Diode-pumped, cryogenically cooled Yb:CaF2 for high efficient and high power laser

Cryogenic cooling is a very interesting and promising apparatus for high power lasers, especially with Yb-doped materials. In fact, it is now well known that operating this type of laser materials at cryogenic temperatures such as 77K (liquid nitrogen temperature) positively affects their performance, especially at high power levels, because of increased thermal conductivities and absorption and emission cross sections. We present a high-power diode-pumped Yb:CaF2 laser operating at cryogenic temperature (77 K). A laser output power of 97 W at 1034 nm was extracted for a pump power of 245 W. The corresponding global extraction efficiency (versus absorbed pump power) is 65%. The laser small signal gain was found equal to 3.1. The laser wavelength could be tuned between 990 and 1052 nm with peaks which well correspond to the structure of the gain cross section spectra registered at low temperature.