Efficient concept generating 3.9 W of diffraction-limited green light with spectrally combined tapered diode lasers

We propose an efficient concept increasing the power of diode laser systems in the visible spectral range. In comparison with second harmonic generation of single emitters, we show that spectral beam combining with subsequent sumfrequency generation enhances the available power significantly. Combining two 1060 nm distributed Bragg reflector tapered diode lasers (M 24σ ≤ 5.2), we achieve a 2.5-3.2 fold increase of green light with a maximum power of 3.9 Watts in a diffraction-limited beam (M 24σ ≤ 1.3). Without any further stabilization the obtained power stability is within ± 2.6 %. The electro-optical and nonlinear conversion efficiencies at maximum performance are 5.7 % and 2.6 %/W, respectively. Due to the intrinsic wavelength stabilization of the diodes we achieve single-mode emission with a sidemode suppression <15 dB and a spectral width as narrow as 5 pm. These results increase the application potential of green diode laser systems, for example, within the biomedical field. In order to enhance the power even further, our proposed concept can be expanded combining multiple diode lasers.