A pound-drever-hall digital laser frequency stabilization system with polyphase filter structure

Abstract

Disclosed is a Pound-Drever-Hall digital laser frequency stabilizing system with a multi-phase filtering structure. A radio frequency signal source only provides the driving voltage for an electro-optical modulator, and does not serve as a demodulation reference signal. An analog-digital converter collects a beat frequency signal of an photoelectric detector, the beat frequency signal enters an FPGA controller, multi-phase filtering orthogonal demodulation operation and frequency drift signal calculation are conducted in the FPGA controller, so that the frequency stabilizing effect is achieved. According to the Pound-Drever-Hall digital laser frequency stabilizing system with the multi-phase filtering structure, a frequency mixer and a low-pass filter are not used, the multi-phase filtering structure is adopted by a demodulation algorithm, and the demodulation algorithm is implemented in the FPGA controller; meanwhile, the FPGA controller further conducts PID control operation. Due to the fact that the frequency mixer and the low-pass filter are replaced by the multi-phase filtering structure, the frequency of distortion and image frequency interference caused by the frequency mixer and the low-pass filter is reduced, and the frequency stabilizing accuracy is improved.

Description

technical field [0001] The invention belongs to the technical field of laser frequency stabilization systems, in particular to a Pound-Drever-Hall digital laser frequency stabilization system with a polyphase filter structure. Background technique [0002] The Pound-Drever-Hall frequency stabilization method is widely used in narrow-linewidth ultra-stable laser frequency stabilization systems due to its advantages such as not easy to lose lock, strong anti-interference ability, high stability, and not limited by wavelength. The principle of this method is: the electro-optic modulator is driven by a radio frequency signal, the laser output beam is phase-modulated by the electro-optic modulator and then vertically incident on the F-P reference cavity, and the three reflected beams are beat on the photodetector. If the laser frequency is equal to the resonance frequency of the reference cavity, the modulation frequency signal output after the beat frequency is zero; otherwise, ...

AI Technical Summary

Problems solved by technology

The long-term amplitude instability of the RF signal and the distortion and image frequency interference brought by the analog mixer greatly reduce the frequency stabilization accuracy

The digital mixer needs to generate a digital quadrature reference signal. This process will bring a certain quantization error and reduce the frequency stabilization accuracy.

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