Delay-tolerant control design for Semiconductor Optical Amplifiers

Semiconductor optical amplifiers (SOAs) are versatile active photonic devices that can provide complex functions in photonic circuits, such as linear amplification. SOAs must be regulated due to their nonlinear nature. We consider the state space formulation of a linear SOA model to design and analyze controller schemes. We show that delay in the feedback path is of fundamental importance to the stability and performance of the SOA system. Due to the sub-nanosecond dynamics, the SOA system is a challenging system to control. We derive a design tradeoff on the feedback controller and delay stability margin of the closed-loop system. Different control schemes are then compared to show that a dual control scheme using a feedforward and a feedback controller offers the best performance.