Coherent lasers turn up the power

Three categories of multiwatt, coherent laser designs are discussed. The designs are single-mode waveguides suitable for output powers in the order of 200 mW, single-mode operation of multimode lasers, which are suitable for operation between 0.5 and 1.0 W, and the monolithically integrated master-oscillator power amplifier (M-MOPA) designs that have demonstrated 4.5 W of spectrally coherent output power and more than 0.8 W of single-lobe diffraction-limited output power in a technology that is scalable to even higher output powers. Laser-diode design architectures and the unique properties of semiconductor materials are reviewed