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Chalcogenide As2S3 Sidewall Bragg Gratings Integrated on LiNbO3 Substrate  [PDF]
Xin Wang, Aiting Jiang, Christi Madsen
Optics and Photonics Journal (OPJ) , 2013, DOI: 10.4236/opj.2013.31013
Abstract:

This paper introduces the design and applications of integrated As2S3 sidewall Bragg gratings on LiNbO3 substrate. The grating reflectance and bandwidth are analyzed with coupled-mode theory. Coupling coefficients are computed by taking overlap integration. Numerical results for uniform gratings, phase-shifted gratings and grating cavities as well as electro-optic tunable gratings are presented. These integrated As2S3 sidewall gratings on LiNbO3 substrate provide an approach to the design of a wide range of integrated optical devices including switches, laser cavities, modulators, sensors and tunable filters.

Generation of correlated photon pairs in a chalcogenide As2S3 waveguide  [PDF]
C. Xiong,G. D. Marshall,A. Peruzzo,M. Lobino,A. S. Clark,D. -Y. Choi,S. J. Madden,C. M. Natarajan,M. G. Tanner,R. H. Hadfield,S. N. Dorenbos,T. Zijlstra,V. Zwiller,M. G. Thompson,J. G. Rarity,M. J. Steel,B. Luther-Davies,B. J. Eggleton,J. L. O'Brien
Physics , 2010, DOI: 10.1063/1.3549744
Abstract: We demonstrate the first 1550 nm correlated photon-pair source in an integrated glass platform-a chalcogenide As2S3 waveguide. A measured pair coincidence rate of 80 per second was achieved using 57 mW of continuous-wave pump. The coincidence to accidental ratio was shown to be limited by spontaneous Raman scattering effects that are expected to be mitigated by using a pulsed pump source.
Electron irradiation induced reduction of the permittivity in chalcogenide glass (As2S3) thin film  [PDF]
Damián P. San-Román-Alerigi,Dalaver H. Anjum,Yaping Zhang,Xiaoming Yang,Ahmed Benslimane,Tien K. Ng,Mohammad Alsunaidi,Boon S. Ooi
Physics , 2012, DOI: 10.1063/1.4789602
Abstract: We investigate the effect of electron beam irradiation on the dielectric properties of As2S3 Chalcogenide glass. By means of low-loss Electron Energy Loss Spectroscopy, we derive the permittivity function, its dispersive relation, and calculate the refractive index and absorption coefficients under the constant permeability approximation. The measured and calculated results show, to the best of our knowledge, a heretofore unseen phenomenon: the reduction in the permittivity of <40%, and consequently a modification of the refractive index follows, reducing it by 20%, hence suggesting a significant change on the optical properties of the material. The plausible physical phenomena leading to these observations are discussed in terms of the homopolar and heteropolar bond dynamics under high energy absorption.
Fabrication of Bragg gratings in sub-wavelength diameter As2Se3 chalcogenide wires  [PDF]
Raja Ahmad,Martin Rochette,Chams Baker
Physics , 2011, DOI: 10.1364/OL.36.002886
Abstract: The inscription of Bragg gratings in chalcogenide (As2Se3) wires with sub-wavelength diameter is proposed and demonstrated. A modified transverse holographic method employing He Ne laser light at a wavelength of {\lambda}w = 633 nm allows the writing of Bragg grating reflectors in the 1550 nm band. The gratings reach an extinction ratio of 40 dB in transmission and a negative photo-induced index change of \delta n~0.01. The inscription of Bragg gratings in chalcogenide microwires will enable the fabrication of new devices with applications in nonlinear optics, and sensing in the near-to-mid-infrared region of wavelengths.
Ellipsometric Characterization of Thin Films from Multicomponent Chalcogenide Glasses for Application in Modern Optical Devices  [PDF]
R. Todorov,J. Tasseva,V. Lozanova,A. Lalova,Tz. Iliev,A. Paneva
Advances in Condensed Matter Physics , 2013, DOI: 10.1155/2013/308258
Abstract: A review is given on the application of the reflectance ellipsometry for optical characterization of bulk materials and thin films with thickness between /20 and 2 (at ?nm). The knowledge of the optical constants (refractive index, , and extinction coefficient, ) of thin films is of a great importance from the point of view of modelling and controlling the manufacture of various optical elements, such as waveguides, diffraction gratings, and microlenses. The presented results concern the optical properties of thin films from multicomponent chalcogenide glasses on the base of As2S3 and GeS2 determined by multiple-angle-of-incidence ellipsometry and regarded as a function of the composition and thickness. The homogeneity of the films is verified by applying single-angle calculations at different angles. Due to decomposition of the bulk glass during thermal evaporation, an optical inhomogeneity of the thin As (Ge)-S-Bi(Tl) films is observed. The profile of in depth of thin As-S-Tl (Bi) films was investigated by evaporation of discrete layers. It is demonstrated that homogenous layers from the previous compounds with controlled composition can be deposited by coevaporation of As2S3 and metals or their compounds (Bi, Tl, In2S3). 1. Introduction The optical constants of the thin films are commonly determined by methods such as spectrophotometry, prism-coupling technique, and ellipsometry. The ellipsometric methods are fast, nondestructive, highly sensitive to the presence of surface inclusions and provide higher accuracy for determination of the refractive index and thickness of thin layers in comparison with the spectrophotometric methods [1–4]. Currently various forms of ellipsometry exist and are applied for investigation of the physical properties of thin films [3]. The most common among these methods are the spectral ellipsometry and multiple-angle-of-incidence ellipsometry [5]. Spectral ellipsometry includes measurement and analysis of the complex reflection ratio in wide range of wavelengths at a fixed angle of light incidence. The method provides information for the optical response functions (complex refractive index, , or complex permittivity, ) [6]. The main problem of the spectral forms of ellipsometry is the selection of an appropriate dispersion model for description of the optical constants [6]. Single-wavelength ellipsometry offers an advantage in this respect since it does not require a dispersion law and enables the in situ control of the process of thin film deposition [5]. Chalcogenide glasses exhibit transmittance in wide spectral range
Degradation of electron-induced dichroism in glassy As2S3-Sb2S3
Balitska V. O.,Shpotyuk O. I.,Vakiv M. M.
