Enhancement of output power from narrow linewidth amplifiers via two-tone effect--high power experimental results.

Two-tone 1064 nm fiber amplifiers having both cold (16°C) and pump induced temperature zones co-seeded with narrow linewidth 1064 nm and broad linewidth 1040 nm photons have been shown to have a power enhancement factor between 1.6 and 1.8 relative to the optimum single-tone 1064 nm amplifier while maintaining an efficiency of 65% or greater. The output power and efficiency of 1064 nm narrow linewidth two-tone amplifiers is dependent on the length of the gain fiber, the narrow to broad linewidth seed ratio, the wavelength of the broad linewidth seed and the temperature of the gain fiber.