Method for producing a preform for producing a multicore fibre and also a preform and a multicore fibre

A preform which is manufactured by a method comprising:

• removing a first part-tube segment comprising a first part-tube segment cross-sectional area from a center of a receiving tube comprising a receiving tube internal diameter so that the receiving tube comprises a first core rod receiving cut-out formed as a remaining annular sector with two opposite edges;
• axially introducing a central filling rod comprising a central filling rod external diameter into the receiving tube, the central filling rod external diameter being less than the receiving tube internal diameter so that the receiving tube contains the central filling rod;
• inserting a first core rod comprising a first core rod cross-sectional area in a radial direction from outside into the first core rod receiving cut-out between the two opposite edges of the remaining annular sector so that the receiving tube contains the first core rod;
• axially introducing the receiving tube containing the first core rod and the central filling rod into a jacketing tube so as to obtain a jacketing tube containing the receiving tube;
• and
• fusing the jacketing tube containing the receiving tube to form the preform.