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We demonstrate 1.7–18 µm mid-infrared coherent supercontinuum generation by means of the full transmission window of a unique dispersion-engineered step-index Ge-Se-Te fiber. Our study thus opens the entire molecular fingerprint region to future chalcogenide fiber platforms.

We experimentally demonstrate 140-THz bandwidth (at −20 dB) supercontinuum generation in a 10 cm-long all-normal dispersion step-index tellurite fiber pumped by a turn-key femtosecond fiber laser emitting at 2 . 11 μ m at a repetition rate of 19 MHz. The soliton self-frequency shifted thulium-doped fiber mode-locked laser emits initial transform-limited pulses, with 85-fs pulse duration, that are subsequently quasi-linearly chirped (over more than 50 THz) during the above nJ-level nonlinear propagation. Moreover, we numerically demonstrate the possible pulse compression down to 12 fs by means of additional linear propagation in a standard step-index fluoride fiber with anomalous dispersion.

Recently, a phosphate glass with composition 20 CaO-20 SrO-10 Na2O-50 P2O5 (mol%) was found to have good potential as a biomaterial and to possess thermal properties suitable for fiber drawing. This study opened the path towards the development of fully bioresorbable fibers promising for biosensing. In the past, this phosphate glass with CeO2 was found to increase the refractive index and the glass stability. Therefore, a new SrO-containing glass was prepared with 1 mol% of CeO2 and core fibers were drawn from it. A core-clad fiber was also processed, where the core was a Ce-doped glass and the clad undoped, to allow for total internal reflection. The mechanical properties of the core and core-clad fibers are discussed as a function of immersion time in TRIS-buffer solution. Finally, a sensing region was created, in the core-clad fiber, by etching the cladding using phosphoric acid. Then, the change in light transmission, upon immersion in TRIS-buffer solution, was quantified to assess the potential use of the novel core-clad fiber as a biosensor. Upon immersion in TRIS, the core-clad fiber was found to guide light effectively and to maintain a tensile strength of ~150–200 MPa up to 6 weeks in TRIS, clearly showing that this fiber has potential as a biosensing device. acceptedVersion

The ability to produce robust fiber-based integrated optical systems operating over a wide spectral domain (UV to mid-infrared), is one of today’s key challenges in photonics. This work reports on the production of crystal-free, light guiding fibers from rich Ga2O3 oxide-based glass compositions. These materials show optical transmission extending from ultraviolet wavelengths (∼0.280 µm) up to 6 µm in the IR for millimeter length scale while exhibiting relatively high vitreous transition temperatures (∼735 °C), nonlinear optical properties and improved surface micro-hardness. This combination of superior thermal, mechanical and optical properties represents a promising alternative for the development of robust fibers operating in the visible up to the 3–5 µm window.

International audience

International audience; The development and the emergence of fully integrated all-fiber optical systems is very interesting from a technical point of view in photonics. Indeed, the development of mutimaterials fibers combining both optical waveguide properties and simultaneous in-fiber electrical excitation could provide plenty of innovative signal-processing, sensing or imaging functionalities. Here, we report the engineering of a new glass/metal composite fiber. For the glass, we have chosen tellurite glasses for their excellent thermo-viscous abilities (low Tg) and linear/nonlinear optical properties. This low Tg allows to have a larger panel of potential metals to be co-drawn with. The synthesis is firstly realized by build-in-casting at room atmosphere which allows to get a large-core. Then, the rod-in-tube technique and the insertion of metallic wires allow to get a step-index fiber with a small-core (7µm) and two continuous metallic electrodes running along the fiber axis (Øelectrodes = 30µm). Thus, we obtain a tellurite-based core-clad dual-electrode composite fiber made by direct, homothetic preform-to-fiber thermal co-drawing. The rheological and optical properties of the selected glasses allow both to regulate the metallic melting flow and to manage the refractive index core/clad waveguide profile. We will discuss the engineering of these multimaterials optical fibers and their characterization: thermal and viscosity properties, linear optical properties (loss), electrical properties with a continuity of the electrodes over meters of fiber.

