Absorption spectra of wide-gap semiconductors in their transparency region

The linear absorption spectra of GaP, TiO2, ZnSe, and ZnS are measured in their transparency range using a two-color, excite-probe Z-scan. ZnS has the lowest absorption coefficient (similar to10(-5) cm(-1)) in the wavelength range 840-900 nm, making it an excellent material for use as a luminescence extracting lens in semiconductor laser cooling experiments. Direct observation of two-photon absorption in ZnSe using only low power, continuous laser beams is also reported. (C) 2003 Elsevier B.V. All rights reserved.