Monolithic integration of substrate input/output resonantphotodetectors and vertical-cavity lasers

摘要

We present theoretical and experimental results on monolithicallynintegrated through-the-substrate input/output vertical-cavity lasersn(VCLs) and resonant photodetectors that are compatible withnsubstrate-side micro optics and flip-chip bonding. The requiredndifference in bottom mirror reflectivity between the VCL and thendetector is achieved by selective oxidation of a few high Al-contentnAlGaAs layers in the bottom mirror for the VCL. The modeling shows thatnusing this approach makes it possible to individually design VCLs andnresonant detectors from the same epitaxial structure withoutncompromising performance of either device. Furthermore, since thenoxidized layers are placed far enough from the active region, the VCLndesign is very robust with respect to uncertainties in the oxidizednlayers. For the detectors, we expect about 60% quantum efficiency, an6-nm full-width at half-maximum optical bandwidth, and less than 1 nmndifference in operating wavelength from the VCLs. Experimentally, VCLsnand adjacent detectors with integrated microlenses have a difference ofnless than 0.5 nm in operating wavelength. The detectors havenresponsivities of 0.48 A/W, corresponding to 60% quantum efficiency andn7-nm optical bandwidths. Single-mode VCL's exhibit threshold currents asnlow as 135 ΜA while maintaining differential efficiencies above 50%.nLarger multimode VCLs have differential efficiencies exceeding 70% withnthreshold currents of 0.5 mA