10-Gsymbol/s IM-based quantum noise encryption system modulated by a dual digital‐to‐analog converter

To attain secure fiber-optic transmissions at a high rate, a realizable scheme is proposed in this paper, that can achieve 10-Gsymbol/s quantum noise encryption based on intensity modulation. Specifically, a dual digital-to-analog converter (DAC) is used to drive a single-drive Mach–Zehnder modulator. Then, to demonstrate the advantage of this scheme, a trial of 10-Gsymbol/s single-channel transmissions over 30 km are confirmed at 4096 intensity levels. Furthermore, specific indicators that affect secure transmissions are analysed, such as the number of modulation levels and noise masking. Finally, experimental results show that a masking number of 370 is achieved to resist direct detection attacks at the 4096 signal levels. Multilevel optical signals are hidden in the quantum noise. It is also apparent that the proposed modulation method realizes highly secure fiber-optic transmission.