Phase-matched third-harmonic generation in silicon nitride waveguides

Surendar Vijayakumar; Kaustubh Vyas; Daniel H G Espinosa; Orad Reshef; Meiting Song; Kashif Masud Awan; Saumya Choudhary; Jaime Cardenas; Robert W Boyd; Ksenia Dolgaleva

doi:10.1515/nanoph-2024-0120

Phase-matched third-harmonic generation in silicon nitride waveguides

Nanophotonics. 2024 May 31;13(18):3385-3393. doi: 10.1515/nanoph-2024-0120. eCollection 2024 Aug.

Authors

Affiliations

¹ Institute of Optics, University of Rochester, 480 Intercampus Dr, Rochester, NY 14627, USA.
² School of Electrical Engineering and Computer Science, University of Ottawa, 800 King Edward Ave., Ottawa, ON, K1N 6N5, Canada.
³ Department of Physics, University of Ottawa, 25 Templeton Street, K1N 6N5, Ottawa, ON, Canada.
⁴ Department of Electrical and Computer Engineering, University of California Santa Barbara, Santa Barbara, CA, USA.
⁵ Institute of Materials Science and Engineering, Washington University, St Louis, MO 63130, USA.

Abstract

Third-harmonic generation (THG) in silicon nitride waveguides is an ideal source of coherent visible light, suited for ultrafast pulse characterization, telecom signal monitoring and self-referenced comb generation due to its relatively large nonlinear susceptibility and CMOS compatibility. We demonstrate third-harmonic generation in silicon nitride waveguides where a fundamental transverse mode at 1,596 nm is phase-matched to a TM₀₂ mode at 532 nm, confirmed by the far-field image. We experimentally measure the waveguide width-dependent phase-matched wavelength with a peak-power-normalized conversion efficiency of 5.78 × 10^-7 %/W² over a 660-μm-long interaction length.

Keywords: frequency conversion; harmonic generation; nonlinear optics; silicon nitride; waveguide.