Integrated frequency-modulated optical parametric oscillator

Hubert S Stokowski; Devin J Dean; Alexander Y Hwang; Taewon Park; Oguz Tolga Celik; Timothy P McKenna; Marc Jankowski; Carsten Langrock; Vahid Ansari; Martin M Fejer; Amir H Safavi-Naeini

doi:10.1038/s41586-024-07071-2

Integrated frequency-modulated optical parametric oscillator

Nature. 2024 Mar;627(8002):95-100. doi: 10.1038/s41586-024-07071-2. Epub 2024 Mar 6.

Authors

Hubert S Stokowski¹, Devin J Dean¹, Alexander Y Hwang¹, Taewon Park^{1

2}, Oguz Tolga Celik^{1

2}, Timothy P McKenna^{1

3}, Marc Jankowski^{1

3}, Carsten Langrock¹, Vahid Ansari¹, Martin M Fejer¹, Amir H Safavi-Naeini⁴

Affiliations

¹ Department of Applied Physics and Ginzton Laboratory, Stanford University, Stanford, CA, USA.
² Department of Electrical Engineering, Stanford University, Stanford, CA, USA.
³ Physics and Informatics Laboratories, NTT Research, Sunnyvale, CA, USA.
⁴ Department of Applied Physics and Ginzton Laboratory, Stanford University, Stanford, CA, USA. safavi@stanford.edu.

PMID: 38448697
DOI: 10.1038/s41586-024-07071-2

Abstract

Optical frequency combs have revolutionized precision measurement, time-keeping and molecular spectroscopy^1-7. A substantial effort has developed around 'microcombs': integrating comb-generating technologies into compact photonic platforms^5,7-9. Current approaches for generating these microcombs involve either the electro-optic¹⁰ or Kerr mechanisms¹¹. Despite rapid progress, maintaining high efficiency and wide bandwidth remains challenging. Here we introduce a previously unknown class of microcomb-an integrated device that combines electro-optics and parametric amplification to yield a frequency-modulated optical parametric oscillator (FM-OPO). In contrast to the other solutions, it does not form pulses but maintains operational simplicity and highly efficient pump power use with an output resembling a frequency-modulated laser¹². We outline the working principles of our device and demonstrate it by fabricating the complete optical system in thin-film lithium niobate. We measure pump-to-comb internal conversion efficiency exceeding 93% (34% out-coupled) over a nearly flat-top spectral distribution spanning about 200 modes (over 1 THz). Compared with an electro-optic comb, the cavity dispersion rather than loss determines the FM-OPO bandwidth, enabling broadband combs with a smaller radio-frequency modulation power. The FM-OPO microcomb offers robust operational dynamics, high efficiency and broad bandwidth, promising compact precision tools for metrology, spectroscopy, telecommunications, sensing and computing.