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21.
A method for fabricating infrared‐transmitting waveguides that yields low optical losses and strong confinement of light is presented. The method minimises the number of fabrication steps by exploiting the photosensitivity of arsenic trisulfide glass, using it both as a photoresist and as a waveguiding material. Controlled annealing/remelting of the waveguides minimises scattering due to fluctuations in refractive index at the interface between the waveguide and the surrounding medium, allowing low losses to be realised. Bends and Y‐splitter structures have been realised, as well as the longest As2S3 serpentine planar waveguides yet reported. 相似文献
22.
Design of a coated thinly clad chalcogenide long-period fiber grating refractive index sensor based on dual-peak resonance near the phase matching turning point
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A novel method for designing chalcogenide long-period fiber grating (LPFG) sensors based on the dual-peak resonance effect of the LPFG near the phase matching turning point (PMTP) is presented. Refractive index sensing in a high-refractive-index chalcogenide fiber is achieved with a coated thinly clad film. The dual-peak resonant characteristics near the PMTP and the refractive index sensing properties of the LPFG are analyzed first by the phase-matching condition of the LPFG. The effects of film parameters and cladding radius on the sensitivity of refractive index sensing are further discussed. The sensor is optimized by selecting the appropriate film parameters and cladding radius. Simulation results show that the ambient refractive index sensitivity of a dual-peak coated thinly clad chalcogenide LPFG at the PMTP can be 2400 nm/RIU, which is significantly higher than that of non-optimized gratings. It has great application potential in the field of chemical sensing and biosensors. 相似文献
23.
The electrical resistivity of bulk Ge20Te80 has been measured as a function of pressure and temperature. At 5 GPa, an amorphous semiconductor-to-crystalline metal transition
has been observed. The sample recovered from the high pressure cell, after the application of 7 GPa, has a face-centred cubic
structure with a lattice constant of 6·42 A. In crystalline sample, the semiconductor-to-metal transition occurs at 7 GPa.
The thermoelectric power has also been measured for glassy samples in the temperature range 300–240 K. 相似文献
24.
大模场光子晶体光纤在高功率激光传输、光纤放大器、光纤激光器中的广泛应用, 使其受到研究者的广泛关注.硫系玻璃在红外波段(1–20μm)具有优良透过性能, 且具有折射率高(2.0–3.5)、声子能量低(小于350 cm-1)、 组分可调等特性, 成为制备红外光纤的理想材料. 本文设计一种基于Ge20Sb15Se65硫系玻璃基质的新型单模传输、低损耗、超大模场面积光子晶体光纤结构, 经理论验证其在λ =10.6 μm处基模限制损耗远低于0.1 dB/m, 高阶限制模损耗大于2 dB/m, 模场面积约为13333 μm2.
关键词:
硫系玻璃
大模场面积
红外光子晶体光纤
结构设计 相似文献
25.
The effect is reported of varying cadmium concentration on the glass transition, thermal stability and crystallization kinetics of Ge20Se80? x Cd x (x = 2.5, 5, 7.5 and 10 at. %) glasses. Differential scanning calorimetry results under non-isothermal conditions for the studied glasses are reported and discussed. The values of the glass transition temperature (Tg ) and the peak temperature of crystallization (Tp ) were found to be dependent on heating rate and Cd content. From the heating rate dependence of Tg and Tp , the values of the activation energy for glass transition (Eg ) and the activation energy for crystallization (Ec ) were evaluated and their composition dependence discussed. The thermal stability of the glasses was evaluated using various thermal stability criteria such as ΔT, Hg and S. The stability calculations emphasize that the thermal stability decreases with increasing Cd content. 相似文献
26.
We report observations of the Meyer–Neldel rule for the non-isothermal crystallization of glassy Se85? x Te15Sb x (x =?0, 2, 4, 6, 8, 10) alloys. We found a strong co-relation between the pre-exponential factor K 0 of the rate constant K(T) for crystallization and the activation energy of crystallization E c. This indicates the presence of a compensation effect for the non-isothermal crystallization process in this glassy system. The composition dependence of the crystallization temperature T c and the activation energy for crystallization E c is discussed. 相似文献
27.
Differential scanning calorimetry was used to study glassy Se100- x Sb x (x = 2, 4, 6, 8 and 10) alloys at a heating rate of 10°C min?1 under non-isothermal conditions. An extremely large increase in the specific heat, Cp , was observed at the glass-transition temperature. It was also found that the values of Cp below and above the glass-transition temperature, Cpg and Cpe , respectively, are highly composition dependent. This indicates that the Sb additive used in the present study influences the structure of the a-Se. The variation of Cp reveals local extrema in the Se–Sb glassy system at x = 4 and x = 8. The composition dependence of both Cpe and Cpg is explained in terms of the atomic structure. 相似文献
28.
29.
Polyvinyl alcohol (PVA) doped (Se80Te20)100–xAgx (0 ≤ x ≤ 4) thin films were prepared by the spin-coating technique on a quartz substrate. The optical parameters of PVA-doped (Se80Te20)100–xAgx (0 ≤ x ≤ 4) composites at the same chalcogen concentration (S0 = 0.1 mg ml?1) and PVA/(Se80Te20)96Ag4 composites at three different chalcogen concentrations viz. S1 = 0.3 mg ml?1, S2 = 0.6 mg ml?1 and S3 = 1 mg ml?1 have been studied. The semi-crystalline nature of the as-deposited thin filmsisdetermined by X-ray diffraction. The transmission and reflection spectra of PVA-doped Se–Te–Ag thin films were obtained in a 350–650 nm spectral region. The optical-band gap has been calculated from the transmission and reflection data. The refractive index has been calculated by the measured reflection data. It has been found that the optical-band gap increases, but the refractive index, extinction coefficient, and the real and imaginary parts of the dielectric constant decrease, with increase in Agcontent in PVA-doped (Se80Te20)100–xAgx (0 ≤ x ≤ 4) thin films. Such type of behavior is explained on the basis of decrease in density of the defect states. However, the optical-band gap has been found to be decreased and all other optical parameters show increase in their values with increase in concentration of (Se80Te20)96Ag4 glass in PVA-doped composites. The results have been explained on the basis of cluster-size formation at the time of dissolution. This study shows that the optical properties of new composites are affected by the change in silver and chalcogen concentration. 相似文献
30.
Daniel E. Bugaris 《Journal of solid state chemistry》2008,181(12):3189-3193
Two new quaternary salts, [Hg3Te2][UCl6] and [Hg4As2][UCl6], have been synthesized and their structures determined by single-crystal X-ray diffraction analysis. [Hg3Te2][UCl6] is the product of a reaction involving UCl4, HgCl2, and HgTe at 873 K. The compound crystallizes in space group P21/c of the monoclinic system. [Hg4As2][UCl6] results from the reaction of U, Hg2Cl2, and As at 788 K. It crystallizes in space group Pbca of the orthorhombic system. [Hg3Te2][UCl6] has a two-dimensional framework of layers, whereas [Hg4As2][UCl6] has a three-dimensional framework of layers interconnected by Hg atoms linearly bonded to As atoms. Both framework structures contain discrete [UCl6]2− anions between the layers. [Hg3Te2][UCl6] exhibits temperature-independent paramagnetism. The optical absorption spectra of these compounds display f-f transitions. 相似文献