Adaptive phase-locked fiber array with wavefront phase tip-tilt compensation using pieezoelectric fiber positioners

In this paper, we present the recent development of a conformal optical system with three adaptive phaselocked fiber elements. The coherent beam combining based on stochastic parallel gradient descent (SPGD) algorithm is investigated. We implement both phase-locking control and wavefront phase tip-tilt control in our conformal optical system. The phase-locking control is performed with fiber-coupled lithium niobate phase shifters which are modulated by an AVR micro-processor based SPGD controller. The perturbation rate of this SPGD controller is similar to 95,000 iterations per second. Phase-locking compensation bandwidth for phase distortion amplitude of 2 pi-radian phase shift is >10011z. The tip-tilt control is realized with piezoelectric fiber positioners which are modulated by a computer-based software SPGD controller. The perturbation rate of the tip-tilt SPGD controller is up to similar to 950 iterations per second. The tip-tilt compensation bandwidth using fiber positioners is similar to 10Hz at 60-mu rad. jitter swing angle.