Abstract: Described are optical devices and related methods wherein a multiple mode input in a Higher Order Mode (an HOM) optical fiber is converted by a complex mode transformer to produce a fundamental mode output in an optical medium with an E-field that is substantially different than that exiting the HOM optical fiber. The medium is preferably a Large Mode Area (LMA) optical fiber, or free space. The mode transformer may be a series of refractive index perturbations created either by photo-induced gratings or by gratings formed by physical deformations of the optical fiber.

Abstract: Described are multimode optical fibers in which the differential in the mode delay for higher order modes is reduced for bending insensitive MMF. The result is preservation of low differential mode delay and high bandwidth while low bend loss is achieved. The designs are based on choosing a combination of a core profile and a cladding structure with a negative trench positioned at a radius related to the core profile. A feature of the preferred embodiments is a core with a hybrid refractive index profile. The hybrid refractive index profile is essentially a combination of a standard alpha profile and a step profile at the outer edge of the alpha profile.

Abstract: The specification describes optical devices and related methods wherein an input mode is converted by multiple LPG mode transformers to produce an output with multiple predetermined modes.