High-Brightness 980-nm Tapered Laser— Optimization of the Laser Rear Facet

We present experimental results on a gain-guided tapered diode laser with rear facet coating variation from 98% down to 5% reflectivity. We show that in comparison to the common high reflection coating, a lower back facet reflectivity is suitable to suppress the propagation of modes outside of the ridge waveguide and the tapered section by keeping the output power at nearly the same level. Therefore, we can improve the spatial as well as the spectral beam quality.