Narrow linewidth stabilized lasers are central to precision applications that operate across the visible to short-wave infrared wavelengths, including optical clocks, quantum sensing and computing, ultra-low noise microwave generation, and fiber sensing. Today, these spectrally pure sources are realized using multiple external cavity tabletop lasers locked to bulk-optic free-space reference cavities. Integration of this technology will enable portable precision applications with improved reliability and robustness. Here, we report wavelength-flexible design and operation, over more than an octave span, of an integrated coil-resonator-stabilized Brillouin laser architecture. Leveraging a versatile two-stage noise reduction approach, we achieve low linewidths and high stability with chip-scale laser designs based on the ultra-low-loss, CMOS-compatible silicon nitride platform. We report operation at 674 and 698 nm for applications to strontium neutral and trapped-ion clocks, quantum sensing and computing, and at 1550 nm for applications to fiber sensing and ultra-low phase noise microwave generation. Over this range we demonstrate frequency noise reduction from 1 to 10 MHz resulting in 1.0–17 Hz fundamental and 181–630 Hz integral linewidths and an Allan deviation of 6.5 × 10−13 at 1 ms for 674 nm, 6.0 × 10−13 at 15 ms for 698 nm, and 2.6 × 10−13 at 15 ms for 1550 nm. This work demonstrates the lowest fundamental and integral linewidths and highest stability achieved to date for stabilized Brillouin lasers with integrated coil-resonator references, with over an order of magnitude improvement in the visible wavelength range. These results unlock the potential of integrated, ultra-low-phase-noise stabilized lasers for precision applications and further integration in systems-on-chip solutions.

The demand for compact and low-loss photonic integrated circuits continues to grow with the rapid expansion of artificial intelligence, data communication, sensing, and emerging quantum technologies. Many photonic systems rely on ultra-low-loss reference cavities, Mach-Zehnder interferometers (MZIs), and resonators based on ultra-thin silicon nitride (Si 3 N 4 ) waveguides for laser frequency stabilization and generating ultra-low phase noise signals. However, the realization of fully integrated stabilization circuits requires high-performance photodiodes (PDs) for efficient optical-to-electrical conversion and feedback, which remain challenging to integrate with ultra-thin Si 3 N 4 platforms. Here, we report the first heterogeneously integrated InGaAs/InP PDs on thin 80 nm Si 3 N 4 waveguides. Our fabrication process involves local removal of the top oxide cladding layer, InGaAs/InP die-to-wafer adhesive bonding, and cladding redeposition to enable efficient evanescent optical coupling while preserving optical confinement. The integrated PDs achieve a 3-dB bandwidth up to 2.1 GHz, with a responsivity of 0.61 A/W at 1550 nm. For ubiquitous integration of monitor PDs, we also demonstrate heterogeneous PDs on vertical grating couplers with 0.33 A/W that can be readily integrated on a 6-μm thick top cladding. Our results highlight the suitability of this heterogeneous ultra-low-loss Si 3 N 4 platform for fully integrated high-precision laser locking and frequency stabilization systems in applications such as quantum information science, atomic clocks, and metrology.

Optical frequency division (OFD) produces low-noise microwave and millimeter-wave (mmWave) signals by transferring the exceptional stability of optical references to electronic frequency domains. Recent developments in integrated optical references and soliton microcombs have paved the way for miniaturizing OFD oscillators to chip scale. Critical to this realization is a rapid tunable frequency comb that is stabilized to the optical references, thereby coherently linking optical and electronic frequencies. In this work, we advance the on-chip OFD technology using an integrated high-speed lead zirconate titanate (PZT) stress-optic actuator on the SiN soliton microcomb resonator. The integrated PZT actuator tunes the resonance frequency of the soliton-generating microresonator with a bandwidth exceeding 10s MHz and thus adjusts the soliton repetition rate. Optical frequency division and low-noise mmWave generation are demonstrated by feedback control of the soliton repetition rate through the integrated PZT-actuator, and the soliton microcomb is stabilized to a pair of reference lasers that are locked to an integrated 4 m SiN coil reference cavity. Our approach provides a fast, versatile, and integrated control mechanism for OFD oscillators and their applications in advanced communications, sensing, and precise timing. (c) 2026 Chinese Laser Press

