Polarization Directions of Non-Collinear Phase Matched Optical Parametric Down-Conversion Output

Jung-Rae Park

Bai Yunfei, 刘洪雨 Liu Hongyu, 郜江瑞 Gao Jiangrui +1 more

Hugues Guillet de Chatellus, Alexander V. Sergienko, Bahaa E. A. Saleh +2 more

A periodically poled lithium niobate (PPLN) crystal has been used as an efficient source of non-collinearly generated polarization-entangled photon pairs at 810 and 1550 nm. The PPLN crystal was endowed with a specially designed poling pattern and the entangled photons were generated via the nonlinear optical process of spontaneous parametric down conversion (SPDC). A novel design based on overlapping two concurrent type-I quasi-phase-matching structures in a single PPLN crystals produced correlated pairs of alternatively polarized photons in largely separated spectral regions. The phase of the resulting two-photon state is directly linked to parameters of the nonlinear grating. Continuous tunability of the generated Bell state, from Phi(+) to Phi(-), has been demonstrated by translating a slightly wedged crystal perpendicular to the pump beam.

Alan L. Migdall

An analysis of the output polarization of a noncollinear type I optical parametric downconversion source is presented. Such a source can be made by pumping a nonlinear crystal with an extraordinary-polarized beam to produce pairs of ordinary-polarized photons. A polarization map of the output light illustrates dramatic variation in the polarization direction at large scattering angles. The effect of this variation in polarization direction is seen on a map of the nonlinear conversion efficiency. The apparent ambiguity in the polarization for the particular case in which one of the outputs propagates along the crystal optic axis is also discussed.

Bai Yunfei, 刘洪雨 Liu Hongyu, 郜江瑞 Gao Jiangrui +1 more

Bai Yunfei, 刘洪雨 Liu Hongyu, 郜江瑞 Gao Jiangrui +1 more