Emission of orbital-angular-momentum-entangled photon pairs in a nonlinear ring fiber utilizing spontaneous parametric down-conversion

Abstract

We suggest the generation of photon pairs in a thermally induced nonlinear periodically poled silica fiber by spontaneous parametric down-conversion. Photons are generated directly in eigenstates of optical angular momentum. Photons in a pair can be entangled in these states as well as in frequencies. We identify suitable spatial and polarization modes giving an efficient nonlinear interaction. By changing the pump field properties both narrow-and broadband down-converted fields can be obtained.

Role of volume and surface spontaneous parametric down-conversion in the generation of photon pairs in layered media

“…Spontaneous parametric down-conversion (SPDC) is a second-order nonlinear process [1][2][3] in which one photon with higher energy is annihilated and two photons of lower energies are simultaneously created. Due to the laws of energy and momentum conservations quantum correlations (entanglement) between the photons in a pair emerge [4][5][6][7]. The process of SPDC occurs either inside the media with non-zero second-order permittivity tensor (non-centrosymmetric crystals) or at the boundaries of these media [8][9][10].…”

“…The process of SPDC has been observed in nonlinear bulk media [10,11], systems of nonlinear thin layers [12][13][14] including metallo-dielectric layers [7,15,16], nonlinear photonic fibers [7,17,18], nonlinear photonic waveguides [19][20][21][22], as well as in complex nonlinear photonic structures [23]. Bulk media including the most common nonlinear crystals LiNbO 3 and KTP represent the historically oldest sources of photon pairs.…”

Scheme for on-chip verification of transverse mode entanglement using the electro-optic effect

“…Entanglement between photons can be produced in various degrees of freedom such as polarization [5][6][7][8], time/frequency [9][10][11][12][13] etc. In the case of multimode waveguides, transverse spatial modes can be also used as the basis for generating a discrete (finite-dimensional) entangled state [10,[14][15][16][17][18].…”