Shawn P. O’Connor

Thermo-optical parameters measured in ytterbium-doped potassium gadolinium tungstate

Oriented absorption and fluorescence spectra, refractive indices, thermal expansion, and thermal conductivities are reported for the anisotropic laser material ytterbium-doped potassium gadolinium tungstate, Yb3+:KGd(WO4)2. Measurements of negative values for dn/dT lead to the report of several useful athermal orientations for laser propagation.

Spectroscopic characterization of Er-doped KPb2Cl5 laser crystals

Abstract A discussion of the spectroscopic properties of the low-phonon energy laser host material potassium lead chloride, KPb 2 Cl 5 , doped with trivalent erbium is presented. In this paper we present room temperature spectroscopic measurements and subsequent analysis based on the Judd–Ofelt model. Additionally, Stark level energies of the Er 3+ ions in the crystal were determined from spectroscopic measurements performed at cryogenic temperatures.

Optical cooling in Er3+:KPb2Cl5.

For the first time, optical cooling has been observed in the (4)I(13/2) excited state of erbium(III), using the low phonon energy host materal, potassium lead chloride (KPb(2)Cl(2)). Cooling was observed when samples were pumped at wavelengths longer than 1557 nm, 17 nm longer than the mean fluorescence wavelength of 1540 nm, which implies a nonradiative heat load of 1.1% for the (4)I(13/2)-->(4)I(15/2) transition. When pumped at 1568 nm, the total cooling efficiency was 0.38% of the absorbed power. These results highlight the potential of Er(3+):KPb(2)Cl(5) as a material for lasers operating in an eye safe spectral region.

Development of periodically oriented gallium nitride for non-linear optics [Invited]

Methods for growing periodically alternating polarities of GaN on GaN substrates have been developed. The resulting periodically oriented samples demonstrate feasibility of using this method to produce structures of utility in optical parametric generation.

Nonradiative losses in Yb:KGd(WO4)2 and Yb:Y3Al5O12

Photothermal deflection spectroscopy was used to measure nonradiative losses in Yb:KGW and Yb:YAG (for both crystal and for the first time in ceramic form). Fluorescent quantum efficiencies for both materials were found to be greater than 98.9%. The reduction of nonradiative losses due to annealing of Yb:YAG is also presented.