Intelligent Frequency Stabilization System Of Semiconductor Laser For Atom Interferometry

The atom interferometer has become a precision measurement tool for many scientific research and technical applications.As an important part of the atom interferometer,the frequency and amplitude stability of semiconductor lasers directly determine the performance of an atom interferometer.The development of high-performance atom interferometers is inseparable from the stable and reliable laser system.In this thesis,aim to develop an intelligent frequency stabilization system of semiconductor laser for atom interferometer,the investigation of frequency stabilization of semiconductor lasers is carried out.The main achievements of this dissertation are as follows:1.The driver of digital acousto-optic modulator(AOM)is designed,and the control program is compiled.The phase noise of the digital driving source for AOM is measured,and the frequency stability of the driving is evaluated by Allan variance.The key factors affecting the frequency stability of the DDS(direct digital frequency synthesizer)are studied.The fifth-order elliptic band-pass filter,which is the key circuit in DDS,is designed,and its s-parameter is analyzed by network analyzer.The result is better than that of the same kind of commercial instrument.2.The servo frequency stabilizer based on lock-in amplifier is designed?The frequency,temperature response and linewidth of ECDL are studied.and the output frequency of the semiconductor laser(ECDL/DFB)is successfully locked to the saturated absorption peak of rubidium atoms.The attenuation characteristic of loop filter is improved.By replacing the analog PID(proportional integral derivative)circuit with a digital PID module and increasing the attenuation characteristics of the loop filter,the long-term stability of the laser is improved,as well as the dynamic range of the frequency locking,thus the continuous locking time of the semiconductor laser is increased from a few hours to more than 7 days.3.Design and implementate an intelligent laser frequency locking system for atom I nterferometers.The intelligent lock frequency circuit is designed and the control program is programmed.The automatic locking system of the laser is realized by the intelligent frequency locking system,and the continuous operation period of the laser locking system is extended to 15 days.4.Design an ultra low noise power supply,which is based on the LDO(Low Dropout Regulator),the time domain noise width as low as 2m V,PSD of the frequency noise as low as-130dBm,both reach the measurement limit of the instruments,completely replace the lithium battery as the power supply of sensitive circuit.Furthermore,the problem of electromagnetic interference in the laser servo circuit is studied,the noise of the digital analog hybrid circuit is restrained,and the SNR(signal-to-noise ratio)of the error feedback signal of the servo circuit system is increased by 6 times.