Planarized interference mirror

摘要

A semiconductor interference mirror principally comprising a large number of pairs (36) of semiconductor layers (38,40) having different dielectric constants and having optical thicknesses equal to one-quarter of the wavelength of light to be reflected. For example, the two semiconductors are InP and InGaAsP for reflecting 1.55- mu m light. However, every 10 to 15 periods in the mirror, the InP layer (44) is grown more slowly to a thickness that is an odd multiple of its usual quarter-wavelength thickness. Because indium is so mobile and binary composition is well defined, the binary InP layer replanarizes the growth, thus assuring a planar mirror. The faster growth rate for the majority of the mirror allows the mirror to be grown in a shorter time, thus reducing process variations.