Tutorial on Single-Photon Detectors
Krister Shalm of National Institute of Standards and Technologies presented a tutorial: Single-photon detectors at the 2013 QCrypt Conference in August. http://2013.qcrypt.net
This is from a while back but an excellent educational resource nevertheless!
The video is roughly 90-minutes long but has several gaps that can be skipped ahead. Or play it at >1x speed!