Probe-type all-fiber tiny-displacement sensor based on orbital-angular-momentum interferometry.

In this study, a probe-type all-fiber tiny-displacement sensor is proposed and experimentally demonstrated, which is realized by using an all-fiber orbital-angular-momentum (OAM) interferometer, where a probe is especially adopted and inserted into the testing arm of the OAM interferometer. The proposed device takes full advantages of the OAM interferometer and the probe-type fiber sensor, making it completely available to the tiny-displacement measurement. As a result, changes in displacement (ranging from 0 nm to 750 nm) with a real resolution of ∼8.

Synthesizing the complex orbital-angular-momentum spectrum of hybrid modes existed in a few-mode fiber.

In this study, a simple and reliable method enabling to well synthesize the complex orbit-angular-momentum (OAM) spectrum of hybrid mode in a few-mode fiber is proposed and numerically demonstrated, which is realized by using the so-called inverse scattering method based on the genetic algorithm (GA), where the main Fourier components of a specially-selected ring in intensity distribution of the hybrid mode is used as the optimization objective. As a proof-of-concept example, power spectrum of a hybrid mode consisted of the first- and second-order OAM modes was successfully reconstructed with an accuracy higher than 0.99.