Selective MOVPE growth for photonic integration circuits

Abstract

Semiconductor photonic integrated circuits (SPIC’s)1 have been developed with the attractive possibility of packaging cost reduction because the number of optical connection points between optical components will be greatly decreased. To take advantage of SPIC’s effectively, a fabrication technology for realizing highly efficient optical coupling between the components should be established. Table 1 summarizes the schematic diagrams of the waveguide interconnection structures reported to date together with resulted or expected optical coupling efficiencies.1,2 A butt- joint coupling scheme has been widely applied.2 However, the complicated fabrication processes for the butt-joint structure, including several steps of etching and regrowth, have resulted in poor uniformity and low device yield. Although a taper coupling scheme1 developed by U. Koren et al. has made it possible to obtain high coupling efficiency as well as small propagation loss in a passive waveguide section, a careful wet-etching process down to an etching stop layer has been needed. In this paper a novel waveguide coupling structure based on selective MOVPE growth is reported along with applications to DFB-MOD SPIC’s and tunable DBR-LD’s.