Abstract

Semiconductor-doped glasses (SDGs), consisting of small (~100Å) inclusions of CdS_xSe_l-x in silicate glass and commercially available as sharp cut-off filters, are the subject of intensive investigation. They are materials with large effective third order susceptibilities at wavelengths near the band-edge and are suitable for optical phase conjugation and four wave mixing [1]. Data on their nonlinear optical properties and relaxation parameters have previously been obtained by means of pulsed nano-, pico- and femto-second lasers [2,3,4]. For this reason relatively slow optical nonlinearities of SDGs and their dynamics have not been examined. This paper presents the results of an experimental study of a SDG light by light modulator using a pump-probe technique. Laser induced darkening and clearing with a millisecond relaxation time have been observed and are shown to lead to complex structure in the subharmonic band of the modulation frequency and a near chaotic response. These processes and their interaction must be understood before SDGs can be used in optoelectronic devices.

© 1988 Optical Society of America