High-Q slow light and its localization in a photonic crystal microring

Abstract

We introduce a photonic crystal ring cavity that resembles an internal gear and unites photonic crystal (PhC) and whispering gallery mode (WGM) concepts. This `microgear' photonic crystal ring (MPhCR) is created by applying a periodic modulation to the inside boundary of a microring resonator to open a large bandgap, as in a PhC cavity, while maintaining the ring's circularly symmetric outside boundary and high quality factor ($Q$), as in a WGM cavity. The MPhCR targets a specific WGM to open a large PhC bandgap up to tens of free spectral ranges, compressing the mode spectrum while maintaining the high-$Q$, angular momenta, and waveguide coupling properties of the WGM modes. In particular, near the dielectric band-edge, we observe modes whose group velocity is slowed down by 10 times relative to conventional microring modes while supporting $Q=(1.1\pm 0.1)\times 10^6$. This $Q$ is $\approx$50$\times$ that of the previous record in slow light devices. Using the slow light design as a starting point, we further demonstrate the ability to localize WGMs into photonic crystal defect (dPhC) modes for the first time, enabling a more than 10$\times$ reduction of mode volume compared to conventional WGMs while maintaining high-$Q$ up to (5.6$\pm$0.1)$\times$10${}^5$. Importantly, this additional dPhC localization is achievable without requiring detailed electromagnetic design. Moreover, controlling their frequencies and waveguide coupling is straightforward in the MPhCR, thanks to its WGM heritage. By using a PhC to strongly modify fundamental properties of WGMs, such as group velocity and localization, the MPhCR provides an exciting platform for a broad range of photonics applications, including sensing/metrology, nonlinear optics, and cavity quantum electrodynamics.

14 pages, 8 figures

References in corpus (3)

• Photonic quantum technologies
• Photonic Crystal Optical Parametric Oscillator
• Selective engineering of cavity resonance for frequency matching in optical parametric processes

Cited by in corpus (17)

• Synthetic-reflection self-injection-locked microcombs
• Chiral exceptional point and coherent suppression of backscattering in silicon microring with low loss Mie scatterer
• Creating boundaries along a synthetic frequency dimension
• Soliton Pulses in Photonic Crystal Fabry-Perot Microresonators
• Fourier synthesis dispersion engineering of photonic crystal microrings for broadband frequency combs
• Mirror-induced reflection in the frequency domain
• Highly-twisted states of light from a high quality factor photonic crystal ring
• Hyperparametric oscillation via bound states in the continuum
• Kerr optical parametric oscillation in a photonic crystal microring for accessing the infrared
• Spectral engineering of optical microresonators in anisotropic lithium niobate crystal
• Fractional optical angular momentum and multi-defect-mediated mode re-normalization and orientation control in photonic crystal microring resonators
• Strong interactions between integrated microresonators and alkali atomic vapors: towards single-atom, single-photon operation
• Multi-mode microcavity frequency engineering through a shifted grating in a photonic crystal ring
• Optimization of the degenerate optical parametric oscillations threshold in bichromatically pumped microresonator
• Imaginary coupling induced Dirac points and group velocity control in non-reciprocal Hermitian Lattice
• A heralded single-photon source implemented with second-order nonlinear photonic crystals
• A vapor-cavity-QED system for quantum computation and communication