Practical study of the effects of exposure conditions on the quality of fiber Bragg gratings written with excimer and argon-ion lasers

An experimental study is presented which evaluates the effects of various important exposure parameters on the quality of fiber Bragg gratings. The parameters addressed include laser repetition rate, fluence and intensity, total exposure dose, numbers of shots, fiber-mask separation and beam scanning speed. In the case of excimer laser writing of gratings, it is seen that the balance between exposure fluence and total dose is crucial in how strong a grating can written and its writing time. It is also observed that the laser repetition rate does not affect the grating quality and that a fiber-mask separation of around 50 - 200 μm is desirable for optimum gratings. The changes in grating quality with argon ion beam scanning speed and exposure power are presented.