B. Viana

Spectroscopic properties of Yb-doped scandium based compounds Yb:CaSc2O4, Yb:SrSc2O4 and Yb:Sc2SiO5

Abstract Three Yb3+-doped scandium based materials are elaborated and their optical properties investigated. Scandium materials exhibit large energy levels splitting and favorable thermal properties. The energy level diagrams for Yb:CaSc2O4, Yb:SrSc2O4, and Yb:Sc2SiO5 are determined through optical spectroscopic analysis and semi-empirical crystal-field calculations using the simple overlap model. Laser parameters for Yb:Sc2SiO5 are compared to Yb:Y2SiO5 ones. Yb:Sc2SiO5 looks promising since it melts congruently and exhibits larger overall splitting of the 2F7/2Yb3+ ground state and broader absorption line width.

Spectroscopic studies of Yb3+-doped rare earth orthosilicate crystals

Infrared transmission and Raman scattering have been used to study Raman active phonons and crystal-field excitations in Yb3+-doped yttrium, lutetium and scandium orthosilicate crystals (Y2SiO5 (YSO), Lu2SiO5 (LSO) and Sc2SiO5 (SSO)), which belong to the same C2h6 crystallographic space group. Energy levels of the Yb3+ ion 2F5/2 manifold are presented. In the three hosts, Yb3+ ions experience high crystal field strength, particularly in Yb:SSO. Satellites in the infrared transmission spectra have been detected for the first time in the Yb3+-doped rare earth orthosilicates. They could be attributed to perturbed Yb3+ sites of the lattices or to magnetically coupled Yb3+ pairs.

Optical and laser properties of Yb:Y2SiO5 single crystals and discussion of the figure of merit relevant to compare ytterbium-doped laser materials

Abstract In this paper, we explore two different directions in the investigation of Yb-doped solid-state laser crystals. At first, we describe the spectroscopic properties, site occupancies, energy-level diagrams and laser performances of Yb:Y2SiO5 (Yb:YSO), a new promising laser material. Then, in a more general point of view, we discuss the problem of evaluating the laser potential of the known Yb-based lasers. The approach proposed by De Loach et al. [IEEE J. Quantum Electron. 29 (1993) 1179] is shown to be incomplete to some extent. In a search for new figures of merit, it seems reasonable to include other parameters such as the thermal properties of the host.

Mechanical, thermal and laser properties of Yb:(Sr1−xCax)3Y(BO3)3 (Yb:CaBOYS) for 1 μm laser applications

Abstract Yb:Sr3Y(BO3)3 also known as Yb:BOYS has recently demonstrated very attractive laser properties, but a drawback with this material is its brittleness. It could break into small pieces, even under weak thermal loading. This behavior is attributed to its very large thermal expansion anisotropy: αc/αa∼4. This ratio can be lowered to ∼1.7 by replacing 50% of Sr2+ by Ca2+ in the structure, which strengthen the crystal lattice and allows to reduce the brittleness. However, the thermal properties are affected by the Sr/Ca substitution as the thermal conductivity decreases by around 20 at.% for a 30 at.% calcium containing material. Laser characteristics under diode pumping with Yb3+:(Sr0.7Ca0.3)3Y(BO3)3 crystals (containing 15% Yb) remain comparable to those obtained with Yb:BOYS.

Multiwatt and broadly tunable laser action from diode-pumping of two silicate ytterbium-doped crystals: Yb:Y/sub 2/SiO/sub 5/ and Yb:SrY/sub 4/(SiO/sub 4/)/sub 3/O

Ytterbium-doped materials are competitors of neodymium-doped materials for high power diode-pumped lasers. Furthermore, some materials exhibit ultrabroad emission spectra, which makes them suitable for tunable or ultrafast sources around 1 /spl mu/m. The high power and tunable cw laser action in Yb:Y/sub 2/SiO/sub 5/ (YSO), and then in a composite crystal made of Yb:SrY/sub 4/(SiO/sub 4/)/sub 3/O (Yb:SYS) diffusion-bonded on an undoped YAG crystal. The pump source is a fiber-coupled laser diode emitting 13.5 W at the zero-line wavelength (977 nm for Yb:YSO and 979 nm for Yb:SYS). The resonator is a 3-mirror cavity designed to support only TEM/sub 00/ oscillation.

Diode-pumped 100-fs lasers based on a new apatite-structure crystal : Yb/sup 3+/:SrY/sub 4/(SiO/sub 4/)/sub 3/O

We demonstrated, for the first time, sub-100-fs lasers based on an Yb-doped apatite crystal: Yh3i:SrY4(Si04)30, also called Yb:SYS. Pulses as short as 94-fs have been obtained at 1070 nm with an average power of 1 IO mW. We also discussed the first results obtained with this crystal in a regenerative amplifier cavity. power was I IO mW and the repetition rate was 108MHz. We also obtained 130 mW of average power with 1 IO-fs-pulses at 1068 nm. We report the results obtained with a Yb3r:SrY4(Si04)30 (also called Yb:SYS) crystal, a new promising ytterbium-doped apatite crystal [ I ] with a 73-nm-large emission bandwidth used in a femtosecond oscillator and a regenerative amplifier.

CW Yb:YSO diode pumped laser emitting at 1003.4 nm for the development of a stable frequency standard

Diode pumped solid-state lasers realizes ultra-stable optical sources for spectroscopy or gravitational wave detection. A laser emitting at 501.7 nm can be stabilized on Iodine transition in order to have an ultra-stable standard of optical frequencies, as this wavelength corresponds to the narrowest transition line in the visible (only a few kHz) for I/sub 2/. This wavelength could be reached by frequency doubling a laser source emitting at 1003.4 nm. Ytterbium-doped materials are good candidates for this kind of source around 1 /spl mu/m. Among numerous selected crystals, Yb:YSO has high stimulated emission cross-section at 1003.4 nm. Developing an ytterbium laser operating at 1003.4 nm is a challenge since the lower level of the laser transition is strongly populated. So, we need a high and homogeneous pump power density all along the crystal in order to reach a sufficient gain at 1003.4 nm.

Enhancement of Yb:BOYS mechanical properties for tunable and ultrafast lasers

Yb3+:BOYS, a new tunable and ultrafast laser material, could have its mechanical properties enhanced by the use of a cationic substitution. In Yb3+:(Sr1−xCax)3Y(BO3)3,0<x<0.5, the thermal expansion and material hardness properties are improved. Laser oscillation has been obtained.

Crystal host requirements for Yb-based high power lasers and laser properties of Yb:YCOB composites

Laser, structural, and crystal growth parameters lead us to a quantification of the thermal behavior of the Yb-based laser material. First results on Yb:YCOB composite obtained by diffusion bonding are also presented.

CW and femtosecond regime of a new very broadband Yb-doped BOYS crystal

We studied a new promising broadband crystal : Yb:BOYS. A femtosecond laser producing largely tunable and sub-100-fs (down to 69fs) pulses was built.