The integrated optical circuit is a promising architecture for the realization of complex quantum optical states and information networks. One element that is required for many of these applications is a high-efficiency photon detector capable of photon-number discrimination. We present an integrated photonic system in the telecom band at 1550 nm based on UV-written silica-on-silicon waveguides and modified transition-edge sensors capable of number resolution and over 40% efficiency. Exploiting the mode transmission failure of these devices, we multiplex three detectors in series to demonstrate a combined 79% +/- 2% detection efficiency with a single pass, and 88% +/- 3% at the operating wavelength of an on-chip terminal reflection grating. Furthermore, our optical measurements clearly demonstrate no significant unexplained loss in this system due to scattering or reflections. This waveguide and detector design therefore allows the placement of number-resolving single-photon detectors of predictable efficiency at arbitrary locations within a photonic circuit - a capability that offers great potential for many quantum optical applications.
@article{arxiv.1305.6627,
title = {High quantum-efficiency photon-number-resolving detector for photonic on-chip information processing},
author = {Brice Calkins and Paolo L. Mennea and Adriana E. Lita and Benjamin J. Metcalf and W. Steven Kolthammer and Antia Lamas Linares and Justin B. Spring and Peter C. Humphreys and Richard P. Mirin and James C. Gates and Peter G. R. Smith and Ian A. Walmsley and Thomas Gerrits and Sae Woo Nam},
journal= {arXiv preprint arXiv:1305.6627},
year = {2015}
}