J.R. Armitage

Ultraviolet absorption studies on photosensitive germanosilicate preforms and fibers

Detailed measurements of the ultraviolet absorption spectra of germanosilicate preforms, multimode and single‐mode fibers are presented. Significant differences between the spectra of preforms and fibers are revealed and these differences are thought to be caused by the stresses induced during fiber pulling. Measurements are also presented of the changes in the absorption spectra in single‐mode fibers into which reflection gratings have been written using an ultraviolet laser. These results suggest that changes in the absorption between 200 and 600 nm are not responsible for the inferred changes in the refractive index.

Rare-Earth Doped Fibre Lasers And Amplifiers For Optical Communications

Recently, the widespread use of single-mode fibres has demonstrated the need for a range of optical components which perform useful optical functions such as routeing, modulation, amplification, and carrier generation. The benefits of achieving these in all-fibre form are considerable. Interest in the latter functions was generated by the pioneering work at SouthamptonVniversity on the fabrication (1) and demonstration of efficient fibre lasers using Pr3+, Nd3+ and Erif as the rare-earth dopants (2), pumped using a variety of sources including inexpensive GaAs semiconductor lasers. Line-narrowed, tuned, mode-locked and Q-switched operation have been reported in these fibre lasers.