TY - JOUR A1 - Boggio, Jose M. Chavez A1 - Bodenmueller, D. A1 - Fremberg, T. A1 - Haynes, R. A1 - Roth, Martin M. A1 - Eisermann, R. A1 - Lisker, M. A1 - Zimmermann, L. A1 - Boehm, Michael T1 - Dispersion engineered silicon nitride waveguides by geometrical and refractive-index optimization JF - Journal of the Optical Society of America : B, Optical physics N2 - Dispersion engineering in silicon nitride (SiXNY) waveguides is investigated through the optimization of the waveguide transversal dimensions and refractive indices in a multicladding arrangement. Ultraflat dispersion of -84.0 +/- 0.5 ps/nm/km between 1700 and 2440 nm and 1.5 +/- 3 ps/nm/km between 1670 and 2500 nm is numerically demonstrated. It is shown that typical refractive index fluctuations as well as dimension fluctuations during fabrication of the SiXNY waveguides are a limitation for obtaining ultraflat dispersion profiles. Single- and multicladding waveguides are fabricated and their dispersion profiles measured (over nearly 1000 nm) using a low-coherence frequency domain interferometric technique. By appropriate thickness optimization, the zero-dispersion wavelength is tuned over a large spectral range in single-and multicladding waveguides with small refractive index contrast (3%). A flat dispersion profile with +/- 3.2 ps/nm/km variation over 500 nm is obtained in a multicladding waveguide fabricated with a refractive index contrast of 37%. Finally, we generate a nearly three-octave supercontinuum in this dispersion flattened multicladding SiXNY waveguide. (C) 2014 Optical Society of America Y1 - 2014 U6 - https://doi.org/10.1364/JOSAB.31.002846 SN - 0740-3224 SN - 1520-8540 VL - 31 IS - 11 SP - 2846 EP - 2857 PB - Optical Society of America CY - Washington ER - TY - JOUR A1 - Schmaelzlin, Elmar A1 - Moralejo, Benito A1 - Rutowska, Monika A1 - Monreal-Ibero, Ana A1 - Sandin, Christer A1 - Tarcea, Nicolae A1 - Popp, Juergen A1 - Roth, Martin M. T1 - Raman imaging with a fiber-coupled multichannel spectrograph JF - Sensors N2 - Until now, spatially resolved Raman Spectroscopy has required to scan a sample under investigation in a time-consuming step-by-step procedure. Here, we present a technique that allows the capture of an entire Raman image with only one single exposure. The Raman scattering arising from the sample was collected with a fiber-coupled high-performance astronomy spectrograph. The probe head consisting of an array of 20 x 20 multimode fibers was linked to the camera port of a microscope. To demonstrate the high potential of this new concept, Raman images of reference samples were recorded. Entire chemical maps were received without the need for a scanning procedure. KW - multichannel Raman spectroscopy KW - astronomy spectrograph KW - optical fiber bundle KW - Raman imaging Y1 - 2014 U6 - https://doi.org/10.3390/s141121968 SN - 1424-8220 VL - 14 IS - 11 SP - 21968 EP - 21980 PB - MDPI CY - Basel ER - TY - JOUR A1 - Bland-Hawthorn, Joss A1 - Ellis, S. C. A1 - Leon-Saval, S. G. A1 - Haynes, R. A1 - Roth, Martin M. A1 - Löhmannsröben, Hans-Gerd A1 - Horton, A. J. A1 - Cuby, J. -G. A1 - Birks, T. A. A1 - Lawrence, J. S. A1 - Gillingham, P. A1 - Ryder, S. D. A1 - Trinh, C. T1 - A complex multi-notch astronomical filter to suppress the bright infrared sky JF - Nature Communications N2 - A long-standing and profound problem in astronomy is the difficulty in obtaining deep near-infrared observations due to the extreme brightness and variability of the night sky at these wavelengths. A solution to this problem is crucial if we are to obtain the deepest possible observations of the early Universe, as redshifted starlight from distant galaxies appears at these wavelengths. The atmospheric emission between 1,000 and 1,800 nm arises almost entirely from a forest of extremely bright, very narrow hydroxyl emission lines that varies on timescales of minutes. The astronomical community has long envisaged the prospect of selectively removing these lines, while retaining high throughput between them. Here we demonstrate