Stanford Advisors

All Publications

  • Probing material absorption and optical nonlinearity of integrated photonic materials NATURE COMMUNICATIONS Gao, M., Yang, Q., Ji, Q., Wang, H., Wu, L., Shen, B., Liu, J., Huang, G., Chang, L., Xie, W., Yu, S., Papp, S. B., Bowers, J. E., Kippenberg, T. J., Vahala, K. J. 2022; 13 (1): 3323


    Optical microresonators with high quality (Q) factors are essential to a wide range of integrated photonic devices. Steady efforts have been directed towards increasing microresonator Q factors across a variety of platforms. With success in reducing microfabrication process-related optical loss as a limitation of Q, the ultimate attainable Q, as determined solely by the constituent microresonator material absorption, has come into focus. Here, we report measurements of the material-limited Q factors in several photonic material platforms. High-Q microresonators are fabricated from thin films of SiO2, Si3N4, Al0.2Ga0.8As, and Ta2O5. By using cavity-enhanced photothermal spectroscopy, the material-limited Q is determined. The method simultaneously measures the Kerr nonlinearity in each material and reveals how material nonlinearity and ultimate Q vary in a complementary fashion across photonic materials. Besides guiding microresonator design and material development in four material platforms, the results help establish performance limits in future photonic integrated systems.

    View details for DOI 10.1038/s41467-022-30966-5

    View details for Web of Science ID 000809423400063

    View details for PubMedID 35680923

    View details for PubMedCentralID PMC9184588

  • Vernier spectrometer using counterpropagating soliton microcombs SCIENCE Yang, Q., Shen, B., Wang, H., Minh Tran, Zhang, Z., Yang, K., Wu, L., Bao, C., Bowers, J., Yariv, A., Vahala, K. 2019; 363 (6430): 965-+
  • Vernier spectrometer using counterpropagating soliton microcombs. Science (New York, N.Y.) Yang, Q., Shen, B., Wang, H., Tran, M., Zhang, Z., Yang, K. Y., Wu, L., Bao, C., Bowers, J., Yariv, A., Vahala, K. 2019


    Determination of laser frequency with high resolution under continuous and abrupt tuning conditions is important for sensing, spectroscopy, and communications. We show that a single microresonator provides rapid and broadband measurement of optical frequencies with a relative frequency precision comparable to that of conventional dual-frequency comb systems. Dual-locked counterpropagating solitons having slightly different repetition rates were used to implement a vernier spectrometer, which enabled characterization of laser tuning rates as high as 10 terahertz per second, broadly step-tuned lasers, multiline laser spectra, and molecular absorption lines. Besides providing a considerable technical simplification through the dual-locked solitons and enhanced capability for measurement of arbitrarily tuned sources, our results reveal possibilities for chip-scale spectrometers that exceed the performance of tabletop grating and interferometer-based devices.

    View details for PubMedID 30792361