Costas-Loop Based Carrier Recovery in Optical Coherent Intersatellite Communications Systems

Optical intersatellite communication is an attractive alternative to current RF satellite communication in order to increase the data rate and lower the power consumption. By using coherent detection, full signal recovery is achieved at the receiver which allows modulating both, amplitude and phase. However, the needed local oscillator requires a complex carrier recovery system. In order to achieve homodyne detection an optical phase-locked loop is used which is characterised by a nonlinear behaviour that influences the data transmission performance. We present a nonlinear characteristic investigation of this Costas-loop based carrier recovery system for optical high-speed intersatellite data transmission. We combine the fundamentals of future optical intersatellite communication with analyses of an optical phase-locked loop based carrier control system. The corresponding nonlinear differential equation system is derived and finally investigated by phase plane diagrams. The impact of noise as well as the cycle slip phenomena will be discussed.