Wavelength Management Method of Telecommunication- Band Polarization-Entangled Twin Photons in Periodically Poled Lithium Niobate Crystals
周期极化铌酸锂中通信波段纠缠双光子的波长管理方法

The wavelength management method was theoretically investigated for the polarization-entangled twin photons in telecommunication band generated by type-II quasi-phase-matched (QPM) spontaneous parametric down-conversion (SPDC) in periodically poled lithium niobate (PPLN) crystals. The wavelength of single-color twin photons from degenerate SPDC can be controlled freely through adjusting the QPM grating period or the working temperature. Especially, adjusting the temperature is more convenient since the QPM grating period is hardly changed once the PPLN structure is fabricated. For the two-color twin photons created by nondegenerate SPDC, strict wavelength exchange of the o-polarization and the e-polarization photons can be realized easily only by tuning the working temperature without pump or structure change.