Efficient excitation and control of integrated photonic circuits with virtual critical coupling

Jakob Hinney; Seunghwi Kim; Graydon J K Flatt; Ipshita Datta; Andrea Alù; Michal Lipson

doi:10.1038/s41467-024-46908-2

Efficient excitation and control of integrated photonic circuits with virtual critical coupling

Nat Commun. 2024 Mar 28;15(1):2741. doi: 10.1038/s41467-024-46908-2.

Authors

Jakob Hinney^#¹, Seunghwi Kim^#², Graydon J K Flatt³, Ipshita Datta¹, Andrea Alù^{4

5}, Michal Lipson^{6

7}

Affiliations

¹ Department of Electrical Engineering, Columbia University, New York, NY, 10027, USA.
² Photonics Initiative, Advanced Science Research Center, City University of New York, New York, NY, 10031, USA.
³ Department of Applied Physics and Applied Mathematics, Columbia University, New York, NY, 10027, USA.
⁴ Photonics Initiative, Advanced Science Research Center, City University of New York, New York, NY, 10031, USA. aalu@gc.cuny.edu.
⁵ Physics Program, Graduate Center, City University of New York, New York, NY, 10016, USA. aalu@gc.cuny.edu.
⁶ Department of Electrical Engineering, Columbia University, New York, NY, 10027, USA. ml3745@columbia.edu.
⁷ Department of Applied Physics and Applied Mathematics, Columbia University, New York, NY, 10027, USA. ml3745@columbia.edu.

^# Contributed equally.

Abstract

Critical coupling in integrated photonic devices enables the efficient transfer of energy from a waveguide to a resonator, a key operation for many applications. This condition is achieved when the resonator loss rate is equal to the coupling rate to the bus waveguide. Carefully matching these quantities is challenging in practice, due to variations in the resonator properties resulting from fabrication and external conditions. Here, we demonstrate that efficient energy transfer to a non-critically coupled resonator can be achieved by tailoring the excitation signal in time. We rely on excitations oscillating at complex frequencies to load an otherwise overcoupled resonator, demonstrating that a virtual critical coupling condition is achieved if the imaginary part of the complex frequency equals the mismatch between loss and coupling rate. We probe a microring resonator with tailored pulses and observe a minimum intensity transmission $T = 0.11$ in contrast to a continuous-wave transmission $T = 0.58$ , corresponding to 8 times enhancement of intracavity intensity. Our technique opens opportunities for enhancing and controlling on-demand light-matter interactions for linear and nonlinear photonic platforms.