An Attempt To Fabricate Long Period Fiber Gratings Using Electron Irradiation

As a new kind of optical device, long period fiber gratings have many virtues that other devices do not have. So the fabrication of it attracts many people. There are already many methods to fabricate long period fiber gratings, but they all have there own disadvantages which limit their applicaton. The method to fabricate long period fiber gratings needs to be enriched.By summarizing the methods to fabricate long period gratings that have already exist, and analyzing the advantange and disadvantages of their principle, it is proposed that long period fiber gratings can be fabricated by use of electron beam irradiation. Then, the theory of long period fiber gratings is analyzed, and the transmission spectrum is simulated, parameters that describing the coupling of fundmental core mode and cladding modes are also calculated. In order to prove the possibility of fabricating long period fiber gratings by use of electron irradiation, the progress of fabricating optical waveguides on SiO₂ with the same method is summarized. It is calculated that electrons with energy of 0.4474MeV will generate the largest refractive index modulation in the single mode fiber core. By synthesizing all kinds of factors, this will be the best energy to fabricate long period fiber gratings. Then the mask were fabricated after analyzing the influence of duty cycle to the grating spectrum, and the fabrication of long period fiber gratings was tested at the same time. Several aspects that need to be improved were presented after analyzing the results of the experiment. As a new way, its success will promote the development of fabricating fiber gratings further more.