Abstract

CW cascaded Raman fibre lsers are a well-known and efficient method of generating new and useful laser wavelengths [1]. The low loss of silica-based fibre combined with both Bragg grating technology and pumping from high brightness Yb³⁺-doped double-clad fibre lasers allows for the effective production of scalable output in the 1 µm to 2 µm region of the spectrum [2]. In an extension of this technique, doping toe Raman fibre with a lanthanide ion that can absorb the Stokes’ radiation and emit at longer wavelengths could prove to be very practical. This method avoids the use of addition coupling optics required for extra-cavity pumping and also the complications that are involved with cascading a large number of Stokes’ frequencies when a significantly longer wavelength from the pump wavelength is required. Quite low concentrations of the lanthanide ion distributed along the entire length of the Raman fibre or a section of highly doped fibre spliced into the system for laser processes requiring a high degree of interionic interaction could facilitate the laser gain requirement.

© 2000 IEEE