Optical power regulator using closed-controlled MEMS variable optical attenuator (VOA)

This paper reports the development of an optical power regulator based on a surface-micromachined variable optical attenuators (VOAs). The VOA module has a size of about 0.6 mm/spl times/1 mm excluding the fibers. It requires only 8 V to obtain an attenuation range of 45 dB. Experiment shows the VOA itself is a nonlinear system and has hysteresis. By use of a digital proportional integration (PI) control system, the VOA module implements an optical power regulation with the functions of power set point tracking and disturbance rejection. The power regulator takes only 24 ms to track an output set point change of 11 dB without experiencing any overshoot. It is also able to reject the disturbance in about 100 ms.