Simulation-guided design of an integrated photonic cavity for frequency-multiplexed Spontaneous Parametric Down Conversion

TL;DR

This paper presents a simulation-based design of an integrated photonic cavity for frequency-multiplexed entangled photon pair generation, achieving high efficiency and narrow bandwidths suitable for quantum networks.

Contribution

It introduces a novel simulation framework combining classical electromagnetic simulations with an analytical model to predict quantum performance of photonic sources.

Findings

Simulated 90 doubly resonant frequency modes with high Schmidt number.

Achieved average bandwidth of 1.08 GHz and pair-generation-rate efficiency of 1.16 GHz/mW.

Derived a closed-form analytical connection between cavity parameters and quantum spectral properties.

Abstract

Frequency-multiplexed entangled photon pair sources with narrow bandwidths and high pair generation efficiency are a key enabling technology for quantum networking. We present a simulation-based design study of an integrated photonic racetrack resonator source for spontaneous parametric down-conversion (SPDC) that simultaneously achieves all three properties. The central result is a simulated set of 90 doubly resonant signal/idler frequency-mode pairs with an effective Schmidt number of 89.62, average bandwidths of 1.08 GHz, a mean free spectral range of 51.9 GHz, and a total internal pair-generation-rate efficiency of 1.16 GHz/mW. Under deterministic wavelength-based splitting, the accessible frequency-state Schmidt number is reduced to 44.93. To support these predictions, we derive a closed-form analytical connection between classical cavity parameters (resonant frequencies, decay rates, coupling coefficients) and the quantum joint spectral amplitude and pair generation rate, extending the dispersive-medium quantization formalism of Raymer to the nonlinear optical cavity case. We demonstrate how classical electromagnetic field simulations can be combined with this analytical framework to predict quantum figures of merit for an integrated photonic source prior to fabrication. Fabrication and experimental validation are left for future work.