Semiconductor Raman laser as a tool for wideband optical communications

The authors describe the fundamental properties of the GaP-Al_xGa_1-xP heterostructure used for the semiconductor Raman laser and the low threshold operation of the buried heterostructure Raman laser, together with the first demonstration of lasing by a new structure having a layer with an intermediate refractive index for pump power introduction, which reduces the loss for the Stokes field. They also describe the important applications of the semiconductor Raman laser to optical-heterodyne demodulation, and frequency difference mixing for frequency-tunable far-infra-red generation, as one of the essential tools for very wideband optical communication beyond 1 THz