Showing papers by "Uwe Griebner published in 2005"
TL;DR: The shortest pulses ever produced with an Yb-doped tungstate laser using a semiconductor saturable absorber are reported and passive mode locking based on the novel monoclinic double tung state crystal Yb:KLu(WO4)2 is demonstrated.
Abstract: We demonstrate passive mode locking based on the novel monoclinic double tungstate crystal Yb:KLu(WO4)2. We report the shortest pulses ever produced with an Yb-doped tungstate laser using a semiconductor saturable absorber. A pulse duration of 81 fs has been achieved for an average power of 70 mW at 1046 nm. We compare the performance of the polarization oriented parallel to the Nm- and Np-crystallo-optic axes. Results in the femtosecond and picosecond regime are presented applying either Ti:sapphire or diode laser pumping. The great potential of Yb:KLu(WO4)2 as an active medium for ultrashort pulses is demonstrated for the first time, to our knowledge.
83 citations
TL;DR: Efficient cw and passively Q-switched operation with self-stimulated Raman scattering conversion was demonstrated in a compact diode-pumped Yb:KLu(WO4)2 laser.
Abstract: Efficient cw and passively Q-switched operation with self-stimulated Raman scattering conversion was demonstrated in a compact diode-pumped Yb:KLu(WO4)2 laser. A cw output power of 3.28?W was obtained with an optical efficiency of 48.2% and a slope efficiency of 78.2% with respect to the incident pump power. Stable Q-switched operation was achieved with a Cr4+:YAG saturable absorber, generating 32.4??J fundamental pulses with a duration of 1.41?ns at 1030.6?nm and 14.4??J Raman pulses with a duration of 0.71?ns at 1137.6?nm. At an incident pump power of 7.0?W, the average output power reached 0.9 and 0.4?W for fundamental and Raman radiation, with slope efficiencies of 32.1% and 14.1%, respectively.
74 citations
TL;DR: The room-temperature spectroscopic properties and continuous-wave laser operation of a new Yb:LuVO4 crystal with peak absorption cross section and slope efficiency of 47% are reported on.
Abstract: We report on the room-temperature spectroscopic properties and continuous-wave laser operation of a new Yb:LuVO4 crystal. The peak absorption cross section for the pi-polarization is 8.42 x 10(-20) cm2 at 985 nm, and the stimulated emission cross section at 1020 nm is 1.03 x 10(-20) cm2. An output power of 0.36 W at 1041 nm was obtained with a slope efficiency of 47% by use of Ti:sapphire laser pumping. With diode pumping the output power reached 1.05 W at the highest available incident pump power of 6.8 W.
59 citations
TL;DR: In this article, the authors acknowledge financial support through Projects MAT2002-4605-C05-05 and CAM-MAT-434-2004 (Spain) and DT-CRYS, NMP3-CT-2003-505580 (EU).
Abstract: We acknowledge financial support through Projects MAT2002-4605-C05-05 and CAM-MAT-434-2004 (Spain) and DT-CRYS, NMP3-CT-2003-505580 (EU).
53 citations
TL;DR: In this article, a monoclinic double tungstate composites based on strongly anisotropic KLu(WO/sub 4/)/sub 2/ (KLuW) were grown with high crystalline quality and laser operation of ytterbium was demonstrated for the first time.
Abstract: Epitaxial monoclinic double tungstate composites based on the strongly anisotropic KLu(WO/sub 4/)/sub 2/ (KLuW) were grown with high crystalline quality and laser operation of ytterbium was demonstrated for the first time. Highly efficient CW laser emission of an Yb:KLuW-KLuW crystal was achieved near 1030 nm. The 100-/spl mu/m-thick Yb:KLuW layer was pumped at wavelengths near 980 nm by a tapered diode laser as well as by a Ti:sapphire laser. More than 500 mW of CW output power and slope efficiencies up to 66% were obtained at room temperature without cooling.
46 citations
TL;DR: In this paper, a continuous-wave Yb3+ laser operation is studied in single crystals of disordered NaLa(MoO4)2 at room temperature, where the effect of the Yb concentration on some of the crystal properties is described as well as the spectroscopic Yb 3+ properties at 5 K.
Abstract: Continuous-wave Yb3+ laser operation is studied in single crystals of disordered NaLa(MoO4)2 at room temperature. The sample used was grown by the Czochralski technique and incorporates an Yb ion density of 3.1×1020 cm-3. The effect of the Yb concentration on some of the crystal properties is described as well as the spectroscopic Yb3+ properties at 5 K. Maximum slope efficiencies of about 40% for π and 38% for σ polarization were obtained under Ti:sapphire laser pumping near 976 nm, respectively. The maximum output power for the π polarization was 400 mW at 1039.5 nm, the threshold in this case amounted to 240 mW (absorbed pump power). The laser emission was tunable between 1016 and 1064 nm with a Lyot filter. Lasing was also realized by pumping with a fiber-coupled diode laser module. Maximum output power of 900 mW at 1035 nm was achieved in this case for the π polarization and the threshold was 280 mW. The results, in terms of output power and tunability, are superior in comparison to all previous reports on Yb-doped disordered double tungstate or molybdate crystals and represent a significant improvement in comparison to earlier experiments with low-doped Yb:NaLa(MoO4)2.
