Abstract: A known method for producing a multicore fiber having a marker zone close to the edge comprises a method step in which a component group is reshaped to form the multicore fiber or to form a pre-form for the multicore fiber. In order to provide a method on this basis for producing multicore fibers having a marker zone close to the edge, in which the risk of rejects is reduced, the marker element is arranged on the an outer lateral surface of a glass cladding cylinder, wherein a longitudinal groove is created in the outer lateral surface of the glass cladding region and extending in the direction of a cylinder longitudinal axis, and the marker element is melted in the longitudinal groove before the reshaping to form the pre-form or the multicore fiber.

Abstract: A target rod comprises a first glass region extending along the target rod longitudinal axis and a marker region extending along the target rod longitudinal axis and adjacent to the first glass region, which marker region contains the marker element or provides a hollow channel that either forms the marker element or is designed for receiving the marker element, and the semi-finished product comprises the cladding material layer and the target rod.

Abstract: Methods for producing a multicore fiber comprise a method step in which a component group is reshaped to form the multicore fiber or a pre-form for the multicore fiber, which comprises a hollow cylinder comprising a central bore and a hollow cylinder longitudinal axis, which hollow cylinder comprises a cladding glass region made of cladding glass and a plurality of core glass regions occupied by a core glass, wherein at least part of the central bore is occupied by a glass filling material. In order to provide a method for producing multicore fibers without central signal core, in which the risk of rejects during the completion of the hollow glass cladding cylinder is reduced, a marker element made of marker glass adjacent to the glass filling material is used, which extends along the longitudinal axis of the central bore.

Abstract: An anti-resonance element preform for producing an anti-resonant hollow-core fiber, comprising a first longitudinal axis, an ARE outer element designed in a circular arc-like manner, and an ARE inner element, wherein the ARE outer element and the ARE inner element are connected to one another along two connecting lines, which are arranged essentially in parallel to the first longitudinal axis. It is provided that the ARE outer element has an inner space, which is at least partially limited by an ARE outer wall and into which the ARE inner element, designed in a circular arc-like manner, protrudes at least partially.