Spectroscopic and Laser Characteristics of Neodymium-doped Calcium Fluorophosphate

Abstract

Laser oscillations have been produced in large crystals of Nd(3+)-doped Ca(5)(PO(4))(3)F (the mineral fluorapatite, whence the coined name FAP) at room temperature under both tungsten lamp and flash lamp excitation. The laser tests show that FAP:Nd crystals have four times greater gain per incident pump energy and over one and a half times greater differential (slope) energy efficiency than equal size YAG: Nd crystals. The fluorescence, excitation, and absorption spectra of FAP:Nd are partially polarized, as expected for Nd(3+) substituting Ca II sites of C(1h) symmetry. The fluorescence lifetime is 0.24 msec at 300 degrees K. Laser oscillations occur at 1.0629 micro in pi polarization (E ||c), which has 2.6 times the gain of sigma polarization (E perpendicularc).