Precision atomic and quantum experiments rely on ultra-stable narrow linewidth lasers constructed using tabletop 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 & times; 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. (c) 2026 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement

Optical frequency division has revolutionized microwave and millimetre-wave generation and set spectral purity records owing to its unique capability to transfer high fractional stability from optical to electronic frequencies. Recently, rapid developments in integrated optical reference cavities and microresonator-based optical frequency combs (microcombs) have created a path to transform optical frequency division technology to the chip scale. Here we demonstrate an ultralow-phase-noise millimetre-wave oscillator by leveraging integrated photonic components and microcavity Kerr optical frequency division. The oscillator derives its stability from an integrated complementary-metal-oxide-semiconductor-compatible SiN coil cavity, and the optical frequency division is achieved spontaneously through Kerr interaction in the integrated SiN microresonator between the soliton microcombs and the injected reference lasers. Besides achieving low phase noise for integrated millimetre-wave oscillators, our demonstration greatly simplifies the implementation of integrated optical frequency division oscillators and could be useful in applications of radar, spectroscopy and astronomy.

We demonstrate stabilization of 698 and 674 nm integrated Brillouin lasers to integrated 3-m coil resonators for neutral and trapped-ion strontium clock applications, achieving record-low 17 Hz fundamental and 660 Hz integral linewidths.

We demonstrate an integrated PZT SiN Kerr-microcomb requiring <10 Volts to initiate a 40-comb line 106.8 GHz soliton without laser frequency tuning. Actuation of 172 MHz/V and modulation bandwidth of 70 MHz, a 10x/4x improvement. © 2023 The Author(s)

We demonstrate a 780 nm PZT-on-Si 3 N 4 stress-optic ring modulator with 2.8 million Q, 11 MHz modulation bandwidth, and 1 GHz/V static tuning. The modulator enables precise laser frequency control for sub-Doppler cooling of rubidium atoms.

We demonstrate a low-power, PZT stress-optic Si3N4 micro-ring blue light modulator with 5.4 million intrinsic Q, 10.5 MHz 3 dB bandwidth, and 760 MHz/V tuning for atomic and quantum applications including trapped barium ions.

Precision applications including quantum computing and sensing, mmWave/RF generation, and metrology, demand widely tunable, ultra-low phase noise lasers. Today, these experiments employ table-scale systems with bulk-optics and isolators to achieve requisite noise, stability, and tunability. Photonic integration will enable scalable, reliable and portable solutions. Here we report a hybrid-integrated external cavity widely tunable laser stabilized to a 10 m-long integrated coil-resonator, achieving record-low 3 - 7 Hz fundamental linewidth across a 60 nm tuning range and 27 - 60 Hz integral linewidth with 1.8E-13 ADEV at 6.4 ms across 40 nm, delivering orders of magnitude frequency noise and integral linewidth reduction over state of the art. Stabilization is achieved without an optical isolator, leveraging resilience to optical feedback of 30 dB beyond that of commercial DFB lasers. The laser and reference cavity are fabricated in the same Si3N4 CMOS-compatible process, unlocking a path towards fully integrated visible to ShortWave-IR frequency-stabilized lasers.

We demonstrate a silicon nitride photonic-integrated two-point-coupled 4-meter-coilresonator capable of tunable critical coupling over a 700 nm range, 910-1610 nm, with 48-77 million intrinsic Q.

Precision atomic and quantum applications including computing and sensing and clocks will benefit from integration of lab-scale lasers and optics. In this talk we will cover integration of visible light to SWIR photonics and components for atom and trapped-ion cooling, trapping, state preparation and measurement.

