Coupled parametric processes in binary nonlinear photonic structures

TL;DR

This paper explores the design and analysis of binary nonlinear photonic structures composed of paired crystals, enabling simultaneous multiple parametric processes with enhanced control over spatial properties and efficiency.

Contribution

It introduces a novel binary structure concept, demonstrating how coupled parametric interactions can be achieved and optimized in paired nonlinear crystals.

Findings

Coupled parametric processes depend on the relative shift of crystal lattices.

Inter-crystal distance significantly influences the spatial spectrum and efficiency.

Binary structures can replicate complex nonlinear functionalities with simpler components.

Abstract

We study parametric interactions in a new type of nonlinear photonic structures, which is realized in the vicinity of a pair of nonlinear crystals. In this kind of structure, which we call binary, multiple nonlinear optical processes can be implemented simultaneously, owing to multiple phase-matching conditions, fulfilled separately in the constituent crystals. The coupling between the nonlinear processes by means of modes sharing similar frequency is attained by the spatially-broadband nature of the parametric fields. We investigate the spatial properties of the fields generated in the binary structure constructed from periodically poled crystals for the two examples: 1) single parametric down-conversion, and 2) coupled parametric down-conversion and up-conversion processes. The efficacy of the fields' generation in these examples is analyzed through comparison with the cases of traditional single periodically poled crystal and aperiodic photonic structure, respectively. It has been shown that the relative shift between the periodic crystal lattices has a crucial effect on the generated spatial field spectrum and the overall efficiency. In addition, the influence of the inter-crystal distance on these characteristics has been studied. Therefore, our study suggests that one can construct optical elements with sophisticated nonlinear properties from simpler elements without significant sacrifice of the efficacy.