Theoretical analysis and fabrication of antireflection coatings on laser-diode facets

Reflectivity of an antireflection-(AR) coated laser-diode (LD) facet is analyzed on the basis of a slab waveguide model and an angular spectrum approach. The reflectivities of single- and double-layer AR coatings on 1.55-μm GaInAsP/InP LD's are numerically calculated. Optimum film parameters, such as thickness and refractive index of single-layer AR coating films, are obtained as functions of the active layer thickness. A minimum reflectivity as low as
1 \times 10^{-4}
was realized using refractive index controlled SiO
x
film as an AR coating for a 1.55-μm GaInAsP/InP buried-heterostructure (BH) LD.