LWIR FSO Receivers using Orientation Patterned Semiconductors

A novel sum frequency generation (SFG) intracavity structure for detecting LWIR light via conversion to the SWIR band is presented. Simulation results using the coupled nonlinear wave equations and a spatially dependent cavity model show that microwatt level power can be generated from milliwatt level sources. Use of orientation-patterned semiconductors for the LWIR as the nonlinear medium is also discussed.