Coherent addition of injection-locked high-power AlGaAs diode lasers

Coherent addition with the use of injection-locked AlGaAs high-power diode lasers has been performed. The linewidths of the master and slave lasers were narrowed to less than 30 kHz by using the optical feedback from an off-axis confocal Fabry-Perot resonator. The coherently added output power of two diode lasers was increased up to 110 mW, which corresponds to an addition efficiency of 0.85. The residual phase fluctuation of the system was controlled within 0.25 rad. Addition of three high-power diode lasers has been also demonstrated for the first time to our knowledge, and a total output power of 150 mW with an addition efficiency of 0.68 was obtained.