Two-photon absorption of IR radiation and its optical saturation in n-type gallium antimonide

Experimental and numerical investigations were made of two-photon absorption of 3-μm erbium laser radiation by an n-type GaSb crystal. Experimental values of the two-photon absorption coefficient K₂ ≈ 0.38 cm MW^–1 and of the free-carrier absorption cross section σ ≈ 2×10^–17 cm^–2 were used in numerical simulation of optical saturation of the transmission of radiation by the semiconductor.