Cross-correlation Femtosecond Time Interval Measuring Technology Based On PPKTP Crystal

Based on cross-correlation femtosecond time interval measuring technology of PPKTP crystal to carry out the research, analyze the frequency doubling characteristics of PPKTP crystal. Combined with nonlinear optics and ultra-short pulse laser technology, using the method of balance cross-correlation to test and verify the micrometer distance measurement technique.The research contents of this paper include the following aspects:(1) Summarized the existing time interval measurement methods. According to the requirements of the micron level measurement, investigate the measuring technology for femtosecond optical frequency comb, select the scheme based on the PPKTP crystal as the research direction of this thesis.(2) On the basis of the intensity correlation, the correlation of the femtosecond laser is analyzed, and the propagation model of the pulse in the crystal is calculated and simulated. These principles lay the theoretical foundation for the analysis of the following chapters.(3) Analyze the characteristics of PPKTP crystal for SHG, using the femtosecond pulse laser of 1053 nm as the fundamental wave, different polarization directions of the two beams of light through the frequency doubling crystal are detected with 527 nm bright green, the power meter to measure the reference light power and green power. By means of power meter, calculate the conversion efficiency is about 0.2%. In the optical platform, build a micron scale distance measurement system, the measurement distance resolution is 15 um, the corresponding time interval measurement resolution is 50 fs.