Ukrainian Journal of Physical Optics , 2000,
Abstract: Experimental results on time degradation of electron-induced dichroism in vitreous chalcogenide semiconductors As2S3-Sb2S3 are discussed. The adequate model for the quantitative description of this process can be developed on the basis of monomolecular relaxation function proper to annihilation of dipol-like coordination defects created on the basis of radiation-induced broken covalent chemical bonds
Sidewall effects in Rayleigh-Bénard convection  [PDF]
Richard J. A. M. Stevens,Detlef Lohse,Roberto Verzicco
Physics , 2014, DOI: 10.1017/jfm.2013.664
Abstract: We investigate the influence of the temperature boundary conditions at the sidewall on the heat transport in Rayleigh-B\'enard (RB) convection using direct numerical simulations. For relatively low Rayleigh numbers Ra the heat transport is higher when the sidewall is isothermal, kept at a temperature $T_c+\Delta/2$ (where $\Delta$ is the temperature difference between the horizontal plates and $T_c$ the temperature of the cold plate), than when the sidewall is adiabatic. The reason is that in the former case part of the heat current avoids the thermal resistance of the fluid layer by escaping through the sidewall that acts as a short-circuit. For higher Ra the bulk becomes more isothermal and this reduces the heat current through the sidewall. Therefore the heat flux in a cell with an isothermal sidewall converges to the value obtained with an adiabatic sidewall for high enough Ra ($\simeq 10^{10}$). However, when the sidewall temperature deviates from $T_c+\Delta/2$ the heat transport at the bottom and top plates is different from the value obtained using an adiabatic sidewall. In this case the difference does not decrease with increasing Ra thus indicating that the ambient temperature of the experimental apparatus can influence the heat transfer. A similar behavior is observed when only a very small sidewall region close to the horizontal plates is kept isothermal, while the rest of the sidewall is adiabatic. The reason is that in the region closest to the horizontal plates the temperature difference between the fluid and the sidewall is highest. This suggests that one should be careful with the placement of thermal shields outside the fluid sample to minimize spurious heat currents.
Transmission measurement at 10.6 microns of Te2As3Se5 rib-waveguides on As2S3 substrate  [PDF]
C. Vigreux-Bercovici,E. Bonhomme,A. Pradel,J. -E. Broquin,L. Labadie,P. Kern
Physics , 2007, DOI: 10.1063/1.2430404
Abstract: The feasibility of chalcogenide rib waveguides working at lambda = 10.6 microns has been demonstrated. The waveguides comprised a several microns thick Te2As3Se5 film deposited by thermal evaporation on a polished As2S3 glass substrate and further etched by physical etching in Ar or CF4/O2 atmosphere. Output images at 10.6 microns and some propagation losses roughly estimated at 10dB/cm proved that the obtained structures behaved as channel waveguides with a good lateral confinement of the light. The work opens the doors to the realisation of components able to work in the mid and thermal infrared up to 20 microns and even more.
Immersion Lithography with Using of Photostimulated Etching of Germanium Chalcogenide Films  [cached]
Dan’ko V.A.,Indutnyi I.Z.,Myn’ko V.I.,Shepeliavyi P.E.
Proceedings of the International Conference Nanomaterials : Applications and Properties , 2013,
Abstract: The new effect of photo-stimulated dissolution of as-evaporated and annealed Ge-based chalcogenide glass (ChG) films was investigated. The etching rate increases with the illumination intensity, and its spectral dependence is correlated with absorption in the film at the absorption edge. The high-frequency diffraction gratings on germanium ChG - more environmentally acceptable compounds than traditionally used arsenic chalcogenides, were recorded by method of interference immersion photolithography with photoinduced etching.
Conduction Mechanism in Amorphous As2S3
RK Nkum, FK Ampong, F Boakye
Journal of Science and Technology (Ghana) , 2012,
Abstract: The conduction mechanism in amorphous As2S3 has been studied by investigating the variation of the electrical resistivity over the temperature range 300 – 450 K. The electrical resistivity is characterised by a mobility gap of 2.15 eV over the temperature range investigated. The dc conductivity provides evidence of conduction by excitation of charge carriers into the band edges near the mobility edges. The results also give the possibility of conduction by a phonon-assisted hopping of polarons between localised states.
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