41 citations
TL;DR: In this article, the nonlinear optical performance of sub-μm ZnO films grown by metal organic aerosol deposition on rplane sapphire substrates was investigated and the robust performance at normal incidence makes this device suitable for advanced pulse characterization.
Abstract: We report on the nonlinear optical performance of sub-μm ZnO films grown by metal organic aerosol deposition on r-plane sapphire substrates. These films display scale-like nanocrystalline structures. Layers of different crystallite sizes and shapes are studied. Both, x-ray diffractometry and the characteristic angular and polarization dependence of the second harmonic generation, indicate a strongly uniform a-axis orientation of the crystallites. Using 35-fs Ti:sapphire laser pulses, we demonstrate much higher conversion efficiencies for ZnO layers than previously reported. The robust performance at normal incidence makes this device suitable for advanced pulse characterization techniques.
38 citations
TL;DR: The great potential of Yb-doped tungstate composite structures as active elements for mode-locked laser systems is demonstrated.
Abstract: Mode locking based on an epitaxial composite of the monoclinic double tungstate crystal Yb:KLu(WO4)2 is realized. A 100 microm thin Yb:KLu(WO4)2 layer grown on a KLu(WO4)2 substrate is used as an active medium in a laser passively mode locked by a semiconductor saturable absorber. Pulse durations of 114 fs have been achieved for an average power of 31 mW at 1030 nm. Results in the femtosecond and picosecond regimes of the Yb:KLu(WO4)2/KLu(WO4)2 laser are presented. The great potential of Yb-doped tungstate composite structures as active elements for mode-locked laser systems is demonstrated.
13 citations
TL;DR: In this article, an Yb-doped Sc2O3 crystal grown by the heat exchanger method provided extremely high pump (62.2%) and slope (72.7%) efficiencies in a continuous-wave (cw) laser operating either at 1041.6 or 1094.6 nm depending on the output coupling.
Abstract: An Yb-doped Sc2O3 crystal grown by the heat exchanger method provided extremely high pump (62.2%) and slope (72.7%) efficiencies in a continuous-wave (cw) laser operating either at 1041.6 or 1094.6 nm depending on the output coupling. Maximum powers of 1.55 and 1.35 W, respectively, were achieved by Ti:sapphire laser pumping without special cooling. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
12 citations
01 Jan 2005
TL;DR: In this article, ordered and disordered phases with sepa-rate sites for monovalent alkali cations and trivalent cations are described. But the sepa rate sites for the trivalents are not known.
Abstract: where M is a monovalent alkali cation (Li–Cs) and T is a trivalent cation (Y, La or rare earth Ln) exhibit ordered phases with sepa-rate sites for M and T cations and disordered phases where M and T cations are randomly distributed over the same cationic sublattice [1]. Some of the optically passive or-dered phases like the monoclinic KGd(WO
8 citations
08 Jun 2005
TL;DR: In this paper, the state-of-the-art for beam shaping of high-power and ultrashort-pulse laser fields is presented, focusing on the generation of localized few-cycle wavepackets from Ti:sapphire laser beams by the aid of broadband microaxicons.
Abstract: Novel types of thin-film microoptical components have been found very advantageous for beam shaping of high-power and ultrashort-pulse lasers. Measuring techniques, nonlinear optics, materials processing, and further advanced photonic applications, will benefit from specific advantages. Compared to conventional microoptics, low dispersion and absorption as well as added degrees of freedom in structure and functionality are accessible. Single or multilayer designs, spherical and non-spherical profiles, extremely small angles, and flexible substrates enable key components for the tailoring of lasers in spatial, temporal, and spectral domain at extreme parameters. By vacuum deposition and selective etching transfer, a cost-effective fabrication of single or array-shaped refractive, reflective, or hybrid components is possible. During the last decade significant progress in this field could be achieved. Including very recent applications for spatio-temporal shaping and characterization of complex and non-stationary laser fields, the state of the art is presented here. Particular emphasis is put on the generation of localized few-cycle wavepackets from Ti:sapphire laser beams by the aid of broadband microaxicons. Special microoptics are capable of transforming vacuum ultraviolet radiation. Wavefronts of strongly divergent sources can be analyzed by advanced Shack-Hartmann sensors based on microaxicon-arrays. Single-maximum nondiffractive beams are generated by different approaches for self-apodizing systems. Prospects for future developments, like robust multichannel information processing with arrays of self-reconstructing X-pulses, are discussed.
06 Feb 2005
TL;DR: In this article, a bulk and epitaxial composites of Yb:KLu(WO4)2 were grown and characterized, achieving conversion efficiencies of 50% and output powers of 1W for the bulk and 25.5% and 0.5W, respectively.
Abstract: Bulk and epitaxial composites of Yb:KLu(WO4)2 were grown and characterized. CW-lasing @1µm was demonstrated achieving conversion efficiencies of 50% and output powers of 1W for the bulk and 25.5% and 0.5W for the composite Yb:KLu(WO4)2.
Proceedings Article•
22 May 2005TL;DR: In this article, the shortest pulses (81 fs) were produced with an Yb-doped tungstate laser using a semiconductor saturable absorber by passive mode-locking of monoclinic Yb:KLu(WO4)2 achieving an average power of 70 mW at 1046 nm.
Abstract: We report the shortest pulses (81 fs) ever produced with an Yb-doped tungstate laser using a semiconductor saturable absorber by passive mode-locking of monoclinic Yb:KLu(WO4)2 achieving an average power of 70 mW at 1046 nm.