Unidirectional frequency conversion in microring resonators for on-chip frequency-multiplexed single-photon sources

Abstract

Microring resonators are attractive for low-power frequency conversion via Bragg-scattering fourwave-mixing due to their comb-like resonance spectrum, which allows resonant enhancement of all four waves while maintaining energy and momentum conservation. However, the symmetry of such mode structures limits the conversion efficiency to 50% due to the equal probability of up-and downconversion. Here, we demonstrate how two coupled microrings enable highly directional conversion between the spectral modes of one of the rings. An extinction between up-and down-conversion of more than 40 dB is experimentally observed. Based on this method, we propose a design for on-chip multiplexed single-photon sources that probabilistically generate photon pairs across many frequency modes of a ring resonator and subsequently convert them to a single frequency-thereby enabling quasi-deterministic photon emission. Our numerical analysis shows that once a photon is generated, it can be converted and emitted into a wave packet having a 90% overlap with a Gaussian with 99% efficiency for a ratio between intrinsic and coupling quality factors of 400.

Photon-photon interactions in dynamically coupled cavities

“…Here, we propose a method to achieve dynamic coupling that uses the parametric nonlinearity of cavity materials (χ (2) or χ (3) ) and therefore avoids loss. Two strong optical control fields may couple two cavity modes via socalled Bragg-scattering four-wave-mixing (FWM) in χ (3)materials [10][11][12] and a single control field may do the same in a χ (2) material [5,13], as illustrated with arrows in Fig. 1b.…”

“…1b). External control over the coupling between the cavity modes therefore introduces a time-dependent effective coupling between the decoupled mode and the waveguide [12]. In other words, photons may be loaded in and out of the decoupled mode via the strongly coupled mode due to their time-dependent mutual coupling.…”

High-Q Interstitial Square Coupled Microring Resonators Arrays

“…The transmission phases of the MRRs at resonance change abruptly and the group velocities reduce dramatically, providing an efficient way to slow the light wave. Such slow-light phenomenon has been explored to realize many critical optical components/devices, including the high-performance filter such as add-drop filters [64] and wavelength division multiplexers [65], [66], optical delay lines [67], Parity-Time (PT) symmetric devices [68], nonlinear light-wave and materials interaction such as four wave mixing [69], optical parametric generation [70], [86], single-photon/photon-pair source [71], [81], [88], frequency comb generation [92], optical quantum computing [84], as well as high-quality sensors [90], [85], [98], [96]. Depending on its geometry, two typical MRRs are actively studied, i.e., the circular MRRs and the racetrack MRRs.…”

On-chip electro-optic frequency shifters and beam splitters

“…However, realizing GHz-scale frequency shifts with high efficiency, low loss and reconfigurability, in particular using a miniature and scalable device, is challenging since it requires efficient and controllable nonlinear optical processes. Existing approaches based on acousto-optics [6, 14-16], all-optical wave mixing [10,13,[17][18][19], and electrooptics [20][21][22][23] are either limited to low efficiencies or frequencies, or are bulky, and have yet to simultaneously demonstrate the required properties mentioned above. Here we demonstrate an onchip electro-optic frequency shifter that is precisely controlled using only a single-tone microwave signal.…”