such a filter for the first time, presenting results from the first on-sky tests. Its use on current 8 m telescopes and future 30 m telescopes will open up many new research avenues in the years to come. Y1 - 2011 U6 - https://doi.org/10.1038/ncomms1584 SN - 2041-1723 VL - 2 IS - 50 PB - Nature Publ. Group CY - London ER - TY - JOUR A1 - Trinh, Christopher Q. A1 - Ellis, Simon C. A1 - Bland-Hawthorn, Joss A1 - Lawrence, Jon S. A1 - Horton, Anthony J. A1 - Leon-Saval, Sergio G. A1 - Shortridge, Keith A1 - Bryant, Julia A1 - Case, Scott A1 - Colless, Matthew A1 - Couch, Warrick A1 - Freeman, Kenneth A1 - Löhmannsröben, Hans-Gerd A1 - Gers, Luke A1 - Glazebrook, Karl A1 - Haynes, Roger A1 - Lee, Steve A1 - O'Byrne, John A1 - Miziarski, Stan A1 - Roth, Martin M. A1 - Schmidt, Brian A1 - Tinney, Christopher G. A1 - Zheng, Jessica T1 - Gnosis - the first instrument to use fiber bragg gratings for OH suppression JF - The astronomical journal N2 - The near-infrared is an important part of the spectrum in astronomy, especially in cosmology because the light from objects in the early universe is redshifted to these wavelengths. However, deep near-infrared observations are extremely difficult to make from ground-based telescopes due to the bright background from the atmosphere. Nearly all of this background comes from the bright and narrow emission lines of atmospheric hydroxyl (OH) molecules. The atmospheric background cannot be easily removed from data because the brightness fluctuates unpredictably on short timescales. The sensitivity of ground-based optical astronomy far exceeds that of near-infrared astronomy because of this long-standing problem. GNOSIS is a prototype astrophotonic instrument that utilizes "OH suppression fibers" consisting of fiber Bragg gratings and photonic lanterns to suppress the 103 brightest atmospheric emission doublets between 1.47 and 1.7 mu m. GNOSIS was commissioned at the 3.9 m Anglo-Australian Telescope with the IRIS2 spectrograph to demonstrate the potential of OH suppression fibers, but may be potentially used with any telescope and spectrograph combination. Unlike previous atmospheric suppression techniques GNOSIS suppresses the lines before dispersion and in a manner that depends purely on wavelength. We present the instrument design and report the results of laboratory and on-sky tests from commissioning. While these tests demonstrated high throughput (approximate to 60%) and excellent suppression of the skylines by the OH suppression fibers, surprisingly GNOSIS produced no significant reduction in the interline background and the sensitivity of GNOSIS+IRIS2 is about the same as IRIS2. It is unclear whether the lack of reduction in the interline background is due to physical sources or systematic errors as the observations are detector noise dominated. OH suppression fibers could potentially impact ground-based astronomy at the level of adaptive optics or greater. However, until a clear reduction in the interline background and the corresponding increasing in sensitivity is demonstrated optimized OH suppression fibers paired with a fiber-fed spectrograph will at least provide a real benefit at low resolving powers. KW - atmospheric effects KW - infrared: diffuse background KW - instrumentation: miscellaneous Y1 - 2013 U6 - https://doi.org/10.1088/0004-6256/145/2/51 SN - 0004-6256 VL - 145 IS - 2 PB - IOP Publ. Ltd. CY - Bristol ER - TY - JOUR A1 - Roth, Martin M. A1 - Löhmannsröben, Hans-Gerd A1 - Kelz, A. A1 - Kumke, Michael Uwe T1 - innoFSPEC : fiber optical spectroscopy and sensing Y1 - 2008 SN - 978-0-819-47228-1 ER - TY - JOUR A1 - Christensen, Lise Bech A1 - Becker, Thomas A1 - Jahnke, Knud A1 - Kelz, A. A1 - Roth, Martin M. A1 - Sanchez, S. S. A1 - Wisotzki, Lutz T1 - Integral field spectroscopy of SN 2002er with PMAS N2 - sent observations of the Type Ia supernova SN 2002er during the brightening phase. The observations were performed with the Potsdam Multi Aperture Spectrophotometer (PMAS) integral field instrument. Due to the 8arcsecx8 