Growth of Ultraviolet-induced H2-loaded long period fiber grating immediately after fabrication

the growth of long period fiber grating written in H2-loaded fiber within one hour immediately after fabrication was measured and analyzed. Fast deepen on difference of refraction index was obviously observed in all the experiments, but the peak wavelength to time and cross-coupling coefficient to time curves are fitted better in exponential decay function than power function, and suggest a same variation pattern in difference of refraction index.