Method for producing a preform of an anti-resonant hollow-core fiber

A method for producing a preform of an anti-resonant hollow-core fiber, comprising the method steps of

• a) providing a cladding tube, which has a cladding tube inner bore and a cladding tube longitudinal axis, along which a cladding tube wall extends, which is limited by an inner side and an outer side,
• b) preparing a number of anti-resonance element preforms formed by nested tubular structural elements including an ARE outer tube and an ARE inner tube inserted therein, wherein the structural elements have a structural element longitudinal axis,
• c) arranging the anti-resonance element preforms on the inner side of the cladding tube wall, and
• d) thermal fixing of the anti-resonance element preforms to the cladding tube wall by means of heat input,
• wherein—the method has the step of
• e) introducing a contact element each into at least one anti-resonance element preform in such a way that the contact element increases the heat-absorbing mass of the anti-resonance element preform in step d), in order to slow down a heat flow from the cladding tube into the anti-resonance element preform during the thermal fixing,
• wherein the contact element is designed in such a way that what applies is
• C_cladding tube>C_contact element>C_anti-resonance element preform, wherein
• C_cladding tube is a heat capacity of the solid material of the cladding tube, averaged over a unit volume,
• C_contact element is a heat capacity of the contact element and of the ambient air, averaged over the unit volume,
• C_anti-resonance element preform is a heat capacity of the anti-resonance element preform and of the ambient air, averaged over the unit volume,
• and the unit volume is 25% by volume larger than a volume of the contact element.