DOI: 10.1016/B978-0-323-90614-2.00013-4
This book chapter outlines the work done by myself and Andrea Mazzanti on using Bound States in the Continuum (BICs) to enhance the generation of entangled photon pairs in metasurfaces. Andrea studied the use of ‘topological BICs’, which can form at an arbitrary incident angle for the illuminating beam, while I studied ‘symmetry protected BICs,’ which can only form at normal incidence. One would expect the photon-pairs to be emitted in an elliptical pattern, but during my research I discovered a novel phenomenon which I dubbed ‘hyperbolic transverse phase matching.’ This new phenomenon can arise when you are using two BICs for the signal and idler which have opposite dispersion. If the symmetry of the metasurface allows it then the dispersions will combine in the form of a hyperbolic paraboloid, which causes the signal and idler to be emitted in a hyperbolic pattern.
Unfortunately, for copyright reasons I am unable to redistribute the chapter, so if you are unable to access the document linked to above then you can find our research summarised in the two articles:
I am quite proud of the fact that my paper has already been cited over 80 times.
Abstract
We present the fundamental concepts for enhancing photon-pair generation through spontaneous parametric downconversion in nonlinear dielectric metasurfaces. We show that in metasurfaces with specially designed two-dimensional (2D) or one-dimensional (1D) nanopatterns, which support optical bound states in the continuum, the photon rate and spectral brightness can be enhanced by orders of magnitude when compared to unpatterned thin films. In the case of our 2D structure, the photon pairs are emitted close to the normal, while our 1D lattice can mediate emission in a broad angular pattern. We also identify the distinct physical mechanism of the enhancement associated with 2D hyperbolic transverse phase matching of the frequencies with nondegenerate photons. These results can provide a foundation for future advances in the development of ultraminiaturized quantum sources of entangled photons tailored for various applications.