Symmetric optical device with quantum well absorption

摘要

An optically bistable device 100 is disclosed having first and second semiconductor multiple quantum well regions 101 and 102 with complementary high and low absorption levels for emitting first and second output light beams 162 and 163 having complementary low and high power levels. The optical device comprises first and second photodetectors 103 and 104 having respective quantum well regions 101 and 102. The photodetectors are responsive to first and second light beams 160 and 161 for electrically controlling the optical absorption of each of the two quantum well regions. The state of the device is determined by the transmission level of light beam 161 passing through multiple quantum well region 102 and being emitted as output light beam 162, whereas the complementary state of the device is determined by the transmission level of complementary output light beam 162. A variable optical attenuator 701 concomitantly and proportionally varies the power level of input light beams 160 and 161 to maintain the state of the device over a wide range of input powers. When operated in the bistable operating region of the device, either one of control light beams 180 and 181 with a low power level changes the device from one state to the other. Two threshold values of the ratio of the power of the light incident on the two photodetectors establishes where the device switches from one state to the other.