2 �m Laser Sources and Their Possible Applications (original) (raw)
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High-power diode-pumped Tm:YLF slab laser
Applied Physics B, 2009
A 2% Tm 3+ -doped LiYF 4 (Tm:YLF) slab is double-end-pumped by two laser diode stacks. The pumped volume has a rectangular cross section. The Tm:YLF laser produced 148 W of continuos-wave output at 1912 nm in a beam with M 2
Directly diode-pumped holmium fiber lasers
Optics Letters, 2007
Sensitizer-free holmium-doped silica and fluoride mid-infrared fiber lasers are pumped using a high-power diode laser operating at 1148 nm. A maximum output power of 162 mW at 2.86 microm was produced at a slope efficiency of 24% using Ho(3+), Pr(3+)-doped fluoride fiber. Using Ho(3+)-doped silica fiber, a maximum output power of 55 mW at 2.1 microm was generated at a slope efficiency of 27%, a value limited by the presence of pump excited state absorption.
High power laser operation with crystal fibers
Applied Physics B, 2009
We present the very last results on the development of high-power lasers with crystal fibers in Nd:YAG and in Yb:YAG grown by the Micro-Pulling Down technique. An overview of the main optical properties of the grown crystal fibers is given as well as the principles of the diode-pumped systems are developed. The average output power obtained with those materials reaches now several tens of watts in the CW regime and in high repetition rate Q-switched operation. Pulses with an energy of several millijoules have been obtained with pulse durations from 10 to 20 ns and peak powers from 100 kW to 350 kW. In each case, the measured M 2 quality factors remained in the range 2.5 to 5. In addition, the first demonstration of high-power laser emission with an Yb:YAG crystal fiber of 0.4 mm in diameter is reported. In this case, we obtained an output power of 27 W at 1030 nm under 100 W of pump power at 940 nm in CW regime. To our knowledge, those results represent the highest powers ever generated with crystal fibers obtained directly from the growth. We finally conclude this work by exposing the potential of crystal fiber lasers for a new generation of high-power laser systems.
Advancement of High Power Laser Diodes for Pumping 2-micron Solid State Lasers
The reliability and lifetime demanded by spacebased applications of 2-micron solid state lasers are beyond the capability of currently available laser diode arrays. This paper provides the status of an ongoing technology advancement effort toward long-lifetime high power laser diode arrays suitable for pumping Thulium and Holmium based solid state lasers.
Enhancement of Thulium-Ytterbium doped fiber laser efficiency using dual-pumping method
Microwave and Optical Technology Letters, 2014
Performance enhancement of laser acquired from a newly developed double-clad Yb 31 /Tm 31 codoped fiber (YTDF) is demonstrated using dual-pumping scheme. The laser uses a 2 m long YTDF fiber with a core dopant concentrations (in wt%) of 2.00 Yb 2 O 3 , 0.5 Tm 2 O 3 , 1.0 Al 2 O 3 , and 3.00 Y 2 O 3 as a gain medium in conjunction with a pair of fiber Bragg grating in a linear cavity resonator to generate lasing at 1901.6 nm. The best efficiency of 2.9% and the highest output power of 27 mW are obtained by combining 927 nm pump with 905 nm pump. As compared to a single pumping scheme using 927 nm pumping source, about 0.43% increment in efficiency is observed with no evidence of rollover at the highest output power. The best combination is to use 200 mW of 800 nm pump with 927 nm pump, wherein only a total pump power of 1900 mW is required to generate 20 mW of 1.9 lm laser output.
IEEE Journal of Selected Topics in Quantum Electronics, 2018
We report a 2.07-µm Holmium-doped all-fiber laser (HDFL) pumped by a 1.13-µm Ytterbium-doped fiber laser (YDFL). Home-made alumino-germano-silicate holmium-doped fiber (HDF) served here as active medium, optimized in terms of chemical composition and co-dopants' concentrations. Laser action at 2.07 µm was assessed in simple Fabry-Perot cavity, formed by a couple of home-made fiber Bragg gratings (FBGs), inscribed directly in the HDF; this allowed notable diminishing of intracavity loss of the 2.07-µm laser. HDF was in-core pumped by the 1.13-µm double-clad YDFL with power of ~12.5 W, in turn pumped in-clad by a laser diode (LD) operated at 0.97 µm with ~24.5-W output. Using optimal length (~5.0…5.5 m) of the HDF and employing FBG couplers with reflections of ~99% and ~33%, the HDFL provided ~5.0-W output at 2.07 µm. At these conditions, maximal absolute (slope) efficiencies at 2.07 µm of 39% (42%) and 20% (22%) were measured with respect to 1.13µm (YDFL) and 0.97-µm (LD) pumps, respectively. Moreover, the record slope efficiency (48%) was obtained for the powers ratio of 2.07-µm output (HDFL) to launched 1.13-µm input (YDFL), which is only slightly less than theoretical quantum efficiency limit (53%) for this kind of pump schemes.
IEEE Journal of Selected Topics in Quantum Electronics, 2000
We investigated the effect of thulium ion concentration on the continuous-wave (CW) power performance of diode single-end-pumped thulium-doped YAlO 3 (Tm:YAP) lasers. Three samples with 1.5%, 3%, and 4% Tm 3+ concentration were examined at 18 • C. Lifetime and fluorescence measurements were further performed to assess the strength of cross relaxation and nonradiative decay. Our results showed that in single-end-pumped configurations, the best CW power performance was obtained with the 1.5% Tm:YAP sample, and laser performance of the samples degraded monotonically with increasing Tm 3+ concentration. By using 9.5 W of incident pump power at 797 nm, a maximum of 1430 mW of output power was obtained with the 1.5% Tm:YAP sample and 2% output coupler. We discuss how the effects of cross relaxation, reabsorption, nonradiative decay, and internal heating vary with increasing concentration. Spectroscopic measurements and rate-equation analysis suggest that cross relaxation should already be effective in samples with 1.5% Tm 3+ ion concentration and doping concentrations larger than 4% will lead to degradation in power performance due to higher nonradiative decay rates and larger reabsorption losses.
Energy-transfer processes in high power Yb:Tm:YLF lasers emitting at 2.3 μm
AIP Conference Proceedings, 2008
Thulium has a large emission spectrum around 2.3 |im when used together with the YLF host. Since thulium concentration should be kept near 1 mol% to avoid cross-relaxation, a highly concentrated sensitizer like ytterbium is used that can be diode-pumped at 970 nm where high-power diodes are available. The population mechanism for the upper laser level includes two energy transfer up-conversion (ETU) processes from ytterbium to thulium. A third ETU process transfers population from the upper laser level. Moreover, back-transfer from thulium upper laser level to ytterbium and thulium cross-relaxation processes affect the efficiency of the 2.3 micrometer transition. Few data are available for these parameters in the literature. In this work we present experimental measurements of energy transfer parameters obtained using an OPO laser to excite selectively the energy levels. In order to establish the values and relevance of each parameter, we used a numerical, time resolved simulation which included the 5 energy levels of thulium and the 2 energy levels of ytterbium. A Yb:Tm:YLF crystal was end-pumped by a 30 W fiber coupled diode laser emitting at 973 nm. With a maximum pump power of 18 W at the crystal, 650 mW of 2.3 micrometer laser radiation were achieved in a quasi-continuous operation.