Use of Co2+:MgAl2O4 transparent ceramics in passive Q-switching of an Er:Glass laser at 1.534†µm.

We present the implementation of Co2+:MgAl2O4 transparent ceramics as passive Q-switching elements in an Er:Glass laser at 1.534 µm. Linearly polarized pulsed output was obtained by Brewster angle inclination of the material Q-switching plate relative to the laser axis. Separate pulses were ∼105 ns long (FWHM), exhibiting ∼6.2 kW peak power at near TEM00 quality. Several fundamental sample properties important for laser intracavity operation were measured; thermo-optic coefficient dn/dT = ( - 3.8 ± 1) × 10-5 °C-1, thermal lensing factor L-1d(nL)/dT = 2.59 × 10-5 °C-1, linear expansion coefficient α = (3.9 ± 0.6) × 10-5 °C-1, polarizability thermal coefficient ϕ = (7.2 ± 2.2) × 10-5 °C-1, and damage threshold ∼6.5 J/cm2.

Inscribing an output coupler grating directly through the fiber coating with a 266 nm femtosecond laser.

We inscribe with 266 nm femtosecond pulses a ∼0.75% output coupler for a 1550 nm fiber laser directly through the coating of an SMF-28. The output coupler was inscribed with the phase-mask technique without H2 loading. This output coupler was spliced to an active Er/Yb fiber, and a fiber laser with an output power of ∼6.4 W and a slope efficiency of ∼30% was obtained. To the best of our knowledge, this is the first reported attempt to inscribe a fiber Bragg grating through the polymer jacket of an optical fiber with a UV femtosecond laser.

Competing radiative and nonradiative decay of embedded ions states in dielectric crystals: theory, and application to Co2+:AgCl0.5Br0.5.

We present a generally applicable theoretical model describing excited-state decay lifetime analysis of metal ions in a host crystal matrix. In contrast to common practice, we include multi-phonon non-radiative transitions competitively to the radiative one. We have applied our theory to Co2+ ions in a mixed AgCl0.5Br0.5 crystal, and as opposed to a previous analysis, find excellent agreement between theory and experiment over the entire measured temperature range. The fit predicts a zero absolute temperature radiative lifetime τrad(0) = 5.5 ms, more than three times longer than the measured effective low-temperature one τeff(0) = 1.48 ms. Furthermore, the fit configuration potential dissociation energy has been estimated as D = 2500 cm-1 and the lattice vibrational cutoff frequency as hωco = 180 cm-1. We have experimentally verified the latter by optical reflection measurement in the far-IR.