Silicon nitride Dissipative Kerr Soliton (DKS) microcombs have emerged as a future solution to bring metrological optical frequency comb capabilities into a photonic integrated platform with mass-scale fabrication benefits. Precision applications demand low comb line phase noise as well as high repetition rate stability, but current approaches to achieve this involve complex architectures, multiple lasers, and high-power components, which are challenging to integrate to the chip scale. To achieve this goal, new architectures are needed to simplify the comb generation, actuation, and pump laser requirements, while enabling chip-integrated solutions. Here we demonstrate a greatly simplified stabilized DKS comb architecture with a single laser and a single point electronic control of both the microcomb generation and its stabilization to a coil-resonator reference. The silicon nitride microcomb is integrated with a low power, broadband PZT actuator that is driven by a simple electronic control sequence that generates a soliton and stabilizes it to the 16-meter silicon nitride coil resonator. PZT-enabled control brings flexibility and simplicity to the soliton generation and stabilization using a single CW pump laser, resulting in significantly reduced electronic and optical infrastructure. We demonstrate coil-resonator locking which suppresses the 1 kHz frequency noise by 40 dB over the 35 nm wide comb spectrum, with comb line linewidths as low as 66 Hz and 108 GHz soliton repetition rate phase noise equivalent to -118 dBc/Hz when divided down to 10 GHz. The low power PZT actuator consumes nW bias power and the coil resonator allows flexible dual locking using arbitrary comb lines. These results show a clear path towards full chip integration of stabilized soliton microcombs with simplicity and versatility absent in other schemes.

Photonic integrated single mode lasers that deliver ultra-low fundamental linewidth and high output power are critical for future precision atomic and quantum sciences, high-capacity coherent fiber communications, fiber sensing, and ultra-low-noise microwave and mmWave generation. Achieving both low frequency noise and high power simultaneously requires a laser that can provide strong nonlinear noise suppression with an ultra-high quality factor (Q) large mode volume lasing cavity to reach a large intra-cavity photon population. Photonic integrated Brillouin lasers are an important candidate for applications requiring high optical power and phase noise suppression. Here, we report a significant breakthrough in integrated laser design using Brillouin lasing in a large mode volume, ultra-high Q, coil resonator cavity. We demonstrate Brillouin lasing in a 4-meter-coil resonator achieving a 31 mHz fundamental linewidth, corresponding to a 10 mHz$^2$/Hz white frequency noise floor, 41 mW output power, and 73 dB sidemode suppression ratio. We further demonstrate that this laser can be Vernier tuned across a 22.5 nm range. The meter-scale cavity enables the photon population and output power to be greatly increased before the onset of second-order Brillouin lasing. The increased mode volume is realized in an ultra-low loss silicon nitride coil-based silicon nitride resonator and the underlying Brillouin physics supports lasing with almost arbitrary cavity geometries. Brillouin lasers with ultra-high-Q and large optical volume waveguide resonator can be adapted to a wide range of wavelengths from visible to infrared and scaled to larger cavities, further reducing the linewidth and increasing the output power, and setting a new domain for on-chip precision lasers.

We report a photonic integrated 17-meter long coil silicon nitride waveguide resonator with 249 million intrinsic Q, operation in the C and L band for laser stabilization applications.

Ultra-low linewidth, high output power, integrated single mode lasers, that operate from the visible to shortwave-IR, are critical for future compact, portable, precision applications. Achieving this performance in a CMOS compatible integration platform that can also enable scaling to lower linewidths and higher powers remains a key challenge. We report demonstration of a class of integrated laser with a 31 mHz instantaneous linewidth, 41 mW output power, and 73 dB sidemode suppression ratio, tunable over 22.5 nm. This performance is possible due to Brillouin nonlinear laser dynamics in a large mode volume, meter-scale, MHz free spectral range, low loss silicon nitride coil resonator with the potential to scale to an operating regime of mHz fundamental linewidth and Watt class lasers. Such lasers hold promise to unlock new sensitivity and fidelity for quantum sensing and computing, ultra-low-noise mmWave and RF generation, fiber sensing, and atomic, molecular, and optical physics.

