Advancing frequency locking: Modified FPGA-Guided direct modulation spectroscopy for laser stabilization

作者：Prosenjit Majumder, Vikash Kumar Yadav, Rakesh Tirupathi, Kamalkant, Shruti Jain, Poonam Yadav, Arnab Ghosh, Apoorav Singh Deo, Deepshikha Singh · 发表于：Optics & Laser Technology · 年份：2023 · DOI：10.1016/j.optlastec.2023.110247 · 被引用次数：5 · 研究领域：Atomic and Subatomic Physics Research、Advanced Fiber Laser Technologies、Advanced Frequency and Time Standards

In this paper, we propose a cost-effective laser frequency locking scheme based on frequency modulation spectroscopy (FMS) for precision measurements and experiments in various fields. We demonstrate that by digitally modulating the detected signal frequency using a Field-Programmable-Gate-Array (FPGA) driven by a home-built lock-in and a proportional–integral–derivative (PID) control system, our system achieves higher precision, user-friendliness, and versatility. Our system generates a 20 V peak-to-peak amplified voltage to a piezo transducer (PZT), which enables a mode-hop free laser scan of approximately 2 ±0.2 GHz. We directly modulate the detected saturation absorption signal with a sinusoidal waveform, then demodulate it to obtain multiple zero crossing locking points on the D2 transition of Cs at 852.35 nm. We optimized the system for three commonly used atomic transitions and found that researchers can select any of the zero crossing peaks for frequency stabilization depending on their experimental requirements, we locked the laser at the crossover transition. We measured the long-time frequency fluctuation and power spectral density and found that the frequency fluctuation of the laser is much less than the natural line width of the D2 transition of Cs. Our results demonstrate that our laser frequency locking scheme is effective and practical for precision measurements and experiments in various fields.