Wavefront shaping in multimode fibers by transmission matrix engineering

We present a new approach for shaping light at the output of a multimode fiber by modulating the transmission matrix of the system rather than the incident light. We apply computer-controlled mechanical perturbations to the fiber and obtain a desired intensity pattern at its output resulting from the changes to its transmission matrix. Using an all-fiber apparatus, we demonstrate focusing light at the distal end of the fiber and dynamic conversion between fiber modes in the few-mode regime. Since in this approach the number of available degrees of control scales with the number of spectral channels and can thus be larger than the number of fiber modes, it potentially opens the door to simultaneous control over multiple inputs and at multiple wavelengths.