Optimal coupling of entangled photons into single-mode optical fibers
Roger Andrews, Edward R. Pike, Sarben Sarkar · Optics Express · 2004
We present a consistent multimode theory that describes the coupling of single photons generated by collinear Type-I parametric downconversion into single-mode optical fibers. We have calculated an analytic expression for the fiber diameter which maximizes the pair photon count rate. For a given focal length and wavelength, a lower limit of the fiber diameter for satisfactory coupling is obtained.