Multiple Quantum Well Optical Modulators for Solid State Lasers,

Realization of multiple quantum well MQW optical modulators that operate at wavelengths in the 1 um range is desirable, because of the ready availability of high-power, reliable solid state lasers at these wavelengths.L Recent advances in diode pumping of solid state laser media such as Neodymium doped Yttrium Aluminum Garnet NdYAG and Yttrium Lithium Fluoride NdYLF has made them efficient and reliable sources of coherent radiation. Such devices might find application in potential optical computing and communication architectures. Production of MQW materials with bandgaps in the 1 micro range is complicated by a lack of lattice-matched substrates and a lattice mismatch between potential quantum barrier and well materials. We describe recent efforts we have made to realize MQW modulators that operate in the 1 micro range and summarize some of our results. We consider both GaAs and InP-based materials. MQW modulators require about 1 um of absorbing material for useful normal incidence absorption modulation. This is in excess of most critical thickness estimates, requiring strain relaxation issues to be addressed. Consider for example the most attractive GaAs-based materials system for 1 micro range MQW applications, InxGa1-xAs AlxGa1-xAs. In0.25Ga0.75As, near the appropriate composition for 1 micro modulators, has about a 1.8 percent lattice mismatch to GaAs.