Adaptive Control of Degenerate Mode Groups in a Highly Multimode Fiber

Using adaptive optics, we selectively excite individual degenerate mode groups within a highly multimode fiber. A deformable mirror is employed to modulate the fiber input wavefront based on a feedback signal provided by a fiber Bragg grating written within the multimode fiber. Selective excitations of low-, intermediate-, and high-order degenerate mode groups are experimentally achieved.