Optical fibers mid-infrared (mid-IR) supercontinuum (SC) generation for sources covering the 1–20 μm range are of great interest for many applications in optics, spectroscopy, sensing for environmental monitoring or medical diagnosis and treatment. We present here our work regarding two low phonon energy glasses families, leading to highly nonlinear optical fibers for SC generation: tellurites and seleno-telluride glasses. Tellurite fibers are suitable for working in the 1-5 μm range, when seleno-telluride ones are intended to the 2-16 μm range. For tellurites, we focus on the definition of glass pairs suitable for the drawing of step index fibers with a controlled chromatic dispersion for a femto-second (fs) pumping around 2 μm. In the case of chalcogenide glasses, we focus on the Ge-Se-Te ternary system, which offers the advantage of allowing the drawing of step index or micro-structured fibers avoiding the usage of toxic arsenic. Depending on the fiber geometry the management of the chromatic dispersion is quite different. Suspended core fibers allow to shift deeply the unique zero dispersion wavelength (ZDW) towards short wavelengths for fs pumping around 2- 3 μm. For step index fibers, it is possible to design waveguides with no, one or two ZDW. Various pumping schemes are available between 3 and 9 μm, with a fs tunable source. As a result, SC generation experiments in these different fibers allows to reach wide spanning spectra, between 1 and more than 5 μm for tellurite fibers, and between 2 and more than 14 μm in the case of chalcogenides ones.

International audience; We provide experimental characterization of stimulated Brillouin scattering at 2-µm wavelength in step-index optical fibers made of various types of infrared materials. Our results show that the main characteristics of the Brillouin process such as the frequency shift, spectral linewidth and gain can be widely tuned through the index-controlled guiding of both acoustic and optical waves as well as the intrinsic material properties of the fiber under test. More precisely, we found that depending on the used material the Brillouin frequency shift can be decreased by 30% in a common step-index fiber design, while its linewidth and gain efficiency can be increased by a factor 5 and 180, respectively, when compared with the standard silica fiber. Four families of fiber materials were analyzed near 2 µm as well as at 1.55 µm for comparison, namely, germanosilicate, zirconium fluoride, tellurium oxide, and sulfur-based chalcogenide. Our findings open the way for further fundamental investigations of stimulated Brillouin scattering and the development of practical applications in the 2-µm spectral range.

Tellurite glasses are good candidates for the development of broadband supercontinuum (SC) laser sources in the 1–5 µm range. At the moment, beside very few exceptions, SC generation in TeO2-based microstructured optical fibers (MOFs) is limited to 3 µm in the mid-infrared (MIR). We present here an observation of an optical aging occurring in six-hole suspended-core tellurite MOFs. When exposed to atmospheric conditions, such fibers show an alteration of their transmission between 3 and 4 µm. This aging phenomenon leads to the growth of strong additional losses in this wavelengths range over time. Impact of the transmission degradation on spectral broadening is studied through numerical simulations of SC generation.

TeO2-ZnO-La2O3 (TZL) ternary glasses were investigated in order to manufacture step-index optical fibers with low optical losses in the near- and mid-infrared ranges and superior mechanical properties. To identify appropriate TZL glass compositions for optical fibers manufacturing, the whole vitreous domain of the ternary diagram was explored by characterizing bulk samples from thermal and optical point of view. Investigations were focused on understanding how the refractive index evolves as a function of the composition. For this, several parameters were analyzed such as density, molar volume, oxygen packing density, molar refractivity, polarizability and optical basicity. Finally, thermal and structural studies such as DSC and X-Ray diffraction allowed to select the most promising core and cladding glasses combination (in terms of stability against crystallization), in order to draw optical fibers. Step-index optical fibers were then successfully fabricated. Optical losses of these first TZL fibers were measured, giving minimum attenuations of 1.25 dB/m at 2.15 µm and less than 2 dB/m up to 2.75 µm and compared to well-known TeO2-ZnO-Na2O (TZN) glass fibers. Finally, first mechanical tests were performed as microhardness and tensile strength measurements with the aim of demonstrating the improvement in workability and resistance of the TZL fibers compared to TZN fibers.

