Resonantly enhanced nonreciprocal silicon Brillouin amplifier

Abstract

The ability to amplify light within silicon waveguides is central to the development of highperformance silicon photonic device technologies. To this end, the large optical nonlinearities made possible through stimulated Brillouin scattering offer a promising avenue for power-efficient allsilicon amplifiers, with recent demonstrations producing several dB of net amplification. However, scaling the degree of amplification to technologically compelling levels (> 10 dB), necessary for everything from filtering to small signal detection, remains an important goal. Here, we significantly enhance the Brillouin amplification process by harnessing an inter-modal Brillouin interaction within a multi-spatial-mode silicon racetrack resonator. Using this approach, we demonstrate more than 20 dB of net Brillouin amplification in silicon, advancing state-of-the-art performance by a factor of 30. This degree of amplification is achieved with modest (∼ 15 mW) continuous-wave pump powers and produces low out-of-band noise. Moreover, we show that this same system behaves as a unidirectional amplifier, providing more than 28 dB of optical nonreciprocity without insertion loss in an all-silicon platform. Building on these results, this device concept opens the door to new types of all-silicon injection-locked Brillouin lasers, high-performance photonic filters, and waveguidecompatible distributed optomechanical phenomena.

Brillouin integrated photonics

“…Silicon Brillouin waveguide systems have produced record forward-SBS gain coefficients using subwavelength modal confinement 26 , as well as net amplification at modest (5 mW) optical powers using low loss (<0.2 dB/cm) larger mode-area waveguides 51 that more effectively manage nonlinear losses. Such waveguide systems have enabled robust on/off gain (6.9 dB) corresponding to ~5.2 dB of net gain in a traveling-wave configuration 51 and more dramatic on/off gain (30 dB) corresponding to ~20 dB of net gain within resonant device configurations 56 .…”

A Cold-Atom Interferometer with Microfabricated Gratings and a Single Seed Laser

“…With the Rb D2 line at 780 nm, the optical frequency and power can be manipulated at 1560 nm using a PIC and then frequency doubled to 780 nm. Additionally, there is ongoing work such as heterogeneously integrated silicon photonics and thin-film lithium niobate electro-optic modulators 51,52 , compound semiconductor and silicon photonics integration for a laser including semiconductor optical amplifiers (SOAs) 53,54 , silicon photonics with Brillouin amplifiers 55 , and nonlinear photonics for second-harmonic generation (SHG) with lithium niobate 56 and aluminum nitride 57 . Those on-going efforts would bring modulators, optical amplifiers, frequency doublers, and even laser sources onto the PIC for a fully integrated laser solution for an LPAI accelerometer.…”

“…Many of these systems are based on discrete components that are connected through fiber-to-fiber connections or free-space optical paths with optomechanical alignment mounts, which limit their ability to withstand high dynamics and their ability to be mass-produced. Photonic integrated circuit (PIC) technology, based on microfabricated optical waveguides and components, offers the ability for robust laser systems that are scalable and readily mass produced [50][51][52][53][54][55][56][57] . Rubidium is particularly amenable to this approach because the optical resonance conveniently matches well with mature PIC technologies for light modulation 50 and optical amplification at telecommunication wavelengths (1560 nm) before frequency doubling to 780 nm to address the atoms.…”

Efficient Brillouin Optomechanical Interaction Assisted by Piezomechanics on the SOI Platform

“…Large FSBS gain has been observed [13]. Brillouin intermode modulation [14], on-chip Brillouin laser [15], resonately enhanced Brillouin amplifier [16], microwave filter [17], [18], backscatter-immune injection-locked Brillouin laser [19] have been demonstrated based on SIMS. Nanoscale photon-phonon interaction (including optical wave-guiding Brillouin scattering and cavity optomechanics) is applied to trap and control dielectric particles [20], squeeze light [21], and quantum nondemolition (QND) detection of light intensity [22].…”