Meson-induced correlations of nucleons in nuclear Compton scattering

The non-resonant (seagull) contribution to the nuclear Compton amplitude at low energies is strongly influenced by nucleon correlations arising from meson exchange. We study this problem in a modified Fermi gas model, where nuclear correlation functions are obtained with the help of perturbation theory. The dependence of the mesonic seagull amplitude on the nuclear radius is investigated and the influence of a realistic nuclear density on this amplitude is dicussed. We found that different form factors appear for the static part (proportional to the enhancement constant $\kappa$) of the mesonic seagull amplitude and for the parts, which contain the contribution from electromagnetic polarizabilities.Comment: 15 pages, Latex, epsf.sty, 9 eps figures

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

All-fiber, single-mode spectral beam combining of high power Tm-doped fiber lasers

Signal beam combining of Tm-doped fiber lasers can increase the laser output power while simultaneously maintaining the single mode beam quality. We demonstrate an all-fiber integrated dual-wavelength Tm-doped fiber laser with an output power of 36 W by using the spectral beam combining method. The constituent lasers are operating at the wavelengths 1949 and 1996 nm and an in-house-made WDM is used for combination of these two different wavelengths. All-fiber truly single mode power combining is demonstrated for the first time in this wavelength region. © OSA 2015

Single-mode spectral beam combining of high power Tm-doped fiber lasers with WDM cascades

Spectral beam combining of Tm-doped fiber lasers can increase the laser output power while simultaneously maintaining the single mode beam quality. We report on a spectral beam combining technique based on highly efficient in-house-made WDM cascade. We demonstrate continuous wave power combining employing a WDM cascade consisting of four fiber laser sources with emission wavelengths of 1920, 1949, 1996 and 2030 nm. A combined power of up to 38 W resulted in a combining efficiency of 69%. © 2016 SPIE

Breitbandig durchstimmbare Laser und sensibilisierte Festfrequenzlaser mit Cr-dotierten Festkoerpermaterialien

SIGLETIB Hannover: DB 3741a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Passively mode locked femtosecond Tm:Sc2O3 laser at 2.1 mu m

This work was supported by EPSRCWe report on the passive mode locking of a Tm3+:Sc2O3 laser at 2.1 mu m using a semiconductor saturable absorber mirror based on InGaAsSb quantum wells. Transform-limited 218 fs pulses are generated with an average power of 210 mW. A maximum output power of 325 mW is produced during mode locking with the corresponding pulse duration of 246 fs at a pulse repetition frequency of 124.3 MHz. A Ti:sapphire laser is used as the pump source operating at 796 nm. (C) 2012 Optical Society of AmericaPublisher PDFPeer reviewe

Grundlegende Untersuchungen an diodengepumpten Festkoerperlasern im Wellenlaengenbereich um 2#mu#m Abschlussbericht

The research work on laser systems operating in the 2 #mu#m wavelength region mainly focused on flashlamp pumped solid state lasers. Ho and/or Tm doped crystals serve as an active medium. These conventionally excited systems operate at low repetition rates and low power levels. In order to reach higher output power levels in continous wave mode, diode pumped solid state lasers with Tm-doped crystals were investigated. The aim was to generate more than 20W of average output power with good beam quality. The characterization of the Tm-doped laser materials used for the 2 #mu#m wavelength region is the basis for new concepts concerning pump and resonator geometries. Such a new concept for longitudinal pumping, designed to reduce thermal effects, was subject of developement. For the pump light the principle of waveguides was intended to be used. The experimental work should be directed by theoretical considerations. Fiber coupled laserdiodes and laserdiode stacks were used as pump sources. In cw operating mode output powers up to 60W were achieved. Additionally this laser system was qualified for extended operational parameters, like Q-switch and wavelength tuned operation. These new cw lasers running in the NIR-wavelength region have various applications in science, industry and medicine. (orig.)SIGLEAvailable from TIB Hannover: F99B1084 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman

Wavelength stabilization and mode selection of a GaSb-based semiconductor disk laser at 2 µm by using a volume Bragg grating

Optically pumped semiconductor disk laser (OPSDL) based on the (AlGaIn)(AsSb) unify preferable features from semiconductor and solid state lasers, therefore they can be an excellent source in this wavelength region. To realize this with standard laser setups is quite difficult. For the first time on an OPSDL system in the 2 mum wavelength region with a volume Bragg grating (VBG) as output coupler and for wavelength selection and stabilization is reported. The approximately 10 mum thick monolithically grown OPSDL device structure comprised a high quality AlAsSb/GaSb distributed Bragg reflector with reflectivity >99.5%. For the laser experiments square peaces of 3x3 mm were used. To improve the heat removal from the active region a 0.4 mm thick SiC heat spreader was attached to the surface by liquid capillary bonding