Method for making long-period optical fiber by employing electron beams

Abstract

This invention relates to long circle fiber grating method by use of electron beam, which belongs to fiber and grating process technique field and is characterized by the following: irradiating the fiber with vibration mask board by electron beam to change the micro structure of the fiber; forming circle refraction ratio distribution on the fiber; the electron beam energy is 150KeV to 4MeV, the irradiating dose is 10 to 800 KGY.

Description

technical field [0001] The invention belongs to the field of optical fiber grating preparation, and relates to a method for preparing long-period optical fiber gratings by using electron beams. Background technique [0002] According to the grating period, fiber gratings can be divided into long-period fiber gratings (LPFG) and fiber Bragg gratings (FBG). LPFG is also known as a transmission grating, and its period is usually tens of microns to hundreds of microns. FBG is also called short-period grating and reflective grating, and its period is a few tenths of a micron to several microns. LPFG has very good transmission spectrum characteristics. It couples the guided mode energy transmitted by the fiber core into the cladding to cause the transmission loss of the corresponding wavelength. It is an ideal band-stop transmission filter and has broadband filtering performance. At the same time, the manufacturing process is simple, the insertion loss is small, there is no back...

AI Technical Summary

Problems solved by technology

At present, the preparation methods of long-period fiber gratings at home and abroad are as follows: one is the exposure method. The light exposed is usually ultraviolet light with a wavelength of 193nm or 248nm. This method is divided into point-by-point exposure method and amplitude mask method. The point exposure method has the advantage of high flexibility and can make gratings with different spectral characteristics, but it cannot be used in mass production; the advantage of the amplitude mask method is that it can realize mass production of fiber gratings, but different gratings need to use different masks , and will block most of the laser light of the excimer laser, reducing the energy efficiency of the laser. In order to shorten the writing time, the excimer laser must work at a high power, which will shorten the life of the laser optical components, but the exposure method. The grating has insufficient photosensitivity and poor thermal stability, so it can only be used for germanium-doped silica fibers with photosensitivity, and the formed fiber grating needs to be processed to improve photosensitivity before writing, and annealing treatment is required after writing, so , the process is complicated, the production time is long, and the cost is high; the second is the physical deformation method, which can be divided into heating stretching and grooving pressure. In the downward slope section, the duration of the arc is used to control the size of the microbend in this section. The advantage is that the grating has low insertion loss and high thermal stability (up to 800C). The disadvantage is that the mechanical properties of the optical fiber decrease and the process conditions It is not easy to control and is not suitable for mass production; in the grooved pressure method, the optical fiber is placed between a flat plate and a panel with periodic grooves, and the pressure is released on the grooved plate. Due to the photoelastic effect, LPFG is formed by changing the refractive index at the pressure point, and its disadvantage is that the thermal stability of the grating is poor

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