Homodyne detection for quantum key distribution: an alternative to   photon counting in BB84 protocol
  This paper presents the principles and experimental results of an optical fiber QKD system operating at 1550 nm, and using the BB84 protocol with QPSK signals. Our experimental setup consists of a time-multiplexed super-homodyne configuration using P.I.N detectors in a differential scheme as an alternative to avalanche photon counting. Transmission over 11km of optical fiber has been done using this detection scheme and major relevant characteristics such as noise, quantum efficiency and bit error rate (BER) are reported. 
M.B.Costa e Silva, Q. Xu, S. Agnolini, P. Gallion, F.J. Mendieta