A TEM∞mode diode-pumped Nd: YAG laser

A GaAlAs semiconductor-pumped Nd:YAG laser is described which has produced more than 80 mW of CW power in the TEM∞mode at a wavelength of 1.06 micrometers. The laser was optically pumped by a 7.5-cm linear array of 120 domed GaAlAs light-emitting diodes operating at room temperature and driven at a current of 250 mA. In earlier experiments, comparable diodes operated under these conditions have exhibited more than 7500 hours of operation with less than 10 percent degradation. Output power from the diode array was coupled to a 1.5-mm-diameter by 7.5- cm-long Nd:YAG rod by a gold-coated hemielliptical reflector. Temperature of the rod was controlled by thermoelectric modules and could be varied from room temperature to -22°C. The diodes, mounted along one axial focus of the elliptical reflector, were maintained near room temperature by circulating room-temperature water through the array heat-sink. The array was fabricated in a modular fashion using 15 subarray modules of eight diodes each. An array packing density of 72 percent was achieved. Average power efficiency of the 18-mil-diameter hemispherical diodes was 4.74 percent. The array produced 2.29 watts of optical pump power with a peak wavelength of 8080 Å and a spectral half-width of 255 Å.