Method and intermediate product for producing a multi-core fibre with a marker

A method for producing a multi-core fiber with a marker zone or a pre-form for such a multi-core fiber, comprising the formation of a semi-finished product which comprises a glass cladding region made of a cladding glass with a plurality of core glass regions made of a core glass embedded therein, and at least one marker element, the multi-core fiber or the pre-form being obtained by elongation of the semi-finished product, and the production of the glass cladding region comprising a method step in which a cladding material layer is deposited on an outer surface of a target rod having a target rod longitudinal axis using an outside deposition method, wherein the 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 which either forms the marker element or is designed to receive the marker element, and in that the semi-finished product comprises the cladding material layer and the target rod.