Method and semi-finished product for producing a multicore fibre

A method for producing a multicore fiber, comprising 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, the component group comprising:

• a glass cladding cylinder having a cylinder longitudinal axis and an outer lateral surface and having a glass cladding region made of cladding glass;
• a plurality of core glass regions provided with a core glass and extending in the direction of the cylinder longitudinal axis, which are surrounded by the cladding glass;
• and,
• at least one marker element extending in the direction of the cylinder longitudinal axis,
• wherein the marker element is arranged on the outer lateral surface of the glass cladding cylinder, a longitudinal groove being created in the outer lateral surface of the glass cladding region and extending in the direction of the cylinder longitudinal axis, and wherein the marker element is melted in the longitudinal groove before the reshaping process to form the pre-form or the multicore fiber.