Laser frequency stabilizing method and optical system for improving performance of optical pumping cesium beam atomic clock

Abstract

The invention discloses a laser frequency stabilizing method and optical system for improving performance of an optical pumping cesium beam atomic clock. According to the method, a detected fluorescence signal of the optical pumping atomic clock is divided into two paths, one path of fluorescence signal is input into a microwave cavity of the optical pumping atomic clock through a feedback deviation correction loop, and the other path of fluorescence signal is input into the spectrum input end of a laser frequency stabilization module; laser output by a laser device sequentially passes an isolator (1), a delay wave plate (6) and a polarizing beam splitter (7), and is divided into two beams, one beam is used as detection light and enters a light pumping atomic clock detection area, and theother beam is focused by a lens, enters an acousto-optic modulator (9) for frequency shift output and then collimated into parallel light by a lens, and the parallel light is used as pumping light andenters a light pumping atomic clock pumping area. According to the invention, only one AOM device is added, and two sets of complex saturated absorption spectrum light paths and one laser are omitted, so that the system complexity of the whole clock is reduced, the cost is reduced, and the system reliability is improved.

Description

Technical field [0001] The invention relates to the field of microwave band frequency standards based on atomic beams, specifically a laser frequency stabilization method and optical system for improving the performance of optically pumped cesium beam atomic clocks. Background technology [0002] The essence of an atomic clock is to output an extremely stable frequency. The basic principle of an optically pumped cesium beam atomic clock is: in a vacuum magnetically shielded cesium beam tube, cesium atoms are ejected from a high-temperature heated cesium furnace and pass through a collimator. An atomic beam is formed, and the atomic beam passes through the laser pumping area, the microwave action area, and the laser detection area in sequence, and then detects the changes in fluorescence signal intensity in the detection area. Through modulation and demodulation, the deviation information of the atomic clock frequency is obtained, and finally the servo control circuit is used ...

AI Technical Summary

Problems solved by technology

However, during the research process, three problems were found: 1. The simple saturable absorption spectroscopy system is sensitive to factors such as ambient temperature and magnetic field. To overcome the influence of the environment, it is necessary to increase the temperature control measures and magnetic shielding of the saturated absorption spectroscopy system structure, etc., resulting in increased system complexity of the whole machine and reduced system reliability; 2. There are six peaks in the saturated absorption spectrum, such as image 3 As shown, the spectral peaks are often closely spaced, and the signal strength varies greatly. It is easy to be affected by the environmental vibration and cause the pumping light and the detection light to jump or lose lock. In addition, the optical system structure is not easy to control the power of the two lasers. ; 3. In the cesium clock structure, theoretically, the atomic beam and the laser are designed to interact vertically, and there is no first-order Doppler frequency shift. However, in practice, it is inevitable that there will be some deviation. Lasers and atomic beams stabilized by saturated absorption spectrum cannot guarantee the best resonance effect, which affects the detection efficiency of lasers and ultimately affects the performance of cesium clocks

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