Research Projects

Nonlinear Photonics & Integrated Lasers

We demonstrate high-power, fully-integrated Kerr frequency combs by self-injection locking multimode gain chips with silicon-nitride resonators. We demonstrate 25 comb lines > 100 μW with 200 kHz linewidth, and OOK modulation at 12.5 Gb/s.

A. Gil-Molina, Y. Antman, O. Westreich, X. Ji, M. C. Shin, G. R. Bhatt, I. Datta, B. Y. Kim, Y. Okawachi, A. L. Gaeta, and M. Lipson, "WDM Transmission via High-Power Fully-Integrated Kerr Frequency Combs," in Conference on Lasers and Electro-Optics, Optica Technical Digest (Optica Publishing Group, 2023), paper STu4L.1.

We demonstrate a foundry-compatible platform based on bilayer LPCVD-PECVD SiN waveguides. Using microrings fabricated from our bilayer waveguide, we show a Kerr soliton frequency comb spanning 300 nm with 125 mW of pump power.

K. J. McNulty, X. Ji, A. Gil-Molina, M. Corato-Zanarella, G. R. Bhatt, I. Datta, S. Chaitanya, Y. Okawachi, A. L. Gaeta, and M. Lipson, "Low Stress Bilayer LPCVD-PECVD SiN Waveguides for Kerr Frequency Comb Generation," in Conference on Lasers and Electro-Optics, Optica Technical Digest (Optica Publishing Group, 2023), paper STh1J.2.

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

We demonstrate an ultra-low loss (down to 3.62 dB/m) SiN platform for visible wavelengths where ultra-high Q (up to 2.07 x 107) microresonators probe the limits of absorption and scattering losses.

M. Corato-Zanarella, X. Ji, A. Mohanty, and M. Lipson, "Pushing the Limits of Photonics in the Visible Spectrum," in Conference on Lasers and Electro-Optics, Optica Technical Digest (Optica Publishing Group, 2023), paper SF3K.1.

Widely tunable and narrow linewidth lasers at visible wavelengths are necessary for applications such as quantum optics, optical clocks, and atomic and molecular physics. Currently used lasers are benchtop, precluding these technologies from getting outside of research laboratories. Here we demonstrate a chip-scale visible lasers platform that enables tunable and narrow linewidth lasers from near-ultraviolet to near-infrared. By using micrometer-scale silicon nitride resonators and commercial Fabry-Perot laser diodes, we achieve coarse tuning up to 12.5 nm and mode-hop-free fine tuning up to 33.9 GHz with intrinsic linewidths down to a few kHz. In addition, we show fine tuning speeds up to 267 GHz/µs, fiber-coupled powers up to 10 mW and typical side-mode suppression ratios above 35 dB. These specifications of our chip-scale lasers had only been previously achieved by large state-of-the-art benchtop laser systems, making our lasers 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 near-ultraviolet to near-infrared wavelengths," Nature Photonics 17(2), 157-164 (2023).

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 induce virtual critical coupling in an overcoupled photonic microresonator using complex-frequency pulses. We observe efficient cavity storage as an incident pulse of time constant 138 ps suppresses the resonant transmission from 0.58 to 0.11.

J. Hinney, S. Kim, G. J. K. Flatt, I. Datta, A. Alù, and M. Lipson, "Efficient Power Transfer via Induced Virtual Critical Coupling in an Overcoupled Silicon Nitride Microresonator," in Conference on Lasers and Electro-Optics, Optica Technical Digest (Optica Publishing Group, 2023), paper JTh2A.69.

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.