Showing papers by "Uwe Griebner published in 2008"
TL;DR: Mode locking of an Yb-doped bulk laser in the 1 microm spectral range using a single-walled carbon nanotube saturable absorber (SWCNT-SA) is demonstrated for the first time, to the authors' knowledge.
Abstract: Mode locking of an Yb-doped bulk laser in the 1 μm spectral range using a single-walled carbon nanotube saturable absorber (SWCNT-SA) is demonstrated for the first time, to our knowledge. Passive mode locking of an Yb:KLuW laser resulted in nearly transform-limited pulses as short as 115 fs at 1048 nm. In addition, the nonlinear response of the SWCNT-SA was measured, yielding a modulation depth of 0.25% and a relaxation time of 750 fs.
170 citations
TL;DR: In this paper, a single-walled carbon nanotubes (CN) is used to reflect ultrafast saturable absorbers for stable mode locking of bulk solid-state lasers operating near 1μm.
Abstract: Transmitting and reflecting ultrafast saturable absorbers based on single-walled carbon nanotubes are developed that are applicable for stable mode locking of bulk solid-state lasers operating near 1μm. For fabrication of these saturable absorbers, relatively simple spin coating and spray methods are employed. Parameters important for stable mode locking, such as transient nonlinear absorption, saturation fluence, and recovery time, are investigated by nonlinear transmission and time-resolved pump-probe measurements near 1μm. Typical modulation depths and recovery times amount to ∼0.21%–0.25% and <1ps, respectively.
102 citations
TL;DR: The maximum average output power of 202 mW obtained with a 5% output coupler at a repetition rate of 79.1 MHz represents, to the best of the knowledge, the highest power level ever reported for SWCNT-SA mode locking of solid-state lasers.
Abstract: We report what we believe to be the first passive mode-locking of Cr:forsterite laser using a single-walled carbon nanotube saturable absorber (SWCNT-SA). The dispersion-compensated Cr:forsterite laser in a self-starting configuration produces nearly Fourier transform-limited pulses as short as 120 fs near 1.25 microm. The maximum average output power of 202 mW obtained with a 5% output coupler at a repetition rate of 79.1 MHz represents, to the best of our knowledge, the highest power level ever reported for SWCNT-SA mode locking of solid-state lasers.
91 citations
TL;DR: Transform-limited pulses as short as 290 fs at 1036 nm are generated by a diode-pumped semiconductor disk laser that employs a graded-gap-barrier design in the gain section.
Abstract: Transform-limited pulses as short as 290 fs at 1036 nm are generated by a diode-pumped semiconductor disk laser. The all-semiconductor laser employs a graded-gap-barrier design in the gain section. A fast saturable absorber mirror serves as a passive mode-locker. No further elements for internal or external dispersion control are required.
49 citations
TL;DR: The thin-disk laser delivered 9 W of continuous wave output power near 1030 nm with a slope efficiency of 77% and single-pass pumping of a thin disk consisting of an only 50 microm thick epitaxial layer of 32 at.% Yb-doped KLu(WO(4))(2) grown on a 0.35 mm thick undoped K Lu(W O(4) substrate is demonstrated.
Abstract: Single-pass pumping of a thin disk consisting of an only 50 μm thick epitaxial layer of 32 at% Yb-doped KLu(WO4)2 grown on a 035 mm thick undoped KLu(WO4)2 substrate is demonstrated The thin-disk laser delivered 9 W of continuous wave output power near 1030 nm with a slope efficiency of 77%
48 citations
TL;DR: In this paper, continuous-wave and mode-locked laser operations of Yb3+ in disordered flux-grown NaY(MoO4)2 have been demonstrated and the maximum slope efficiency achieved with Ti:sapphire and diode laser pumping is 63% and 38.6%, respectively.
Abstract: Continuous-wave and mode-locked laser operations of Yb3+ in the disordered flux-grown NaY(MoO4)2 are demonstrated. The maximum slope efficiency achieved with Ti:sapphire and diode laser pumping is 63% and 38.6%, respectively. The continuous-wave tunability extends from 1005 to 1059 nm, and laser pulses with a duration of 91 fs at 1026 nm are obtained at a repetition rate of 90 MHz and an average power of 20 mW under Ti:sapphire laser pumping. Yb3+-doped NaY(MoO4)2 is locally disordered and exhibits the largest absorption and emission cross sections known so far for tetragonal double tungstates or molybdates.
35 citations
TL;DR: In this paper, the relative energy and characteristics of the Tm3+ levels in tetragonal double tungstate (DT) and double molybdate (DMo) crystals are investigated by low temperature optical spectroscopy with special emphasis on NaLa(WO4)2.
Abstract: The relative energy and characteristics of the Tm3+ levels in tetragonal double tungstate (DT) and double molybdate (DMo) crystals are investigated by low temperature optical spectroscopy with special emphasis on NaLa(WO4)2. In this host the transition bandwidths are intermediate between those found in ordered monoclinic DT and in other disordered tetragonal DT and DMo crystals. This allows for better band resolution of the S4 site symmetry features in the disordered scheelite-like structure. The potential of such Tm-doped crystals for building infrared tunable lasers is discussed on the basis of the calculated cross sections and their comparison with the experimental photoluminescence. Information on the crystal growth and Tm3+ spectroscopic details are provided. Tm:NaLa(WO4)2 laser operation with the available sample is more efficient for σ-polarized configuration. Up to 200 mW of output power was obtained at λ = 1888 nm and laser tunability extends from 1789 to 1950 nm.
31 citations
TL;DR: In this paper, continuous wave and tunable laser operation at room temperature with single crystals of Tm-doped NaLu(WO4)2 has been demonstrated with a Ti:sapphire laser pumping and tuning by an intracavity Lyot filter, the Tm3+ emission extended from 1799to2026nm.
