Study Of Spectroscopic Properties Of Rare Earth Doped Photo-thermo-refractive Glasses

Photo-thermal-refractive (PTR) glass has been widely used for phase volumeholograme recording owing to its outstanding photosensitivity, wide transparent window,thermal stability and high torlance to laser radiation and harsh environment. Bragg gratingsrecorded in this material provide angular filtering, output spectrum stabilization andnarrowing of diode lasers, stretching and compression of laser pulses, and spectral beamcombining of high power lasers. Further development by incorporating the rare earth ionsinto this glass makes it into a new multifunctional optical material possessing bothphotosensitivity and spectroscopic properties, which paves a way for developingnew-type integrated solid state lasers.Based on the concept of integrated solid state laser with reflecting volume Bragggratings (RVBG) recorded in the both ends of the gain material as the feedback mirrors, thespectroscopic characteristics on the PTR glass doped with Nd or Yb ions are studied in thisthesis. A new kind of multifunctional glass doped with Nd or Yb ions based on the PTRglass developed was fabricated by conventional melt-quenching method. Density andrefractive index of PTR glass were measured. The absorption spectrum, fluorecencespectrum and fluerecence intensity decay of Nd or Yb ions in PTR glass were recorded.Spectroscopic parameters, such as the absorption cross section, stimulated emission crosssection, fluorescence efficient linewidth and fluorescence lifetime for Nd-PTR glass andYb-PTR glass, were analyzed with Judd-Oflet theory and the reciprocity method,respectively. The differential scanning calorimeter (DSC) curves of the virgin andUV-exposed Nd-PTR glasses were used to figure out the transformation temperature andcrystallization onset temperature for the further photo-thermal development. With theidentical UV exposure dosage, nucleation temperature, nucleation time andcrystallization temperature, the variation of the measured fluorescence branching ratio withthe crystallization time for the transition at1057nm in Nd-PTR glass was investigated, andthe optimal crystallization time was determined with the largest branching ratio and low scattering loss.The laser output was demonstrated in an uncoated2mm thick Nd-PTR with individualcomponents under laser diode array pumping. At the output coupler of2%, the laser outputof94.2mJ and slope efficiency of16%were obtained, which indicates that Nd-PTR maybe a new-type laser material for integrated solid state lasers.