The effects of phase matching method and of uniaxial crystal symmetry on the polar distribution of second-order non-linear optical polarization

Phase-matching for optical up-conversion with maximum angular aperture ? theory and practice

“…Tangential phase-matching for negative uniaxial crystals therefore corresponds to a noncollinear wave normal situation since (dksed0)0p =/= 0 and hence ~o =/= 0. For a positive uniaxial crystal the polarisations of the sum-frequency and pumpfrequency would be orthogonal to those for a negative crystal and if we choose the infra-red signal to be an ordinary wave also (type II phase matching [7]) then both (dks/d0)0p = 0 and (dkjr/d0)0p = 0, and therefore ~bo = 0 as the expression for ~bo following equation 4 shows. With a positive uniaxial crystal therefore tangential phase-matching could occur with collinear wave normals.…”

LARGE NONLINEAR OPTICAL COEFFICIENT AND PHASE MATCHED SECOND HARMONIC GENERATION IN LiIO3

“…In the type II process the corresponding polarization p e (w) depends only on the nonlinear coefficient t 14 as can be seen following the calculation of Midwinter and Warner in Ref. 9. For this case, pe(w) linear coefficient predicted to be zero by the Kleinman symmetry condition.…”

Simple scheme to enhance the generation probability of the single-photon-added coherent state

“…i) In order to non-locally select a pure state in the signal channel, idler photons must pass through a narrow spatial and frequency filtering before being detected by the SPD. ii) To make sure of phase matching, one may modulate the incident angle of the pump light [22]. iii) Since high conversion rate depends on not only phase matching but also group velocity matching, one simple method is to make the crystal thicker.…”