The real refractive index n and power absorption coefficient alpha of high resistivity GaAs and CdTe have been directly measured at 300 K and 8 K in the wavelength region from 12.5 micro to 300 micro. This spectral region contains the fundamental lattice resonance of both materials: 37.2 micro for GaAs and 71.4 micro for CdTe. This resonance causes large dispersion in the linear material properties. Single Drude-type oscillators have been visually fit to the measured n data with the results that for GaAs, epsilon(dc)' = 12.8 +/- 0.5 at 300 K and 12.6 +/- 0.5 at 8 K, and epsilonalpha(') = 10.9 +/- 0.4 at 300 K and 8 K ; for CdTe, epsilon(dc)' = 9.4 +/- 0.4 at 300 K and 9.0 +/- 0.4 at 8 K, and epsilon(alpha)' = 6.7 +/- 0.3 at 300 K and 8 K. The GaAs data clarifies the role of dispersion in n in the 5-20 micro region where previous results differ considerably. For both materials the n and alpha data in the region past 30 micro are the first to be reported.
The magnitudes of the nonlinear optical susceptibilities of trigonal selenium, cadmium telluride, and indium antimonide have been measured at 28.0 μm relative to d11 (tellurium). By comparison to the recently measured absolute value for tellurium, d11(Te)=(5.7±1.6×10−10 m/V, the values obtained in this work are d11(Se)=(18.4±8.6)×10−10 m/V, d14 (CdTe)=(5.9±2.4)×10−11 m/V, and d14(InSb)=(5.6±2.3)×10−10 m/V. For Te, CdTe, and InSb, the measured 28.0 μm value is less than the 10.6 μm value, while for Se, the 28.0 μm value is considerably larger than the 10.6 value. These seemingly inconsistent results are explained using Garrett's anharmonic oscillator model.
It has been found that vacuum-deposited films of CsI, AgCl, TlBr, and TlCl are useful as antireflection coatings for silicon over a broad spectral range in the infrared. Measurements performed on a plane-parallel silicon plate coated with various thicknesses of the above materials yield transmittance values ranging from 99% at lambda = 2.9 microm to 88% at lambda = 27 microm. Experimental details of the coating process and properties of the coatings are discussed.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.