2.12-micron Ho:YAG laser

An efficient version of the Ho:YAG active medium with an output near 2 microns is described which extends the spectral capabilities of YAG laser materials. In the medium proposed here, (Y0.89Tm0.10Ho0.01)3(Al0.99Cr0.01)5O12, lasing is easily excitable at a wavelength of 2.12 microns at room temperature; the medium has a comparatively low threshold of about 45 J and an efficiency of about 0.5 percent. The satisfactory lasing characteristics of the medium are attributed to a good spectral match of the pump light and the excitation spectrum of the medium and to the cross-relaxation mechanism of energy absorption.