[Research on the Distribution of Broad-Band Correlated Photon Spectra and the Measurement of Time-Correlation]

The correlated photon technique makes it possible to achieve a radiation calibration processing without chain transferring. The study of the spectral radiation character and time correlation of the photon is of great significance for broad-band radiometric calibration. To absolutely calibrate quantum efficiency of photoelectric detector, it is necessary to extend calibration band from single band to more bands. According to the phase-matching condition of the spontaneous parametric down-conversion, non-collinear angle formula of correlated photon in the crystal is derived. The distribution of the photon spectrum is simulated. Meanwhile, the phase-matching angle of the crystal is optimized. The photon generated by the spontaneous parameters down-conversion has a broad spectral distribution and the correlated photon wavelength is corresponding to its emission angle. Based on the result of the simulation, the experimental measurement system of the spectral distribution and time-correlation of the correlated photon is established. The spectral distribution, the time-correlation and the polarization properties of the four pair photon were measured by using this system. The experimental results show that, (1) the spectral distribution of the measurements is 633~808 nm, where the maximum spectral distribution measurement bias is 1.51 mm. The experiment result is highly consistent with theoretical ones; (2) the correlation time of four pairs correlated photon is measured, during which “three coincidence-peaks” is observed and the minimum correlation time was 0.32 ns; (3) single photon count rate along with coincidence count rate of correlated photon vary with the polarization direction of the pump as sine function. The experimental result is shown that the correlated photon pairs are ranging from the visible to near infrared band distribution, and that the spectrum has time-correlation and polarization characteristic. The research result is firstly reported at home and abroad, and the results are promising for the application of the photoelectric detector in the multi-band radiometric calibration.