Focal-plane wavefront sensing with photonic lanterns: theoretical framework

The photonic lantern (PL) is a tapered waveguide that can efficiently couple light into multiple single-mode optical fibers. Such devices are currently being considered for number of tasks, including the coupling telescopes and high-resolution, fiber-fed spectrometers, coherent detection, nulling interferometry, vortex-fiber nulling. In conjunction with these use cases, PLs simultaneously perform low-order focal-plane wavefront sensing. this work, we provide mathematical framework analysis PL sensor (PLWFS), deriving linear higher-order reconstruction models as well metrics through which sensing performance—in both nonlinear regimes—can be quantified. This extended to account additional optics such beam-shaping vortex masks, generalized other architectures. Finally, initial numerical verification our by simulating six-port PLWFS. forthcoming companion paper (Lin Fitzgerald), more comprehensive characterization few-port PLWFSs, consider how properties controlled optimized.