Growth characteristics of long-period gratings in hydrogen-loaded fibre during and after 193 nm UV inscription

In this paper, we report the growth behaviour of long-period gratings (LPGs) in a hydrogen-loaded fibre during and immediately after 193 nm UV inscription. The LPG's peak loss follows a sinusoidal function of the amplitude of the index modulation in the fibre core, thus the peak loss increases first and then decreases with further increase of writing pulses during UV inscription. After UV inscription has stopped, the LPG continues to grow with time owing to the hydrogen diffusion, and an increase of as much as 14 dB in the LPG peak loss was measured. We offer a qualitative explanation for the growth dynamics of the LPGs immediately after 193 nm UV inscription and discuss the effects of temperature and initial grating strength on the growth behaviour. We also investigate the impact of post-UV irradiation on the LPGs after annealing. Our study shows that post-irradiation trims not only the peak loss intensity but also the peak wavelength of the LPGs. This provides an opportunity to control the resonance peaks of the LPGs.

[1]  John E. Sipe,et al.  Long-period fiber gratings as band-rejection filters , 1995 .

[2]  S. B. Lee,et al.  Displacements of the resonant peaks of a long-period fiber grating induced by a change of ambient refractive index. , 1997, Optics letters.

[3]  Jacques Albert,et al.  Effective index drift from molecular hydrogen diffusion in hydrogen-loaded optical fibres and its effect on Bragg grating fabrication , 1994 .

[4]  Turan Erdogan,et al.  Cladding-mode resonances in short- and long-period fiber grating filters , 2000 .

[5]  Don Monroe,et al.  DECAY OF ULTRAVIOLET-INDUCED FIBER BRAGG GRATINGS , 1994 .

[6]  J. Judkins,et al.  Broad-band erbium-doped fiber amplifier flattened beyond 40 nm using long-period grating filter , 1997, IEEE Photonics Technology Letters.

[7]  Byeong Ha Lee.  Temperature sensor using the self-interference of a long-period fiber grating , 1999, International Conference on Optical Fibre Sensors.

[8]  M.A. Jackson,et al.  Generalized expression for the growth of long period gratings , 1998, IEEE Photonics Technology Letters.

[9]  I. Bennion,et al.  Optical bend sensor based on measurement of resonance mode splitting of long-period fiber grating , 2000, IEEE Photonics Technology Letters.

[10]  Heather Patrick,et al.  Annealing of Bragg gratings in hydrogen‐loaded optical fiber , 1995 .

[11]  T. Erdogan.  Fiber grating spectra , 1997 .

[12]  John Canning,et al.  Photosensitization and Photostabilization of Laser-Induced Index Changes in Optical Fibers , 2000 .

[13]  Shan Jiang,et al.  Dual resonant peaks of LP/sub 015/ cladding mode in long-period gratings , 1999 .

[14]  Heather Patrick,et al.  Long period fibre gratings for structural bend sensing , 1998 .

[15]  R O Claus,et al.  Simultaneous strain and temperature measurement with long-period gratings. , 1997, Optics letters.

[16]  N. S. Bergano,et al.  Long-period fiber-grating-based gain equalizers. , 1996, Optics letters.

[17]  A. Vengsarkar,et al.  Optical fiber long-period grating sensors. , 1996, Optics letters.