670 nm tapered lasers and amplifier with output powers P ⩾ 1 W and nearly diffraction limited beam quality

High-brightness tapered lasers and amplifiers at 670 nm with output powers up to 1 W and nearly diffraction limited beam quality were realised. The devices consist of a 750 &mgr;m long straight section and a 1250 &mgr;m long tapered section. Devices with a taper angle of 2°, 3° and 4° were manufactured. The material quality was studied in a long-term test for ridge-waveguide lasers. Devices with 7.5 &mgr;m ridge width show reliable operation at 100 mW output power over more than 10000 h. At a temperature of 15°C a tapered lasers with an angle of 4° reached an output power of 1 W at a current of 2.1 A. The highest conversion efficiency for this device was 24%, the peak wavelength of the emission was 668 nm and the spectral width was smaller than 0.2 nm. The beam propagation factor was M2 = 1.7 (1/e2) and M2 = 3.0 (second moments). At 500 mW output power, master-oscillator power-amplifier (MOPA) devices showed also a nearly diffraction limited beam quality with M2 < 1.5 and reliable operation with degradation rates as low as 7x10-6 h-1 over 1200 h. The spectral line-width in this arrangement is determined by the master oscillator and is suitable for high-resolution spectroscopy.