Effect of Sequential Exposition to Short- and Long-Wavelength Radiation on the Optical Absorption in the Bismuth Titanium Oxide Crystal Doped by Aluminum

Abstract

Changes in the spectral dependences of the optical absorption induced in the bismuth titanium oxide crystal doped by aluminum as a result of sequential exposition to cw laser radiation first with the wavelength λi = 532nm and then with the longer wavelength λn = 633, 655, 663, 780, 871, or 1064nm are investigated. Our experiments show that after the short-wavelength exposition to radiation with λi = 532nm, the optical absorption in the crystal increases, and in the range 470–1000nm, yields the spectrum whose form is independent of the initial crystal state. The subsequent exposition to longer-wavelength radiation leads to enhanced transmittance of the crystal in the examined spectral range. A maximum decrease of the optical absorption in the crystal is observed upon exposure to radiation with the wavelength λn = 663nm.