A MZ Modulator Bias Control System Based on Variable Step P&O Algorithm

A variable step perturb and observe(P&O) algorithm is proposed to realize the automatic bias control of Mach-Zehnder(MZ) modulator. A weak sinusoidal disturbance signal is added to the bias input port of the EOM. The control system based on the principle of phase-locked amplification provides the foundation for the algorithm. The simulation results of variable step and fixed step algorithms show the superiority of variable step algorithm in rapidity and accuracy. The step size of the algorithm is related to the slope, and the difficulty of parameter adjustment is greatly reduced. The operating point can be automatically stabilized at ±Quad points without the initial bias sweep. The experiments show that the drift in one hour of the system with bias control is 88.9% lower than that of the system without bias control.