Distributed Bragg reflector (DBR) lasers have found promising prospects in quantum sensing, cold atom physics, and precision spectroscopy. However, a broader implementation is challenged by their MHz-scale linewidths and the absence of autonomous atomic resonance alignment. Here, we demonstrate a turnkey 795 nm DBR laser system locked to the Rb 85 D 1 hyperfine transition. Our approach employs a dual-stage architecture: stage 1 utilizes the Faraday anomalous dispersion optical filter (FADOF) with optical feedback, achieving automatic frequency resonance and confinement to the vicinity of the Rb 85 D 1 line, while reducing the 1/ π integral linewidth from 461.8 kHz to 28.8 kHz, and the Lorentzian linewidth from 25.8 kHz to 426.9 Hz. This mechanism is quantitatively investigated using Lang–Kobayashi equations. Stage 2 applies modulation transfer spectroscopy (MTS) to further stabilize the frequency of the optically locked laser, which yields an Allan deviation of 3.29×10 −13 / τ . Our system unlocks DBR lasers’ potential in quantum precision measurements, offering a convenient, compact, low-noise light source for atomic clocks, magnetometers, and gyroscopes.
Distributed Bragg reflector (DBR) lasers have found promising prospects in quantum sensing, cold atom physics, and precision spectroscopy. However, a broader implementation is challenged by their MHz-scale linewidths and the absence of autonomous atomic resonance alignment. Here, we demonstrate a turnkey 795 nm DBR laser system locked to the Rb 85 D 1 hyperfine transition. Our approach employs a dual-stage architecture: stage 1 utilizes the Faraday anomalous dispersion optical filter (FADOF) with optical feedback, achieving automatic frequency resonance and confinement to the vicinity of the Rb 85 D 1 line, while reducing the 1/ π integral linewidth from 461.8 kHz to 28.8 kHz, and the Lorentzian linewidth from 25.8 kHz to 426.9 Hz. This mechanism is quantitatively investigated using Lang–Kobayashi equations. Stage 2 applies modulation transfer spectroscopy (MTS) to further stabilize the frequency of the optically locked laser, which yields an Allan deviation of 3.29×10 −13 / τ . Our system unlocks DBR lasers’ potential in quantum precision measurements, offering a convenient, compact, low-noise light source for atomic clocks, magnetometers, and gyroscopes.
In the development of atomic physics, laser sources with Frequencies corresponding to atomic transition and high stability are essential. The Faraday laser is a special diode laser using the Faraday anomalous dispersion optical filter (FADOF) to realize frequency selection, so the output laser frequency is automatically limited to the atomic Doppler broadening. However, the frequency of a Faraday laser corresponds to the range around only one atomic hyperfine transition. Here, we realize a switchable Faraday laser with two isotopes laser frequencies corresponding to 85Rb 52S1/2 (F=3)→52P3/2 and 87Rb 52S1/2 (F=2)→52P3/2 transitions based on a single isotope 87Rb-FADOF. The laser has good robustness against the fluctuation of diode current and temperature, with wavelength fluctuating within 0.8 pm from 16 to 30 °C of diode temperature, and has a free-running linewidth of 18 kHz. We also lock the laser frequency to the two cycling transitions of 85Rb 52S1/2 (F=3)→52P3/2 (F′=4) and 87Rb 52S1/2 (F=2)→52P3/2 (F′=3) by the modulation transfer spectroscopy technique. The Allan deviation of the residual error signal is 3×10−14/τ, and the frequency stability of the beat detection reaches 2.8×10−12 at 1 s integration time. This 780 nm switchable Faraday laser expands the application scenarios of Faraday lasers, which can be used in laser cooling atoms, optical frequency standards, and other quantum precision measurement fields.
Dual-frequency (DF) lasers with specific frequency intervals have crucial applications in geometric measurement, optical microwave generation, quantum precision measurement, etc. Here, we report a 780 nm DF rubidium Faraday laser, with two modes’ frequencies corresponding to the 85 Rb and 87 Rb D 2 transitions. The microwave signal generated from the two laser modes’ beat has a linewidth of 671 Hz and is tunable from 4.7–4.95 GHz to 5.94–6.7 GHz by adjusting the diode current. Moreover, we use modulation transfer spectroscopy to lock one of the laser modes to the 87 Rb hyperfine transition, and the frequency stability improves nearly an order of magnitude. The noise characteristics are also measured, where the phase noise is suppressed over 25 dB at 100 Hz offset compared to the microwave signal generated by two single-mode lasers’ heterodyne beat. This 780 nm DF rubidium Faraday laser has two coherent modes with frequencies related to Rb transitions, which provides a promising and convenient method for compact atomic physics applications, such as coherent population trapping clocks, atom gravimeters, and so on.
