Parametric down-conversion in ppLN ridge waveguide: a quantum analysis for efficient twin photons generation at 1550 nm

We study modal characteristics of a customized ridge waveguide in lithium niobate designed to generate twin photons at telecom wavelength. A quantum analysis of SPDC predicts the possible down conversion processes and optimizes the input beam parameters for fundamental mode emission. Further, a joint spectral amplitude analysis ensures that the parameters are ambient for generating frequency-correlated photons throughout the phase-matching spectrum. Moreover, negatively correlated degenerate signal/idler photon pairs in the fundamental mode emission occurs at 1550 nm. A key result of our paper is an explicit expression and plot for comparing the generated signal power in case of waveguides as compared to bulk crystals. Our calculations clearly show a dependence of for a waveguide of length compared to a linear dependence in case of a bulk crystal.