arcsec field of view of the spectrograph an accurate background subtraction was possible. Results from analyses of the evolution of absorption features in comparisons with other SNe show that SN 2002er is a fairly bright Type Ia supernova with a peak brightness of MB=-19.6+/-0.1. Y1 - 2003 ER - TY - JOUR A1 - Wisotzki, Lutz A1 - Becker, Thomas A1 - Christensen, Lise Bech A1 - Helms, Andreas A1 - Jahnke, Knud A1 - Kelz, A. A1 - Roth, Martin M. A1 - Sanchez, Sebastian F. T1 - Integral-field spectrophotometry of the quadruple QSO HE 0435-1223 : Evidence for microlensing N2 - We present the first spatially resolved spectroscopic observations of the recently discovered quadruple QSO and gravitational lens HE 0435-1223. Using the Potsdam Multi-Aperture Spectrophotometer (PMAS), we show that all four QSO components have very similar but not identical spectra. In particular, the spectral slopes of components A, B, and D are indistinguishable, implying that extinction due to dust plays no major role in the lensing galaxy. While also the emission line profiles are identical within the error bars, as expected from lensing, the equivalent widths show significant differences between components. Most likely, microlensing is responsible for this phenomenon. This is also consistent with the fact that component D, which shows the highest relative continuum level, has brightened by 0.07 mag since Dec. 2001. We find that the emission line flux ratios between the components are in better agreement with simple lens models than broad band or continuum measurements, but that the discrepancies between model and data are still unacceptably large. Finally, we present a detection of the lensing galaxy, although this is close to the limits of the data. Comparing with a model galaxy spectrum, we obtain a redshift estimate of zlens=0.44+/- 0.02. Y1 - 2003 ER - TY - JOUR A1 - Wisotzki, Lutz A1 - Becker, Thomas A1 - Christensen, Lise Bech A1 - Jahnke, Knud A1 - Helms, Andreas A1 - Kelz, A. A1 - Roth, Martin M. A1 - Sanchez, Sebastian F. T1 - Integral field spectrophotometry of gravitationally lensed QSOs with PMAS N2 - We present spatially resolved spectrophotometric observations of multiply imaged QSOs, using the Potsdam Multi- Aperture Spectrophotometer (PMAS), with the intention to search for spectral differences between components indicative of either microlensing or dust extinction. For the quadruple QSO HE 0435-1223 we find that the continuum shapes are indistinguishable, therefore differential extinction is negligible. The equivalent widths of the broad emission lines are however significantly different, and we argue that this is most likely due to microlensing. Contrariwise, the two components of the well-known object UM 673 have virtually identical emission line properties, but the continuum slopes differ significantly and indicate different dust extinction along both lines of sight Y1 - 2004 SN - 0004-6337 ER - TY - JOUR A1 - Jahnke, Knud A1 - Wisotzki, Lutz A1 - Sanchez, Sebastian F. A1 - Christensen, Lise Bech A1 - Becker, Thomas A1 - Kelz, A. A1 - Roth, Martin M. T1 - Integral field spectroscopy of QSO host galaxies N2 - We describe a project to study the state of the ISM in similar to20 low redshift (z < 0.3) QSO host galaxies observed with the PMAS integral field spectrograph. We describe the development of the method to access the stellar and gas components of the spectrum without the strong nuclear emission, in order to access the host galaxy properties in the central region. It shows that integral field spectroscopy promises to be very efficient in studying the gas distribution and its velocity field, and also the spatially resolved stellar population in the host galaxies of luminous AGN Y1 - 2004 ER - TY - JOUR A1 - Christensen, Lise Bech A1 - Sanchez, Sebastian F. A1 - Jahnke, Knud A1 - Becker, Thomas A1 - Wisotzki, Lutz A1 - Kelz, A. A1 - Popovic, L. C. A1 - Roth, Martin M. T1 - Integral field spectroscopy of extended Ly alpha emission from the DLA galaxy in Q2233+131 N2 - This paper presents