Stable bias control of Mach-Zehnder modulator for arbitrary optical pulse picking via reference pulse power monitoring

A stable bias control scheme of Mach-Zehnder modulator (MZM) for optical pulse picking is proposed. The key to this method is introducing a reference optical pulse signal that is time-shifted relative to the electrical selection signal, ensuring that the output power of the reference pulse is independent of the selection signal and reaches its minimum value at the MZM's minimum bias point. This method is particularly suited for optical pulse picking systems, as it remains stable despite variations in optical power and division ratio. Experimental results demonstrate that the proposed bias control method maintains an extinction ratio of over 17.7 dB in optical pulse picking for over one hour, significantly outperforming systems without bias control. Additionally, the system supports arbitrary division ratios across a wide range from 2 to 200, demonstrating the flexibility of the bias control method.