All Publications

  • Ultra-low-power second-order nonlinear optics on a chip. Nature communications McKenna, T. P., Stokowski, H. S., Ansari, V., Mishra, J., Jankowski, M., Sarabalis, C. J., Herrmann, J. F., Langrock, C., Fejer, M. M., Safavi-Naeini, A. H. 2022; 13 (1): 4532


    Second-order nonlinear optical processes convert light from one wavelength to another and generate quantum entanglement. Creating chip-scale devices to efficiently control these interactions greatly increases the reach of photonics. Existing silicon-based photonic circuits utilize the third-order optical nonlinearity, but an analogous integrated platform for second-order nonlinear optics remains an outstanding challenge. Here we demonstrate efficient frequency doubling and parametric oscillation with a threshold of tens of micro-watts in an integrated thin-film lithium niobate photonic circuit. We achieve degenerate and non-degenerate operation of the parametric oscillator at room temperature and tune its emission over one terahertz by varying the pump frequency by hundreds of megahertz. Finally, we observe cascaded second-order processes that result in parametric oscillation. These resonant second-order nonlinear circuits will form a crucial part of the emerging nonlinear and quantum photonics platforms.

    View details for DOI 10.1038/s41467-022-31134-5

    View details for PubMedID 35927246

  • Mirror symmetric on-chip frequency circulation of light NATURE PHOTONICS Herrmann, J. F., Ansari, V., Wang, J., Witmer, J. D., Fan, S., Safavi-Naeini, A. H. 2022
  • High-bandwidth CMOS-voltage-level electro-optic modulation of 780 nm light in thin-film lithium niobate OPTICS EXPRESS Celik, O., Sarabalis, C. J., Mayor, F. M., Stokowski, H. S., Herrmann, J. F., McKenna, T. P., Lee, N. A., Jiang, W., Multani, K. S., Safavi-Naeini, A. H. 2022; 30 (13): 23177-23186

    View details for DOI 10.1364/OE.460119

    View details for Web of Science ID 000813479600073

  • III/V-on-lithium niobate amplifiers and lasers OPTICA de Beeck, C., Mayor, F. M., Cuyvers, S., Poelman, S., Herrmann, J. F., Atalar, O., McKenna, T. P., Haq, B., Jiang, W., Witmer, J. D., Roelkens, G., Safavi-Naeini, A. H., Van Laer, R., Kuyken, B. 2021; 8 (10): 1288-1289
  • Photonic Modal Circulator Using Temporal Refractive-Index Modulation with Spatial Inversion Symmetry. Physical review letters Wang, J., Herrmann, J. F., Witmer, J. D., Safavi-Naeini, A. H., Fan, S. 2021; 126 (19): 193901


    It has been demonstrated that dynamic refractive-index modulation, which breaks time-reversal symmetry, can be used to create on-chip nonreciprocal photonic devices. In order to achieve amplitude nonreciprocity, all such devices moreover require modulations that break spatial symmetries, which adds complexity in implementations. Here we introduce a modal circulator, which achieves amplitude nonreciprocity through a circulation motion among three modes. We show that such a circulator can be achieved in a dynamically modulated structure that preserves mirror symmetry, and as a result can be implemented using only a single standing-wave modulator, which significantly simplifies the implementation of dynamically modulated nonreciprocal devices. We also prove that in terms of the number of modes involved in the transport process, the modal circulator represents the minimum configuration in which complete amplitude nonreciprocity can be achieved while preserving spatial symmetry.

    View details for DOI 10.1103/PhysRevLett.126.193901

    View details for PubMedID 34047603

  • Cryogenic microwave-to-optical conversion using a triply resonant lithium-niobate-on-sapphire transducer OPTICA McKenna, T. P., Witmer, J. D., Patel, R. N., Jiang, W., Van Laer, R., Arrangoiz-Arriola, P., Wollack, E., Herrmann, J. F., Safavi-Naeini, A. H. 2020; 7 (12): 1737–45