Optical NIR Research Articles

Study of optical absorption, visible emission and NIR–vis luminescence spectra of Tm3+/Yb3+, Ho3+/Yb3+ and Tm3+/Ho3+/Yb3+ doped tellurite glasses

Tm3+/Yb3+, Ho3+/Yb3+ co-doped and Tm3+/Ho3+/Yb3+ triply doped TeO2–Bi2O3–ZnO–Li2O–Nb2O5 (TBZLN) tellurite glasses were prepared by melt quenching method. Judd–Ofelt intensity parameters (Ωλ, λ=2, 4 and 6), radiative transition probabilities, branching ratios and radiative lifetimes of Tm3+, Ho3+ ions in co-doped TBZLN glasses were calculated from the optical absorption spectra. Excitation, visible luminescence and decay lifetimes in visible region were also investigated. The stimulated emission and gain cross-sections for the Tm3+:3F4→3H6 (1700nm) and Ho3+:5I7→5I8 (1956nm) transitions in co-doped TBZLN glasses have been analyzed and compared with those of other reported glasses. Up-conversion luminescence was observed in TBZLN glasses under 980nm laser excitation and energy transfer mechanisms have been discussed. Finally, CIE color co-ordinates were calculated and it is observed that the color co-ordinates fall in blue and green regions for Tm3+/Yb3+ and Ho3+/Yb3+ co-doped TBZLN glasses, respectively. A subsequent shift in color co-ordinates from green to greenish-yellow region has been observed with an increase in the concentration (0.1, 0.5 and 1.0mol%) of Tm3+ ions in Tm3+/Ho3+/Yb3+ triply doped TBZLN glasses.

Characterizing Transiting Planet Atmospheres through 2025

The discovery of planets around other stars is revolutionizing our notions of planet formation and is poised to do the same for planetary climate. Studying transiting planets is complementary to eventual studies of directly imaged planets: (1) we can readily measure the mass and radius of transiting planets, linking atmospheric properties to bulk composition and formation, (2) many transiting planets are strongly irradiated and exhibit novel atmospheric physics, and (3) the most common temperate terrestrial planets orbit close to red dwarf stars and are difficult to image directly. We have only been able to comprehensively characterize the atmospheres of a handful of transiting planets, because most orbit faint stars. The Transiting Exoplanet Survey Satellite (TESS) will discover transiting planets orbiting the brightest stars, enabling, in principle, an atmospheric survey of 102–103 bright hot Jupiters and warm sub-Neptunes. Uniform observations of such a statistically significant sample would provide leverage to understand—and learn from—the diversity of short-period planets, and would identify the minority of truly special planets worthy of more intensive follow-up. We argue that the best way to maximize the scientific returns of TESS is to adopt a triage approach. A space mission consisting of a ∼1 m telescope with an optical–NIR spectrograph could measure molecular absorption for nonterrestrial planets discovered by TESS, as well as eclipses and phase variations for the hottest jovians. Such a mission could observe up to 103 transits per year, thus enabling it to survey a large fraction of the bright (J < 11) hot-Jupiters and warm sub-Neptunes TESS is expected to find. The James Webb Space Telescope (JWST) could be used to perform detailed atmospheric characterization of the most interesting transiting targets (transit, eclipse, and—when possible—phase-resolved spectroscopy). TESS is also expected to discover a few temperate terrestrial planets transiting nearby M-Dwarfs. Characterizing these worlds will be time-intensive: JWST will need months to provide tantalizing constraints on the presence of an atmosphere, planetary rotational state, clouds, and greenhouse gases. Future flagship missions should be designed to provide better constraints on the habitability of M-Dwarf temperate terrestrial planets.

Energy transfer and NIR emission in rare earth tri-doped barium lanthanum fluoro tellurite glasses

Barium lanthanum fluoro tellurite (BLFT) glasses doped with rare earth ions (ErF3, PrF3 and YbF3) both singly or in combinations were prepared by melt-quench technique and analysed spectroscopically. The prepared glasses were found to be mechanically strong and transparent. Optical absorption and NIR fluorescence were measured to the highly transparent and stable glass samples. Judd–Ofelt parameters and radiative properties were estimated for the single rare earth doped BLFT glasses using the optical absorption spectra. NIR fluorescence is measured using laser excitation. From the NIR emission spectra, energy transfer among the rare earth ions is analysed in the rare earth tri-doped BLFT glasses. These rare earth tri-doped BLFT glasses are found to be highly useful for the multi- wavelength emission in the NIR region for opto-electronic applications.

