We propose and evaluate the performance of a novel RF pulse against rectangular pulse for three modulation formats: QPSK, PM-QPSK, and Star 16 QAM. The proposed pulse shows BER improvement by over an order of magnitude even for large phase and pre-amplifier noise.

We propose and analyze decoy state method for OFDM-QKD systems. Carrier ratio optimization of individual subcarriers increases key generation rate and maximum transmission distance. (C) 2012 Optical Society of America

We propose OFDM to improve key generation rate of frequency-coded QKD system. Simulation results show raw keylength of 20 kbits/s for link lengths upto 50 km. Frequency guard bands and the choice of orthogonal sub-carrier spacing reduces noise power, leading to lower QBER and increased link length.