OPTICAL FIBER FOR RECORDING THE BRAGG GRATING WITH LASER WITH A WAVE LENGTH IN THE NEAR AND MIDDLE UV RANGE, METHOD OF PRODUCING THE PROTECTIVE FLUOROPOLYMER COATING OF OPTICAL FIBER AND METHOD OF APPLYING THE COATING TO QUARTZ FIBER Russian patent published in 2018 - IPC G02B6/34 

FIELD: optical fibers.

SUBSTANCE: group of inventions refers to optical fibers, in the structure of the light-conducting part of which Bragg gratings are formed. Optical fiber with a fluoropolymer protective coating, transparent at the wavelength of the laser source, makes it possible to record the Bragg grating directly through such coating. Inventions solve the problem of increasing the manufacturability of optical fibers for recording distributed Bragg gratings with a high reflection coefficient. Optical fiber for recording the Bragg grating is a light-conducting quartz part with a photorefractive core and applied with a protective fluoropolymer coating on it, which is a copolymer of vinylidene fluoride and trifluorochloroethylene, wherein the thickness of the fluoropolymer coating is at least 8 mcm and not more than 20 mcm. Protective fluoropolymer coating is a varnish prepared by dissolving the fluoropolymer, which is a copolymer of vinylidene fluoride and trifluorochloroethylene in organic solvents. Amount of fluoropolymer in the lacquer is 30–50 % by weight. In the preparation of varnish, a mixture of ethyl acetate and butyl acetate, acetone, cyclohexanone and toluene are used as solvents. Protective fluoropolymer coating on the quartz portion of the optical fiber is applied by two successive layers by passing the fiber elongated from the preform through a spinneret filled with a varnish based on a dissolved fluoropolymer containing a copolymer of vinylidene fluoride and trifluorochloroethylene, and subsequent thermal curing of each applied coating layer. After drawing the finished fiber is kept in a thermostat at a temperature of 90 °C for 3 hours.

EFFECT: increasing the manufacturability of producing optical fibers for recording distributed VBR.

3 cl, 2 dwg