Kilowatt CW Cryogenic 940-nm Diode Lasers

Cryogenically cooled high-power Yb:YAG disk lasers are ideally optically pumped with cryogenically cooled 940-nm diode lasers, but commercially available diode lasers are not optimized for 940-nm cryogenic emission. Special epitaxial designs were used to fabricate diode laser arrays which were mounted on liquid nitrogen impingement heat exchangers. The improved cryogenic thermal characteristics resulted in reduced laser threshold currents and CW operating powers > 1 kW for diode laser arrays with a 1 × 5 cm footprint. The industrial availability of liquid nitrogen makes this mode of operation an excellent candidate for industrial lasers, eliminating large, noisy, expensive and inefficient water-cooled heat exchangers.