Abstract: Continuous wave and tunable laser operation at room temperature is demonstrated with single crystals of Tm-doped NaLu(WO4)2. Under Ti:sapphire laser pumping and tuning by an intracavity Lyot filter, the Tm3+ emission extended from 1799to2026nm. The maximum output power exceeded 0.5W and the maximum slope efficiency with respect to the absorbed power was above 58%. These good laser properties are related to the locally disordered tetragonal (I4¯) structure of the crystalline host. Using low temperature spectroscopy and energy level simulation methods, the energy levels and spectroscopic properties of Tm3+ have been shown to be compatible with the S4 site symmetry. This allowed the reliable determination of the emission cross sections related to the laser transitions.
20 citations
TL;DR: In this article, a strongly anisotropic double tungstate (Yb:KY(WO4)2/KY (WO 4)2)2 composite crystals with high quality interfaces were successfully implemented for continuous-wave and mode-locked laser systems.
Abstract: Diffusion bonding of strongly anisotropic double tungstate crystals with high quality interfaces was successfully implemented. The bonded Yb:KY(WO4)2/KY(WO4)2 composite crystals showed an impressive performance both in the continuous-wave and mode-locked laser regime. More than 800 mW of continuous-wave output power at 1.04 µm and slope efficiencies up to 70% were obtained at room temperature without cooling. In the passively mode-locked regime, pulse durations as short as 66 and 62 fs have been achieved directly from the oscillator and with external compression, respectively.
16 citations
TL;DR: In this article, a self-frequency doubling Yb:YAB crystal with a saturable absorber mirror was studied at the fundamental wavelength, and a very low threshold was obtained for Ti:sapphire and diode laser pumping, respectively.
Abstract: Passive mode locking of the self-frequency doubling Yb:YAB crystal with a saturable absorber mirror is studied at the fundamental wavelength This laser has a very low threshold, and pulses as short as 85 and 87 fs are obtained for Ti:sapphire and diode laser pumping, respectively
14 citations
TL;DR: In this article, the design of semiconductor gain structures grown by metal-organic vapor phase epitaxy (MOVPE) was discussed, and the shortest pulses were achieved with an asymmetric 4-QW-graded index barrier.
04 May 2008
TL;DR: In this paper, Czochralski-grown disordered NaY(WO 4 ) 2 crystals were used for CW operation of Tm3+ in CZO 4 2 crystals with tunability from 1847 to 2069 nm.
Abstract: CW laser operation of Tm3+ in Czochralski-grown disordered NaY(WO 4 ) 2 crystals is demonstrated. The tunability extends from 1847 to 2069 nm. The maximum slope efficiency and output power amount to ≈43% and ≈400 mW, respectively.
TL;DR: In this paper, a SESAM modelocked diode pumped laser based on the tetragonal NaY(WO 4 ) 2, a locally disordered double tungstate, doped with Yb.
Abstract: Pulses as short as 97 fs for an average power of 70 mW were obtained directly from a SESAM modelocked diode pumped laser based on the tetragonal NaY(WO 4 ) 2 , a locally disordered double tungstate, doped with Yb. An extracavity prism pair helped to reduce the pulse duration to 90 fs with a corresponding time-bandwidth product of 0.321.
16 Apr 2008
TL;DR: In this article, the authors studied diode pumping of the locally disordered Yb-doped NaY(WO 4 ) 2 crystal, which was oriented for pumping and emission in S -polarization (E //c).
Abstract: We studied diode pumping of the locally disordered Yb-doped NaY(WO 4 ) 2 crystal. An a-cut 1.514-mm thick sample (6.9 at % Yb doping or 4.52×10 20 cm -3 ) was placed under Brewster angle in a z-shaped astigmatically compensated cavity, without any active cooling. It was oriented for pumping and emission in S -polarization ( E //c). Laser experiments were performed applying a high brightness laser diode as a pump source. The laser diode delivered up to 2.1 W of input power and the emission wavelength was selected in the broad absorption peak of Yb:NaY(WO 4 ) 2 around 961nm. Continuous-wave operation in the 1-P m range was obtained for output coupler transmission between 1% and 10%. A maximum output power of | 180 mW and slope efficiencies up to 30%, rela ted to the absorbed power, were achieved. For femtosecond mode-locked operation, a semiconductor saturable absorber mirror as well as two SF10 prisms were included in the cavity. Aligning the cavity for shortest pulses, we obtained stable passive mode-locking with pulse durations as short as 97 fs directly from the oscillator. Applying external compression, the pulse duration could be further reduced to 90 fs with a corresponding time-bandwidth-product of 0.321. The average output power amounted to 59 mW at a repetition rate of 90 MHz and the corresponding output spectrum was centered at 1044 nm
27 Jan 2008
TL;DR: In this article, a passively mode-locked semiconductor disk laser employing a graded gap-barrier design in the gain section is presented, which generates transform-limited pulses as short as 290 fs at 1036 nm.
Abstract: A passively mode-locked semiconductor disk laser employing a graded-gap-barrier design in the gain section is presented. The all-semiconductor laser generates transform-limited pulses as short as 290 fs at 1036 nm.
27 Jan 2008
TL;DR: In this paper, single-walled carbon nanotube saturable absorbers were designed and characterized (modulation depth < 0.5, relaxation time <450 fs) for passive mode-locking near 1 µm.
Abstract: Single-walled carbon nanotube saturable absorbers were designed and characterized (modulation depth <0.5%, relaxation time <450 fs) for passive mode-locking near 1 µm. Pulses of 115 fs were generated at 1048 nm with an Yb:KLuW laser.