# Development of Compact and Robust Physical System for Strontium Optical Lattice Clock
## 3 Operation and Results  
Adjusting the laser wavelength to its operating point is a critical and primary step in operating an optical clock system. Traditionally, this process has been performed manually in optical clock experiments. However, in complex environments outside the laboratory, automating this process becomes necessary. We innovatively employed a wavemeter to achieve automatic and efficient laser wavelength optimization. The proposed methodology is illustrated schematically in Figure 5a. All lasers are linked to a wavemeter via a multichannel laser switch. Initially, software presets parameters for each laser, including temperature, current, and voltage. Subsequently, software-controlled iterations were conducted to explore parameter combinations, recording wavelength data every 500 ms. After completing iterations, multiple parameter combinations matching the target wavelength were identified based on the recorded wavelength data. Each laser's parameters were then sequentially adjusted to match these combinations. The internal piezoelectric ceramics (PZT) within the lasers were scanned to determine the parameter combination with the largest frequency tuning range, serving as the optimal configuration for the lasers. Leveraging a multichannel laser switch enabled simultaneous wavelength searches for all lasers, completing the process in under 5 min, surpassing manual operations in efficiency. This automated approach significantly enhances experimental efficiency, particularly in complex environments. Subsequently, based on the distinct frequency linewidth requirements of each laser, they were individually referenced to different frequency standards. Specifically, lasers operating at 689-nm, 698-nm were referenced to an ultra-high stability optical cavity; the 461-nm laser was referenced to the atomic transition \({}^{1}\)S\({}_{0}\)\(\rightarrow\)\({}^{1}\)P\({}_{1}\), while the 679-nm and 707-nm lasers underwent frequency calibration using the wavemeter. The 813 nm laser was also referenced to the wavemeter since we did not have an ultra-stable cavity for 813-nm. We are considering the option of locking the 813-nm laser to a femtosecond optical frequency comb referenced to the 698-nm clock laser. Figure 5: (**a**) Schematic of automatic laser wavelength searching; (**b**) time consumption. Figure 4: Support structure design of the physics package. effect of the MOT beams (with a single-beam power of 6 mW and a beam radius of 4 mm), repumping beam (where the 707-nm laser had a power of approximately 8 mW and the 679-nm laser had a power of approximately 4 mW, both with a beam radius of 4 mm), and a gradient magnetic field over a duration of 550 ms, up to \(3\times 10^{6.87}\)Sr atoms were loaded into the Blue MOT, achieving a temperature of approximately 5 mK. Throughout this phase, the magnetic field gradient remained at 50 Gs/cm. The transfer of atoms from the Blue MOT to the Red MOT took place in two phases. The first phase was a Broadband Red MOT, where each beam of the 689-nm MOT lasers operated at a power of approximately 3 mW, and each stirring laser operated at a power of approximately 0.8 mW. The beam radius for both lasers was set at 4 mm. Simultaneously, an acousto-optic modulator (AOM) widened the 689-nm laser linewidth to around 2 MHz, with a modulation frequency of around 40 kHz. It is noteworthy that we optimized spatial efficiency and system reliability by utilizing a Fiber Array from Evanescent Optics. This Fiber Array, measuring only \(12.5\times 10\times 1.3\) cm\({}^{3}\), was used to combine Blue MOT, Red MOT, and stirring lasers and was split into three outputs for the MOT beams. Concurrently, the magnetic field gradient decreased to 3 Gs/cm and held for 10 ms, followed by a linear increase to 10 Gs/cm over the subsequent 90 ms to ensure a sufficient atom transfer to the Red MOT. The second phase involved a single-frequency Red MOT, deactivating the modulation of the 689-nm laser and reducing its power.