The development of an alumina-rich cobalt-doped spinel saturable absorber for the passive q-switching of 1530-1555 nm lasing is reported1. This optimized composition results in crystals with excellent dopant uniformity that are highly manufacturable. The crystal growth and materials characterization are described as well as initial passive qswitch testing of the material. The single crystals grown and investigated crystallized in the Fd3m space group and have the formula Mg1-xCoxAlyOz where x is greater than 0 and less than 1, y is greater than 2 and less than about 8, and z is between about 4 and 13. Comparison data of stoichiometric spinel MgAl2O4 and alumina-rich non-stoichiometric spinel MgAl6O10 are presented. The spinel lattice is comprised of octahedral and tetrahedral cationic sites, and in the alumina-rich spinel essentially all of the magnesium and cobalt occupy tetrahedral sites. The alumina-rich cobalt-doped spinel studied exhibited uniform cobalt-dopant distribution throughout the crystal and desirable mechanical and physical properties. Q-switched pulses were produced using the alumina-rich Co2+:MgAl6O10 saturable absorber in a 980 nm diode-pumped Yb:Er:glass solid-state-laser operating at 1543 nm. The q-switching established employed the 4T1 absorption band of the Co2+: MgAl6O10 and with quasi-CW pumping, pulsewidths greater than 20 ns, pulse energies of greater than 250 mJ, and free-running pulse repetition frequencies (PRFs) up to 1.2 kHz were demonstrated.
In this paper, pulsed operation of the 980 nm diode-pumped Yb:Er:glass solid-state-laser operating at 1543 nm using Co:Spinel saturable absorber is described. The Yb:Er:glass gain medium was end-pumped using a 10 W fiber-coupled 980 nm laser diode. Passively q-switched laser operation was accomplished for both CW and quasi-CW operations. Up to 2 mm thick uncoated Co:Spinel samples were used for our tests. With quasi-CW pumping, pulsewidths greater than 20 ns, pulse energies of greater than 250 μJ and free-running PRFs up to 1.2 kHz have been demonstrated. So far, up to 3 % optical-to-optical efficiency has been achieved with uncoated q-switch materials. Currently, this laser is being developed for pumping a long-wave IR (8-12 μm) optical parametric oscillator for use in spectrapolarimetric applications.
Single crystals of the noncentrosymmetric barium borate, Ba2B10O17, have been grown by slowly cooling a stoichiometric melt.The material crystallizes in the triclinic space group P1 with cell parameters a equals 9.858(1), b equals 9.990(1), c equals 6.706(1) angstrom, (alpha) equals 96.79(1), (beta) equals 106.64(1), and (gamma) equals 76.89(1) degree(s). The structure is a new type characterized by a condensation of B3O8 rings and BO3 triangles. A calculation of the second-order nonlinear susceptibility coefficients on the basis of the orientations of the tetrahedral and triangular borate groups in the rings and triangles has yielded a maximum coefficient of d11 equals 0.2 pm/V. This result is consistent with the measured second- harmonic signal -- 0.5*KDP. Partial solid solubility of Sr in the host -- Ba2-xSrxB10O17 (0 < X