Filamentation of infrared femtosecond pulses in Tellurite glass is reported, leading to the generation of a supercontinuum generation spanning from the visible up to 4 μm. The angular distribution of the supercontinuum shows clear evidence of conical waves generation, in particular, in the visible region. Moreover, taking advantage of the spatio-temporal self-focusing effect occurring in the Tellurite glass, a twofold pulse shortening is demonstrated. Tellurite glass appears as a very convenient, versatile and promising medium for femtosecond nonlinear optics in the infrared region.

We report on the generation of multiple-octave supercontinuum laser source spanning from 0.5 μm to 11 μm induced by multi-filamentation in a ZnSe crystal. The generated supercontinuum is both spatially and spectrally characterized. It is then exploited in a proof-of-principle experiment for methane spectroscopy measurements by means of the supercontinuum absorption spectroscopy technique. The entire absorption spectrum is successfully recorded within the whole spectral bandwidth of the supercontinuum. Experimental results are in fairly good agreement with the HITRAN database, confirming the reliability and stability over several hours of the generated supercontinuum.

Here, we propose to design a new class of glass/metal composite fibers for all-guided optical-electrical signals. The objective is to combine metal and glass materials by using additive manufacturing approach to engineer multimaterials fibers. Thus, after manual insertion of metallic electrodes into the tellurite glass preform, we can obtain the first tellurite-based core-clad dualelectrode composite fiber made by direct, homothetic preform-to-fiber thermal co-drawing.

International audience; Properties of the tellurite glasses 80TeO2–10ZnO–[(10−x)Na2O–xAg2O] are investigated as a function of the substitution ratio x between Na2O and Ag2O. One observe that the variation of glass transition temperature decreases monotonously with x and that surface crystallization mechanism is favored. The assignment of the Raman bands and their relation with the underlying glass structure is discussed. While both Na2O and Ag2O oxides act as glass network modifiers, their progressive equimolar substitution does not lead to a meaningful evolution in the structure of the TZ[Na10-xAgx] glass. The refractive index and the cut-off wavelength are found to increase with x. The compositional and wavelength dependence of refractive indices, cut-off wavelength and optical band gap energy is discussed in terms of changes brought about by Na2O/Ag2O substitution in the glass network. Finally, it is shown that interaction between the platinum crucible and the glass melt increases with the silver content in the glass

Mid-infrared supercontinuum generation from 1.5 to 4.5 &micro, m with sub-nanojoule femtosecond pump pulses is demonstrated by using a short segment of dispersion-engineered step-index tellurite fiber with very low OH content. Distinct group-velocity dispersion regimes in a simple design of step-index tellurite fiber are also reported, which allows to choose the nonlinear pulse propagation regime according to the required tailoring of the supercontinuum source. Numerical simulations based on the generalized nonlinear Schr&ouml, dinger equation are used to determine optimized fiber parameters before experimental demonstrations. We also analyse the coherence properties of the resulting supercontinuum sources.

We demonstrate 400-THz (0.6–3.3 µm) bandwidth infrared supercontinuum generation in a 10 cm-long tapered tellurite suspended core fiber pumped by nJ-level 200-fs pulses from an optical parametric oscillator. The increased nonlinearity and dispersion engineering extended by the moderate reduction of the fiber core size are exploited for supercontinuum optimization on both frequency edges (i.e., 155-THz overall gain), while keeping efficient power coupling into the untapered fiber input. The remaining limitation of supercontinuum bandwidth is related to the presence of the high absorption beyond 3 µm whereas spectral broadening is expected to fully cover the glass transmission window (0.5–4.5 µm).

