Investigation Of Acoustic Response And Sound Insulation Characteristics Of ECDL

With the research and development of physical precision measurement and sensing technology,there is a higher requirement for the stability of the laser frequency and the anti-interference of the laser sensor system.Especially in the field of precision measurement such as atomic and molecular spectrum and atomic frequency standards,linewidth reduction of laser and enhancing system stability are critical to improving measurement accuracy.In general,atomic transfer spectra lines and an optical cavity can be used as frequency reference in laser frequency locked loop,in addition,working in a constant temperature and closed environment,laser system would have less noise which caused by external environmental factors such as room temperature fluctuations and random irregular disturbances,in this way,the stability of the output frequency of the laser can be greatly improved.However,the random disturbance is unpredictable in the environment and it usually corresponds to different characteristic frequency,therefore,it's not enough to depress noises of several frequency points,optimizing the laser system frequency response characteristics and enhancing the system stability become very important,the optimization of the laser's dynamic characteristics.Besides,the laser system in the actual environment needs to be targeted for correction and optimization,so it is necessary to study the acoustic response characteristics of the laser.In this way,the acoustic signal and sound insulation characteristics can be measured accurately.In this paper,the dynamic characteristics of laser closed-loop frequency stabilization system are studied firstly.The sine wave is replaced by square wave as the modulation signal modulates the output frequency of the laser via the constant current modulation port.Acquire input signal and the corresponding fluctuations of the electrical signal in the frequency stabilization loop,fast Fourier transform is used to analysis the input signal and output signal in frequency domain,the relationship between the system gain and the phase shift with the frequency can be observed.Finally,the laser system dynamic response characteristics at multiple frequencies are measured quickly and efficiently.Based on this,the loop parameters are optimized,and a dual-channel feedback loop is built to broaden the system bandwidth to the order of hundred kHz,which greatly improves system stability.Moreover,on the basis of studying the dynamic characteristics of the system,using the characteristics of grating feedback external cavity diode laser is sensitive to acoustic signal,the acoustic response characteristics of the laser were studied.Signal generators were used to generate sinusoidal electric signals with different frequencies to drive the speakers,thereby generating the acoustic signals of different frequencies.Recording the acoustic signal and the fluctuation of the laser output frequency under the perturbation of the acoustic signal,the sound response characteristics of the laser can be obtained.Comparing the difference between laser acoustic response characteristics when there is the aluminum soundproof shell or not,it's easy to get the sound insulation characteristics of aluminum soundproof shell.The experimental results show that the sound insulation effect of the aluminum soundproof shell is related to its own mechanical structure and size,which provides experimental basis for the design of the laser's mechanical structure and sound insulation system.