We have demonstrated upconversion detection at the single photon level in the 2 um spectral window using a pump wavelength near 1550nm, a periodically poled lithium niobate (PPLN) waveguide, and a volume Bragg grating (VBG) to reduce noise. We achieve a system photon detection efficiency of 10%, with a noise count rate of 24,500 counts per second, competitive with other 2 um single photon detection technologies. This detector has potential applications in environmental gas monitoring, life science, and classical and quantum communication.
@article{arxiv.1310.7422,
title = {Upconversion single photon detection near 2 um},
author = {Guo-Liang Shentu and Xiu-Xiu Xia and Qi-Chao Sun and Jason S. Pelc and M. M. Fejer and Qiang Zhang and Jian-Wei Pan},
journal= {arXiv preprint arXiv:1310.7422},
year = {2013}
}