Near-infrared upconversion nanoparticles for bio-applications

Upconversion nanoparticles (UCNs) attract intensive attentions in biomedical applications. They have shown great potential in bioimaging, biomolecule detection, drug delivery, photodynamic therapy and cellular molecules interactions. Due to the anti-Stokes optical property and NIR excitation, UCNs overcome the drawbacks encountered in conventional luminescent biomarkers. High signal to noise ratio, low cytotoxicity and stable high throughput results are obtained using UCNs as luminescent labels or light triggers in biomedical applications. In this review article, the reason for choosing UCNs as biomedical agents, the progress of the UCNs development and case studies of their biomedical applications will be discussed.

A BOINC based, citizen-science project for pixel spectral energy distribution fitting of resolved galaxies in multi-wavelength surveys

Abstract In this work we present our experience from the first year of theSkyNet Pan-STARRS1 Optical Galaxy Survey (POGS) project. This citizen-scientist driven research project uses the Berkeley Open Infrastructure for Network Computing (BOINC) middleware and thousands of Internet-connected computers to measure the resolved galactic structural properties of ∼ 100,000 low redshift galaxies. We are combining the spectral coverage of GALEX, Pan-STARRS1, SDSS, and WISE to generate a value-added, multi-wavelength UV–optical–NIR galaxy atlas for the nearby Universe. Specifically, we are measuring physical parameters (such as local stellar mass, star formation rate, and first-order star formation history) on a resolved pixel-by-pixel basis using spectral energy distribution (SED) fitting techniques in a distributed computing mode.

Erratum to: Nonlinear optical absorption and NIR to blue conversion in highly stable polymeric dye rod

The output photoluminescence was collected using a 10-cm lens and detected by a grating spectrometer or monochromator of 1 A spectral resolution (SPEX 750M), connected with a photomultiplier and a data scan [SPEX DS1010]. (Fig. 4a and 4b) The narrow emission bands presented in the article are detected again but from different samples indicating that they arise from the laser itself. Blue and blue-greenish upconversion luminescences are observed to the naked eye by excitation at 1046 nm of Nd:YAG laser pulses. Their pictures are presented below in Figs. 1a and 1b. The samples are located before the focus, where a breakdown in air is formed. Fig.1c pictures the samples’ luminescence upon exposed to a UV lamp. High photo-stability was again confirmed by continuously pumping the samples for two hours using a laser diode of photon energy 3.06 eV and power 200 mW. The detected output powers for both samples were decreased to an average of *65% of their initial values.

NIR fluorescence studies of neodymium ions doped sodium fluoroborate glasses for 1.06 μm laser applications

The concentration dependent luminescence properties of Nd3+ ions doped lead calcium zinc sodium fluoroborate (LCZSFB) glasses were prepared via a melt quenching technique and reported through optical absorption, NIR luminescence and lifetime measurements. The optical transition properties of Nd3+ ions have been analyzed using Judd–Ofelt theory. The present glasses have high stimulated emission cross – sections, entail that they have high potential laser applications. The decay curves of all the glasses show single exponential behavior. The discrepancy between the experimental and calculated lifetimes of emitting level was ascribed to energy transfer through cross-relaxation. The estimated values of radiative and saturation intensity of 4F3/2→4I11/2 transition indicates the favorable lasing action at 1.06μm.

The 3-D extinction law in the 2nd quadrant of the Galactic disk

AbstractWe estimate the 3D extinction law in the optical–NIR bands for a line of sight in the 2nd quadrant of the Galactic disk. Two dust lanes are identified at ~9 and ~10.25 kpc in both AV and RV, indicating that the size of the dust grains in the spiral arms is larger than that in the inter-arm regions.

Optical fibre probe NIR Raman measurements in ambient light and in combination with a tactile resonance sensor for possible cancer detection

First measurements on a combined instrument with a thin fibre optic Raman probe mounted inside a hollow tactile resonance sensor have been performed in ambient light on porcine tissue. The ambient fluorescent light was removed successfully from the spectra. The stiffness and the biomolecular composition of the tissue were analysed.

