to the E'ă center. These features suggest the existence of two different precursors of this center. After thermal treatment the EPR orthorhombic line shape converts to the axial symmetric one together with a blue shift in the peak position of the absorption band pointing out a structural degree of freedom of the E'ă centers.


Photo-conversion of oxygen deficient Ge-related canters in natural silica

F.Messina, M.Cannas, R.Boscaino

*INFM and Dipartimento di Scienze Fisiche ed Astronomiche dell'Universitŕ di Palermo, via Archirafi 36, I-90123 Palermo, Italy

Abstract:
Conversion processes of Ge-related centers in natural silica induced by ultraviolet pulsed irradiation with Nd:YAG laser were investigated. After exposure we observed a reduction of the absorption and emission bands ascribed to the two fold coordinated Ge (=Ge••) centers pre-existing in our samples. The bleaching is due to the transformation of =Gem- in two paramagnetic centers: H(II) by diffusion limited reaction with mobile hydrogen and Ge(2) by photo-ionization of the precursor =Ge••.


Influence of the modulation instability on the formation of supercontinuum in tapered and cobweb fibres

Serguei M.Kobtsev, Serguei V.Smirnov

Laboratory of Laser Systems, Novosibirsk State University, Russia, 630090 Novosibirsk, Pirogova Street, 2. E-mail: kobtsev@lab.nsu.ru, Telephone / fax : +7 3832 397224

Abstract:
Numerical modelling and study has been conducted of the specific properties of super-continuum generation in tapered and cobweb fibers for different pump pulse lengths. For the first time the key role of the modulation instability in continuum formation has been pointed out both for long (> 1 ps) and short (~100 fs) pump pulses.


Changes in etch rate due to hydrogen loading and UV-irradiation in phosphorus-doped fibers

F.Dürr, G.Kulik, H.G.Limberger, R.P.Salathé

    Institute of Applied Optics, Swiss Federal Institute of Technology, CH-1015 Lausanne, Switzerland Phone: +41-21-693 51 93, fax: +41-21-693 37 01, e-mail: florian.duerr@epfl.ch

S.L.Semjonov

    Fiber Optics Research Center at the General Institute of the Russian Academy of Science, 38 Vavilov Street, 117942 Moscow, Russia. Phone: 7 (095) 125-0566, fax: 7 (095) 135-8139, e-mail: sls@fo.gpi.ru

Abstract:
Changes in etch rate due to hydrogen loading and subsequent UV-irradiation have been observed for phosphorus-doped fiber cores using an atomic force microscope. The etch rate of the core is found to decrease after hydrogen loading. UV-irradiation of the hydrogenated fiber enhances the core etch rate considerably, resulting in a higher etch rate as compared to the pristine fiber. The change in etch rate does not depend on pulse fluence, but only on total dose. We attribute the changes in etch rate to a hydrogen- and radiation-induced modification of color center population.


Raman fibre 1 μm => 2 μm converter

A.E.Rakitin, I.A.Bufetov, V.M.Mashinsky, O.I.Medvedkov, A.V.Shubin, S.A.Vasiliev, E.M.Dianov

Fibre Optics Research Center at General Physics Institute of the Russian Academy of Sciences, 38 Vavilov Str., 119991 Moscow, Russia rakitin@fo.gpi.ru, iabuf@fo.gpi.ru, vrnrn@fa.gpi.ru, shubin@fa.gpi.ru, sav@fo.gpi.ru, dianov@gpi.ru

Abstract:
A Raman fibre laser with the output in the spectral range beyond 2 μm, converting 1.06 μm radiation into 2.06 μm, has been demonstrated. Raman fibre converter of 1 μm to 2 μm consists of two successive Raman lasers based on phosphosilicate and germania-core fibres.


