Randomly poled crystals as a source of photon pairs

Generation of photon pairs from randomly poled nonlinear crystals is investigated using analytically soluble model and numerical calculations. Randomly poled crystals are discovered as sources of entangled ultra broad-band signal and idler fields. Their photon-pair generation rates scale linearly with the number of domains. Entanglement times as short as several fs can be reached. Comparison with chirped periodically-poled structures is given and reveals close similarity.Comment: 13 pages, 29 figure

Measurement-based tailoring of Anderson localization of partially coherent light

We put forward an experimental configuration to observe transverse Anderson localization of partially coherent light beams with a tunable degree of first-order coherence. The scheme makes use of entangled photons propagating in disordered waveguide arrays, and is based on the unique relationship between the degree of entanglement of a pair of photons and the coherence properties of the individual photons constituting the pair. The scheme can be readily implemented with current waveguide-on-a-chip technology, and surprisingly, the tunability of the coherence properties of the individual photons is done at the measurement stage, without resorting changes of the light source itself.Comment: 7 pages, 5 figures, additional correction

Proposal for the generation of photon pairs with nonzero orbital angular momentum in a ring fiber

We present a method for the generation of correlated photon pairs in desired orbital-angular-momentum states using a non-linear silica ring fiber and spontaneous parametric down-conversion. Photon-pair emission under quasi-phase-matching conditions with quantum conversion efficiency $6\times 10^{-11}$ is found in a 1-m long fiber with a thermally induced $\chi^{(2)}$ nonlinearity in a ring-shaped core