SPIDER - VII. Revealing the stellar population content of massive early-type galaxies out to 8Re

Radial trends of stellar populations in galaxies provide a valuable tool to understand the mechanisms of galaxy growth. In this paper, we present the first comprehensive analysis of optical–optical and optical–NIR colours, as a function of galaxy mass, out to the halo region (8Re) of early-type galaxies (ETGs). We select a sample of 674 massive ETGs (M★ ≳ 3 × 1010 M⊙) from the Sloan Digital Sky Survey (SDSS)-based SPIDER survey. By comparing with a large range of population synthesis models, we derive robust constraints on the radial trends in age and metallicity. Metallicity is unambiguously found to decrease outwards, with a measurable steepening of the slope in the outer regions (Re < R < 8Re). The gradients in stellar age are found to be more sensitive to the models used, but in general, the outer regions of ETGs feature older populations compared to the cores. This trend is strongest for the most massive galaxies in our sample (M★ ≳ 1011 M⊙). Furthermore, when segregating with respect to large-scale environment, the age gradient is more significant in ETGs residing in higher density regions. These results shed light on the processes leading from the formation of the central core to the growth of the stellar envelope of massive galaxies. The fact that the populations in the outer regions are older and more metal-poor than in the core suggests a process whereby the envelope of massive galaxies is made up of accreted small satellites (i.e. minor mergers) whose stars were born during the first stages of galaxy formation.

Development of optical instrument as turbidimeter: a comparative study

Purpose – The purpose of this paper is to present a comparative study between two low‐cost turbidimeter designs using a multi purpose Optical Fiber NIR System (OF‐NIRS), Optical Fiber NIR System‐Modified (OF‐NIRS‐M) and High Sensitivity NIR System (HS‐NIRS) conducted in the development of a turbidimeter by closely replicating the existing standard design guideline. Optical method is a typical measuring technique that has been applied intensively for the measurement of water turbidity.

Nonlinear optical absorption and NIR to blue conversion in highly stable polymeric dye rod

A simple method for preparing transparent crack-free solid polymeric matrices is presented. Different dopants may be hosted in the polymeric matrix. The method is applied to prepare Glycidyl-methacrylate polymeric rods doped with solutions of coumarin 500 laser dye (ethanol and chloroform). The solvent’s effect has appeared as a shift in the absorption and photoluminous spectral bands of the laser dye in the solid polymeric host. The prepared solid samples showed nonlinear optical response on excitation with 532 nm of nanosecond laser pulses using the open aperture z-scan technique. Each sample shows different nonlinear behavior in response to the irradiating laser beam. The theoretical fitting of the experimental data indicates that the dominant mechanism of nonlinear absorption is the two-photon absorption process. Visible amplified spontaneous emission is reported in both polymeric dye rods by NIR pumping. High photostability is reported for the samples.

Structural and luminescence properties of Nd3+-doped PbO–B2O3–TiO2–AlF3 glass for 1.07 μm laser applications

Trivalent neodymium doped multi-component lead borate titanate aluminumfluoride (LBTAFNd) glasses were prepared and characterized as a function of Nd3+ ions concentration through optical absorption, NIR luminescence and decay measurements. The intensity (Ω2,4,6) and other radiative parameters were determined within the frame work of Judd–Ofelt theory. The intensities of absorption bands were expressed in terms of experimental oscillator strengths. Reasonably small root mean square deviation of ±0.384×10−6 obtained between the experimental and calculated oscillator strengths indicates the validity of intensity parameters. Upon 805nm laser excitation, the NIR emissions at 0.92μm (4F3/2→4I9/2), 1.07μm (4F3/2→4I11/2) and 1.35μm (4F3/2→4I13/2) were observed. The spectroscopic quality factor has been determined from the Ω4 and Ω6 intensity parameters as well as the intensities of emission bands centered at 1.07 and 1.35μm. The decay curves of the 4F3/2 excited state were recorded by monitoring the emission and excitation wavelengths at 1.07μm and 805nm, respectively. The decay curves exhibit single exponential behavior for all the glasses. The laser characteristic parameters of 4F3/2→4I11/2 (1.07μm) transition were determined and compared with other reported glasses.

Judd–Ofelt theory: optical absorption and NIR emission spectral studies of Nd3+:CdO–Bi2O3–B2O3 glasses for laser applications

This article reports on the optical absorption and NIR emission properties of Nd3+ ions doped CdO–Bi2O3–B2O3 (CdBiB) glasses. Judd–Ofelt theory has been applied to calculate the oscillatory strengths of the transitions in the absorption spectra and also the intensity parameters Ωλ (λ = 2, 4, and 6). These results were then used to compute the radiative properties of emission transitions of Nd3+:CdBiB glasses. From the NIR emission spectra of Nd3+:CdBiB glasses, three NIR emission bands are observed at 900, 1069, and 1338 nm and assigned to the transitions (4F3/2 → 4I9/2), (4F3/2 → 4I11/2), and (4F3/2 → 4I13/2), respectively. The concentration quenching phenomenon has also been explained. The stimulated emission cross-section and FWHM values were calculated for all the Nd3+:CdBiB glasses.