observations of an extended Lyman-alpha emission nebula surrounding the galaxy responsible for the Damped Lyman-alpha Absorption (DLA) line in the spectrum of the quasar Q2233+131. With the Potsdam Multi Aperture Spectrophotometer (PMAS) we measure the properties of the extended Lyalpha emission in an area of 3" x 5" having a total line flux of (2.8 +/- 0.3) x 10(-16) erg cm(-2) s(-1), which at redshift z = 3.15 corresponds to a luminosity of (2.4(-0.2)(+0.3)) x 10(43) erg s(-1) and a size of 23 x 38 kpc. The location of the emission is spatially coincident with the previously detected DLA galaxy, but extends significantly beyond its limb. We argue that the Lya emission is likely to be caused by an outflow from the DLA galaxy, presumably powered by star formation. In the case of negligible dust extinction, the Lya luminosity indicates a star-formation rate of 19 +/- 10 M-. yr(-1) consistent with that derived from the UV continuum flux from the parent galaxy. The wind velocity indicated by the integral field spectra is of the order of several hundred km s(-1). We find no indication of emission originating in a rotating disk Y1 - 2004 ER - TY - JOUR A1 - Christensen, Lise Bech A1 - Sanchez, Sebastian F. A1 - Jahnke, Knud A1 - Becker, Thomas A1 - Kelz, A. A1 - Wisotzki, Lutz A1 - Roth, Martin M. T1 - Integral field observations of damped Lyman-alpha galaxies N2 - We report preliminary results from a targeted investigation on quasars containing damped Lyman-alpha absorption (DLA) lines as well strong metal absorption lines, carried out with the Potsdam Multi Aperture Spectrophotometer (PMAS). We search for line-emitting objects at the same redshift as the absorption lines and close to the line of sight of the QSOs. We have observed and detected the already confirmed absorbing galaxies in Q2233+131 (Z(abs) = 3.15) and Q0151+045 (Z(abs),= 0.168), while failing to find spectral signatures for the z = 0.091 absorber in Q0738+313. From the Q2233+131 DLA galaxy, we have detected extended Lyalpha emission from an area of 3" x 5" Y1 - 2004 ER - TY - JOUR A1 - Christensen, Lise Bech A1 - Schulte-Ladbeck, R. E. A1 - Sanchez, Sebastian F. A1 - Becker, Thomas A1 - Jahnke, Knud A1 - Kelz, A. A1 - Roth, Martin M. A1 - Wisotzki, Lutz T1 - Abundances and kinematics of a candidate sub-damped Lymana galaxy toward PHL 1226 N2 - The spectrum of the quasar PHL 1226 is known to have a strong Mg II and sub-damped Lymanalpha (sub-DLA) absorption line system with N(H I) = (5 +/- 2) x 10(19) cm(-2) at z = 0.1602. Using integral field spectra from the Potsdam Multi Aperture Spectrophotometer (PMAS) we investigate a galaxy at an impact parameter of 6".4 which is most probably responsible for the absorption lines. A fainter galaxy at a similar redshift and a slightly larger distance from the QSO is known to exist, but we assume that the absorption is caused by the more nearby galaxy. From optical Balmer lines we estimate an intrinsic reddening consistent with 0, and a moderate star formation rate of 0.5 M-circle dot yr(-1) is inferred from the Ha luminosity. Using nebular emission line ratios we find a solar oxygen abundance 12 + log (O/H) = 8.7 +/- 0.1 and a solar nitrogen to oxygen abundance ratio log (N/O) = -1.0 +/- 0.2. This abundance is larger than those of all known sub-DLA systems derived from analyses of metal absorption lines in quasar spectra. On the other hand, the properties are compatible with the most metal rich galaxies responsible for strong Mg II absorption systems. These two categories can be reconciled if we assume an abundance gradient similar to local galaxies. Under that assumption we predict abundances 12 + log (O/H) = 7.1 and log (N/O) = -1.9 for the sub-DLA cloud, which is similar to high redshift DLA and sub-DLA systems. We find evidence for a rotational velocity of similar to200 km s(-1) over a length of similar to7 kpc. From the geometry and kinematics of the galaxy we estimate that the absorbing cloud does not belong to a rotating disk, but could originate in a rotating halo Y1 - 2005 ER -