Glass optical fibre doped with rare earth elements - acts as pumped laser in which element is present to enhance laser transfer of the dopant thulium

摘要

Optical fibre consists of a glass, pref. an oxygen-free fluoride glass from the gp. of heavy metal-fluoride glasses (HMF) or quartz-glass, which is doped with thulium, pref. less than 0.1 mole%. The feature is that the glass also contains dopant of another element at a relatively higher doping level, pref. up to 50x, which shows an energy-term ((5)I7,(7)F2,(7)F6) which is close to that of the term (3)H4 of Tm. The other dopant(s) pref. also has (have) multiple energy terms, e.g. (7F3) to (7)F6 for Tb and (7)F5 to (7)F0 for Eu, which effect a multi-phonon emission. USE/ADVANTAGE - The use of codopants causes deactivation of the (3)H4 level of Tm, which is present in lower concn. the output. The use of multiphonon emission reduces deactivation of the (3)F4 level by acceptor states, which can have high lifetimes. The inter-ionic transfer between Tm and e.g. Tb causes a redn. of the occupation density of the laser level. The laser is used for optical fibre communication, at a wavelength of 1.5 microns.