Indexed on: 16 May '17Published on: 16 May '17Published in: arXiv - Physics - Optics
The ability to shape and control light using silicon---the leading material in microchip manufacturing---has fueled rapid growth of the field of silicon photonics. By routing and manipulating optical signals using silicon waveguides, modulators, and detectors, this burgeoning field has brought about an array of new technologies, spanning from energy-efficient computing to protein sequencing on a chip. Despite this tremendous progress, there remains a pressing need for new laser technologies in silicon as the basis for metrology, sensing, and signal processing applications. One promising class of highly-tailorable laser oscillators which could address this need are based on stimulated Brillouin scattering. Such Brillouin lasers---whose internal dynamics are known to support ultra low-noise oscillation---have been harnessed to create world-class filters, microwave sources, and optical gyroscopes in glass-based waveguide technologies. Until recently, however, the prospects for silicon-based Brillouin lasers seemed bleak because the nonlinear light-sound coupling---which is the basis for Brillouin amplification---was puzzlingly absent in silicon waveguides. Only with the recent advent of a new class of optomechanical waveguides---which control both light and sound---have Brillouin interactions become the strongest and most tailorable nonlinearity in silicon waveguides. In this paper, we harness these engineered nonlinearities to create a Brillouin laser in silicon for the first time. By comparing experimental results with theoretical models, we identify the intriguing dynamics of this new silicon Brillouin laser and explore the various ways that this interaction can be harnessed. Beyond this study, these new silicon-based Brillouin laser technologies open the door to a host of new applications that can be seamlessly integrated within silicon photonic circuits.