Up to 2.5-kW on non-PM fiber and 2.0-kW linear polarized on PM fiber narrow linewidth CW diffraction-limited fiber amplifiers in all-fiber format

We report test data for narrow linewidth fiber amplifiers in a compact modular package and in all-fiber format with power up to 2.5kW and 2.0kW in non-PM and PM fiber configuration respectively for various scientific and advanced applications. Both fiber amplifiers have been pumped directly by laser diodes and have 3m output delivery cable. The fiber amplifiers have more than 35% wall-plug efficiency. Measured M² values are ≤ 1.1. The amplifier data are discussed for different input linewidth and test conditions.