Preparation method for writing in spiral long-period fiber Bragg grating based on bilateral CO2 laser

Abstract

The invention discloses a preparation method for writing in a spiral long-period fiber Bragg grating based on a bilateral CO2 laser. By adopting the bilateral CO2 laser, emitting laser can be perpendicularly irradiated to the region where a coating layer is removed from single mode fiber from the two sides, and CO2 laser beams are formed in two directions by a certain angle and emitted into the optical fiber with no overlapping. The two laser beams meet at the two sides of the optical fiber, a large-angle wrapping hot field is formed, and the uniform and effective optical fiber heating processcan be achieved. Torsion and irradiation boosting are separated, the CO2 laser freezes the mechanically-introduced torsion into the optical fiber, the periodic refractive index is introduced for modulation, the special long-period fiber Bragg grating is formed, and the technical problems that when laser heating and screwing are performed at the same time, due to the fact that the optical fiber issubjected to motor torsion and laser impact force at the same time, the optical fiber is likely to deform, the stepped structure is formed, and consumption is increased are solved.

Description

technical field [0001] The invention belongs to the technical field of fiber gratings, and more specifically relates to a double-sided CO 2 Fabrication method of laser-written helical long-period fiber gratings. Background technique [0002] Helical Long-Period Fiber Grating (HLPFG) has attracted widespread attention once it was proposed, and there are various preparation methods. In common experimental preparation methods, the method of twisting the optical fiber while heating with a suitable heat source is generally used. The heat source here can be a high-temperature furnace, a hydrogen-oxygen flame or laser heating. CO 2 The laser heating method stands out for its clean energy, high energy density, flexible control mode and high energy utilization efficiency. [0003] In prior art, CO 2 Methods for laser fabrication of helical long-period fiber gratings include: Seungtae Oh et al. using single-sided focusing CO 2 The laser irradiates the optical fiber, and the motor...

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Problems solved by technology

[0005] For the defects of the prior art, the purpose of the present invention is to solve the prior art single-sided CO 2 The technical problems of high loss and poor writing accuracy caused by the easy deformation of the fiber when the laser is used to prepare the long-period fiber grating

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