BROAD-BAND MULTILAYER ANTIREFLECTION COATING FOR SEMICONDUCTOR-LASER FACETS

Using a triple-layer antireflection coating of Al2O3, Si, and SiO2, we have achieved a minimum facet reflectivity of 1 x 10(-6) and a bandwi dth of 90 nm for a reflectivity of 5 x 10(-5) or less for 1550-nm cent er-wavelength InGaAsP semiconductor lasers. A facet reflectivity of 3 x 10(-6) and a bandwidth of 30 nm for a reflectivity of 5 x 10(-5) wer e achieved for 1310-nm InGaAsP lasers. This coating is applicable to b roadband external-cavity-tuned laser sources, edge-emitting light-emit ting diodes, and semiconductor laser amplifiers.