Full vectorial modal solutions for photonic crystal fibres by use of the finite element method

B.M.Azizur Rahman, A.K.M.Saiful Kabir, M.Irfan Ahmed, Muttukrishnan Rajarajan, and Kenneth T.V.Grattan

School of Engineering and Mathematical Sciences, City University Northampton Square, London EClV OHB Tel: +44-20-7040-8123 Fax: +44-20-7040-8568 Email: B.M.A.Rahman@city.ac.uk

Abstract:
Modal solutions for photonic crystal fibres are presented by using a rigorous full vectorial finite element-based approach. The effective indices, spot-sizes, modal hybridness, beat lengths and group velocity dispersion values are determined for the quasi-TE and TM modes.


Coherent octave-spanning supercontinuum generation in a SF6-fiber for a frequency comb around 1560 nm

Holger Hundertmark, Dieter Wandt, Carsten Fallnich

    Laser Zentrurn Hannover e.V., Hollerithallee 8, 30419 Hannover, Germany Tel: +49-511-2788-264: Fax: +49-511-2788-100; Email: hu@lzh.de

V.V.Ravi Kanth Kumar, A.K.George, J.C.Knight, P.St.J.Russell

    Optoelectronics Group, Department of Physics, University of Bath, Claverton Down, Bath, BA2 7AY, U.K. Email: pysrkk@bath.ac.uk

Nits Haverkamp, Harald R.Telle

    Physikalisch-Technische Bundesanstalt, Bundesallee 100,381 16 Braunschweig, Germany Email: Harald.Telle@ptb.de

Abstract:
We report the octave-broad supercontinuum generation in an extruded SF6-PCF with an Erbium fiber laser oscillator-amplifier system around 1560 nm. The oscillator's carrier-envelope-offset-frequency was measured in a modified f-2f-interferometer and phase-locked to an external reference source by pump power control.


Cascaded nonlinearity and two-color solitons in photonic band-gap fibres filled with a Raman active gas

Dmitry V.Skryabin, Fabio Biancalana, Bavid M.Bird, Fetah Benabid

Department of Physics, Univemity of Bath, Claverton Down, Bath, BA2 7AY, U.K.

Abstract:
We report the existence of two-color, temporal bright-bright solitons supported by cascaded nonlinearity in hollow-core photonic crystal fibres filled with a Raman active gas and demonstrate the feasibility of their experimental observation.


Magnetic Domain Imaging Using Linear and Non-Linear Scanning Near-Field Optical Microscopy

Wayne Dickson, Satoshi Takahashi and Anatoly V.Zayats

School of Mathematics and Physics, The Queen's University Belfast, Belfast, BE' INN, UK Tel: +44 2890973511; Fax: +44 2890973110; E-mail: w.dickson@qub.ac.uk

Abstract:
High-resolution optical imaging of magnetic domains in ferromagnetic materials using both linear and non-linear scanning near-field optical microscopy is discussed. Magnetic domain visualisation is required for characterisation of the micro-magnetic and magneto-optical properties of novel magnetic materials and devices for data storage applications.


Radioluminescence and luminescence kinetics of fluoride glasses.

Kurdvavko P.V., Stepanov V.A., Stepanov P.A.

249031 Kaluga region, Obninsk, Bondarenko I, IPPE tel: 8[08439) 9-83-82, fax : 8 (095) 230-23-26, e-mail: pkurd@mail.ru

Abstract:
Radioluminescence (RL) spectra of fluoride glasses (AFG, ZBLAN, HFG) have been measured under irradiation by 8 MeV . protons. Also luminescence time of fluoride glasses (HFG and HFG with Ce) have been measured. Luminescence have been excited by 180 keV electrons.


Quasi-CW purely rotational stimulated Raman scattering in H2-filled hollow-core photonic crystal fibre

G.Antonopoulos, F.Benabid, J.C.Knight and P.St.J.Russell

Department of Physics, University of Bath, Claverton Down, Bath, BA2 7AY U.K. pypga@bath.ac.uk

Abstract:
We report on low-threshold stimulated Raman scattering in hydrogen-filled hollow-core photonic crystal fibre using low-energy nanosecond pulses. Different purely rotational Raman transitions have been observed. The Raman gain dependence on pulse duration over long interaction lengths is also investigated.


