Raman gain from waveguides inscribed in KGd(WO4)2 by high repetition rate femtosecond laser

We report the formation of waveguides in Raman-active KGd(WO(4))(2) with a focused, high repetition rate femtosecond laser. Parallel guiding regions, formed to either side of the laser-induced damage track, supported TE and TM modes that coupled efficiently to optical fiber at telecom wavelengths. Micro-Raman spectroscopy of the guiding regions revealed the preservation of the characteristic 768 and 901 cm(-1) Raman mode intensities. Raman gain with 6% efficiency was demonstrated for the 768 cm(-1) Raman line by pumping the waveguide with an infrared 80 ps source, the first time Raman gain has been reported in laser formed waveguides. (c) 2008 American Institute of Physics.