Backscatter-Immune Injection-Locked Brillouin Laser in Silicon

$I\phantom{\rule{0}{0ex}}n\phantom{\rule{0}{0ex}}j\phantom{\rule{0}{0ex}}e\phantom{\rule{0}{0ex}}c\phantom{\rule{0}{0ex}}t\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}o\phantom{\rule{0}{0ex}}n$ $l\phantom{\rule{0}{0ex}}o\phantom{\rule{0}{0ex}}c\phantom{\rule{0}{0ex}}k\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}n\phantom{\rule{0}{0ex}}g$ is a simple yet powerful means to stabilize and control laser oscillators, with many applications, but in the context of integrated photonics the technique has remained relatively unexplored. Here researchers demonstrate injection locking in a chip-integrated, all-silicon laser oscillator, and use this approach to achieve more than 23 dB of Brillouin-based on-chip amplification. Due to the phase-matched properties of the stimulated intermodal Brillouin process, this form of control is intrinsically $n\phantom{\rule{0}{0ex}}o\phantom{\rule{0}{0ex}}n\phantom{\rule{0}{0ex}}r\phantom{\rule{0}{0ex}}e\phantom{\rule{0}{0ex}}c\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}p\phantom{\rule{0}{0ex}}r\phantom{\rule{0}{0ex}}o\phantom{\rule{0}{0ex}}c\phantom{\rule{0}{0ex}}a\phantom{\rule{0}{0ex}}l$, meaning that the laser oscillator is naturally impervious to unwanted backscattering.