Surface acoustic wave photonic devices in silicon on insulator

Abstract

Opto-mechanical interactions in planar photonic integrated circuits draw great interest in basic research and applications. However, opto-mechanics is practically absent in the most technologically significant photonics platform: silicon on insulator. Previous demonstrations required the under-etching and suspension of silicon structures. Here we present surface acoustic wave-photonic devices in silicon on insulator, up to 8 GHz frequency. Surface waves are launched through absorption of modulated pump light in metallic gratings and thermo-elastic expansion. The surface waves are detected through photo-elastic modulation of an optical probe in standard race-track resonators. Devices do not involve piezo-electric actuation, suspension of waveguides or hybrid material integration. Wavelength conversion of incident microwave signals and acoustic true time delays up to 40 ns are demonstrated on-chip. Lastly, discrete-time microwave-photonic filters with up to six taps and 20 MHz-wide passbands are realized using acoustic delays. The concept is suitable for integrated microwave-photonics signal processing.

High-Frequency Mechanical Excitation of a Silicon Nanostring with Piezoelectric Aluminum Nitride Layers

“…The SAW is a Rayleigh wave; it does not require piezoelectricity to propagate, but it is easily generated by fabricating metallic interdigitated transducers (IDTs) on a piezoelectric material. This approach requires a simple ac bias to be fed to the IDTs rather than strong pulsed lasers, which can generate a SAW in a nonpiezoelectric material through thermally induced local deformations [19]; despite the reduced generation efficiency, the latter approach has been recently applied to SOI material for optomechanical applications [20]. Within the electrically generated SAW scenario, several material platforms have been investigated [21], starting from compact builds made of GaAs [7,[22][23][24], AlN [25], or LiNbO 3 [26].…”

Circulator‐Free Brillouin Photonic Planar Circuit

“…The recent emergence of on‐chip surface acoustic wave (SAW) transducers [ 11,50 ] provides a promising way to efficiently excite acoustic waves in integrated photonic circuits, without requiring complex waveguide structures or hybrid material integration. [ 51,52 ] Among these reported, the recent electrically driven approach utilizing a non‐suspended silicon waveguides promises a flexible control of photon–phonon interaction without the need of optical pump to excite acoustic waveguides, which provides an alternative technique to facilitate advanced Brillouin‐based applications.…”

Coupling of Integrated Waveguide and Optomechanic Cavity for Microwave Phonon Excitation in Si Nanobeams

“…Such cavities have been designed in phoxonic (or OM) crystals that exhibit simultaneous photonic and phononic band gaps [13][14][15]. Current research trends on OM structures include topics such as radiation-pressure cavity cooling [16,17], quantum coherent optomechanics [1,18], coherent amplification/cooling of Surface Acoustic Waves (SAWs) in optomechanical microcavities [6,[19][20][21][22][23][24], and high resolution sensing, in particular of biomolecules [25][26][27]. The basic phonon circuits which are typically taken into consideration are resonant mechanical cavities, as promising building blocks of more complex devices, including filters, couplers, and mechanical sources/detectors.…”