A vapor cell provides a well-controlled and stable inner atmosphere for atomic sensors, such as atomic gyroscopes, atomic magnetometers, and atomic clocks, and its hermeticity affects the stability and aging of atomic sensors. We present the micro-fabrication of a micro-electromechanical system wafer-level hermit vapor cell based on deep reactive ion etching and vacuum anodic-bonding technology. The anodic-bonding process with the voltage increasing in steps of 200 V had a critical influence on vapor cell hermeticity. Further, the silicon–glass bonding surface was experimentally investigated by a scanning electron microscope, which illustrated that there were no visual cracks and defects in the bonding surface. The leak rate was measured using a helium leak detector. The result shows that the vapor cells with different optical cavity lengths comply with the MIL-STD-883E standard (5 × 10 ⁸ mbar·L/s). Moreover, D2 absorption spectroscopy was characterized via optical absorption. The bonding strength was determined to be 13 MPa, which further verified the quality of the vapor cells.

Atomic Doppler broadening thermometry (DBT) is potentially an accurate and practical approach for thermodynamic temperature measurement. However, previous reported atomic DBT had a long acquisition time and had only been proved at the triple point of water, 0°C, for the purpose of determination of the Boltzmann constant. This research implemented the cesium atomic DBT for fast room temperature measurement. The Cs¹³³ D1 (6S^1/2 → 6p^1/2 transition) line was measured by direct laser absorption spectroscopy, and the quantity of thermal-induced linewidth broadening was precisely retrieved by the Voigt profile fitting algorithm. The preliminary results showed the proposed approach had a 4 min single-scan acquisition time and 0.2% reproducibility. It is expected that the atomic DBT could be used as an accurate, chip-scale, and calibration-free temperature sensor and standard.

As the key part of chip-scale atomic clocks (CSACs), the vapor cell directly determines the volume, stability, and power consumption of the CSAC. The reduction of the power consumption and CSAC volumes demands the manufacture of corresponding vapor cells. This overview presents the research development of vapor cells of the past few years and analyzes the shortages of the current preparation technology. By comparing several different vapor cell preparation methods, we successfully realized the micro-fabrication of vapor cells using anodic bonding and deep silicon etching. This cell fabrication method is simple and effective in avoiding weak bonding strengths caused by alkali metal volatilization during anodic bonding under high temperatures. Finally, the vapor cell D2 line was characterized via optical-absorption resonance. According to the results, the proposed method is suitable for CSAC.

A simple and robust technique is reported to offset lock a single semiconductor laser to the atom resonance line with a frequency difference easily adjustable from a few tens of megahertz up to tens of gigahertz. The proposed scheme makes use of the frequency modulation spectroscopy by modulating sidebands of a fiber electro-optic modulator output. The short-term performances of a frequency offset locked semiconductor laser are experimentally demonstrated with the Allan variance of around 3.9×10 11 at a 2 s integration time. This method may have many applications, such as in Raman optics for an atom interferometer.

We present the long-term stability of the integrating sphere cold atom clock (ISCAC) and analyze its systematic limitations. The relative frequency instability of 2.6×10 15 is reached for an averaging time of 2×105 s. The second-order Zeeman effect and the cavity pulling effect in ISCAC, which would induce the frequency drift from the clock transition, are analyzed. The analytical and experimental results indicate that the cavity pulling effect is the main contribution to the long-term frequency instability of the ISCAC. Further technical improvements to the microwave cavity are also discussed.

The intensities of fluorescence spectral lines of Ca atoms and Sr atoms in two different hollow cathode lamps (HCLs) are measured by element-balance-detection technology. In the wavelength range of 350–750 nm in the visible spectral region, using the individual strongest line (Ca 422.67 nm, Sr 460.73 nm) as the bench mark, the population ratios between the excited states of Ca atoms and Sr atoms are calculated by rate equations and the spontaneous transition probabilities. The HCLs with populations at excited states can be used to realize the frequency stabilization reference of the laser frequency standard.

Vector beams with spatially variant polarization have attracted much attention in recent years, with potential applications in both classical optics and quantum optics. In this work, we study a polarization selection of spatial intensity distribution by utilizing a hybridly polarized beam as a coupling beam and a circularly polarized beam as a probe beam in Rb87 atom vapor. We experimentally observe that the spatial intensity distribution of the probe beam after passing through atoms can be modulated by the hybridly polarized beam due to the optical pumping effect. Then, the information loaded in the probe beam can be designedly filtrated by an atomic system with a high extinction ratio. A detailed process of the optical pumping effect in our configurations and the corresponding absorption spectra are presented to interpret our experimental results, which can be used for the spatial optical information locally extracted based on an atomic system, which has potential applications in quantum communication and computation.

We report on the observation of the highly forbidden S10–P30 optical clock transition in laser-cooled Hg199 atoms. More than 95% depletion of cold Hg199 atoms is detected in the magneto-optical trap. Using the free-of-field detection method, the AC Stark shift from the cooling laser is removed from the in-field spectroscopy. At low-power clock laser pumping, the linewidth of the clock spectroscopy is approximately 450 kHz (full width at half-maximum), which corresponds to a Doppler broadening at the atom temperature of 60 μK. We determine the S10–P30 transition frequency to be 1,128,575,290.819(14) MHz by referencing with a hydrogen maser and measuring with a fiber optical frequency comb. Moreover, a weak Doppler-free signal is observed.