Engineering the dispersion of tapered fibres for supercontinuum generation

C.M.B.Cordeiro, W.J.Wadsworth, T.A.Birks and P.St.J.Russell

Optoelectronics Group, Department of Physics, University of Bath, BA2 7AY, Bath, England

Abstract:
We have experimentally demonstrated engineering the chromatic dispersion of tapered fibres by immersing them in a fluid. This enabled us to generate a 1200 nm wide supercontinuum using two tapers, one immersed in heavy water, pumped by a low-cost diode-pumped Nd:YAG laser with a pulse width of 0.6ns and an output power of 40mW.


Room temperature stability of the second order susceptibility induced in thermally poled silica glasses

Alexandre Kudlinski, Yves Quiquempois, Gilbert Martinelli

University des Sciences et Technologies de Lille, Laboratoire de Physique des Lasers Atornes et Molecules, Centre d'Etude et de Recherche sur les Lasers et Applications UFR de Physique, bâtiment P5, 59655 Villeneuve d'Ascq, France Email: alexandre.kudlinski@phlam.univ-lille1.fr

Abstract:
The stability of the χ(2) susceptibility induced in thermally poled fused silica is investigated. A significant reduction of the nonlinear width with no modification of the χ(2) susceptibility magnitude is observed after six months at room temperature.


Cross comparison between theoretical and experimental modal field patterns in a doped-core microstructured fiber

R.Parmentier, M.C.Phan Huy, G.Laffont, V.Dewynter-Marty and P.Ferdinand

    CEA-DRT-LIST-DETECS-SYSSC-LMO, Centre de Saclay, 91191 Gif-sur-Yvette Cedex, FRANCE Tel.:+33 1 69 08 29 38 Fax:+33 1 69 08 83 95 guillaume.laffont@cea.fr

P.Roy, J-M.Blondy and D.Pagnoux

    IRCOM/OGI, UMR-CNRS 6615,123 avenue Albert Thomas, 87060 Limoges Cedex, FRANCE Tel.:+33 5 55 45 72 69 Fax:+33 5 55 45 72 53 pagnoux@ircom.unilim.fr

B.Dussardier

    LPMC/FOA, UMR-CNRS 6622, Universite de Nice Sophia-Antipolis, Pan: Valrose, 06108 Nice Cedex 2, FRANCE Tel.:+33 4 92 07 67 48 Fax:+33 4 92 07 67 54 bernard.dussardier@unice.fr

Abstract:
A scalar version of the localized function method is implemented and tailored to model doped-core microstructured optical fibers starting from a microscope picture of the fiber cross section. The program is evaluated with respect to state-of-the-art modeling results. We report first data on comparison between calculated and experimentally observed guided modes of a photosensitive air-silica microstructured fiber.


Photosensitivity of H-free Phosphosilicate Fibers

Yu.W.Larionov, A.A.Rybaltovsky, E.8.Ksyukova, W.O.Sokolov, V.G.Plotnichenko.

Fiber Optics Research Center at the General Physics Institute, Russian Academy of Sciences 38 Vavilov Street, 11 9991 Moscow, Russia Tel.: 7(095)132 8207, Fax: 7(095)135 8139, E-mail : luv@fo.gpi.ac.ru

Abstract:
Photosensitivity of H-free phosphosilicate fibers is investigated by means of intrafiber interferometer and IR spectrophotometry. Induced refractive index increases stepwise with dose and its maximum value is evaluated to be 4.5*10-4. The depth of investigated absorption peaks changes periodically. Variations in rigidity of glass matrix under UV exposure can explain the both phenomena.


Giant pulses generation with all-fibre Raman laser

G.Ravet, A.A.Fotiadi*, M.Blondel, P.Megret

Service d'Electromagnetisme et de telecommunications, Faculté polytechnique de Mons, 31 bld Dolez, 7000 Mons, Belgium Tel:+3265374 144, fax: +3265374 199, e-mail: ravetg@telecom.fpms.ac.be
*also with loffe Physico-Technical Institute of the Russian Academy of Sciences, 194021 Politekhnicheskaya 26, St. Petersburg, Russia.

