Smokeless manufacturing process for preforms of structured optical fibers

The invention relates to a preform (100, 200) for manufacturing an anti-resonant hollow-core optical fiber. The invention relates to a method for producing an anti-resonant element (100, 100 ', 100' '), comprising the following steps: a) providing (1000) a cladding tube (200) having a cladding tube bore and a cladding tube longitudinal axis along which a cladding tube wall extends, the cladding tube wall being defined by an inner side and an outer side, b) preparing (1100) a plurality of anti-resonant element preforms (300), each anti-resonant element preform comprises an ARE outer tube and an ARE inner tube inserted into the ARE outer tube, c) preparing (1200) a positioning template (400, 400 '); the present invention relates to a method for producing an anti-resonant element (100) comprising the steps of: a) providing a cladding tube (200) having a first end (400, 400 ', 400' '), a positioning template (400, 400', 400 '') having a plurality of channel openings through the positioning template (400, 400 ', 4