We experimentally investigate supercontinuum generation in conventional As2S3 and GeS3 bulk chalcogenide glass materials pumped by high-power mid-infrared femtosecond pulses. Mid-infrared supercontinuum spectra are successfully reported through the filamentation of µJ-level energy pulses at wavelengths close to the bulk’s zero dispersion wavelength, i.e., in both normal and anomalous dispersion regimes. The main features of our results are twofold. On the one hand, a GeS3 non-toxic As-free glass is successfully conceived and proved suitable for mid-infrared supercontinuum generation. On the other hand, 3.3-mm-long bulk samples are sufficient to enable the spectral coverage from 2.5 to ~11 µm in a 20-dB dynamic range, thus reaching the multiphonon absorption edge for both chalcogenide glasses.

We report on far-infrared filament-induced supercontinuum obtained with three chalcogenide glasses. The introduction of more polarizable elements (Se instead of S and Te instead of S and Se) into the glasses increases their non-linearity and transmission window and also shifts gradually corresponding zero-dispersion wavelength in the infrared region. Overall chalcogenide glasses were pumped with 65-fs pulses at the optimal wavelength with respect to supercontinuum extension. An infrared spanning reaching the 16-µm threshold is obtained.

Development of broadband supercontinuum sources has been studied since decades for its high application potential in various fields like spectroscopy, medical science and others. First experiments were made with silica but the results shown the need to find new materials for supercontinuum generation in the IR wavelength range. Two types of materials have been found interesting for supercontinuum generation: chalcogenide and tellurite glasses. These materials have a high non-linear refractive index and a good transmission in infrared which provides a high potential for applications. Bulks tellurite glasses transmit until 5µm while bulks chalcogenide glasses transmit until 12-20µm depending on their composition. We report here the synthesis of low-OH step-index tellurite fibers and their linear and non-linear characterization. The synthesis is firstly realized by build-in-casting in a glovebox which allows to get a large-core preform(∅clad/∅core  2) and a large core corresponding fiber(∅core  60µm). Then, the rod-in-tube technique allows, from the jacketing of the stretched initial preform, to get a small-core preform and subsequently a small core fiber (∅core  3.5µm). The minimum of losses of the large-core fiber is below 1dB/m, the IR transmission wavelength exceeds 4 µm on several meters of fibers and reaches more than 5 µm on small samples (several centimeters long). We have developed core-clad composition with a large refractive index difference (∆n=0.132) which provides a high confinement in our step-index fibers. We discuss the supercontinuum generation in these fibers exploiting numerical simulations based on the generalized nonlinear Schrodinger equation and then we present the supercontinuum experimental results obtained between 1 and 5µm. Most of pollutant and greenhouse gases emitted by human activity, including methane, carbon dioxide and nitrous oxide, absorbs in the mid-IR. The spectroscopic experiments realized on the gases through supercontinuum generation between 1 and 5 µm are presented.

We present the experimental development of dispersion-engineered tellurite fibers based on a simple step-index profile for mid-infrared supercontinuum generation. A supercontinuum spanning from 1.5 to 4.5 μm is obtained in a 12-cm-long fiber.

Microstructured optical fibers (MOF) can be seen as next generation fiber of significance in advancing the compact optics because of its excellent compatibility in integrated optics. However, the degradation of their physicochemical properties limits their efficiency and lifetime. Atmospheric moisture is responsible for the degradation of amorphous systems especially chalcogenide glasses. In the light of previously reported studies, in order to clarify the aging process continuously evolving in sulfide microstructured optical fiber over time, a detailed investigation of this phenomenon has been conducted. The time-dependent transmission and glass chemical deterioration have been studied for As 2 S 3 MOF with regard to their exposure to different atmospheric conditions. Results show a substantial impact of atmospheric moisture through an interaction with the glass network. Significant improvement has been registered by storing the fibers under dry atmosphere.

