Abstract Fabry‐Pérot (F‐P) cavities are highly desirable for atom cooling and narrow‐linewidth generation. However, there are few studies on integrated F‐P cavities with high‐quality factors in the visible and near‐visible wavelength ranges, particularly at 780 nm, which corresponds to the energy transition of rubidium atoms. In this work, an integrated F‐P cavity design based on silicon nitride is demonstrated achieving an intrinsic quality factor of 6.1 × 105 at 780 nm without thermal annealing, along with a broad operating bandwidth of 500 nm and high fabrication tolerance. To the best of the knowledge, this quality factor represents the highest reported value in these wavelength ranges, accompanied by the largest operating bandwidth. These results offer significant potential for advancing on‐chip atom cooling and contribute to the broader development of photonic integrated circuits and quantum optics.
Abstract Fabry‐Pérot (F‐P) cavities are highly desirable for atom cooling and narrow‐linewidth generation. However, there are few studies on integrated F‐P cavities with high‐quality factors in the visible and near‐visible wavelength ranges, particularly at 780 nm, which corresponds to the energy transition of rubidium atoms. In this work, an integrated F‐P cavity design based on silicon nitride is demonstrated achieving an intrinsic quality factor of 6.1 × 105 at 780 nm without thermal annealing, along with a broad operating bandwidth of 500 nm and high fabrication tolerance. To the best of the knowledge, this quality factor represents the highest reported value in these wavelength ranges, accompanied by the largest operating bandwidth. These results offer significant potential for advancing on‐chip atom cooling and contribute to the broader development of photonic integrated circuits and quantum optics.
We demonstrate a silicon nitride integrated FabryPérot cavity achieving quality of6.1×105at 780 nm, bandwidth of 500 nm and high fabrication tolerance. This represents the highest Q-factor and widest bandwidth in visible/near-visible wavelengths, enabling on-chip atom cooling, advancing photonic integrated circuits and quantum optics.
Abstract Multi‐wavelength quantum light sources are extremely desired in establishing communication links among multiple users for realizing quantum networks. Despite recent impressive advances, developing such a quantum light source with high quality remains challenging. Here a multi‐wavelength quantum light source using a silicon nitride micro‐ring with a free spectral range of 200 GHz is demonstrated. The generation of eight‐wavelength‐paired photon pairs is ensured in a wavelength range of 25.6 nm. With device optimization and noise‐rejecting filters, this source enables the generation of heralded single‐photons at a rate of 62 kHz with and the generation of energy‐time entangled photons with a visibility of in the Franson interferometer. These results, at room temperature and telecom wavelength, in a CMOS‐compatible platform, represent an important step toward integrated quantum photonic devices, which pave the way for realizing a large‐scale quantum network.
Precision atomic and quantum experiments rely on ultra-stable narrow linewidth lasers constructed using table-top ultra-low expansion reference cavities. These experiments often require multiple lasers, operating at different wavelengths, to perform key steps used in state preparation and measurement required in quantum sensing and computing. This is traditionally achieved by disciplining a cavity-stabilized laser to a key atomic transition and then transferring the transition linewidth and stability to other lasers using the same reference cavity in combination with bulk-optic frequency shifting such as acousto-optic modulators. Transitioning such capabilities to a future potentially low-cost photonic-integrated platform will enable a wide range of portable, low power, scalable quantum experiments and applications. Yet, today’s bulk optic approaches pose challenges related to lack of cavity tunability, large free spectral range, and limited photonic integration potential. Here, we address these challenges with demonstration of an agile photonic-integrated 780 nm ultra-high-Q tunable silicon nitride reference cavity that performs multiple critical experimental steps including laser linewidth narrowing, high resolution rubidium spectroscopy, dual-stage stabilization to a rubidium transition, and stability transfer to other lasers. We achieve up to 20 dB of frequency noise reduction at 10 kHz offset, precision spectroscopy over a 250 MHz range, and dual-stage locking to rubidium with an Allan deviation of 8.5 × 10 −12 at 1 s and up to 40 dB frequency noise reduction at 100 Hz frequency offset. We further use the rubidium-disciplined cavity to provide atomic-referenced frequency stability to a second laser and demonstrate multi-wavelength Rydberg electrometry quantum sensing. These results pave the path for integrated, compact, and scalable solutions for quantum sensing, computing, and other atomic and trapped ion applications.
