Any Bias Point Control Technique for Mach–Zehnder Modulator

A versatile any point bias control scheme for the Mach-Zehnder modulator is proposed. The ratio of first-order harmonic and average output power was used as feedback signal. We also demonstrate its effectiveness with simulations and experiments. This technique has been shown to be independent of optical input power to the modulator. The results show that this is an effective bias control technique suitable for a variety of modulation formats. The penalty for locking is small and it is 0.5 dB in OSNR penalty. The system BER performance has been observed for 72 h without degradation.