In this paper, a compact laser system for ⁸⁷Rb atom interferometry based on only one free-space electro-optic modulator (EOM) was realized, where repumping and Raman beams were generated with a free-space EOM. In addition, this laser system does not require a laser amplifier compared to fibered EOM since fibered EOM cannot transmit high-power lasers. However, due to the narrow modulation linewidth of free-space EOM, it is impossible to obtain the frequencies of repumping and Raman beams separately, which would lead to some complicated effects. Therefore, a theoretical analysis was carried out to solve this problem, and a new frequency scheme for AI is proposed. For the experiment, the laser system of AI was built up. Moreover, the atomic interference fringes were obtained with a contrast of 20.7% (T = 60 ms) and the fitted phase resolution is approximately 1.25 mrad. The presented laser system could provide a new solution for compact AI systems in the future.

Laser diffraction (LD) has many obvious advantages for measuring. However, the measurement accuracy is limited by a number of factors, such as imaging noise, sensor threshold, and fitting methods. In this paper, we present a novel method for measuring filament diameter based on image-based fitting, which maintains more information. Before fitting the diffraction image, image processing is applied to solve the problem of image noise and the non-linear response of the charge-coupled device (CCD). Then, a fitting formula is established based on the distribution of laser intensity on a diffraction image, and the fitted results are solved with the Levenberg–Marquardt (LM) algorithm. Finally, the initial parameters of a fit are obtained by calculation, which speeds up the calculation and improves the accuracy of the fitting. The measurement accuracy of this method is verified by experimental and theoretical analysis. In experiments, the filament diameters of 125 and 125.2 μm are measured with a relative error of approximately 0.12%, Furthermore, the superiority of this method is demonstrated by comparing the measurements with other methods. To verify the stability of the measurements, filament diameters of 110–180 μm are chosen to be measured with a relative standard deviation of less than 0.14%.

In cold atom physics, the complexity of traditional magneto-optical trap system limits the use of their associated instruments for field applications in atomic physics, such as gravity mapping, space navigation and deep space exploration. This study introduces a novel compact MOT design that addresses these issues by simplifying the structure and reducing the size. The height of the unit is 0.7 m, the volume is $6.3\times {10}^{-2}$${\mathrm{m}}^3$ and the mass is 11.32 kg. The new design utilizes a single laser to generate the two different frequencies needed for laser cooling by internally splitting the beam, shifting the frequency and then combining them, effectively controlling both the cooling and repumping beams. The compact vacuum chamber optical path, in conjunction with the magnetic field, facilitates the capture of ⁸⁷Rb atoms in an ultra-high vacuum environment. Experimental results demonstrate an atom loading rate of up to $1.79\times {10}^7$⁸⁷Rb atoms per second, confirming the system’s effectiveness in capturing and cooling ⁸⁷Rb atoms. This design provides a flexible and portable solution, offering valuable insights for the advancement of compact MOT and its applications in cold atom physics.