Quantum cascade lasers with large optical waveguides

Quantum cascade lasers with large optical cavities that exhibit low waveguide losses, high saturation intensities, and low beam divergence, emitting between /spl lambda//spl ap/4.3 and 5.2μm were studied. Peak-pulsed powers up to 14 W at 15 K and 5 W at 280 K at /spl lambda//spl ap/5.2 μm are demonstrated. A full-width at half-maximum of only 30/spl deg/ was measured for the transverse far-field pattern of the device operating at /spl lambda//spl ap/4.3 μm, a significant reduction compared to conventional waveguides.