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To achieve on-chip lasers for Si-photonics, monolithic integration using selective epitaxy is a favorable option due to the unique defect engineering and resultant bufferless structure. Among the intensively investigated selective epitaxy methods, lateral aspect ratio trapping generates III-V devices in the same plane as the Si layer enabling efficient coupling with Si waveguides. Here, we demonstrate telecom InGaAs/InP quantum well lasers selectively grown on commercial silicon-on-insulator substrates with an in-plane structure using a simple structural design and growth scheme without any regrowth steps. Leveraging on the lateral aspect ratio trapping technique, uniform quantum wells with high crystalline quality were obtained and shown by comprehensive material characterizations. Room temperature pulsed lasing was achieved on the fabricated micro-ring lasers with a low threshold of 20 μJ/cm2. The results present a crucial step towards electrically pumped lasers at telecom band as well as fully integrated Si-photonics. [ABSTRACT FROM AUTHOR]

A theoretical and experimental study of phase-controlled beam combining based on noncollinear frequency doubling is described. Optimized second-harmonic power and improved output intensity distribution are simultaneously achieved by a closed-loop phase control system via an adaptive algorithm. It is shown that the profile of the combined beam at the second-harmonic with 12 noncollinear frequency inputs can be shaped to a near-fundamental Gaussian mode, with a power enhancement of more than two orders of magnitude, compared to the second-harmonic signal generated with a single beam. [ABSTRACT FROM PUBLISHER]