Novel rare earth solid state lasers with emission wavelengths in the visible spectral range

Recent developments in blue emitting laser sources, in particular InGaN laser diodes (InGaN-LDs) and frequency doubled optically pumped semiconductor lasers (2ω-OPSLs), opened access both to visible laser operation with unprecedented efficiencies in the well-established praseodymium doped laser systems [1, 2] as well as to the realization of new rare earth based solid state laser systems with emission wavelengths in the visible spectral range [3].