Abstract Lasers with high spectral purity can enable a diverse application space, including precision spectroscopy, coherent high‐speed communications, physical sensing, and manipulation of quantum systems. Already, meticulous design and construction of bench Fabry–Perot cavities has made possible dramatic achievements in active laser‐linewidth reduction, predominantly for optical‐atomic clocks. Yet, there is increasing demand for miniaturized laser systems operating with high performance in ambient environments. Here, a compact and robust photonic‐atomic laser comprising a 2.5 centimeter long, 20 000 finesse, monolithic Fabry–Perot cavity integrated with a micromachined rubidium vapor cell is presented. By leveraging the short‐time frequency stability of the cavity and the long‐time frequency stability of atoms, an ultranarrow‐linewidth laser that enables integration for extended measurements is realized. Specifically, the laser supports a fractional‐frequency stability of at an averaging time of 20 millisecond, at 300 second, an integrated linewidth of 25 Hz that results from thermal noise, frequency noise floor as low as 0.06 Hz2 Hz−1, and a passive vibration immunity as low as 10−10 g−1. The present work explores hybrid laser systems with monolithic photonic and atomic packages based on physical design.
Scaling quantum processors and optical atomic clocks fundamentally requires orders-of-magnitude reductions in the size, weight, power, and cost of optical control systems. Photonic integration of lasers is critical to fulfill these requirements. At the near-infrared wavelengths required for atomic clocks and quantum computing through manipulation of rubidium atoms, laser integration is hindered by difficulty in light coupling and poor heat dissipation. Here, we introduce a wafer-scalable method utilizing micro-transfer printing to integrate GaAs-based amplifiers in etched recesses, directly butt-coupled to silicon nitride waveguides. We demonstrate extended-cavity single-mode lasers using this integration approach. Our compact microgear laser achieves a narrow 3 kHz fundamental linewidth at an on-chip output power of >22 mW -- a record for a single-mode heterogeneously integrated laser in the 780-800 nm band -- with a wall-plug efficiency of 9.4%, showcasing the high-power and efficiency potential of this integration approach. Additionally, we demonstrate a widely tunable laser leveraging Vernier filters to achieve lasing with 9 nm coarse tuning, a quasi-continuous fine-tuning range exceeding 140 GHz, and a mode-hop-free tuning range of 45 GHz. Our scalable integrated laser toolkit shows great promise for replacing macroscopic external-cavity diode lasers in next-generation quantum technologies and optical atomic clocks.
ABSTRACT High‐brightness–integrated quantum light sources represent a fundamental element for large‐scale photonic quantum technologies. Integrated microring resonator (MRR) in highly nonlinear and ultralow‐loss material platforms enable entangled photon‐pair generation, but device performance is affected by fabrication tolerances and can thus not be judiciously controlled. Redundant designs based on parameter variation are impractical for chip‐scale circuits, as the sheer number of parameters would be too complex. To address this, passive photonic circuits must be combined with active control elements to optimize photon‐pair emission and to match emission characteristics among sources. Here, we present a comprehensive study of an actively tunable, interferometrically coupled integrated MRR implemented in silicon nitride (SiN). By manipulating two thermally controlled phase shifters, the ring–bus coupling and the resonator phase can be dynamically adjusted, enabling post‐fabrication control of its quality factor (Q‐factor) between 10 5 and 10 6 to optimize the photon emission bandwidth and the pair generation rate. We directly demonstrate for the first time that the optimal coupling and emission characteristics do not occur at critical coupling and vary across frequency modes due to dispersion effects, in good agreement with our theoretical model. These findings highlight the role of adaptive integrated photon sources for single‐batch fabrication of reconfigurable devices with application‐specific spectral properties.