Fluoride fibres yield blue-green lasers

A doped fibre laser, developed by a group from Southampton University and British Telecom, marks a new and stimulating development in the search for a compact blue light source. Richard Smart and colleagues report that their continuous wave (CW) laser, in fluorozirconate fibres doped with praseodymium (Pr 3+ ) ions, operates at room temperature and emits, amongst others, light in the coveted blue-green region of the spectrum (Electronics Letters (1991) 27 1307).