Subwavelength Control of Photons and Phonons in Release-Free Silicon Optomechanical Resonators

Abstract

Integrated optomechanics finds increasingly broadening applications, requiring tight confinement of photons and phonons within nanometric-scale photonic circuits. However, most existing integrated optomechanical devices use unconventional materials or suspended structures that hinder co-integration with scalable photonic technologies. Here, we show a new optomechanical confinement approach, using subwavelength structuration of silicon to tightly confine near-infrared photons and 600-MHz phonons in nonsuspended silicon waveguides, fully compatible with standard silicon photonics. Indeed, phonons are confined by velocity reduction in silicon and destructive interference of radiation to the cladding, while photons are confined by metamaterial index guiding. We experimentally demonstrate optomechanical microresonators with optical excitation and readout of mechanical modes with a record quality factor of 1120 for silicon-on-insulator devices, measured under ambient conditions and room temperature. The measured optical quality factor is ∼40,000, and the estimated coupling rate is 51 ± 18 kHz. These results are the first step for a new generation of optomechanical devices implemented with scalable silicon photonic technology, having great potential for applications in optical and wireless communications, radar, sensing, metrology, and quantum technologies.

Optomechanical cavities in silicon-on-insulator

“…This fingerprint-like spectrum results from the limited repetition of segment structures and coherence breakdown due to the tapering structures. From the frequency dynamics and the intra-cavity power, we estimated an optomechanical coupling rate g0 of 51 ± 18 kHz [10]. This mechanical quality factoris the highest value demonstrated of an SOI optomechanical resonator without silica under-cladding removal, with 1 order of magnitude increase compared to previously reported SOI optomechanical microresonators [6].…”

“…The width W is tapered in a segment array of limited number to ensure optical wave can propagate in a subwavelength regime [8] without diffraction meanwhile effective bandgap is formed at the two sides [9] of the structure for optical resonance. This structure is fabricated using standard silicon photonics process, based on electron-beam lithography and dry etching [10]. Fig.…”

Mesoporous-based responsive acoustic resonators operating in the GHz range

“…This may involve investigating the devices at different humidity conditions, exploring alternative pore size distributions, optimizing fabrication processes, and exploring novel integration schemes with complementary materials, geometries, and components. 7,15,23,24…”

Sub-Hz Closed-Loop Electro-Optomechanical Oscillator with Gallium Phosphide Photonic Crystal Integrated on SoI Circuitry

“…Then, the external fiber-based delay line is one of the main contributors to the total footprint of the device implemented here. An important step toward fully on-chip oscillators can be taken with integrated, compact delay lines based on the slow propagation of phonons in engineered phononic waveguides ,− with optimized electrical to mechanical transduction and focused acoustic waves . Finally, small-footprint and low phase-noise oscillators could be achieved with heterodyne integration on SoI, using the on-chip stabilization feedback loop.…”