Tapered high-brightness diode lasers are finding use in a variety of applications today. An increased brightness makes tapered lasers especially attractive for fiber applications, even for telecom applications like pumping of Er-doped fiber amplifiers or Raman amplifiers. In addition the use of tapered lasers in external resonator configurations is common practice for several applications, such as frequency doubling, which necessitate diffraction-limited tunable narrow linewidths together with high output powers.
However, two disadvantages of the tapered laser concept are the reduced output power provoked by their additional resonator losses and the astigmatism. In case of high-brightness diode lasers it is important to discuss the methods needed for an advanced output power also from the beam quality point of view. The control of astigmatism is essential for designing micro-optics for laser modules.
We have realized high-efficiency ridge-waveguided tapered diode lasers. These low modal gain, single quantum well InGaAs/AlGaAs devices emitting at 980 nm were grown by molecular beam epitaxy. The influence of the thermal resistance and of the tapered section length on output power as well as on beam quality has been investigated. The high-efficiency tapered diode lasers show promising output powers of more than 5 W and a nearly diffraction limited behav-iour up to 4 W.
Used in an external-cavity configuration these tunable diode lasers show output powers of more than 3 W. The beam-quality parameter remains well below M2 < 1.5 for output powers up to 2 W.© (2005) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.