Abstract:
We report on the giant pulse operation of a Raman fibre laser. Pulses with peak power up to 1 kW and duration down to 1 ns were obtained with a 10km long all-fibre cavity configuration pumped by a 2.4W continuous wave fibre laser source.


Tapered dual-core airclad fiber for generation of polarized supercontinuum

Sergei Kobtsev, Sergei Kukarin, and Nikolai Fateev

    Laser Systems Laboratory, Novosibirsk State University; Novosibirsk 630090, Russia + 7 (3832) 39 7224, kobtsev@lab.nsu.ru

Vladimir Mezentsev and Sergei Turitsyn

    Photonics Research Group, Aston Universrty, Birmingham 84 7ET, United Kingdom +44 (121) 359 3611, v.mezentsev@aston.ac.uk

Abstract:
A special dual-core tapered fibre is fabricated for generation of supercontinuum (SC) with polarization control. A numerical modal analysis demonstrates a possibility to optimize design of a hybrid 3-in-1 device comprising taper, coupler and polarized SC generator.


Radiation and Scattering of Linear Waves and Solitons in Photonic Crystal Fibers

D.V.Skryabin, A.V.Yulin, F.Biancalana, F.Luan, J.C.Knight, N.Joly and P.St.J.Russell

Department of Physics, University of Bath, Bath BA2 7AY, UK email: d.v.skryabin@bath.ac.uk

Abstract:
We report theoretical and experimental results on several novel soliton related effects in ultra-small core photonic crystal fibers. Effects reported rely on peculiar dispersion characteristics, which are not attainable in telecom fibers.


Output spectra and longitudinal mode structure of the Raman fiber laser

S.A.Babin, D.V.Churkin, S.I.Kablukov

Institute of Automation and Electrometry, Siberian Branch, Russian Academy of Sciences, 1 Ac. Koptug Ave., Novosibirsk 630090, Russia Tel/fax: +7 (3832) 341832 e-mail: dimkins@yandex.ru

Abstract:
The shape of output spectrum and its internal structure arising from multiple longitudinal modes generating in the cascaded cavity of the two-stage phosphosilicate Raman fiber laser has been studied experimentally and theoretically. The mode structure has been analyzed using measurements of rf beat frequency spectra. An adequate analytical model has been developed and tested experimentally. It describes qualitative behavior and the observed spectral features for the first and the second Stokes components.


FBG-based asymmetrical off-centred VSB filters for transmission with 0.8 bit/s/Hz spectral efficiency

E.G.Turitsyna, A.Gillooly, V.K.Mezentsev, and S.K.Turitsyn

Photonics Research Group, School of Engineering and Applied Science, Aston University, Birmingham B4 7ET, UK. Tel:+441213593611, ext 4952, Fax:: +44 1213590156, Email: e.a.turitsyna@aston.ac.uk

Abstract:
We propose a novel approach to ultra-narrow optical filtering based on a specially designed slightly asymmetric VSB filter and fabricate a fibre Bragg gratings with desirable spectral response. A feasibility of 8x40 Gbit/s DWDM RZ transmission with 0.8 bit/s/Hz spectral efficiency (without polarization multiplexing) over 1170km of SMF/DCF link without FEC has been confirmed by numerical modeling.


Polarization mode dispersion reduction in spun silica holey fibres

M.Fuochi1, J.R.Hayes, M.N.Petrovich, J.C.Baggett, T.M.Monro, D.J.Richardson

0ptoelectronics Research Centre, University of Southampton, Southampton SO17 1BJ, UK
1. also with Dipartimento di Ingegneria dell'Informazione, Universita di Parma, 43100 Parma, Italy maf@orc.soton.ac.uk

Abstract:
We report the fabrication of a spun holey optical fibre. Our experiments show that the complex air/glass transverse structure can be retained when the preform is spun during the fibre drawing process. Measurements of differential group delay (DGD) confirm that significant reductions in polarization mode dispersion (PMD) can be readily achieved using this approach.


