Planar waveguide structures for production of modally entangled biphotons with spectrum broadening

TL;DR

This paper investigates how specific planar waveguide structures can be designed to generate broad-spectrum, modally entangled biphotons through spontaneous parametric down conversion, with analytical control over spectrum discretization.

Contribution

It provides an analytical framework for designing waveguide structures that produce controllable, broad-spectrum biphoton entangled states with spectrum broadening and discretization capabilities.

Findings

Biphoton spectra depend on waveguide structure characteristics.

Chirped biphotons with discrete and continuous spectra can be generated.

Spectrum discretization conditions are analytically derived.

Abstract

We study the generation of biphoton modally entangled states in such waveguide structures that lead to spectrum broadening. The process of spontaneous parametric down conversion (SPDC) has been considered for the biphoton generation. The main subject of our study is the dependence of the biphoton spectra on the structure spatial characteristics. The representation of the core structures as definite assembles of nonlinear layers allows us to find analytical description for biphoton spectrum. We show that chirped biphotons with discrete as well as continuous spectra can be generated depending on the waveguide structure. The conditions for spectrum discretization are obtained analytically. It is shown that the biphoton entangled states can be controlled by varying the parameters of the waveguide structure.