We propose a new method to narrow the linewidth of entangled photons generated from spontaneous parametric down conversion (SPDC). An internal Bragg grating is incorporated onto a nonlinear optical crystal waveguide. We study theoretically the spectral characteristics of SPDC under two Bragg grating structures. We show that using the Bragg grating with a midway pi-phase shifter, it is a promising way to generate narrow-line entangled photons.
@article{arxiv.0912.4286,
title = {Bragg-Grating Enhanced Narrow-Band Spontaneous Parametric Down Conversion},
author = {Li Yan and Lijun Ma and Xiao Tang},
journal= {arXiv preprint arXiv:0912.4286},
year = {2015}
}