Broadband multilayer antireflection coating for semiconductor laser facets

Using a triple-layer antireflection coating of Al(2)O(3), Si, and SiO(2), we have achieved a minimum facet reflectivity of 1 x 10(-6) and a bandwidth of 90 nm for a reflectivity of 5 x 10(-5) or less for 1550-nm center-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) were achieved for 1310-nm InGaAsP lasers. This coating is applicable to broadband external-cavity-tuned laser sources, edge-emitting light-emitting diodes, and semiconductor laser amplifiers.