THE 100 Myr STAR FORMATION HISTORY OF NGC 5471 FROM CLUSTER AND RESOLVED STELLAR PHOTOMETRY

We show that star formation in the giant H ii region NGC 5471 has been ongoing during the past 100 Myr. Using Hubble Space Telescope/Wide-Field Planetary Camera 2 F547M and F675W, ground-based JHKs, and GALEX FUV and NUV images, we have conducted a photometric study of the star formation history (SFH) in the massive giant extragalactic H ii region NGC 5471 in M101. We perform a photometric study of the color–magnitude diagram (CMD) of the resolved stars and an integrated analysis of the main individual star-forming clusters and of NGC 5471 as a whole. The integrated UV–optical–NIR photometry for the whole region provides two different reference ages, 8 Myr and 60 Myr, revealing a complex SFH, clearly confirmed by the CMD-resolved stellar photometry analysis. The spatial distribution of the stars shows that the star formation in NGC 5471 has proceeded along the whole region during, at least, the last 100 Myr. The current ionizing clusters are enclosed within a large bubble, which is likely to have been produced by the stars that formed in a major event ∼20 Myr ago.

Stellar population trends in S0 galaxies

We present stellar population age and metallicity trends for a sample of 59 S0 galaxies based on optical SDSS and NIR J & H photometry. When combined with optical g and r passband imaging data from the SDSS archive and stellar population models, we obtain radial age and metallicity trends out to at least 5 effective radii for most of the galaxies in our sample. The sample covers a range in stellar mass and light concentration. We find an average central light-weighted age of ~ 4 Gyr and central metallicity [Z/H] ~ 0.2 dex. Almost all galaxies show a negative metallicity gradient from the center out, with an average value of Delta[Z/H]/Delta(log(r/Re)) = -0.6. An age increase, decrease, and minimal change with radius is observed for 58%, 19%, and 23%, respectively, for a mean age gradient of Delta(age)/Delta(log(r/Re)) = 2.3 Gyr dex^{-1}. For 14 out of 59 galaxies, the light-weighted age of the outer region is greater than 10 Gyr. We find that galaxies with both lower mass and lower concentration have younger light-weighted ages and lower light-weighted metallicities. This mass-metallicity relation extends into the outer regions of our S0 galaxies. Our results are consistent with the formation of S0 galaxies through the transformation of spiral galaxy disks. Determining the structural component that makes up the outer region of galaxies with old outksirts is a necessary step to understand the formation history of S0 galaxies.

MULTIWAVELENGTH OBSERVATIONS OF 3C 454.3. I. THEAGILE2007 NOVEMBER CAMPAIGN ON THE “CRAZY DIAMOND”

We report on a multiwavelength observation of the blazar 3C 454.3 (which we dubbedcrazydiamond) carried out on November 2007 by means of the astrophysical satellitesAGILE,InternationalGamma-RayAstrophysicsLaboratory (INTEGRAL), Swift, the Whole Earth Blazar Telescope (WEBT) Consortium, and the optical–NIR telescope Rapid Eye Mount (REM). Thanks to the wide field of view of theAGILE satellite and its prompt alert dissemination to other observatories, we obtained a long (three weeks), almost continuous γ -ray coverage of the blazar 3C 454.3 across 14 decades of energy. This broadband monitoring allows us to study in great detail light curves, correlations, time lags, and spectral energy distributions (SEDs) during different physical states. Gamma-ray data were collected during an AGILE pointing toward the Cygnus Region. Target of Opportunity (ToO) observations were performed to follow up the γ -ray observations in the soft and hard X-ray energy bands. Optical data were acquired continuously by means of a preplanned WEBT campaign and through an REM ToO repointing. 3C 454.3 is detected at a ∼19σ level during the three-week observing period, with an average flux above 100 MeV of FE>100 MeV = (170 ± 13) × 10 −8 photons cm −2 s −1 .T heγ -ray spectrum can be fitted with a single power law with photon index ΓGRID = 1.73 ± 0.16 between 100 MeV and 1 GeV. We detect significant day-by-day variability of the γ -ray emission during our observations, and we can exclude that the fluxes are constant at the 99.6% (∼ 2.9σ ) level. The source was detected typically around 40 deg off-axis, and it was substantially off–axis in the field of view of the AGILE hard X-ray imager. However, a five-day long ToO observation by INTEGRAL detected 3C 454.3 at an average flux of about F20–200 keV = 1.49 × 10 −3 photons cm −2 s −1 with an average photon index of ΓIBIS = 1.75 ± 0.24 between 20– 200 keV. Swift also detected 3C 454.3 with a flux in the 0.3–10 keV energy band in the range (1.23–1.40) × 10 −2 photons cm −2 s −1 and a photon index in the range ΓXRT = 1.56–1.73. In the optical band, both WEBT and REM show an extremely variable behavior in the R band. A correlation analysis based on the entire data set is consistent with no time lags between the γ -ray and the optical flux variations. Our simultaneous multifrequency observations strongly indicate that the dominant emission mechanism between 30 MeV and 30 GeV is dominated by inverse Compton scattering of relativistic electrons in the jet on the external photons from the broad line region.

