Nonlinear adaptive control of optical jitter with a new liquid crystal beam steering device

This paper presents a new approach to active control of optical jitter with a new transmissive liquid crystal beam steering device, or tilt corrector. The device is driven by a linear time-invariant feedback control loop and an adaptive control loop to maximize the jitter-rejection bandwidth. In contrast to conventional fast steering mirrors, the liquid crystal device optically redirects the laser beam. The new device has no moving parts and requires low operating power. The paper presents experimental results that demonstrate the capabilities of the liquid crystal device and the adaptive controller to suppress high-bandwidth jitter. For the control system, the liquid crystal device presents nonlinearities due to a rate limit and quantization. The experimental results show the importance of modeling the nonlinearities in the adaptive controller.