All-fiber LP11 mode convertors

Opt Lett. 2008 Feb 15;33(4):306-8. doi: 10.1364/ol.33.000306.

Abstract

We describe two all-fiber devices for converting light from the fundamental mode to the second-order set of modes in optical fibers. The first is made by controlled hole collapse in a photonic crystal fiber, and the second is a twisted fused coupler made from few-moded conventional fiber. As well as having applications within fiber optics, the devices can be used to generate azimuthally polarized free-space beams.