Femtosecond laser assisted rewriting 3D data storage in composite glass with Ag nanoparticles

A.Podlipensky, A.Abdolvand, G.Seifert, M.Graener

Martin-Luther-University Halle- Wittenberg, Physics department, Optics, HoherWeg 8, 06099 Halle, Germany Tel:+49 345 55253 15, Fax:+49 345 5527221, e-mail: podlipensky@physik.uni-halle.de

Abstract:
3D anisotropic modifications induced in glass with spherical Ag nanoparticles by multicolor fs laser irradiation was demonstrated as promising technique for 3D storage by spectral data coding. The modifications reversible by heating at 600 oC or irradiation by 200 ns laser pulses at 527 nm allow producing of rewriting data storage devices.


Extruded small-core bismuth oxide glass holey fibres

P.Petropoulos, H.Ebendorff-Heidepriem, S.Azimakis, R.C.Moore, K.Frampton, F.Koizumi, T.M.Monro, D.J.Richardson

Optoelectronics Research Centre, University of Southampton, Southampton SO17 1BJ, United Kingdom. pp@orc.soton.ac.uk

Abstract:
We report our progress on the fabrication and characterisation of highly nonlinear bismuth oxide glass holey fibres. The measured losses for these fibres were ~3 dB/m at 1.55 μm, and the effective nonlinearity of the smallest core fibre was as high as 1100 W-1km-1 at the same wavelength.


Nonlinear optics in photonic crystal fibers with negative-dispersion slope

N.Y.Joly1, A.Efimov2, F.G.Ornenetto3, A.J.Taylor2, J.C.Knight1 and P.St.J.Russell1

1. Optoelectronics group, Dept. of Physics, University of Bath, BA2 7AY, UK Tel+44 1225 384532, Fax: +44 1225 386110 e-mail: pvsnai@bath.ac.uk
2. MST-10, MSK764 Los Alamos National Laboratory, Los Alamos, New-Mexico 87545, USA
3. P-23, MSH803 Los Alamos National Laboratory, Los Alamos, New-Mexico 87545, USA

Abstract:
We present the nonlinear behavior of large air-filling fraction photonic crystal fibers specifically designed to have a negative slope in the vicinity of the zero dispersion point. When ultrashort pulses are coupled into them, transmission spectra shows unexpected solitonic effect due to the unusual dispersion curve.


Cascaded nonlinearity and two-color solitons in photonic band-gap fibres filled with a Raman active gas

F.Biancalana, D.V.Skryabin, D.M.Bird and F.Benabid

Department of Physics, University of Bath, Bath BA2 7AY, UK

Abstract:
We report the existence of two-color, temporal bright-bright and dark-bright solitons supported by effective Kerr nonlinearity in hollow-core photonic crystal fibres filled with a Raman active gas and demonstrate the feasibility of their experimental observation.


Visible broadband continuum generation in nano-scale silica-air waveguides

S.G.Leon-Saval, T.A.Birks, W.J.Wadsworth and P.St.J.Russell

    Department of Physics, University of Bath, Claverton Down, Bath BA2 7AY, United Kingdom. Email: pypsgl@bath.ac.uk

M.W.Mason

    BlazePhotonics Ltd, University of Bath Campus, Claverton Down, Bath BA2 7AY, United Kingdom.

Abstract:
Single-mode supercontinuum spanning (and largely confined to) the visible spectrum is generated from the nanosecond pulses output of a 532-nm microchip laser, using tens of millimeters of nano-tapered fibres or photonic crystal fibre cores.


Ultraviolet-induced absorption during very short continuous exposure in Ge-doped optical fiber

K.Medjahdi, F.Goutaland, A.Boukenter and Y.Ouerdane

Laboratoire Traitement du Signal et Instrumentation, UMR 5516 CNRS Université de Saint-Etienne, 10 rue Barrouin, Bât. F 42000 Saint-Etienne, France Tel: +33 (0)4 77 91 58 14 Fax: +33 (0)4 77 91 57 81 e-mail: kader.medjahdi@univ-st-etienne.fr

Abstract:
We report ultraviolet (UV)-induced absorption measurements, in the 360-440 nm spectral region, in germanium (Ge) doped fiber, H2-loaded or not. This technique allows gives evidence of the photoinduced mechanisms occurring during very short continuous (cw) UV exposure, contrary to the usual absorption technique. Our results show that the 4.5 eV absorption band, extending in the visible region, is responsible for the measured absorption. We demonstrate that two different defects absorbing at around 4.5 eV are involved in the two successive reactions, leading to the creation and the partial of the absorption respectively.


