The fact that most terrestrial optical fibre communications systems installed around the world today operate at 1.3µm means that a practical fibre amplifier operating in this window is of key strategic importance. The primary contender to provide amplification within this window is the praseodymium doped fluoride fibre amplifier(PDFFA). To date high gains (>30dB) and high saturated output powers ( >200mW) have been achieved but have required the use of large- frame ion lasers as primary optical pump sources. The main difficulty in using semiconductor laser diodes as a pump source is the very high level of pump power needed in this comparatively low efficiency system. One approach that has proved successful in erbium doped fibre power amplifiers is to use a solid state crystal laser to convert the large, but spatially incoherent output from 800nm semiconductor laser diode bars into a TEM00 output which can then be efficiently coupled into the doped fibre.
© 1992 Optical Society of AmericaPDF Article