AChandraStudy of the Rosette Star‐forming Complex. I. The Stellar Population and Structure of the Young Open Cluster NGC 2244

We present the first high spatial resolution X-ray study of NGC 2244, the 2 Myr old stellar cluster in the Rosette Nebula, using Chandra. Over 900 X-ray sources are detected; 77% have optical or FLAMINGOS NIR stellar counterparts and are mostly previously uncataloged young cluster members. The X-ray-selected population is estimated to be nearly complete between 0.5 and 3 M☉. A number of further results emerge from our analysis: (1) The X-ray LF and the associated K-band LF indicate a normal Salpeter IMF for NGC 2244. This is inconsistent with the top-heavy IMF reported from earlier optical studies that lacked a good census of log (LX/Lbol) ~ − 7 relation. The Rosette OB X-ray spectra are soft and consistent with the standard model of small-scale shocks in the inner wind of a single massive star.

Electrochemical growth of CuInSe2 thin film on different substrates from alkaline medium. Characterization of the films

The simultaneous electrodeposition of the system Cu–In–Se was investigated. The study was carried out at pH 8.5 using diethylentriamine as complexing agent for the Cu+2 ion. The synthesis of CuInSe2 semiconductor thin films was carried out by electrodeposition on different substrates [indium–tin oxide (ITO) on glass, aluminum and type 304 steel]. The simultaneous codeposition of the Cu, In, and Se was achieved by constant potential electrolysis technique in aqueous solutions containing the elements that conform this material. The deposits of CuInSe2 were about 4 μm thick, which is thick enough for the photovoltaic effect to take place. The as-deposited films were characterized by atomic emission spectroscopy with inductive coupling plasm (AES-ICP) and scanning electronic microscopy (SEM). Annealed films were characterized X-ray diffraction, optical NIR spectroscopy, and photoelectrochemical studies The films were obtained with a well-defined composition, very close to the expected one. Homogeneous deposit with chalcopyrite structure was produced. A In2O3 phase was also observed. Annealing of the film improved the crystallinity of the films. Good photo response, an appropriate absorption coefficient, and a band gap of 1.09 eV were obtained.

045 Optical imaging of lung cancer using near-infrared fluorescence

Introduction We report here the in vitro and in vivo characteristics of a new molecular conjugate vector for targeting and imaging of tumors. Its core is a cyclo-decapeptide plateform named RAFT, onto which two spatially independent functional domains can be cova-lently and stereo-specifically linked : a cell targeting domain for tumor targeting and a labeling domain able to carry two drugs and/or labeling agent. In order to prove the interest of this carrier, we used a well known cRGD cyclopeptide, a ligand for the α v β 3 integrin. Methods Using competition assays and confocal microscopy in vitro , as well as in vivo tumor formation and near-infrared optical imaging in mice, we analyzed the characteristics of the RAFT(cRGD)4 vector. Results We demonstrate that this vector presenting 4 cRGD motifs very efficiently prevents (α v β 3 -mediated cell adhesion to vit-ronectin. Furthermore, it is actively endocytosed because of the multivalent cRGD presentation, a major advantage for drug delivery. In vivo experiments in nude mice reveal that repeated intratu-moral injections of low doses of RAFT(cRGD)4 reduce tumor growth by reducing the number of tumor blood vessels. Furthermore, RAFT(cRGD)4 significantly improves the targeting specifi-city of subcutaneous tumor masses as well as disseminated metastasis after intravenous injection. Conclusion Thus, RAFT (cRGD)4 is specific, internalized, perfectly controlled and can carry multiple biological functions on a single, spatially defined backbone, making of it a powerful and versatile synthetic vector for drug delivery, molecular imaging or both. This versatility is a major advantage since we can load it with multiple functions. This was demonstrated by the addition of a cytotoxic KL peptide on the cargo domain of the RAFT. RAFT-RGD-KL shows a very promissing specific antitumoral activity when injected intravenously in tumors bearing mice. Finally, recent developments in the optical System allowed us to follow these optical probes using a new 3D optical tomographic system in lung metastasis. This allowed us to detect lung metastasis in 3D for the first time to our knowledge using optical NIR probes.