High-power, high-brightness and low-weight fiber coupled diode laser device

New solid-state laser devices, especially fiber laser systems, require increasingly higher optical pump power provided by fiber-coupled diode laser modules. In particular for defense technology, robust but lightweight high-power diode laser sources with high brightness are needed. We have developed a novel diode laser device combining high power, high brightness, wavelength stabilization and low weight, which becomes more and more important for a multitude of applications. Heart of the device is a specially tailored laser bar, which epitaxial and lateral structure is designed such that only standard fast-and slow-axis collimator lenses are required to couple the beam into a 200 mu m fiber with numerical aperture of 0.22. In this paper we present a detailed characterization of the new diode laser device with up to 775 W of optical power coupled into a 200 mu m, NA 0.22 fiber. One important feature of the device is a lightweight design due to a special housing optimized for low weight. In addition we present results of a diode laser device with 675 W of optical output power and improved spectral quality, which is ensured over a wide range of temperature and current by means of volume holographic gratings for wavelength stabilization. For this device an overall efficiency of more than 42.5 % has been achieved. Furthermore we present a compact diode laser source with 230 W of optical power coupled into a 200 mu m, NA 0.22 fiber. This diode laser device is optimized with regard to highest efficiency and yields an overall electro-optical efficiency of more than 50 %.