Precision applications such as quantum computing, quantum and fiber sensing, and mmWave and RF generation, require ultra-low phase noise stabilized lasers operating at wavelengths across the visible to near-IR. These applications employ widely tunable table-scale laser systems, bulk-optic reference cavities, and optical isolation to achieve ultra-low frequency noise and high stability across wide wavelength ranges. Photonic integration promises to bring these laser systems to the chip-scale, enabling reliable, scalable and portable precision applications. Here we report record-low integrated laser linewidths with a coil-cavity stabilized 1550 nm tunable laser, that achieves 3 to 7 Hz fundamental linewidth across a 60 nm tuning range and 27 - 60 Hz integral linewidths with an Allan deviation of 1.8E-13 at 6.4 ms across 40 nm. These results represent 5 orders of magnitude noise reduction and almost 2-orders magnitude reduction in integral linewidth for widely tunable integrated lasers. The hybrid integrated silicon nitride external cavity tunable laser is stabilized to a silicon nitride 10-meter long integrated coil-resonator without the need for an optical isolator by leveraging the inherent 45 dB isolation. The laser and reference cavity are fabricated in the same 80 nm-thick ultra-low loss silicon nitride waveguide CMOS foundry compatible process, which combined with the inherent isolation, unlocks the path towards fully integrated visible to NIR frequency-stabilized lasers.

Ultra-stable lasers are crucial for precise phasesensitive measurements. This paper overviews our research on a modulation-free laser frequency stabilization scheme and a hybrid-integrated multi-channel narrow-linewidth laser for fiber sensing, enhancing the sensitivity and scalability of fiber sensing interrogators.

We demonstrate dual-wavelength distributed acoustic sensing over 37 km of standard single-mode fiber using φ -OFDR, utilizing a scalable hybrid-integrated dual-wavelength laser chip frequency-locked to a high-Q integrated SiN coil resonator.

Photonic integrated lasers with an ultra-low fundamental linewidth and a high output power are important for precision atomic and quantum applications, high-capacity communications, and fiber sensing, yet wafer-scale solutions have remained elusive. Here we report an integrated stimulated Brillouin laser (SBL), based on a photonic molecule coupled resonator design, that achieves a sub-100-mHz fundamental linewidth with greater than 10-mW output power in the C band, fabricated on a 200-mm silicon nitride (Si3N4) CMOS-foundry compatible wafer-scale platform. The photonic molecule design is used to suppress the second-order Stokes (S2) emission, allowing the primary lasing mode to increase with the pump power without phase noise feedback from higher Stokes orders. The nested waveguide resonators have a 184 million intrinsic and 92 million loaded Q, over an order of magnitude improvement over prior photonic molecules, enabling precision resonance splitting of 198 MHz at the S2 frequency. We demonstrate S2-suppressed single-mode SBL with a minimum fundamental linewidth of 71±18 mHz, corresponding to a 23±6-mHz2/Hz white-frequency-noise floor, over an order of magnitude lower than prior integrated SBLs, with an ∼11-mW output power and 2.3-mW threshold power. The frequency noise reaches the resonator-intrinsic thermo-refractive noise from 2-kHz to 1-MHz offset. The laser phase noise reaches -155 dBc/Hz at 10-MHz offset. The performance of this chip-scale SBL shows promise not only to improve the reliability and reduce size and cost but also to enable new precision experiments that require the high-speed manipulation, control, and interrogation of atoms and qubits. Realization in the silicon nitride ultra-low loss platform is adaptable to a wide range of wavelengths from the visible to infrared and enables integration with other components for systems-on-chip solutions for a wide range of precision scientific and engineering applications including quantum sensing, gravitometers, atom interferometers, precision metrology, optical atomic clocks, and ultra-low noise microwave generation.