True mid-infrared Pr3+ absorption cross-section in a selenide-chalcogenide host-glass

The mid-infrared (MIR) spans the 3-25 m wavelength range. Rare-earth-ion doped selenide-chalcogenide glasses are being developed for direct-emission MIR fibre lasers. The true Pr3+ absorption cross-section in the 3.5-6 µm wavelength region of a Pr3+-doped (500 ppmw of Pr3+ i.e. 9.47 x 1019 Pr3+ ions cm-3) GeAsGaSe host-glass is presented, after numerically removing the underlying, extrinsic vibrational absorption due to [H-Se-] contamination of the host-glass

True mid-infrared Pr3+ absorption cross-section in a selenide-chalcogenide host-glass

The mid-infrared (MIR) spans the 3-25 m wavelength range. Rare-earth-ion doped selenide-chalcogenide glasses are being developed for direct-emission MIR fibre lasers. The true Pr3+ absorption cross-section in the 3.5-6 µm wavelength region of a Pr3+-doped (500 ppmw of Pr3+ i.e. 9.47 x 1019 Pr3+ ions cm-3) GeAsGaSe host-glass is presented, after numerically removing the underlying, extrinsic vibrational absorption due to [H-Se-] contamination of the host-glass

Promising emission behavior in Pr 3+ /In selenide-chalcogenide-glass small-core step index fiber (SIF)

Selenide-chalcogenide glass, small-core, step-index fiber (SIF), core-doped with Pr3+: 9.51 × 1024 ions m−3 (500 ppmw) is fabricated for the first time with indium to help solubilize Pr3+. Core diameters of 20 or 40 μm are confirmed using scanning electron microscopy and near-field imaging; fibre numerical aperture is ∼0.4. Optical loss is ≥ 4.9 dB m−1 across the 3–9 μm mid-infrared (MIR) spectral range. On pumping at 1.55 μm or 2.013 μm, the SIFs give broad MIR emission across 3.5–6 μm assigned to 3H6 → 3H5 and 3H5 → 3H4. The Pr3+ emission-lifetime at 4.7 μm decreases from bulk-glass (10.1 ± 0.3 ms), to intermediately processed fiber (8.10 ± 0.5 ms) to SIF (7.1 ± 0.5 ms) induced by the processing. On end-pumping SIFs at 2.013 μm, the output pump-power and emission intensity at 4.7 μm became sub-linear and super-linear, respectively, suggesting MIR excited-state saturation is occurring

Characterising refractive index dispersion in chalcogenide glasses

Much effort has been devoted to the study of glasses that contain the chalcogen elements (sulfur, selenium and tellurium) for photonics’ applications out to MIR wavelengths. In this paper we describe some techniques for determining the refractive index dispersion characteristics of these glasses. Knowledge of material dispersion is critical in delivering step-index fibres including with high numerical aperture for mid-infrared supercontinuum generation

Numerical modeling of lathanide-ion doped fibre lasers operating within mid-infrared wavelength region

We discuss the numerical modelling of lanthanide-ion doped chalcogenide glass fibre lasers for operation in the mid-infrared wavelength region. We extract the modelling parameters from emission and absorption measurements using Judd-Ofelt and McCumber theory. Numerical algorithms are developed based on the experimentally extracted fibre parameters. The simulation results predict lasing with slope efficiency of at least 20 % provided, that the fibre loss can be kept at the level of 1 dB/m or less

Numerical modelling of Tb3+ doped selenide-chalcogenide multimode fibre based spontaneous emission sources

A model is developed of a terbium (III) ion doped selenide chalcogenide glass fibre source that provides spontaneous emission within the mid-infrared (MIR) wavelength range. Three numerical algorithms are used to calculate the solution and compare their properties

Modelling of multimode selenide-chalcogenide glass fibre based MIR spontaneous emission sources

Chalcogenide glass fibres have been demonstrated as a suitable medium for the realisation of spontaneous emission sources for mid-infrared photonics applications with a particular emphasis on sensor technology. Such sources give a viable alternative to other solutions due to their potentially low cost, high reliability and robustness when pumped using commercially available semiconductor lasers. We present a comprehensive analysis of the properties of selenide-chalcogenide glass fibres applied as spontaneous emission sources. We extract the modelling parameters from measurements using in house fabricated bulk glass and fibre samples. We apply the well-established rate equations approach to determine the level populations, the distribution of the photon intensity within the fibre and the output power levels. We compare the modelling results with experiment

Targeting Superficial or Nodular Basal Cell Carcinoma with Topically Formulated Small Molecule Inhibitor of Smoothened

Purpose: Inappropriate activation of the Hedgehog (Hh) signaling pathway in skin is critical for the development of basal cell carcinomas (BCC). We have investigated the anti-BCC efficacy of topically-applied CUR61414, an inhibitor of the Hh signal transduction molecule Smoothened. Experimental Design: In preclinical studies, we used a depilatory model to evaluate the ability of topical formulations of CUR61414 to repress Hh responsive cells found at the base of hair follicles in normal skin. We also tested the in vivo effects of topical CUR61414 on murine BCCs developed in $Ptch1^{ +/−}$ K14-CreER2 p53 fl/fl mice. In a phase I clinical study, we evaluated the safety, tolerability, and efficacy of a multidose regimen of CUR61414 (0.09%, 0.35%, 1.1%, and 3.1%) applied topically to human superficial or nodular BCCs for up to 28 days. Results: In mice, topical CUR61414 significantly inhibited skin Hh signaling, blocked the induction of hair follicle anagen, and shrank existing BCCs. However, we observed no clinical activity of this formulation in human superficial or nodular BCCs in a phase I clinical study. Conclusions: Our data highlight some of the challenges of translating preclinical experience into successful human results for a topical anticancer agent.Stem Cell and Regenerative Biolog

Study of mid-infrared laser action in chalcogenide rare earth doped glass with Dy3+, Pr3+ and Tb3+

We present a study of chalcogenide glass fiber lasers doped withDy3+, Pr3+ or Tb3+ that would operate in the mid-infrared wavelength range.A set of chalcogenide glass samples doped with different concentrations ofrare earth ions is fabricated. The modeling parameters are directly extractedfrom FTIR absorption measurements of the fabricated bulk glass samplesusing Judd-Ofelt, Füchtbauer–Ladenburg theory and McCumber theory.The modeling results show that, for all the dopants considered, an efficientmid-infrared laser action is possible if optical losses are kept at the level of1dB/m or below

The Dense Gas Mass Fraction and the Relationship to Star Formation in M51

Observations of 12CO J = 1 - 0 and HCN J = 1 - 0 emission from NGC 5194 (M51) made with the 50 m Large Millimeter Telescope and the SEQUOIA focal plane array are presented. Using the HCN-to-CO ratio, we examine the dense gas mass fraction over a range of environmental conditions within the galaxy. Within the disk, the dense gas mass fraction varies along the spiral arms but the average value over all spiral arms is comparable to the mean value of interarm regions. We suggest that the near-constant dense gas mass fraction throughout the disk arises from a population of density-stratified, self-gravitating molecular clouds and the required density threshold to detect each spectral line. The measured dense gas fraction significantly increases in the central bulge in response to the effective pressure, P e , from the weight of the stellar and gas components. This pressure modifies the dynamical state of the molecular cloud population and, possibly, the HCN-emitting regions in the central bulge from self-gravitating to diffuse configurations in which P e is greater than the gravitational energy density of individual clouds. Diffuse molecular clouds comprise a significant fraction of the molecular gas mass in the central bulge, which may account for the measured sublinear relationships between the surface densities of the star formation rate and molecular and dense gas