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Esta es la versión de autor del artículo publicado en: This is an author produced version of a paper published in: Yb 3+ excitation provides thermal sensing during optical manipulation. Thus, three-dimensional particle scanning allows for the measurement of thermal gradients in the surroundings of individual cancer cells subjected to a plasmonic-mediated photothermal therapy. It is found that such thermal gradients extends for distances larger than 10 microns, avoiding real single cell photothermal treatments under in vitro conditions. This work introduces to the scientific community a novel and simple approach for high resolution thermal sensing at the cellular level that could constitute a powerful tool for a better understanding of cell dynamics during thermal treatments.

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This work reviews several properties of liquid water, including the dielectric constant and the proton-spin lattice relaxation, and draws attention to a bilinear behaviour defining a crossover in the temperature range 50 ± 10°C between two possible states in liquid water. The existence of these two states in liquid water plays an important role in nanometric and biological systems. For example, the optical properties of metallic (gold and silver) nanoparticles dispersed in water, used as nanoprobes, and the emission properties of CdTe quantum dots (QDs), used for fluorescence bioimaging and tumour targeting, show a singular behaviour in this temperature range. In addition, the structural changes in liquid water may be associated with the behaviour of biological macromolecules in aqueous solutions and in particular with protein denaturation.

We report on femtosecond laser writing of channel waveguides in Nd 3+ ion doped YAG ceramics by multiple inscriptions of damage filaments. Waveguiding between filaments was found to resist annealing temperatures as high as 1500°C. Microluminescence imaging experiments have been carried out to elucidate the potential application of the obtained waveguides as integrated laser sources as well as to elucidate the waveguiding mechanisms. © 2010 Optical Society of America OCIS codes: 230.7380, 180.2520, 160.3380. Neodymium-doped transparent YAG ceramics (hereafter Nd:cYAG) is nowadays one of the most promising laser materials with outstanding properties [1][2][3]. The future incorporation of Nd:cYAG in compact devices requires the fabrication of channel waveguides in which the 2D light confinement would lead to a much higher optical intensities. Among the different methods already used for the fabrication of channel waveguides in the Nd:cYAG system [4], direct laser writing with femtosecond pulses is of special relevance because of its reduced processing times, its simplicity, and its true 3D versatility [5]. In the case of a Nd:cYAG system, waveguides based on the so-called double-line approach have shown excellent optical and superior laser properties [6,7]. The main drawback of these waveguides is the instability of the strain-field-induced refractive index increment, i.e., of the waveguide, against thermally induced lattice relaxation [6]. This is a negative aspect in laser waveguides, where relevant pump induced thermal loadings are expected to occur [8].In this Letter we report on the fabrication of thermally resistant Nd:cYAG waveguides by an approach consisting of the consecutive inscription of two orthogonal pairs of femtosecond filaments. The ability of the obtained structure for light confinement and its thermal stability has been investigated. The potential application of the obtained waveguides as laser sources has been explored by luminescence imaging experiments.The Nd:cYAG sample used in this work was provided by Baikowskii Ltd. (Japan) and was a 1 ϫ 1 ϫ 1 cm 3 prism with a nominal Nd 3+ concentration of 2 at. %. Damage filaments were inscribed by using an amplified Ti:sapphire laser system providing 120 fs pulses linearly polarized at 796 nm and 1 kHz of repetition rate. The laser beam was focused 250 m below the surface with a 10ϫ microscope objective ͑NA= 0.3͒. The on-target pulse energy was set to 3 J, leading to ϳ40-m-long filaments. In a first step, two filaments were written separated 30 m by translating the sample in the direction perpendicular to the laser polarization and the pulse propagation, with a speed of 50 m / s. Then the sample was turned 90°and a second pair of filaments, overlapping to the first one was inscribed. The end-face of the obtained quadruple-line structure is shown in Fig. 1(a). The ability of the obtained structure as an optical waveguide was investigated by both endcoupling experiments using a He-Ne laser [ Fig. 1(b)] as well as by transmission scanning near-field m...