Abstract: A section of tapered optical fiber is provided to protect optical components from catastrophic damage that may propagate within an optical route. The tapered section functions as a fuse to arrest the propagation of optical power induced damage by leaking optical power from a waveguiding region below a threshold, below which further propagation of damage is not supported.

Abstract: A thulium doped silica based glass capable of supporting lasing activity including Tm3+ as a lasing species disposed in a host composition, including oxides of germanium, silicon and tantalum. The preferred concentration of silicon in the host composition being between 15-25 weight percent. The preferred concentration of germanium in the host composition being between 0.1-1 weight percent. The preferred concentration of tantalum in the host composition is greater than 15 weight percent. The preferred concentration of thulium ions being in the range of 500-1000 parts per million by weight.

Abstract: Optical device and method for protecting an optical communications route A section of tapered optical fiber is provided to protect optical components from catastrophic damage that may propagate within an optical route. The tapered section functions as a fuse to arrest the propagation of optical power induced damage by leaking optical power from a waveguiding region to below a threshold, below which further propagation of damage is not supported.

Abstract: A thulium doped silica based glass capable of supporting lasing activity including Tm3+as a lasing species disposed in a host composition, including oxides of germanium, silicon and tantalum. The preferred concentration of silicon in the host composition being between 15-25 weight percent. The preferred concentration of germanium in the host composition being between 0.1-1 weight percent. The preferred concentration of tantalum in the host composition is greater than 15 weight percent. The preferred concentration of thulium ions being in the range of 500-1000 parts per million by weight.

Abstract: A laser has a resonant cavity defined by a pair of mirrors butted to respective ends of a fluorozirconate optical fiber. The fiber has a numerical aperture of 0.205 and an LP.sub.11 mode cut-off of about 2.0 .mu.m. The fibre is co-doped with thulium ions to a concentration of about 0.1%, and with terbium ions to a concentration of about 1%. An optical pump source provides a pump signal at 775 nm which excites the thulium ions into the .sup.1 G.sub.4 energy level to provide lasing at about 475 nm. The pump source is preferably a high power semiconductor laser.