Demonstration of Forward Brillouin Gain in a Hybrid Photonic–Phononic Silicon Waveguide

Abstract

Silicon-based stimulated Brillouin scattering (SBS) promotes the on-chip all-optical signal processing network by interfacing silicon photonic and phononic technologies. Controllable and strong Brillouin coupling in silicon is a key requirement for this purpose. Here, we demonstrate traveling-wave forward SBS and Brillouin gain through a class of hybrid photonic-phononic silicon waveguides on the silicon-on-insulator (SOI) platform. This design combines the advantages of a silicon ridge waveguide and phononic crystal slab, allowing the independent control on the confined optical and acoustic modes. The strong and tailorable Brillouin nonlinearity is demonstrated via the heterodyne four-wave mixing spectroscopy. Three-tone gain experiment reveals a small-signal Stokes gain of 0.9 dB in a 1.085 cm length straight waveguide device at moderate pump power. The limiting factors and further improvements of net Brillouin amplification in our system are also discussed. This design can also be applied to the intermodal SBS as well as other silicon-based material platforms, and thus it offers the pathway toward on-chip microwave photonic filters, Brillouin amplifiers, and nonreciprocal devices.

Band Gap Trapping of Acoustic Phonons Boosts the Acousto-optical Interaction

“…20−22 In a hybrid photonic−phononic silicon waveguide, a small-signal Stokes gain of 0.9 dB is realized with only a 1.085 cm length straight waveguide device at moderate pump power. 22 The compact size and high Brillouin gain in the integrated waveguide are critical for future phonon−photon signal processing. This kind of integrated hybrid waveguide provides a universal platform for the investigation of integrated Brillouin photonics.…”

Compact ring resonators of silicon nanorods for strong optomechanical interaction

“…To further tailor the dispersion of optical waves, waveguides consisting of periodic structures have been proposed and studied. [41][42][43][44][45][46] Especially, novel optical waveguides formed by chains of silicon nanoparticles have been experimentally demonstrated and are possible to realize advanced functionalities. [47][48][49] Recently, we have also proposed and shown that chain-like silicon waveguides can confine optical waves via the quasi-bound states in the continuum while each silicon unit acts as a mechanical resonator, thus realizing a considerable optomechanical coupling rate.…”

Fiber-Integrated All-Optical Signal Processing Device for Storage and Computing

“…The rapid progress of optical communication networks relies heavily on two fundamental technologies: high-speed optical transmission and all-optical signal processing. , The advancement of high-speed optical transmission has been remarkable with the reported transmission of a system over 1.8 Pbit/s at a distance of approximately 8 km . As a result, all-optical signal processing is increasingly becoming essential in the construction of high-speed optical fiber communication networks. , All-optical signal processing is a critical operation for optical communication systems and data networks, and it is commonly achieved by utilizing nonlinear optical media such as periodic polarization lithium niobate waveguide (PPLN), − sulfide waveguide, , silicon-based waveguide, − semiconductor optical amplifier (SOA), − etc. While these platforms have achieved notable success, they are not without limitations.…”