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International Conference on Transparent Optical Networks

Spontaneous parametric downconversion in periodically poled linearly uncoupled resonators

Matteo Piccolini, Alessia Stefano, Luca Zatti, Marco Liscidini

Published Jul 6, 2025• 0 citations
Publisher

Abstract

We demonstrate a reconfigurable photon pair source based on spontaneous parametric downconversion in a periodically poled aluminum nitride doubly resonant system. The device features two linearly uncoupled microring resonators integrated in a Mach-Zehnder interferometer, enabling independent tuning of pump and signal/idler resonances without complex dispersion engineering. Using a silicon nitride strip-loaded waveguide on poled aluminum nitride, we achieve quasi-phase-matching and resonant enhancement over a broad spectral range. Simulations predict efficient generation across a bandwidth of over 200 nm, with rates exceeding 4 MHz/mW per resonance. This platform offers high performance, spectral tunability, and fabrication tolerance for integrated quantum photonic applications.

DOI
10.1109/icton67126.2025.11125186

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We demonstrate a reconfigurable photon pair source based on spontaneous parametric downconversion in a periodically poled aluminum nitride doubly resonant system. The device features two linearly uncoupled microring resonators integrated in a Mach-Zehnder interferometer, enabling independent tuning of pump and signal/idler resonances without complex dispersion engineering. Using a silicon nitride strip-loaded waveguide on poled aluminum nitride, we achieve quasi-phase-matching and resonant enhancement over a broad spectral range. Simulations predict efficient generation across a bandwidth of over 200 nm, with rates exceeding 4 MHz/mW per resonance. This platform offers high performance, spectral tunability, and fabrication tolerance for integrated quantum photonic applications.
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We report an integrated platform for efficient second-order nonlinear interactions based on linearly uncoupled resonators and angular phase matching. The proposed architecture confines phase control to a limited section of the device, maximizing field enhancement and effective nonlinear interaction length while simultaneously reducing the overall footprint. As an example we show the results for an AlGaAs-on-insulator structure demonstrating a photon-pair generation rate of 3.16 GHz/mW in the continuous-wave regime and 5.89 MHz under pulsed pumping. The generated biphoton state exhibits a Schmidt number K=1.02, indicating nearly uncorrelated photon pairs. The compact and reconfigurable nature of this approach, together with its independence from material-specific poling techniques, makes it applicable to a broad class of integrated χ2χ_2χ2​ nonlinear platforms.
Abstract Microring resonators (MRRs) are extensively utilized in photonic chips for generating quantum light sources and enabling high-efficiency nonlinear frequency conversion. However, conventional microrings are typically optimized for a single specific function, limiting their versatility in multifunctional applications. In this work, we propose a reconfigurable microring resonator architecture designed to accommodate diverse application requirements. By integrating a cascaded Mach–Zehnder interferometer (MZI) as the microring coupler, the design enables independent control of the quality factors for pump, signal and idler photons through two tunable phase shifters. This capability allows for dynamic tuning and optimization of critical performance parameters, including photon-pair generation rate (PGR), spectral purity and single photon heralding efficiency (HE). The proposed structure is implemented on a silicon photonic chip, and experimental results exhibit a wide range of tunability for these parameters, with excellent agreement with theoretical predictions. This flexible and multi-functional design offers a promising pathway for high-performance, highly integrated on-chip quantum information processing systems.
Ring resonators are used as photon pair sources by taking advantage of the materials second or third order non- linearities through the processes of spontaneous parametric downconversion and spontaneous four wave mixing respectively. Two materials of interest for these applications are silicon for the infrared and aluminum nitride for the ultraviolet through the infrared. When fabricated into ring type sources they are capable of producing pairs of indistinguishable photons but typically suffer from an effective 50% loss. By slightly decoupling the input waveguide from the ring, the drop port coincidence ratio can be significantly increased with the trade-off being that the pump is less efficiently coupled into the ring. Ring resonators with this design have been demonstrated having coincidence ratios of 96% but requiring a factor of ~10 increase in the pump power. Through the modification of the coupling design that relies on additional spectral dependence, it is possible to achieve similar coincidence ratios without the increased pumping requirement. This can be achieved by coupling the input waveguide to the ring multiple times, thus creating a Mach-Zehnder interferometer. This coupler design can be used on both sides of the ring resonator so that resonances supported by one of the couplers are suppressed by the other. This is the ideal configuration for a photon-pair source as it can only support the pump photons at the input side while only allowing the generated photons to leave through the output side. Recently, this device has been realized with preliminary results exhibiting the desired spectral dependence and with a coincidence ratio as high as ~ 97% while allowing the pump to be nearly critically coupled to the ring. The demonstrated near unity coincidence ratio infers a near maximal heralding efficiency from the fabricated device. This device has the potential to greatly improve the scalability and performance of quantum computing and communication systems.
We report the design of an innovative visible-telecom photon pair source based on counter-propagating spontaneous four wave mixing (CP-SFWM) in a silicon nitride microring resonator. Unlike previous designs, the proposed integrated source achieves automatic phase matching, eliminating the need for dispersion engineering. By employing two lasers at wavelengths of 800 nm and 1550 nm as pumps on opposite ends of the bus waveguides, the resonator generates signal and idler photons at the same wavelengths as the pumps, but propagating in opposite directions. The photon pairs are produced in high-quality factor resonant modes, exhibiting a purity of 1, a brightness of 118.70pairs⋅s−1⋅mW−2, and bandwidths of 157.9 MHz and 79.7 MHz for signal and idler photons, respectively. Our proposal outperforms previous CP-SFWM designs in terms of spectral properties of the photon pairs, emission rate, and scalability, making it an interesting alternative for the implementation of integrated photon pair sources for photonic networks.