Spektral hochaufgelöste Untersuchung von Pikosekundenimpulsen aus modengekoppelten Hochleistungsdiodenlaser Oszillator-Verstärker-Systemen mit der Methode des Frequency Resolved Optical Gating (English shop)

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Abstract

In this work, high-power diode laser oscillator–amplifier systems in the indium gallium arsenide material system were investigated. These compact and powerful laser sources emit at wavelengths around 920 nm and are therefore highly suitable for generating blue laser radiation by frequency doubling in nonlinear crystals. The three-stage oscillator–amplifier systems studied consist of a single-stripe oscillator, a subsequent single-stripe preamplifier and finally a high-power amplifier.

The key components of these systems are high-power amplifiers with a tapered geometry of the active region. These so-called tapered amplifiers achieve high output powers together with very good beam quality. In this work, both the spatial and the spectral beam properties of tapered amplifiers of different geometries and from various manufacturers were investigated in detail. Amplifiers from the Ferdinand-Braun-Institut für Höchstfrequenztechnik (FBH) stood out in particular owing to their excellent beam quality. By means of comparative measurements of the amplification properties and the saturation behaviour, the optimal parameters for continuous-wave operation were determined. In continuous-wave operation at a wavelength of 920 nm, these sources emit optical powers of up to 3.4 W (FBH), with about 75 % of the optical power emitted in a nearly diffraction-limited beam with a beam propagation factor M² ≤ 1.1.