Circularly polarized light interference-based double-longitudinal-mode offset frequency locking method and device

Abstract

A circularly polarized light interference-based double-longitudinal-mode offset frequency locking method and a device. According to the invention, lambda / 4 wave plates are respectively added to the output ends of a double-longitudinal-mode laser and a reference laser of which the frequency is to be stable; the circularly polarized light interference replaces a traditional linearly polarized light interference so as to obtain the frequency difference output by the double-longitudinal-mode laser and the reference laser of which the frequency is to be stable; and a frequency stabilizing control system is adopted to adjust the cavity length of the double-longitudinal-mode laser, the difference value of the laser frequency and the criteria light frequency output by the double-longitudinal-mode laser can be maintained, thereby stabilizing the frequency. The method provided by the invention adopts the circularly polarized light interference with better interference uniformity contrast compared with the linearly polarized light interference, the light transmission ratio of the lambda / 4 wave plates is higher than that of a polaroid, the light energy loss caused before the frequency mixing can be reduced, the signal-to-noise ratio of the light signal detected by a photoelectric detector is improved, and the frequency stabilizing precision is also improved.

Description

technical field [0001] The invention belongs to the technical field of laser applications, and mainly relates to a dual longitudinal mode bias frequency locking method and device based on circularly polarized light interference. Background technique [0002] Due to the development of precision machining technology, higher requirements are put forward for the measurement system. It is required that the measurement system not only have high measurement accuracy, but also meet the requirements of measuring high-speed moving machinery. [0003] With its high sensitivity, high precision and non-contact characteristics, laser interferometry occupies an increasingly important application position in the fields of precision and ultra-precision processing, microelectronic equipment, nanotechnology and other cutting-edge industrial equipment and national defense equipment, and has been widely used . However, due to the influence of various unstable factors, the optical frequency drif...

AI Technical Summary

Problems solved by technology

Although the frequency consistency can be improved to 10 -9 However, the system is limited by the interference contrast of linearly polarized light and the light transmittance of the polarizer, and it is difficult to increase the intensity of the optical mixing signal received by the photodetector, resulting in the difficulty of improving the signal-to-noise ratio of the optical beat frequency signal. , which limits the improvement of the frequency accuracy of deviation frequency locking, and the polarization-maintaining fiber coupling process is very complicated, which is not conducive to the field application of ultra-precision measurement and processing

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