We present an overview of the fabrication process and characterization of germanate, germanate-tellurite and tellurite microstructured fibers or step-index fibers with different index contrasts. For microstructured fibers, we exploit the generated SC for methane spectroscopy measurements in the mid-infrared by means of the supercontinuum absorption spectroscopy technique. We demonstrate also an ageing process of microstructured fibers in ambient atmosphere. For stepindex fibers, several compatible core/cladding glasses were explored for fiber manufacturing with a dehydration process, allowing the drawing of low-OH tellurite fibers. We report both numerical and experimental demonstrations supercontinuum (SC) generation in these fibers. Finally we report our latest results in the generation of SC until 5.3 μm in a step-index tellurite fiber.

This chapter presents a state of the art of infrared supercontinuum generation in heavy oxide tellurite optical fibers from the experimental results published by the international community. As a first part, a bibliographic table gathers the literature on which this work is based. Then, the second part briefly returns on the tellurite glass compositions, the third part presents the different fiber structures (microstructured, suspended core or step-index fibers, tapered fibers), the fourth part discusses the pumping sources in relation with the fiber chromatic dispersion as well as coupling issues, the supercontinuum performances are presented in the fifth part, and the sixth part deals with modelization and nonlinear propagation phenomena in relation with supercontinuum generation, before a conclusion of the chapter.

Eggshell fragments attributed to large birds have been known from the Palaeogene of southern France for half a century, but reconstructing their original dimensions and identifying the birds that laid the eggs has been fraught with difficulties. On the basis of numerous newly collected specimens and using geometrical calculations, the original size of the thick-shelled eggs is reconstructed, showing that they were slightly larger than ostrich eggs, with a greatest length of 17.8 cm and a mean diameter of 12.0 cm in transversal section. The estimated volume is 1330.4 cm3. The fossil eggs from southern France are thus among the largest known avian eggs, being only surpassed byAepyornisand some moas. Estimated egg mass is about 1.4 kg. On the basis of egg mass, the body mass of the parent bird is estimated at between 135.4 kg and 156.4 kg, assuming that the hatchlings were precocial. These calculations are in good agreement with the dimensions and mass estimates for the Palaeogene giant birdGastornis, a probable anseriform, which lived in Europe at the time the eggs were laid. Other large Early Tertiary birds from Europe (Remiornis,Palaeotis) are too small to have laid these eggs. In all likelihood, the large eggs from the Palaeogene of southern France were laid by gastornithid birds.

International audience

International audience; We demonstrate the fabrication of arsenic-and antimony-free chalcogenide glasses compatible with glass fiber processing. Optical fibers with distinct index profiles are presented and characterized, namely, single-material fibers with or without a suspended core and standard step-index fibers with varying core diameter. In addition, we evidence their potential for nonlinear photonic devices in the mid-infrared spectral region by means of super-continuum generation experiments in the femtosecond regime. Spectral broadenings extend on several octaves in the mid-infrared from 2 to 14 μm.

We report the fabrication and the characterization of low OH content and low loss tellurite optical fibers. The influence of different methods of glass fabrication on fiber losses has been investigated. The use of the purest commercial raw materials can reduce the losses below 0.1 dB/m at 1.55 μm. Incorporation of fluoride ions into the tellurite glass matrix makes the optical fibers transparent up to 4 μm. A suspended core microstructured fiber has been fabricated and pumped by nanojoule-level femtosecond pulses, thus resulting in more than 2000-nm bandwidth supercontinuum after a few centimeters of propagation.

The evolution of supercontinuum generation in chalcogenide suspended-core microstructured optical fibers is studied with regard to their exposure to the room atmosphere. We report the experimental proof of aging-induced supercontinuum generation drift in chalcogenide microstructured fibers. Mid-infrared supercontinuum covering the 2.5–5.5-µm spectral region is demonstrated in a fresh and 7-month-aged counterpart As2S3 fibers, by means of a home-built multistage oscillator power amplifier delivering 300 fs pulses at a repetition rate of 43 MHz in the 3.0–4.1-µm range. Numerical simulations based on the generalized nonlinear Schrodinger equation confirm the significant alteration of supercontinuum generation due to increasing fundamental OH and SH absorption bands.

