Publications (3)2.91 Total impact
- [Show abstract] [Hide abstract] ABSTRACT: The authors demonstrate the inscription of several Bragg gratings at the same location of a photosensitive fiber. This superimposed Bragg grating was fabricated by two-beam interference method using UV laser light. Effects due to the inscription of multiple gratings at the same location of the fiber such as changes of reflectivity and shift of wavelength are studied.
- [Show abstract] [Hide abstract] ABSTRACT: Cylindrical convex lenses are commonly used in fabricating fiber Bragg gratings (FBGs) by the phase mask method to increase the energy fluence of UV laser light and thereby enhance FBG productivity. We have found that lens aberrations can affect the efficiency of FBG fabrication by this method. Comparisons of the experimental measurements of FBG transmission minimum as a function of fiber position during irradiation by focussed excimer laser light with ray tracing calculations demonstrate the effect of spherical aberration, particularly for lenses with shorter focal lengths.
- [Show abstract] [Hide abstract] ABSTRACT: Long-period fiber Bragg gratings fabricated by exposure of hydrogen-loaded fiber to UV laser light exhibit large-scale dynamic evolution for approximately two weeks at room temperature. During this time two distinct features show up in their spectrum: a large upswing in wavelength and a substantial deepening of the transmission minimum. The dynamic evolution of the transmission spectrum is explained quantitatively by use of Malo's theory of UV-induced quenching [Electron. Lett. 30, 442 (1994)] followed by refilling of hydrogen in the fiber core and the theory of hydrogen diffusion in the fiber material. The amount of hydrogen quenched by the UV irradiation is 6% of the loaded hydrogen.
Takamatu, Kagawa, Japan
- Faculty of Engineering