Fabrication and characteristics of very narrow waveguide semiconductor Raman amplifiers and lasers

In this paper, we proposed the fabrication technique for semiconductor Raman lasers and amplifiers with a narrow waveguide made of the GaP core and Al_xGa_l=xP cladding layers. To realize devices with high performance, improvement of optical loss at the interface caused by crystal imperfections, in particular, the excess free carriers at the interface is the most important. We have investigated the interface imperfection by capacitance-voltage method and secondary ion mass spectroscopy measurement and found that excess ion density at the interface can be reduced by selecting etching solution such as HC1/H₂O, and by controlling growth rate. We discuss the low noise characteristics of cw operated semiconductor Raman lasers and also the Raman amplifiers characteristics such as gain and bandwidth. We have realized these devices by achieving low optical loss in very narrow waveguide.