Backward Wave Optical Parametric Oscillator Pumped by a Bessel Beam

Backward wave optical parametric oscillators (BWOPO) represent a class of nonlinear optical devices where the signal and idler photons are generated in strictly opposite directions [1]. Realizing such an oscillation requires a quasi-phase-matching (QPM) approach with sub-μm-periodicity structures [2]. Theoretically and experimentally, the temporal phases of the forward and backward waves generated in BWOPO have been shown to be well determined [3]. In particular, the forward-generated wave inherits the temporal phase modulation of the pump [4]. In contrast, the temporal phase of the backward-generated wave remains fixed as required by the general phase relations in the parametric interaction. Spatially structured beams have been receiving increasing interest due to substantial advantages offered for many applications, including optical communications [5]. The synthesis of parametric beams with spatially and temporally designed phases at any wavelength allowed by the transparency of the QPM material would be of great interest. So far, there has been no theoretical or experimental investigation on generating spatially structured beams in BWOPO.