Abstract

Variation of the refractive index of amorphous selenium with hydrostatic pressure to 7 kbar was measured using an interferometric technique and a laser source at a wavelength of 1.15 μ. The refractive index increases, linearly with pressure, with a slope of 2.74·10⁻² kbar up to 2 kbar; thereafter, it increases nonlinearly. However, the increase of refractive index is linear with respect to lagrangian strain, even though the total volume strain is as high as 6%. The results are interpreted in the light of Mueller’s theory of photoelasticity of amorphous solids. The individual values of the elasto-optic constants of amorphous selenium, p₁₁ and p₁₂, were also determined by use of the results from both hydrostatic and uniaxial pressure measurements. Their values at λ = 1.15 μ are p₁₁ = 0.34₅ and p₁₂ = 0.36₂. From considerations of figure of merit it appears that amorphous selenium is a highly promising acousto-optic device material for use at λ = 1.15 μ. From a detailed analysis of the data on dn/dρ and the shift of the absorption edge of selenium by pressure, it is shown for the first time that the resonance-absorption frequency derived from the Drude–Sellmeier dispersion relation corresponds to the experimentally observed frequency. On the other hand, the corresponding frequency derived from the Lorentz–Lorenz equation represents the frequency of the individual oscillator in its free state, but not that in the solid state.

© 1970 Optical Society of America

Nonlinear Variation of the Refractive Indices of α-Quartz with Pressure*

K. Vedam and T. A. Davis
J. Opt. Soc. Am. 57(9) 1140-1145 (1967)

Pressure Dependence of the Refractive Indices of the Tetragonal Crystals: ADP, KDP, CaMoO₄, CaWO₄, and Rutile*

T. A. Davis and K. Vedam
J. Opt. Soc. Am. 58(11) 1446-1451 (1968)

Pressure and Temperature Variation of the Optical Rotatory Power of α-Quartz*

K. Vedam and T. A. Davis
J. Opt. Soc. Am. 58(11) 1451-1455 (1968)

Optical Properties of Amorphous Selenium in the Vacuum Ultraviolet

Algird G. Leiga
J. Opt. Soc. Am. 58(11) 1441-1445 (1968)

Piezo- and thermo-optical properties of Bi₁₂GeO₂₀, II. Refractive index*

K. Vedam and P. Hennessey
J. Opt. Soc. Am. 65(4) 442-445 (1975)