Distributed feedback Er ³⁺ -doped fibre laser

Ultraviolet-induced birefringence in hydrogen-loaded optical fiber

“…53 dc offsets using a piezo produce even worse results since the precision in displacement has to be significantly better than half of the fringe period desired ͑Ӷ250 nm in physical displacement which is beyond the limits of many systems to produce reliably and reproducibility, even when combined with advanced interferometric monitoring despite piezo manufacturer and commercial grating supplier claims͒. Postprocessing remains the most popular choice of commercial manufacturers of phase-shifted devices such as fiber DFB lasers, 54 since active monitoring allows precise adjustment without the interferometric precision that raises substantially the costs of gratings produced by alternative methods. Unfortunately, the additional complexity of understanding the impact on birefringence from a different fluence in the center compared to the rest of the grating 48 makes this inappropriate for this work.…”

Ultraviolet-light-induced processes in germanium-doped silica

“…In addition, there is a weak singlet-triplet transition near 327 nm. Most UV writing uses wavelengths near the 242 nm absorption, [19][20][21] some work has been performed with 193-nm excimer lasers making use of the tail of the 180-nm absorption, 22,23 and a few experiments have been performed near 327 nm. 24 In Fig.…”

A dual wavelength distributed-feedback fiber laser

“…Although there were unpublished demonstrations of these lasers as well as reported structures that were unlikely to be DFB action, the first reported DFB fiber laser that was unambiguously a distributed-feedback structure, which also employed UV-postprocessing, was by Asseh et al 6 Since this development, the field of research in DFB fiber lasers has been extensive. [7][8][9] The phase-shifted DFB structure is usually an UVwritten Bragg grating with an induced phase shift at or near the center. For fiber-based DFB lasers the easiest method to introduce the phase shift is through a localized refractive index change arising from exposure to UV light.…”