Building further upon the high spatial resolution offered by ultrasonic imaging and the high optical contrast yielded by laser excitation of photoacoustic imaging, and exploiting the temperature dependence of photoacoustic signal amplitudes, this paper addresses the question whether the rich information given by multispectral optoacoustic tomography (MSOT) allows to obtain 3D temperature images. Numerical simulations and experimental results are reported on agarose phantoms containing gold nanoparticles and the effects of shadowing, reconstruction flaws, etc. on the accuracy are determined.

Using a 14-mm thick volume Bragg grating, spectral bandwidth of a cw-operated diode laser array is narrowed to 7 GHz (FWHM). Total output power reaches 13.5 W cw, of which 86% is in the 7-GHz band. With such a narrow bandwidth, it is possible to temperature tune laser frequency across O(2) X(3)Pi --> b(1)Sigma(+) absorption line at 763.8 nm, efficiently generating O(2)((1)Delta) molecules.

By frequency-stabilizing the output from an Erbium fiber amplifier at 1580 nm to a high-finesse cavity (finesse ~6300) formed by two high-reflectance, low-loss, concave mirrors, we achieve 22.4+/-2.0 kW intracavity circulating power and 101+/-9 MW/cm(2) cw intracavity intensities on the surfaces of the mirrors. Repeated experiments show no damage to the mirrors' coating. In addition, small variations of the mirrors' radius of curvature are observed and measured by recording the cavity's transverse-mode range. The mirrors' 10 cm radius of curvature changes as function of laser intensity at a rate of 105 mum/(MW/cm(2)).

Manipulation of light below the diffraction limit forms the basis of nanophotonics. Metals can confine light at the subwavelength scale but suffer from high loss of energy. Recent reports have theoretically demonstrated the possibility of light confinement below the diffraction limit using transparent dielectric metamaterials. Here, nanoscale light confinement (<λ/20) in transparent dielectric materials is shown experimentally through a luminescent nanosystem with rationally designed dielectric claddings. Theoretically, green light with a wavelength of 540 nm has a transmission of 98.8% when passing through an ultrathin NaYF4/NaGdF4 superlattice cladding (thickness: 6.9 nm). Unexpectedly, the complete confinement of green emission (540 nm) by such an ultrathin dielectric cladding is directly observed. FDTD calculations are used to confirm that the ultrathin dielectric cladding has negligible influence on the transmission of propagating light, but extraordinary confinement of evanescent waves. This will provide new opportunities for nanophotonics by completely averting the use of metals.

Optimized single stripe 975-nm broad area devices deliver 76% power conversion efficiency at 10°C. Cooling the material leads to 85% efficiency at -50°C. External differential quantum efficiency is the dominant term.