OPTICAL-PROPERTIES OF ALGAAS GAAS NIPI SUPERLATTICES AND THEIR APPLICATION IN ASYMMETRIC CAVITY SPATIAL LIGHT MODULATORS/

Homo-nipi and hetero-nipi superlattices incorporated into asymmetric F abry-Perot cavity structures are compared and evaluated for possible u se as bit plane optical memory elements in terms of the magnitude of t heir optical nonlinearities, on-off contrast ratio, insertion loss, ca rrier lifetimes, and power required to change the state of the structu re. Changes in superlattice absorption coefficient as high as 1500 cm- 1 and 1300 cm-1 have been achieved in type I and type II AlGaAs/GaAs h etero-nipi structures, respectively. When normalized to the GaAs quant um well layer thicknesses, the change in absorption coefficient in the Type I superlattice was as high as 12000 cm-1. In asymmetric cavity m odulator structures, on-off reflection contrast ratios as high as 60 : 1, carrier lifetimes as long as 4 ms, and on-state reflectivities as high as 0.62 have been observed. A 54 : 1 contrast ratio and an insert ion loss of 8.5 dB were achieved simultaneously in a planar Fabry-Pero t cavity structure excited with a pump beam power of 3.8 mW. The effec tive carrier lifetime in this case was 25 mus.