Electrically driven acousto-optics and broadband non-reciprocity in silicon photonics

• Published in: Nature photonics Vol. 15; no. 1; pp. 43 - 52
• Main Authors: Kittlaus, Eric A., Jones, William M., Rakich, Peter T., Otterstrom, Nils T., Muller, Richard E., Rais-Zadeh, Mina
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.01.2021; Nature Publishing Group
• Subjects: 639/624/1075/1079; 639/624/1075/401; 639/624/399/1099; 639/624/400/1021; Acousto-optics; Applied and Technical Physics; Broadband; Circuits; Computer architecture; Couplings; Data processing; Fabrication; Information processing; Insertion loss; Isolators; Metal oxide semiconductors; Modulation; Modulators; New technology; Optics; Photonics; Physics; Physics and Astronomy; Quantum Physics; Reciprocity; Silicon; Single sideband transmission; Surface acoustic waves; Transducers; Waveguides
• ISSN: 1749-4885; 1749-4893
• DOI: 10.1038/s41566-020-00711-9

Emerging technologies based on tailorable photon–phonon interactions promise new capabilities ranging from high-fidelity information processing to non-reciprocal optics and quantum state control. However, many existing realizations of such light–sound couplings involve unconventional materials and fabrication schemes challenging to co-implement with scalable integrated photonic circuitry. Here, we demonstrate direct acousto-optic modulation within silicon waveguides using electrically driven surface acoustic waves (SAWs). By co-integrating electromechanical SAW transducers with a standard silicon-on-insulator photonic platform, we harness silicon’s strong elasto-optic effect to create travelling-wave phase and single-sideband amplitude modulators from 1 to 5 GHz, with index modulation strengths comparable to electro-optic technologies. Extending this non-local interaction to centimetre scales, we demonstrate non-reciprocal modulation with operation bandwidths of >100 GHz and insertion losses of <0.6 dB. This acousto-optic platform is compatible with complementary metal–oxide–semiconductor fabrication processes and existing silicon photonic device architectures, opening the door to flexible, low-loss modulators and non-magnetic optical isolators and circulators in integrated photonic circuits. Direct acousto-optic modulation within complementary metal–oxide–semiconductor compatible silicon photonic waveguides using electrically driven surface acoustic waves is demonstrated. Non-reciprocal operation bandwidths of >100 GHz and insertion losses of <0.6 dB are obtained.