International audience; Tailored silver-containing zinc-phosphate glasses possess excellent thermoviscous ability and optical properties. Beyond they have proven to form a favorable matrix for the direct laser writing of photoluminescent and nonlinear patterns. Here, bringing together the merits of these materials with fiber optic technology, the first photosensitive, photowritable silver-containing glass ribbon fibers are reported. These novel devices are thermally scaled-down in a homothetic fashion from a macroscopic preform to produce tens-of-meters of continuous structure. It is demonstrated that luminescence properties of the native glass are preserved after the shaping process. Furthermore it is established that the unique fiber's flat geometry allows for the convenient, accurate laser writing of complex luminescent silver clusters patterns within the glass matrix. It is believed that the drawing of silver-containing zinc-phosphate glasses could lead to a decisive breakthrough in the field of photosensitive fibers. They would offer a promising platform for the design of highly efficient sensing devices based on amplified optical processes effects, for metamaterials or as fundamental bricks for photonics.

Crystalline selenium nanostructures were synthesized from the reaction of a GeSe3 glass with water at 85°C for 144 hours. The hydrolysis of the Ge-Se bonds releases Se fragments in the solution where they form a colloidal suspension of amorphous nanospheres. The later evolve toward a more stable hexagonal phase (trigonal) leading to the anisotropic growth of one-dimensional monocrystalline structures. Filaments, bars and tubes of monocrystalline trigonal selenium were obtained with diameters ranging from 10 nm to 1 µm and aspect ratio up to 180. This simple process in aqueous solution opens new perspectives for the synthesis of 1D nanoparticles of trigonal selenium at large scale.

The feasibility of a photonic crystal fiber laser (PCF laser), made of a novel Er 3+ -doped chalcogenide glass and operating at the wavelength λ s = 4.5 μm is investigated. The design is performed on the basis of spectroscopic and optical parameters measured on a fabricated Er 3+ -doped Ga 5 Ge 20 Sb 10 S 65 chalcogenide bulk sample. The simulations have been performed by employing a home made numerical code that solves the multilevel rate equations and the power propagation equations via a Runge-Kutta iterative method. The numerical results indicate that a laser exhibiting slope efficiency close to the maximum theoretical one and a wide tunability in the wavelengths range where the atmosphere is transparent can be obtained.

We report the manufacturing and characterization of Tellurite micro structured fibres (MOFs) with low OH content. The different purification processes used during the fabrication of the TeO2 - ZnO - Na2O glass allowed us to reduce the hydroxyl compounds concentration down to 1ppm mass. A suspended core MOF was drawn from this material and then pumped by nanojoule-level femtosecond pulses at 1.7μm, its zero dispersion wavelength (ZDW), and well above it at 2.5μm. We show the related supercontinuum (SC) generated in the two distinct dispersion regimes of the waveguide. Moreover, the SC spanning was extended in both visible and mid-IR regions (between 600nm up to 3300nm) by the taperisation of the previously tested MOFs.

International audience; Conditions of formation of bulk tellurium chalcogenide glasses, containing 70-80 at % Te associated to Ga and Ge are described. The characteristic temperatures are measured: the glass-transition temperature, Tg, is situated in the range 140-185 °C and the difference Tx - Tg, where Tx is the onset crystallization temperature, is in the range 76-113 °C. Moreover, the optical transmission window is exceptional, ranging from 1.99 μm in the bandgap up to 28 μm in the phonon region. Developed within the framework of requirements for the Darwin mission (a search for and study of extrasolar planets), feasibility of infrared optical fibers formed from these glasses is studied. Drawing experiments are conducted with the glass Ga2-Ge3Te15, which possesses the maximum Tx - Tg, and a first optical fiber is presented.

