Optical fiber coupler for selectively coupling radiation to a selected core in a multicore optical fiber and method for selectively coupling radiation from a single-core optical fiber to a selected core of a multicore optical fiber

Abstract

An optical fiber coupler for selectively coupling radiation to a selected core of a multi-core optical fiber is characterized in that it comprises, successively, in the optical path a lightsaber-type structure (S1), an imaging lens (S2), and focusing lenses (S3), wherein the radiation beam emerging from the lightsaber-type structure (S1) to the imaging lens (S2) is positioned only in the beam propagation axis. A method for selectively coupling radiation from a single-core optical fiber to a selected core of a multi-core optical fiber is characterized in that it comprises the steps of: illuminating the lightsaber-type structure (S1) with a radiation beam emerging from the single-core optical fiber; focusing, using the lightsaber-type structure (S1), the radiation into a spiral focal section along the optical axis;enlarging and imaging the distribution of the focal intensity in subsequent planes within the focal section distance range using an imaging lens (S2), wherein the radiation beam emerging from the lightsaber-type structure (S1) to the imaging lens (S2) is positioned only in the beam propagation axis; introducing radiation into a specific core of the multi-core optical fiber using one of the focusing lenses (S3), wherein the introduction into the specific core depends on the selected distance between the lightsaber-type structure (S1) and the imaging lens (S2).;