Hybrid silicon evanescent devices

The indirect bandgap of Si has been a key hurdle in the achievement of optical gain elements. Raman lasers and amplifiers1-3 have been demonstrated, and optical gain in nanopatterned Si4 has also been observed, but an electrically pumped all-Si gain element has yet to be realized. An alternative to creating an electrically pumped all-Si gain mechanism is to take prefabricated lasers and couple them to Si waveguides. However, because of the tight alignment tolerances of the optical modes and the need to align each laser individually, this method has a limited scalability and it is difficult to envision die attaching more than a few lasers to each chip without prohibitive costs. We are developing wafer-scale approaches that could result in the simultaneous fabrication of thousands of lasers on a single Si wafer. Recently, we demonstrated an electrically driven laser5 and amplifier6 based on a hybrid waveguide structure that uses III-V quantum wells bonded to Si waveguides to achieve optical gain. In addition, under reverse bias operation, the same structure acts as a photodetector7. The lateral homogeneous nature of the III-V quantum layer structure allows the optical mode to be defined by the Si waveguide, leading to an alignment-free bonding process. Moreover, the mode lies primarily in the Si region, leading to low coupling losses from the active hybrid waveguide to passive Si waveguide regions. This architecture allows for Si photonics as an integration platform has recently been a focus of optoelectronics research because of the promise of low-cost manufacturing based on the ubiquitous electronics fabrication infrastructure. The key challenge for Si photonic systems is the realization of compact, electrically driven optical gain elements. We review our recent developments in hybrid Si evanescent devices. We have demonstrated electrically pumped lasers, amplifiers, and photodetectors that can provide a low-cost, scalable solution for hybrid integration on a Si platform by using a novel hybrid waveguide architecture, consisting of III-V quantum wells bonded to Si waveguides.