Research on spontaneous parametric down-conversion characteristics by 488 nm pumped
The spectrum,photon count rate and time correlation of spontaneous parametric down-conversion are of great significance for the broadband photodetector calibration.In the work,the spectrum and photon count rate distribution of 488 nm continuous laser pumped barium metaborate(BBO)crystal are simulated theoretically,and an experimental measurement system of spectrum,photon count rate,and time correlation are set up.Based on the theoretical results,BBO crystal phase-matching angle is selected as 24.3184°,which can achieve 605-2523 nm continuous broadband correlated photon spectral preparation,and the maximum of photon count rate can reach to 4.2716×107 s-1.CMOS camera and photomultiplier tube are used to measure the correlated photon ring and photon count rate,and the corresponding photodetector is selected according to the wavelength and detector response band to measure the time correlation.As a result,the correlated photon spectrum of 605-1000 nm is measured,and it is found that the measured photon count rate deviates from the theoretical value by an order of magnitude.Besides,the coincidence peaks are also observed in the range of 710 nm to 1560 nm.The experimental results verify the correctness of the theoretical model and the wide spectral characteristics and time correlation of spontaneous parametric down-conversion process,which provides a research foundation for the realization of the wide spectral correlation photon calibration in the visible-near-infrared band.
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