form an angle with each other such that the directions of propagation of the laser modes become different fig6 a and 6b illustrate examples in this respect below follows an example of a concrete choice of components included in a laser resonator of the invention and the construction thereof the laser medium 2 may consist of an yttrium lithium fluoride crystal which is doped with thulium and holmium th ho ylf which results in the laser oscillating at a wavelength of 2 06 u03bcm the pump source 1 should then pump through the laser medium at a pump wavelength which is adapted to the absorption of the laser medium in this case at a wavelength of 0 792 u03bcm the design and position of the output mirrors 5 6 are determined by the desired design of the laser resonators when using a plane highly reflective mirror 4 an output mirror having a radius of curvature is required for stable function the radius of curvature is determined by the selected cavity length the optical pumping results in amplification in the laser medium the amplification then determines the amount of transmission in the output mirror for the laser wavelength 2 06 u03bcm that is permitted for optimum function to achieve optimum function it.