A control system design for the optimal bias point of external modulator

This paper deals with the effects of direct current bias voltage to X-cut y conduction Mach-Zehnder intensity modulator´s export optical power, and achieves a cosine function equation of direct current bias voltage versus export optical power of modulator. The modulator works on an approximate linear region nearby the optimal bias point Vpi/2(plusmn 10 mV). Considering the approximate linear region´s range of variation is infinitesimal, a high-accuracy digital signal processing (DSP) control system has been designed which achieves precise control for the optimal bias point, in addition, its control precision can be attained 1mV.