A laser with a switchable wavelength between 770 nm and 767 nm, corresponding to the potassium D1 and D2 lines, is a promising tool for manipulating potassium atoms. Here, we develop a potassium Faraday laser using a potassium atom-based Faraday anomalous dispersion optical filter (FADOF) as its frequency selection element. By dynamically adjusting the central frequency of the peak transmission across the entire transmitted spectrum of the potassium FADOF, the laser can operate either in single mode at either 770 nm or 767 nm, or emit both simultaneously. In single-mode operation, the laser wavelength remains aligned with the atomic transitions, exhibiting a narrow linewidth of 14.96 kHz at 770 nm and 13.07 kHz at 767 nm. In dual-mode operation, both modes are sustained continuously, with frequency drifts of less than 0.3 GHz for 200 minutes. Furthermore, we perform modulation transfer spectroscopy (MTS) and stabilize the laser to the 39 K 4S 1/2 F = (1, 2) → 4P 1/2 F ′ = 2 and 4S 1/2 F = (1, 2) → 4P 3/2 F ′ transitions. The corresponding frequency stability, measured by the optical heterodyne beat note between two identical systems, is 1.57 × 10 −12 and 8.77 × 10 −13 at 1 s, respectively. This architecture introduces a novel approach to the generation of wide-range wavelength switching within a single laser. In addition, with its narrow linewidth and impressive frequency stability, it serves as a reliable source for ultracold atom physics and quantum precision measurement.
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.
Narrow-linewidth lasers with absolute frequency anchoring are essential for precision metrology, coherent sensing, and emerging quantum technologies beyond laboratory environments. Optical cavities and interferometers provide exceptional short-term spectral purity but lack intrinsic absolute frequency references. Atomic transitions, in contrast, provide stable frequency anchors but offer limited discrimination sensitivity. Recent hybrid approaches have demonstrated the combination of compact optical resonators with atomic references, yet achieving the Hz-level regime remains challenging. Here, we present a hybrid architecture that enables simultaneous realization of Hz-level linewidth and atomic-referenced frequency stability. An external-cavity diode laser is first stabilized to a fiber interferometer to achieve Hz-level spectral purity, while the interferometer is subsequently anchored to an 87Rb D2 transition via modulation transfer spectroscopy to suppress long-term drift and define the laser frequency relative to the atomic transition. This dual-stabilization scheme realizes a compact atomic-referenced laser with a 3.4-Hz linewidth (1-rad integrated-phase method), a minimum fractional frequency stability of 3.4x10-14 at 0.56 s, and 9x10-13 at 100 s. This architecture establishes a practical and scalable route toward compact and field-deployable atomic-referenced narrow-linewidth lasers for precision metrology and quantum technologies.
Dual-Faraday-laser-pumped cesium beam clock with 7.7×10−13/τ frequency stability
Compact cesium beam clocks are major frequency references for deployable timing systems. However, further improvement of their short-term frequency stability is limited by the clock signal-to-noise ratio (SNR). Although two-laser optical pumping can increase the effective atomic utilization, the achievable clock SNR has long been limited by laser-induced frequency-to-amplitude noise conversion. Here, we demonstrate a compact dual-Faraday-laser-pumped (DFP) Cs beam clock enabled by a low-frequency-noise atom-referenced laser architecture. The intracavity Faraday anomalous dispersion optical filter provides inherent alignment to the Cs D2 resonances, while modulation transfer spectroscopy offers suppressed frequency noise and drift. The resulting laser system supports robust turnkey operation with a Lorentzian linewidth of 2.12 kHz. The DFP Cs clock achieves a clock SNR of 46,365 in a 1-Hz bandwidth and a fractional Allan deviation of 7.7×10−13/τ , with Hadamard deviation reaching 7.7×10−15 at 10,000 s. This work pushes the fractional frequency stability of a compact Cs beam clock into the 10−13/τ regime, providing a pathway toward high-performance Cs frequency references for field-deployable precision timing, navigation, and synchronization.