A regenerative ring amplifier and regenerative ring oscillator which function to feed back a portion of the Stokes signal to complete the ring cavity. The ring cavity configuration allows the CO.sub.2 laser pump signal and Stokes signal to copropagate through the Raman capillary waveguide amplifier....http://www.google.se/patents/US4394623?utm_source=gb-gplus-sharePatent US4394623 - Ring cavity for a raman capillary waveguide amplifier
