Laser

A laser for emitting laser light in the visible spectral range, the laser comprising:

• a laser resonator, characterized by
• a rare earth doped anisotropic crystal comprising a 5d-4f transition, wherein the crystal is arranged within the laser resonator,
• a pumping light source for pumping the crystal by illuminating the crystal with pump light for generating laser light in the visible spectral range by using the 5d-4f transition,
• wherein the crystal is adapted to comprise a specific indicatrix axis, wherein the sum of the cross section of the stimulated emission at a visible wavelength range on the 5d-4f transition of a rare earth doping element with respect to the specific indicatrix axis and the cross section of the excited state absorption at the same visible wavelength range with respect to the same specific indicatrix axis is positive, wherein the cross section of the stimulated emission is denoted with a positive sign and the cross section of the excited state absorption is denoted with a negative sign.