Research On Frequency-locking Related Technologies In Laser Cooling Molecules

In recent years,research on laser cooling of polar molecules has made great progress,profoundly affecting the fields of atom,molecule and photophysics.And it has also promoted research in the fields of multi-physics,precision measurement,quantum computing,and quantum simulation.In the study of laser cooling molecules,laser frequency locking is the most basic technology.The so-called laser frequency locking is to use the feedback device to stabilize the laser frequency to a reference frequency.In the general cold atom study,the laser is locked to the atomic line.In the study of laser cooling molecules,the laser can be locked to an F-P cavity because the spectral lines of the molecules are not easily available.This master s thesis mainly studies the laser-cooling BaF molecular frequency-locking related technologies including the transfer cavity frequency-locking scheme and the modulation transfer frequency-locking scheme,successfully locking the laser to the transfer cavity and the atomic line.We used a locked 780 nm laser to calibrate the transfer cavity,and finally realized a frequency stabilization scheme in which three lasers were simultaneously locked into one cavity.The long-term drift due to the nonlinear response of the piezoelectric ceramics is carefully characterized.With the passive feedback of the environment of the cavity and zero-offset locking,the linewidth and long-term drift of the laser frequency is maintained to be less than 1 MHz,satisfying the stability required by the laser cooling experiment.Then the modulation transfer spectrum lock frequency scheme is introduced.The EOM is used to generate the sideband,and then the demodulation is used to obtain the differential signal.The frequency of the self-made semiconductor laser is successfully locked to the D2 line from 52S1/2 F=2 to 52P3/2 F'=3 of 87Rb.The linewidth of laser frequency and long-term frequency drift is about 1MHz.This paper will introduce the research background and significance,the principle and fabrication of external cavity semiconductor laser,the principle and experiment of transfer cavity frequency locking and modulation transfer frequency locking.The work of the last two parts will be comprehensively explained.