Abstract: A thulium-doped solid state laser is provided capable of operation at a wlength having a shallow absorption depth in tissue. The laser is comprised of a laser cavity defined by first and second reflecting surfaces opposing each other on an optical axis, a thulium-doped YALO crystal disposed in the cavity, and a pump source for pumping the crystal with a pump beam at a preselected wavelength to enable the crystal to emit a most preferred 1.94 micron laser output. The thulium-doped YALO crystal is preferably an a-cut crystal. Such alignment of this material provides a reliable mode at 1.94 microns which has excellent tissue absorption characteristics for medical applications. The length l of the crystal, the concentration N of the dopant and the transmissivity T of the output coupler, which define an expression Nl/T, can be varied as long as the expression Nl/T produces a value which does not exceed about 0.32 centimeters.