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Optical clocks with high precision are practical and necessary in atomic physics, geodesy, gravitational wave measurement, etc. Transportability and environmental adaptability are two key indicators to measure the performance of frequency standards. Here, we utilized a highly robust atomic-filter-based Faraday laser as the local oscillator, and achieved two compact Faraday optical frequency standards based on 133 Cs 6 S 1 / 2 | F = 3 ⟩ → 6 P 3 / 2 | F ′ = 2 ⟩ and 6 S 1 / 2 | F = 4 ⟩ → 6 P 3 / 2 | F ′ = 5 ⟩ transitions at 852 nm, leveraging modulation transfer spectroscopy for laser frequency stabilization. The Faraday laser automatically aligns atomic transition spectral lines, due to the use of atomic filters as frequency selective elements. Therefore, the laser wavelength has strong robustness against environmental changes. This setup not only simplifies the operational complexity but also ensures frequency stability. By heterodyne beating between two such compact optical frequency standards, the beatnote achieved a short-term frequency stability of 1.68 × 10−13 at 3 s, remained at the 10−13 level for up to 400 s, and stayed below 2.7 × 10−12 for up to 1600 s, predominantly exhibiting white frequency noise. This underscores the potential of atomic-filter-based Faraday laser in realizing compact and stable frequency standards, mitigating coherent communication error rates, and enhancing the precision of quantum interferometric measurements. Moreover, this approach eliminates the continuous need for external monitoring and adjustments, thereby, offering a practical and robust solution for out of laboratory applications demanding high frequency stability. [ABSTRACT FROM AUTHOR]

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 5 2 S 1 / 2 (F = 3) → 5 2 P 3 / 2 and 87Rb 5 2 S 1 / 2 (F = 2) → 5 2 P 3 / 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 5 2 S 1 / 2 (F = 3) → 5 2 P 3 / 2 (F ′ = 4) and 87Rb 5 2 S 1 / 2 (F = 2) → 5 2 P 3 / 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. [ABSTRACT FROM AUTHOR]

The study of atomic physics has been greatly influenced by the development of high-stability diode lasers whose output corresponds to the atomic transition. Recently, an atomic filter laser "Faraday laser" shines on stage, owing to its great robustness to the fluctuation of the diode parameters and potentially higher tolerance to vibration. However, cost reduction and portability require the Faraday laser to have a more compact structure. Here, we report on the development of a promising atomic filter laser—a "Voigt laser"—using a Voigt anomalous dispersion optical filter (VADOF) as the frequency-selective element, which has a structural advantage in miniaturization. The influencing factors toward the VADOF are investigated in detail to produce a parameter set for the best performance of a Voigt laser. In this case, the Voigt laser has great robustness to the fluctuation in the diode current and temperature, where the wavelength fluctuation is ±0.5 pm with the variation of the diode parameters (diode current: 73–150 mA and diode temperature: 12–30 °C). In addition, the wavelength of the Voigt laser fluctuates about ± 0.5 pm for 48-h free-running operation and shows excellent reproducibility without manual adjustment. The laser system developed here provides a stable and reliable laser source for substantially improving existing technologies such as the atomic clock, electromagnetically induced transparency, and laser cooling of atoms. [ABSTRACT FROM AUTHOR]

In this Letter, stabilizing a Faraday laser frequency to the atomic transition is proposed and experimentally demonstrated, where the Faraday laser can work at single- or dual-frequency modes. High-resolution spectroscopy of a cesium atom induced by a Faraday laser is obtained. By stabilizing a Faraday laser with atomic spectroscopy, the frequency fluctuations of the Faraday laser are suppressed without the need of a high-cost Pound–Drever–Hall system. The fractional frequency Allan deviation of the residual error signal is 3 × 10 − 14 / τ at the single-frequency mode. While at the dual-frequency mode, the linewidth of the beat-note spectra between the two modes of the Faraday laser after locking is narrowed to be 85 Hz, which is an order of magnitude better than the free-running linewidth. It can be used for microwave atomic clocks and may have the potential to be used in the application of optical microwave generation when the performance is further improved. [ABSTRACT FROM AUTHOR]

All-inorganic cesium lead halide perovskites (CsPbX 3 , X = Cl, I, Br) have attracted great attention for developing high-performance photovoltaics due to their superb thermal stability. However, the short electron-hole diffusion lengths (L D s) in CsPbI 2 Br perovskite are the primary limiting factor for further improvement of the power conversion efficiencies (PCEs) of the CsPbI 2 Br solar cells. Herein, a simple yet effective method is reported to prolong the L D s in CsPbI 2 Br via codoping of Zn2+ and acetate (Ac−) ions (i.e., using Zn(Ac) 2 as dopant). It is demonstrated that Zn2+ partially replaces Pb2+ to form a more stable black phase, and Ac− coordinates with Pb2+ to passivate the defects at the perovskite grain boundaries which reduces electron-hole recombination within the perovskite. As a result, the L D s of Zn(Ac) 2 doped CsPbI 2 Br are greater than 1 μm, which is the first report on all-inorganic perovskites. The champion PCE of the CsPbI 2 Br solar cells is drastically increased from 12.31% to 14.93% upon doping with Zn(Ac) 2 , stemming mainly from the increased open-circuit voltage and fill factor. Furthermore, the non-encapsulated devices with Zn(Ac) 2 doped CsPbI 2 Br show less than 10% efficiency loss after storage in dry air for 30 days. Image 1 • Doping Zn(Ac) 2 into CsPbI 2 Br can passivate defects and enhance phase stability. • Electron-hole diffusion lengths of CsPbI 2 Br are prolonged to over 1 μm by Zn(Ac) 2. • The Zn(Ac) 2 doped CsPbI 2 Br solar cells exhibit high efficiency of 14.93%. [ABSTRACT FROM AUTHOR]