Towards metallic microstructuring in nanocomposite glass

A.Abdolvand1, A Bodlipensky1, G.Seifert1, H.Graener1, O.Deparis2, P.G.Kazansky3

1. Optics Group, Physics Department, Martin-Luther-University, Halle D-06099, Germany e-mail: abdolvand@physik.uni-halle.de; Tel.: +49 (0)345 5525315; Fax: +49 (0)345 5527221
2. Faculté polytechnique de Mons, Service d'Electromagnetisme et de Telecommunications, Mons B-7000, Belgium
3. Optoelectronics Research Centre, University of Southampton, Southampton SO17 1BJ, United Kingdom

Abstract:
A novel, easy-to-implement, method to create fine optical structures in dielectric metal-doped nanocomposite materials is presented. We believe that our results pave a route towards creation of future optoelectronic elements based on surface-plasmon integrated circuits.


Effects of interface modes on hollow core photonic crystal fibres

G.Humbert, J.C.Knight, P.St.J.Russell

Department of Physics, University of Bath, Claverton Down, Bath, BA2 7AY United Kingdom Tel: +44 1225 384368, Fax: +44 1225 386110, email: pysgh@bath.ac.uk

Abstract:
Hollow-core photonic crystal fibres which guide light in a air core have very low nonlinearity, unusual dispersion and a high damage threshold. These unusual properties make them ideally suited to delivery of laser beams. In specific wavelength ranges, interface or "surface" modes are guided and interact with core modes. We describe the observed effects of anti-crossings with interface modes on the fibre properties.


Genetic algorithm: a solution to design photonic crystal fibers

Emmanuel Kerrinckx, Laurent Bigot, Geraud Bouwmans, Marc Douay, Yves Quiquempois

Laboratoire de Physique des Lasers, Atomes et Molecules, UMR 8523 Institut de Recherche sur les Composants logiciels et matériels pour l'Information et les Communications Avancées, Université de Lille I - UFR de Physique, Bâtiment P5, 59655 Villeneuve d'Ascq Cedex, France Tel: 33.3 20.43.48.14, Fax 33.3 20.33.70.20 Emmanuel.Kerrinckx@phlam.univ-lille1.fr

Abstract:
The optimization of the design of photonic crystal fiber by genetic algorithm is demonstrated for the first time. It is shown how the combination of this inverse problem approach with a full vectorial finite element method enables to reach user-defined propagation property. The definition of a fiber geometry enabling near-zero flat dispersion over a wide wavelength range is performed as an illustration of the possibilities offered by this approach.


Spatial manipulation of the valence state of rare-earth ions in macroporous media prepared by a sol-gel method

Shunsuke Murai, Koji Fujita, Kazuki Nakanishi, and Kazuyuki Hirao

Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Kyotodaigaku-katsura, Nishikyo-ku, Kyoto 61 5-8510, Japan Tel/fax: +81-75-383-2413/2410, e-mail: murai@collonl.kuic.kyoto-u.ac.jp

Abstract:
Sm2+-doped Al2O3-SiO2 glasses with three-dimensionally interconnected macroporous morphology have been prepared via an alkoxy-derived sol-gel process containing poly (ethylene oxide) and SmCl3.6H20. The macroporous structure is obtained by concurrently inducing the phase separation and sol-gel transition. Using a visible laser with the wavelength of 590 nm, the valence state of Sm2+ has been manipulated spatially. When the photoionization of Sm2+ is combined with multiple light scattering in the porous glasses, holes are burned in wave-vector domain. The hole profile can be controlled by the macroporous morphology.


