Pound-drever-hall laser frequency stabilization system without phase shifter

Abstract

Pound-Drever-Hall laser frequency stabilization system without phase shifter, including laser source, MCU controller, DDS RF signal source, electro-optic modulator, reference cavity, photodetector, frequency selective amplifier network, mixer, low-pass filter device, A / D, D / A converter, DSP processor, switch module and PZT drive circuit. The system has two working modes, the working mode is selected by the DSP processor, and one of the RF reference signals output by the DDS RF signal source is switched by the switch module or the frequency drift signal output by the conditioned photodetector enters the mixer; DDS The radio frequency signal source generates two orthogonal radio frequency reference signals, which are mixed with the signal selected by the switch module respectively. After acquisition, phase sensitive detection and control strategy calculation are performed in the DSP processor to achieve the effect of frequency stabilization. The invention improves the frequency stabilization accuracy and realizes laser automatic tracking and locking.

Description

technical field [0001] The invention belongs to the technical field of laser frequency stabilization systems, and relates to a Pound-Drever-Hall laser frequency stabilization system without a phase shifter. Background technique [0002] The Pound-Drever-Hall frequency stabilization method is widely used in narrow linewidth laser frequency stabilization systems due to its strong anti-interference ability, not easy to lose lock, high stability, and not limited by wavelength. The principle of this method is: the output beam of the laser is phase-modulated by the electro-optic modulator, and then it is vertically incident on the F-P reference cavity, and the reflected light is beat on the photodetector. If the laser frequency is equal to the resonance frequency of the reference cavity, the beat frequency output is zero; otherwise, there is a beat frequency current output. After a certain phase shift, the RF reference signal is mixed and demodulated with the beat frequency signa...

AI Technical Summary

Problems solved by technology

This method is based on human eye observation and manual adjustment, so the error is large; the digital phase shifter needs to add a phase detection and phase shift control unit to the system, which increases the complexity of the system. At the same time, the added unit itself inevitably introduces Phase error reduces the frequency stabilization accuracy of the system

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