Shared optical parametric generation interactions in square lattice nonlinear photonic crystals

Abstract

In this work, we investigated common optical parametric generation (OPG) with a 532-nm beam pumped along the x-axis of a square lattice two-dimensional periodically poled lithium tantalate (2D-PPLT). Twin-beam generation are observed with either the signal or the idler beams propagating collinearly to the pump beam due to participation of reciprocal lattice vectors (RLV) of $\mathbf K _{1,\pm 1}$. With both of the signal and the idler beams generated non-collinearly to the pump beam, multi-wavelength dual-beam generation are also observed due to contribution from $\mathbf K _{1,0}$ and $\mathbf K _{1,\pm 1}$. Because of mirror symmetry in the domain patterns/structures of the 2D-PPLT, all the OPG processes are doubled with the generated waves spectrally degenerated and spatially separated. By analyzing the spectral and angular distribution of the OPG beams, we confirm that the angular crossing of the $\mathbf {K_{m,n}}$-assisted quasi-phase matching (QPM) spectral tuning curves result in a shared signal or idler wave configuration which leads to intensity enhancement in these parametric beams.