We have developed a high-resolution wavefront control system based on an optically addressed nematic liquid crystal spatial light modulator with several hundred thousand phase control points, a Shack-Hartmann wavefront sensor with two thousand subapertures, and an efficient reconstruction algorithm using Fourier transform techniques. We present quantitative results of experiments to characterize the performance of this system.
We report a new theoretical study of the effects of anisotropic erbium dipoles on the polarization of Er-doped fiber lasers (EDFLs), as well as measurements of the polarization of EDFLs made of a polarization-maintaining fiber. Convenient closed-form expressions are presented for the gain of a signal polarized either parallel or perpendicular to the pump. These results are used to interpret the polarization behavior of our EDFLs, stressing the effects of pump orientation, fiber length, and cavity Q. We identify in particular operating conditions that produce a fiber laser with either a linearly polarized output or equal power in both polarizations.