The Research Of High Stability ECDL System And Its Dynamic Characteristics

The stability of laser system has a pivotal position in many fields,such as laser technology,precision measurement,quantum information,and so on.The above experimental research is based on a very good light source.In the laboratory,we need to keep the laser in the same state for several hours.If in the field,it is required to keep the laser in the same state as long as possible.Thus,it is very important to obtain a narrow line-width laser with long-term frequency stability.The better performance of the ECDL(External cavity diode laser)semiconductor laser is selected as the research object.Using the method of magnetically-induced dichroism(DAVLL-Dichroic Atomic Vapor Laser Lock)frequency stabilization with a fixed amplitude sinusoidal modulating signal in the ECDL laser,we have recorded the frequency fluctuation of the laser,and obtained the response of a system with a single frequency sinusoidal electrical disturbance by the FFT,to study the dynamic response characteristics of the laser system.We construct the measurement system with high frequency resolution(the experimental result show that the characteristic frequency of the laser frequency fluctuation is better than the 0.2Hz).So we can measure the resonant frequency,the system bandwidth,the damping ratio and other performance parameters of the closed loop system.The selection of test parameters and the quantization of the closed-loop gain parameters are studied in detail.According to the dynamic response characteristics of the frequency stabilization system under different closed-loop gain parameters,the optimal operating parameters of the system are obtained by the mature theoretical model in the automatic control system.With square wave current excitation,the system dynamic response is also characterized;the results are similar to the sinusoidal current disturbance results.This method greatly simplifies the experimental process and provides a method for the closed-loop system's dynamic characteristics.Our next works are establishing a reasonable mathematical model for the research.The response for external shocks is also measured.