J. García Solé

Red, green, and blue laser light from a single Nd:YAl3(BO3)4 crystal based on laser oscillation at 1.3 μm

Laser radiation corresponding to the three fundamental colors (red, green, and blue) has been generated from the same Nd:YAl3(BO3)4 crystal, operating on a fundamental laser wavelength of 1338 nm in an end-pumping configuration. Continuous wave generation was obtained by pumping with a tunable Ti: sapphire laser. Red (669 nm) has been obtained by self-frequency doubling of the fundamental laser line. Green (505 nm) and blue (481 nm) have been obtained by self-sum-frequency mixing of the fundamental laser radiation at 1338 nm and the pump radiation (807 nm for green and 755 nm for blue).

Optical bands and energy levels of ion in the nonlinear laser crystal

In this paper the polarized optical spectra (absorption and fluorescence) of the ion in the nonlinear crystal have been systematically investigated at low (10 K) and room temperature. Most energy levels of in this crystal (103) have been identified and conveniently labelled with their crystal field quantum numbers, and . The radiative emitting states have been identified. Analysing the optical absorption spectra with the anisotropic Judd - Ofelt theory, the radiative lifetimes and branching ratios from the metastable state have been calculated. Then, relevant spectroscopic parameters (quantum efficiency and emission cross sections) for laser applications have been estimated. Infrared to visible up-conversion is reported for the first time in this host crystal.

Comparison of optical spectra of Nd3+ in NdAl3(BO3)4 (NAB), Nd:GdAl3(BO3)4 (NGAB) and Nd:Gd0.2Y0.8Al3(BO3)4 (NGYAB) crystals

A comparative study of the optical absorption and luminescence of crystals of NdAl3(BO3)4 (NAB), Nd:GdAl3(BO3)4 (NGAB) and Nd:Gd0.2Y0.8Al3(BO3)4 (NGYAB) is presented. The Judd-Ofelt theory is applied to the fitting of experimental absorption line strengths to obtain the intensity parameters Ωt (t = 2,4,6) with root mean square errors of 11.8%, 3.8% and 8.6% for NAB, NGAB and NGYAB respectively. The intensity parameters are used to calculate the radiative transition rates, branching ratios and radiative lifetimes of Nd3+ ions undergoing transitions from 4F3/2 to 4IJ manifolds. The relevant spectroscopic parameters for laser applications (quantum efficiency and emission cross section) are also estimated. The results are compared among the three samples and other borate crystals. It is concluded that NAB is a laser crystal with high gain and thus a promising candidate for microchip laser application, while NGAB (or NGYAB) can be used as an alternative to the celebrated nonlinear laser crystal NYAB.

Diffuse multiself-frequency conversion processes in the blue and green by quasicylindrical ferroelectric domains in Nd3+:Sr0.6Ba0.4(NbO3)2 laser crystal

In this letter we demonstrate continuous-wave blue and green diffuse laser light generation from a Nd3+-doped Sr0.6Ba0.4(NbO3)2 crystal located in an end-pumped laser cavity and operating at the 4F3/2→4I11/2 laser channel. The diffuse nature of the visible radiation is attributed to numerous ferroelectric cylindrical domains, which appear in the as-grown crystal. Green radiation is obtained by self-frequency doubling of the infrared radiation, whereas tunable blue radiation is generated by self-frequency sum mixing of infrared and pump radiations. The variety of visible colors is due to the spread in the domain sizes. Finally, we report on the spectral and spatial distribution of this visible radiation.

Rare earth and transition metal ion centers in LiNbO3

Abstract In this work the present state of art about the rare earth and transition metal ion centers phenomenon in LiNbO3 has been analyzed. Particular emphasis has been given to lanthanide trivalent rare earth ions (Pr3+, Nd3+, Eu3+, Dy3+, Ho3+, Er3+, Tm3+ and Yb3+) and to the Cr3+ ion, where most of information has been reported. The structure of these centers is consistent with different off-centered positions of the optically active ions inside the Li+ octahedral site. Stoichiometry and codoping effects on the center distribution are discussed. Finally, possible models to explain the origin of the different centers are discussed.

Continuous wave laser radiation at 524 nm from a self-frequency-doubled laser of LaBGeO5:Nd3+

This letter reports continuous wave laser emission at 524 nm from a self-frequency-doubled infrared laser of LaBGeO5:Nd3+ operating at a fundamental wavelength of 1048 nm. Resonant pumping in the spectral region around 800 nm for laser diode pumping is investigated and optical losses are estimated.

Optical characterization and laser gain modeling of a NdAl3(BO3)4 (NAB) microchip laser crystal

In this work a systematic optical characterization of the NdAl3(BO3)4 (NAB) crystal has been carried out by means of spectroscopic measurements. The energy levels (118) of the Nd3+ constituent ions have been identified and labeled by appropriate crystal field quantum numbers (μ=1/2 or μ=3/2). Laser site selective experiments revealed the presence of two nonequivalent environments for the Nd3+ ions. From room temperature absorption and emission spectra and using the Judd–Ofelt formalism the emission cross sections and quantum efficiency (η=0.1) of the metastable state 4F3/2 have been determined. By further modeling we have estimated the crystal length and output coupler transmittance which optimize laser efficiency of a diode pumped NAB laser. The optimum crystal length found in all cases is around 100 μm. Finally, the high laser efficiencies predicted (up to 61% and 45% for laser oscillation at 1.06 and 1.34 μm, respectively) make NAB an excellent candidate to be incorporated in a diode pumped microchip l...

Infrared continuous-wave laser gain in neodymium aluminum borate: A promising candidate for microchip diode-pumped solid state lasers

In this letter, continuous-wave laser gain at 1.06 and 1.3 μm is demonstrated in the neodymium aluminum borate [NdAl3(BO3)4] system. End pumping is achieved by means of a tunable argon-pumped Ti:sapphire and a diode laser. We report on low absorbed pump power at threshold and high pump-to-laser conversion efficiencies (up to 43% and 25% for laser oscillations at 1.06 and 1.3 μm, respectively) in a 0.3 mm long crystal. These good laser properties together with some other spectroscopic parameters described in this work (such as a 100% absorbance, a broad absorption spectrum around 800 nm and high emission cross section at 1.3 μm) make NdAl3(BO3)4 a promising material for diode-pumped microchip lasers.

Blue-light laser source by sum-frequency mixing in Nd:YAl3(BO3)4

Sum-frequency mixing in neodymium-doped YAl3(BO3)4 of its fundamental laser line at 1062 nm and the pump light from a tunable Ti:sapphire laser has been used to generate blue radiation from 435 to 465 nm in an end-pumped configuration. In nonoptimal preliminary experiments 22 μW at 458 nm was obtained out of 200 mW absorbed power at 807 nm. Nd:YAB, therefore, emerges as a promising laser material for diode-pumped solid-state lasers in the blue spectral region.

Nd3+ ion based self frequency doubling solid state lasers

Abstract Spectral and laser properties of three non-linear crystals (LiNbO3, LaBGeO5 and YAl3(BO3)4) activated with Nd3+ ions have been investigated. The main laser parameters (absorption and emission cross section, radiative lifetime and quantum efficiency) are determined and compared by means of optical spectroscopy. Optical spectroscopy is also used to estimate losses due to second harmonic (SH) self-absorption, energy transfer, excited state absorption and non-equivalent Nd centres. Continuous wave laser properties of the crystals in the fundamental and SH wavelengths are investigated under similar cavity geometry and pumping conditions using a tunable Ti–sapphire pump laser.