CaF_2透明衬底中生长CdS VPE单晶膜的光学双稳态(英文)

Optical Bistability in VPE CdS Single Crystal Film on CaF2 Transparent Substrate

Optical bistability (OB) in semiconductors is of increasing interest in both basic and applied research. Much is known about optical nonlineari-ties and OB in CdS crystals. This paper reports, for the first time, about the optical bistability in CdS single crystal film grown on a CaF2 transparent substrate. High quality of the film has been identified by photolumines- cence and absorption. The OB is measured by 514.5nm line of Ar+ laser modulated into 6ms square light pules at room temperature. Two spikes appear at the front and back edges of transmitted light pulses. The switchins time is about 200μs at 200mW power level, smaller than the time in CdS bulk crystal at the same condition. The mechanism of the OB is due to the increasing absorption and thermal red shift of the absorption edge.