ALXGA1-XAS-ALAS QUANTUM-WELL SURFACE-NORMAL ELECTROABSORPTION MODULATORS OPERATING AT VISIBLE WAVELENGTHS

We have produced AlxGa1-xAs-AlAs quantum well p-i-n diode electroabsorption modulators with x as high as 0.56. Even though the material is indirect in momentum space, strong excitonic absorption exists at the direct band gap which can be modulated with an applied field. For x = 0.33, 0.43 and 0.56, we measure relative transmission changes (DELTA-T/T0, in a surface-normal configuration) of 62%, 51%, and 23%, respectively, at wavelengths of 677, 622, and 575 nm for 15 V bias with the intrinsic layer being 0.6-mu-m thick.