Long distance QKD propagation using optical single sideband scheme

Implementation of the passive radio over-fiber technique permits modulating the low-frequency sub-carrier onto an optical channel for dissemination through a light-wave fiber network. Single-sideband modulation for optical signals allows the impressive utilization of channel capacity in optical fiber. Dispersion reduction techniques limit the pulse spreading of a propagated signal in any photonic scheme. To control pulse-spreading effects, the optical single-sideband modulation technique at different phase shifts is modeled, analyzed, and compared to examine the performance of a sub-carrier multiplexing system. Hence, in this paper, a quantum key distribution network using a single sideband modulation technique based on a Li-Nb Mach-Zehnder modulator has been proposed at different electrical phase shifts. In this suggested model, the Optisystem 14.2 simulator is used to analyze the nonlinear characteristics. We have designed a single-sideband contour reduction and amplification with each couplet of 120 km by increasing the distance up to 720 km, and the phase between quantum states is determined. The system performance of the suggested model is investigated and compared based on output power (dBm), quality factor, eye diagram, bit error rate (BER), extinction ratio (ER), and optical spectrum of the received signal by varying link distance (km), channel spacing (nm), input power (dBm), and fiber dispersion (ps/ns/km).