多波段相关光子光谱分布与时间相关性测量实验研究

基于相关光子的定标技术能够实现“无标准传递”绝对定标，研究相关光子的光谱辐射特性及时间相关特性对遥感器在宽波段的辐射定标具有重要意义。为满足光电探测器在宽谱段量子效率定标需求，基于相关光子的定标技术有必要从单一波段向更多波段扩展。根据自发参量下转换所满足的相位匹配条件，推导出相关光子在晶体内的非共线角计算公式，通过数值模拟相关光子光谱辐射角度分布规律，优化晶体相位匹配角，使得自发参量下转换产生的相关光子具有宽光谱分布，并且相关光子辐射角度与光谱波长能够一一对应。根据光谱分布数值模拟结果，建立了多波段相关光子的光谱分布和时间相关性测量实验系统，利用该系统测量了四对相关光子的光谱分布、符合计数、相关时间以及偏振特性。其中，测量的光谱分布范围为633~808 nm，最大光谱分布测量偏差为1.51 mm，光谱分布实验测量结果与数值模拟结果符合一致;测量了四对相关光子对的相关时间，最小相关时间为0.32 ns，并在实验中观察到了“符合三峰”现象;相关光子单光子计数及符合计数与泵浦光的偏振方向呈正弦函数关系。实验研究表明，相关光子对具有可见光~近红外宽波段分布、时间相关及偏振特性。论文研究结果在国内外尚属首次报道，该研究结果有望应用于光电探测器在多波段的辐射定标。

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 transfer-ring.The study of the spectral radiation character and time correlation of the photon is of great significance for broad-band radio-metric 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 cor-related photon is established.The spectral distribution,the time-correlation and the polarization properties of the four pair pho-ton 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 con-sistent with theoretical ones;(2)the correlation time of four pairs correlated photon is measured,during which “three coinci-dence-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.