G. Lifante

Red, green, and blue simultaneous generation in aperiodically poled Zn-diffused LiNbO3:Er3+/Yb3+ nonlinear channel waveguides

In this work, continuous-wave broadly tunable simultaneous generation of red (650–690 nm), green (520–575 nm), and blue (425–495 nm) light in aperiodically poled Zn-diffused LiNbO3:Er3+/Yb3+ channel waveguides is reported after Ti:sapphire excitation in the 850–990 nm range. The red and green emissions arise from energy transfer and upconversion mechanisms between Yb3+ and Er3+ ions, while the blue light with a maximum efficiency of 0.04% W−1 cm−1 is produced by quasi-phase matching processes.

Single polarized Tm3+ laser in Zn-diffused LiNbO3 channel waveguides

In this work, laser operation at 1.76μm in Tm3+:LiNbO3 Zn-diffused channel waveguides is reported. The laser emission is single polarized with the electric field parallel to the optic axis(π-polarization) and operates in continuous-wave regime, at room temperature. The threshold of laser oscillation is in the range of 40mW, the slope efficiency is around 1%, and both magnitudes are dependent on the channel width, in accordance with the mode overlap between the pump and signal modes within the waveguides.

Concentration Dependence of the 1.5 μm Emission Lifetime of Er3+ in LiNbO3 by Radiation Trapping

The lifetime of the 1.5 μm transition of Er 3+ doped LiNbO 3 has been measured for different doping concentrations and geometries of luminescence collection. It has been found that this emission suffers of a strong radiation trapping effect, which affects the measured lifetime depending on the concentration and the geometry adopted.

Site-selective spectroscopy of Nd3+ in LiNbO3:Nd and LiNbO3:Nd, Mg crystals

Site-selection spectroscopy techniques have been used to investigate the different Nd3+ crystal-field sites appearing in LiNbO3:Nd3+ and LiNbO3:Nd3+, Mg2+ crystals. Singly doped crystals show the presence of two nonequivalent sites for Nd3+ (here labelled as Nd-1 and Nd-2 sites). Codoping the crystals with Mg2+ ions induces the presence of a new Nd3+ site (labelled as Nd—Mg site) concomitant with fewer Nd-1 sites. These three crystal-field sites have been optically characterized by their highest-energy emission peak of the 4F3 → 4I92 transitions. The possible location for these sites is the host matrix is discussed.

Continuous-wave laser action at λ=1064.3 nm in proton- and carbon-implanted Nd:YAG waveguides

This work reports continuous laser oscillation at λ=1064.3 nm at room temperature in Nd:YAG planar waveguides fabricated by two different techniques: proton implantation with a multi-implant of energies around 1 MeV and carbon implantation with a single-implant at an energy of 7 MeV. Threshold powers of 11 and 22 mW and slope efficiencies of 7% and 9% were achieved in the proton- and carbon-implanted guides, respectively. The laser outputs show a very high stability operating in cw regime at room temperature.

Continuous-wave laser oscillation at 1.3μm in Nd:YAG proton-implanted planar waveguides

This work reports continuous laser oscillation around 1.3μm at room temperature in Nd:YAG planar waveguides fabricated by MeV proton implantation. The performance of the waveguide lasers fabricated with different implantation parameters has been studied in terms of the threshold pump powers and slope efficiencies. These results have been compared with those obtained in Nd:YAG waveguide lasers operating at a wavelength of 1.06μm, taking into account the different emission cross-sectional values of the F3∕24→I11∕24 and F3∕24→I13∕24 transitions.

Optical and structural properties in the amorphous to polycrystalline transition in Sb2S3 thin films

Sb2S3 thin films have been obtained by physical vapour deposition on LiNbO3 and glass substrates. Films with amorphous structure originally became polycrystalline by annealing in a sulfur atmosphere. Changes in optical and structural properties have been studied as a function of annealing temperature. A drastic variation in optical transmission, energy gaps, refractive index, crystallite size, etc is observed at a temperature near 200 °C.

Continuous-wave and Q-switched Tm-doped KY(WO 4 ) 2 planar waveguide laser at 1.84 µm

High-quality monoclinic planar waveguide crystals of Tm-doped KY(WO4)2 codoped with Gd3+ and Lu3+ were grown by liquid-phase epitaxy. For the first time, planar waveguide lasing was demonstrated in a monolithic cavity in the 2 µm spectral range. The laser was operated in the Q-switched mode using a Cr2+:ZnSe crystal as saturable absorber and in the continuous-wave regimes. The Q-switched planar waveguide laser delivered pulse energies up to 120 nJ at a repetition rate of 7 kHz.

Mirrorless buried waveguide laser in monoclinic double tungstates fabricated by a novel combination of ion milling and liquid phase epitaxy

Buried channel waveguides were fabricated by liquid phase epitaxial growth of a lattice-matched KY(0.58)Gd(0.22)Lu(0.17)Tm(0.03)(WO4)2 film on a microstructured KY(WO4)2 substrate. Channels were transferred to the substrates by standard photolithography and Ar-ion milling. The bottom and sidewalls of the milled channels were smooth enough (rms roughness = 70 nm and 20 nm, respectively) to favour the epitaxial growth of the active layer without defects at the boundary of substrate/epitaxial layer. The refractive index contrast was sufficient to enable light confinement and guided modes with low scattering losses were observed at wavelengths between 1440 nm and 1640 nm. CW laser operation at 1840 nm at room temperature was observed with feedback provided only by Fresnel reflection at the end faces, with slope efficiencies of 4% and 9% for TE and TM polarizations, respectively.

Europium-doped alkali halides as a selective ultraviolet dosimeter material in the actinic region

The NaCl:Eu2+ thermoluminescence characteristics after ultraviolet irradiation as well as solar exposure have been analyzed. The TL excitation spectra of this material is coincident with the actinic region and its sensibility limit is less than 0.2 μJ/cm2 for 240 nm wavelength irradation. A model for the thermoluminescence emission is provided.