International audience; Holey fibres have a broad range of optical properties thanks to their microstructuration and offer a wide range of applications. The combination of intrinsic properties of compound glass, such as chalcogenide glass, and a microstructured fibre geometry allows to consider exacerbated optical properties such as dispersion and nonlinearity for these fibres. In this study, high-index sulphide glass holey fibres (n = 2.251 at 1.55 μm) have been accomplished using the capillary-stacking technique. Sulphide glasses from the GeGaSbS system are used. The drawing step is crucial for microstructuration and for determination of optical properties. Sulphide holey fibres, which were optically characterised with near-field spectroscopy at 1.55 μm, show a single-mode guidance with an effective mode area of 108 μm2.

11 pages; International audience; An accumulation of vertebrate remains in Late Cretaceous continental deposits at Cruzy (Hérault, south-western France) is studied, using sedimentological (clay mineralogy, granulometry, cathodoluminescence) and taphonomic approaches, in order to reconstruct the depositional environment under which it was formed. The fossil-bearing conglomerates, sands and clays were apparently deposited during brief flood episodes affecting a braided river system, under a “tropical” type of climate with alternating dry and wet seasons. This type of depositional environment shows close similarities with those reconstructed for Late Cretaceous vertebrate sites in Romania.

New phosphate glasses have been developed in order to incorporate high rare-earth ions concentrations. These glasses present a great chemical stability and a high optical quality. The phosphate glass network is open, very flexible, with a linkage of the tetrahedrons very disordered and contains a larger number of non-bridging oxygens (66%). The great stability and resistance against crystallization associated with the possibility to incorporate high doping concentration of rare-earth ions in these phosphate glasses make them very good candidates for the realization of ultra short single mode amplifiers with a high gain at 1.55 μm.

This work presents a laser desorption study of Ga 5 Ge 20 Sb 10 S 65 chalcogenide glasses. The desorption products have been analyzed by UV multi-photon ionization and time-of-flight mass spectrometry. Desorption mechanisms and plume dynamics have been investigated by studying the desorption products velocity distribution profiles in the frame of a Knudsen layer model. A peculiar behavior (broadening of the mass spectral lines) of the Ga component was found at high desorption–ionization delays and a tentative explanation has been proposed, based on the very different thermal properties of the sample constituents.

We investigate the linear and nonlinear coefficient of chalcogenide glasses containing different amount of tellurium (Ge 10 As 10 Se 80− x Te x , where x = 0, 10, 15, 20). We give, for the first time to our knowledge, the values of the linear indices as well as the nonlinear refraction coefficient near the band gap of these materials. We give also, in the transparency region, the Cauchy coefficients for all the compositions (near infrared domain). An estimation of the linear absorption is also made using a ‘cut-back’ method. Nonlinear characterization of these materials is performed using the Z -scan technique at 1064 nm and 15 ps pulsewidth. A good agreement is found when we compare some of the results with those obtained using other techniques (at the same incident intensity). We show that the nonlinear refraction coefficients measured here are among the largest values reported on chalcogenide glasses. Furthermore, we found that the addition of tellurium does not enhance significantly the nonlinear refraction coefficient but exalts more the nonlinear absorption.

Compared to oxide-based glasses, vitreous materials involving chalcogens form a rather new family of glasses which have received attention, mainly because of their transmission in the mid-infrared. Indeed as low phonon compounds, these heavy-anion glasses allow the fabrication of molded optics for infrared cameras as well as infrared fibers operating in a large spectral range. These waveguides, when correctly tapered, allows the development of a new generation of sensitive evanescent-wave optical sensors which have been used for biomedical applications. Here we will focus on the spectral analysis of biomolecules present in human lung cells by measuring their infrared signatures. Because they contain heavy polarizable anions as well as lone-pair electrons, these glasses exhibit very large non-linear properties compared to silica and are candidates for fast optical switching and signal regeneration in telecom. Due to the technological interest in chalcogenide glasses, more information is needed on their structural organization and 77Se NMR spectroscopy appears to be a useful tool for checking the local environment of the Se atoms.