Research Studies on Neodymium Pentaphosphate Miniature Lasers.

The thermal conductivity and specific heat of NdP5O14 have been measured using a dynamic electrical heating technique. The values of the thermal conductivity tensor elements in Wcm-K are Lambda sub a .021, Lambda sub b .00966, and Lambda sub c .014. The specific heat is 0.141 calg-K, in excellent agreement with the value of 0.139 calg-K that was measured by differential scanning calorimetry. We have calculated the time-dependent heating effects of typical flash-lamp-excited round and rectangular laser rods. With repetition rates limited to approx. 10 ppm, simple conductive cooling by an ambient-temperature heat-sink should be adequate. Computer simulation of the flash-lamp-excited NPP laser has been carried out by numerical solution of the laser rate equations. With 1 J electrical input, typical calculated output energies are 24 mJ for normal-mode operation and 10 mJ for passively Q-switched operation. Optimum Q-switch absorption and output mirror transmission have also been calculated. Experimental studies of such lasers have been made with varying laser rod size and laser resonator parameters.