Research Projects

Nonlinear Photonics & Integrated Lasers

We generate an integrated high-power Kerr frequency comb in a silicon-nitride resonator via self-injection locking of a high-power multimode gain chip. We generate 27 comb lines with total power exceeding 0.1 W.

A. Gil-Molina, Y. Antman, O. Westreich, X. Ji, M. C. Shin, G. R. Bhatt, B. Y. Kim, Y. Okawachi, A. L. Gaeta, and M. Lipson, "High-Power Fully-Integrated Frequency Comb Generation," in Conference on Lasers and Electro-Optics, Optica Technical Digest (Optica Publishing Group, 2022), paper SF2G.2.

We demonstrate a supercontinuum light source for OCT imaging in a compact 1 mm2 Si3N4 chip. We achieve 105 dB sensitivity and a 6-dB sensitivity roll-off at 1.81 mm with only 300 µW incident power.

X. Ji, D. Mojahed, Y. Okawachi, A. L. Gaeta, C. P. Hendon, and M. Lipson, "Millimeter-Scale Chip-Based Supercontinuum Generation for Optical Coherence Tomography," in Conference on Lasers and Electro-Optics, OSA Technical Digest (Optical Society of America, 2021), paper STh1H.6.

We demonstrate a highly efficient integrated laser, with more than 200 mW single mode output, overcoming the tradeoff between high power, efficiency and coherence in traditional lasers. The laser is based on the collapsing of a multimode gain into a single mode via self-injection locking.

Y. Antman, A. Gil-Molina, O. Westreich, X. Ji, A. L. Gaeta, and M. Lipson, "High Power and High Efficiency on-chip Integrated Laser," in Conference on Lasers and Electro-Optics, Optica Technical Digest (Optica Publishing Group, 2022), paper SM2P.2.

Visible Photonics for Emerging Fields

Widely-tunable and narrow-linewidth integrated lasers across all visible wavelengths are necessary to enable on-chip technologies such as quantum photonics, optical trapping, and biophotonics. However, such lasers have not been realized due to the strong wavelength sensitivity and high loss of integrated optical devices at short wavelengths. Here we overcome these challenges and demonstrate a chip-scale visible lasers platform by using tightly-confined, micrometer-scale silicon nitride resonators and commercial Fabry-Perot laser diodes. We achieve tunable and narrow-linewidth lasing in the deep blue (450 nm), blue (488 nm), green (520 nm), red (660 nm) and near-IR (785 nm) with coarse tuning up to 12 nm, fine tuning up to 33.9 GHz, linewidth down to sub-kHz, side-mode suppression ratio > 35 dB, and fiber-coupled power up to 10 mW. These specifications of our chip-scale lasers are comparable to those of state-of-the-art commercial laser systems, making them stand out as powerful tools for the next generation of visible-light technologies.

M. Corato-Zanarella, A. Gil-Molina, X. Ji, M. C. Shin, A. Mohanty, and M. Lipson, "Widely tunable and narrow linewidth chip-scale lasers from deep visible to near-IR," arXiv preprint arXiv:2109.08337 (2021).

chip-scale visible lasers

We demonstrate the first phased array operating at blue wavelengths. We show wide-angle beam steering over a 50° field-of-view with a beam width of less than 0.17° using a high confinement silicon nitride waveguide platform.

M. C. Shin, A. Mohanty, K. Watson, G. R. Bhatt, C. T. Phare, S. A. Miller, M. Zadka, B. S. Lee, X. Ji, E. Shim, I. Datta, and M. Lipson, "Chip-scale Blue Phased Array," in Conference on Lasers and Electro-Optics, OSA Technical Digest (Optical Society of America, 2019), paper JTh5B.5.

chip-scale blue phased array

2D Material Nanophotonics

We show low insertion loss platform based on loss modulation of hybrid SiN/graphene structure. We measure an intrinsic quality factor of 80,000 in a ring resonator based device when the graphene is in its high loss state.

I. Datta, X. Ji, G. R. Bhatt, B. S. Lee, and M. Lipson, "Low insertion loss, graphene-based platform for loss modulation," in Conference on Lasers and Electro-Optics, Optica Technical Digest (Optica Publishing Group, 2022), paper SM5P.4.

Novel Concepts in Integrated Photonics

We demonstrate the loading of very short optical pulses into a high-Q cavity with linewidth much narrower than the pulse frequency envelope. We show that loading into the cavity is significantly enhanced if the pulse is combined with a cw-field, thus altering the pulse frequency profile to better match the cavity profile.

J. Hinney, U. D. Dave, A. G. Molina, X. Ji, and M. Lipson, "Loading short pulses into long lifetime cavities," in Conference on Lasers and Electro-Optics, Optica Technical Digest (Optica Publishing Group, 2022), paper FM5B.3.

We demonstrate SiN-based passive waveguides with ultra-low thermo-optic effect, based on a novel waveguiding mechanism that confines light in the lower index of refraction. We demonstrate broadband operation over at least 200nm, with less than 0.01% change in the index over 200 degrees.

J. R. Rodrigues, G. R. Bhatt, I. Datta, U. D. Dave, S. Chaitanya, E. Shim, and M. Lipson, "SiN-based waveguides with ultra-low thermo-optic effect," in Conference on Lasers and Electro-Optics, Optica Technical Digest (Optica Publishing Group, 2022), paper SM4G.3.

We demonstrate passive PT symmetry breaking between the spatial modes within a single SOI waveguide with metal deposited directly on top. By leveraging this effect, we show low propagation loss of < 1 dB for a 100 μm long, 10 μm wide waveguide partially covered with 100 nm thick metal.

U. D. Dave and M. Lipson, "Low Loss Propagation in a Metal-clad Waveguide via PT-Symmetry Breaking," in Conference on Lasers and Electro-Optics, OSA Technical Digest (Optical Society of America, 2019), paper FW4D.4.

metal-clad waveguide via PT

We demonstrate robust mode conversion up to the 12th higher order mode in silicon waveguides by using an optimized adiabatic directional coupler and using subwavelength waveguides. The conversion efficiency is better than -1.5 dB over a 75 nm bandwidth and tolerating ±30 nm fabrication variations.

U. D. Dave and M. Lipson, "Efficient Conversion to Very High Order Modes in Silicon Waveguides," in Conference on Lasers and Electro-Optics, OSA Technical Digest (Optical Society of America, 2019), paper SM3J.6.

very high order modes

Manipulating Mid-IR and Far-IR Light

We demonstrate a single longitudinal mode, tunable mid-IR laser by self-injection locking a multiple longitudinal mode Interband Cascade Laser (ICL) to a high-Q Si microresonator at 3.4 μm.

E. Shim, A. G. Molina, O. Westreich, Y. Dikmelik, K. Lascola, A. L. Gaeta, and M. Lipson, "Single-mode tunable mid-IR laser based on a high-Q silicon microresonator," in Conference on Lasers and Electro-Optics, OSA Technical Digest (Optical Society of America, 2020), paper STh1E.2.

We demonstrate a platform for heat-to-electricity conversion based on near-field radiative heat transfer. The platform is based on tens-of-μm long suspended micro-heaters at >400˚C, placed <100 nm away from a room temperature photodetector.

G. R. Bhatt, S. Roberts, R. St-Gelais, T. Lin, A. Mohanty, B. Zhao, J. Hartmann, S. Fan, and M. Lipson, "Near-field thermo-photovoltaic platform," in Conference on Lasers and Electro-Optics, OSA Terchnical Digest (online) (Optical Society of America, 2018), paper FTu3E.2.