Nonlinear optical properties of CuxS and CuInS2 nanoparticles in sol-gel glasses

Silica glasses with ultrafine CuxS and CuInS2 particles (average radius of 5 +/- 3 nm) were fabricated by means of a sol-gel technique. Linear and differential absorption spectra were studied. The glasses reveal absorption peaks in the 600-700 nm range associated with the first excitonic resonance in the quantum confined particles. Laser excitation by 540 nm pulses leads to the induced absorption effect in the 480-980 nm spectral range. The relaxation of the induced absorption has a time constant equal to about 500 ps for CuS-doped glasses and a biexponential type (with tau(1)approximate to 30 ps and tau(2)> 1 ns) for CuInS2-doped ones. (C) 2000 American Institute of Physics. [S0021-8979(00)03101-7].