Fabrication of fibre Bragg gratings with 267 nm ferntosecond radiation

K.A.Zagorulko, P.G.Kryukov, Yu.V.Larionov, A.A.Rybaltovsky, E.M.Dianov

Fibre Optics research Center at the A M Prokhorov General Physics Institute of the Russian Academy of Sciences, 38 Vavilov Street, Moscow 119991 Russia Tel: 7 (095) 135-7530, Fax: 7 (095) 135-8139, E-mail: zagorulko@fo.gpi.ru

Abstract:
Strong high-quality fibre Bragg gratings, with photoinduced refractive-index modulations of more than 10-3, were written in fibres of various types by third-harmonic radiation (267 nm, 300 fs and 6-9 x 1010 W/cm2) of a femtosecond Ti:sapphire laser. It was shown that the 267-nm photosensitivity responses of the fibres of the fibres may be higher than in the case of deep UV 157-nm F2- laser irradiation. The annealing characteristics of the fabricated gratings point to a photochemical nature of the induced refractive index.


Optical properties of nano-hole arrays in thin metallic films

Jill Elliott, Igor I.Smolyaninov*, Satoshi Takahashi, Anatoly V.Zayats

School of Mathematics and Physics, Queens University Belfast, Belfast BT7 1NN, UK Tel: 02890 973941, Fax: 028990 9731 10, Email: j.elliott@qub.ac.uk
* Electrical and Computer Engineering Department, University of Maryland, College Park MD 20742, USA

Abstract:
Optical properties of nano-hole arrays in thin metallic films, related to surface plasmon polariton excitations, have been studied. Such nanostructured films reveal strong light-polarisation related effects of the enhanced optical transmission.


Initial and radiation-induced loss in holey optical fibres with silica core

A.F.Kosolapov, I.K.Nikolin, A.L.Tomashuk, S.L.Semjonov, M.O.Zabezhailov

Fibre Optics research Center at the A.M.Prokhorov General Physics Institute of the Russian Academy of Sciences, 38 Vavilov Street, Moscow 119991 Russia

Abstract:
Initial and radiation-induced loss spectra are analyzed in three multimode holey fibres with a high-OH KU-1 silica core. A fibre with an optimized cross-section is shown to have no leakage loss. A high concentration of gamma-radiation-induced non-bridging oxygen is argued to be due to a high cooling rate during fibre drawing.


Large core holey fibers with a few air channels in cladding - modelling and experimental investigation of the modal properties

V.P.Minkowich and A.V.Kir'yanow

    Centro de Investigaciones en Optica, Loma del Bosque. #115, Col. Lomas del Campestre, Leon 37150, Gto, Mexico Tel: (52) (477) 717-5823, Fax: (52) (477) 7175000, Email: vladimir@cio.mx

A.B.Sotsky and I.B.Sotskaya

    Institute of Applied Optics of National Academy of Sciences of Belarus, B.-Biruli Str., #11, Mogilev 212793, Belarus

Abstract:
Large core silica holey fibres with a limited number of air channels in the cladding are investigated theoretically and experimentally. An impact of the relative hole diameter on single-mode operation, the fiber transmission, an bending loss is addressed.


Lasing in hexagonal molecular sieve waveguide resonators

U.Förster

Institut für Angewandte Physik, Technische Universitaet Darmstadt, Germany

Abstract:
Molecular sieves are crystalline solid state materials with crystallographically defined nanometer size pores. This property stimulates attempts to use the sieves as an ordering framework for arranging optically functional molecules, so creating a compound material with new optical properties. It has been possible to induce laser emission in AlPO4-5 crystals filled with organic dye material. Lasing in this compound material occurs in micrometer size ring resonators, in which the laser mode is confined by total internal reflection at the natural hexagonal crystal side faces resembling a whispering gallery mode. As the compounds are synthesized with the inexpensive method of hydrothermal growth, already in laboratory scale we can obtain several grams of microlasers, or "lasing powder".

Closer examination of the symbiotic system can lead to a better understanding of the optical conditions for the lasing process as well as the morphological requirement for the crystal to function as a laser. Several aspects of the compound are examined for a better understanding of the system: mode existence, coupling of modes as well as different resonators, photostability of the dyes, and arrangement of the dye guests inside the host, which introduces new symmetries leading e.g. to pyroelectricitic properties of the composite.