Abstract
In this paper, we report the growth behaviour of long-periodgratings (LPGs) in a hydrogen-loaded fibre during and immediately after 193 nmUV inscription. The LPG's peak loss follows a sinusoidal function of theamplitude of the index modulation in the fibre core, thus the peak lossincreases first and then decreases with further increase of writing pulsesduring UV inscription. After UV inscription has stopped, the LPG continues togrow with time owing to the hydrogen diffusion, and an increase of as much as14 dB in the LPG peak loss was measured. We offer a qualitative explanationfor the growth dynamics of the LPGs immediately after 193 nm UV inscriptionand discuss the effects of temperature and initial grating strength on thegrowth behaviour. We also investigate the impact of post-UV irradiation on theLPGs after annealing. Our study shows that post-irradiation trims not only thepeak loss intensity but also the peak wavelength of the LPGs. This provides anopportunity to control the resonance peaks of the LPGs.
Published Version
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