The Dynamic Characteristics Of Laser Frequency Stabilization System And Atomic Coherent Spectrum

The laser with its frequency stabilization system and the atomic coherent spectrum research have entered a new stage,as the progress and depth of development of science theory and scientific research technology.In the research and application of laser technology,precision measurement and quantum information,we need the higher laser frequency stabilization system,and can observe the dynamic progress of laser frequency and atomic coherent spectrum during measuring.So,researching the dynamic characteristics will be one of the important tools to measure the system property.At present,home and abroad many research teams have done a lot of fruitful work in these two aspects,their study involve the scope and content of also more and more deeply and extensive.In the experiment,we will introduce two aspects to research the dynamic characteristics in this paper.On the one hand,we study the dynamic characteristics of ECDL semiconductor laser and its frequency stabilization system,with the help of external modulation signal to modulate laser frequency and collect input modulation signal and laser frequency variation signal.We use the FFT to analyze frequency response characteristics of laser system to obtain amplitude-frequency characteristic and phase-frequency characteristic of the system.So we can evaluate the laser and its frequency stabilization system and response bandwidth of the system.The results show that using square wave signal is more fast and efficient.At the same time,the mechanical shock was introduced to analyze the response characteristics of the laser in a particular environment,so as to design and optimize the system closed-loop feedback parameters and to make laser work and apply in a relatively harsh environment.In the experiment,We can distinguish the concurrence of two sinusoidal wave modulation signals,whose frequencyinterval are 0.008 Hz.We measure that the frequency resolution of the system is 0.002 Hz.On the other hand,this paper mainly takes attention to the dynamic characteristic of atomic coherent spectrum.First of all,A cavity with an atomic gas chamber is set up,and when the cavity is resonance with the atoms and the light field,the atom is divided by Rabi.The vertical pump is coupled with cavity,the interval of split peak frequency and amplitude increase during pump power is increasing.At the same time,using square wave signal control the switch of AOM is to realize the light switch.When the frequency of square wave signal increases,we observe the change of the transmission spectrum to research dynamic process of atomic spectrum.In practice,this method can be promoted to cold atomic system.In the cold atomic system,we optimize and improve the original light,use the light power amplifier to improve the output power of cooling light,and use PBS to make the cooling light and repumping light couple into the fiber.The laser output of optical fiber is divided into three beams to enter into the magneto optical trap,which is composed of atomic chamber and magnetic field.Finally,we can achieve more number of cold atoms.In order to control the cooling laser,repumping laser,detecting laser and magnetic field,we design the control switch and use Labview software and NI6733 card to realize time sequence control program.This process laid the foundation on cold atomic system for the study of dynamic characteristics of coherent spectrum.