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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Population Lensing in Alexandrite Lasers
摘要： Alexandrite (Cr3+:BeAl2O4) is a vibronic laser at 701-858 nm. Its excellent thermo-mechanical properties and high energy storage make it an ideal high power and high energy Q-switched source with recent development in mJ-level red-diode-pumped Alexandrite oscillators and amplifiers [1-3]. Further power scaling of these systems is limited by thermal lensing which has yet to be addressed in great detail. In this work we present experimental and finite element analysis (FEA) results on the investigation of thermal lensing in a red-diode-pumped Alexandrite laser. Differences in the thermal lensing power for non-lasing and lasing conditions are attributed to a ‘population lens’ effect. In a separate study stable self-Q-switching (SQS) is observed in an Alexandrite laser cavity containing only the gain medium where the SQS loss mechanism is attributed to the population lens.
关键词： self-Q-switching,diode-pumped,population lens,thermal lensing,Alexandrite
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Tm <sup>3+</sup> :LuF <sub/>3</sub> -CaF <sub/>2</sub> Diode Pumped Laser in 1.9 μm Region
摘要： The thulium (Tm3+) doped solid state lasers, operating on the transition 3F4→3H6 are source of broadly tunable “eye-safe” laser radiation in 1.8 to 2.0 μm region where are located important absorption bands of H2O, CO2. This spectral region is interesting for application such as coherent radar systems, atmospheric remote sensing, high-resolution spectroscopy, and medical surgery. This high possibility of applications stimulates research on thulium solid state lasers and search for new host materials [1-3]. The new investigated Tm:LuF3-CaF2 mixed fluoride crystal was grown in A. M. Prokhorov General Physics institute by the Bridgmann-Stockbauer technique in fluorinating atmosphere. The composition of the melt was (TmF3)1 (CaF2)97 (LuF3)2 resulting in 1 mol % doping concentration of Tm3+ active ions. The sample was cut from the grown crystal in the form of 7.1 mm thick block with plan-parallel polished faces without any anti-reflection coating. The absorption spectrum was obtained using a spectrophotometer (Shimadzu UV-3600 UV-VIS-NIR sampling interval 0.05 nm). For laser performance measurement the 142 mm long, semi-hemispherical resonator was used. The resonator consisted of a flat pumping mirror PM (reflectivity R > 99.9 % @ 1890 nm, and transmittance T = 95 % @ 763 nm) and curved output coupler OC (r = -150 mm). Three output couplers with reflectivity 97.5 %, 94.5 % and 92.0 % were tested. The Tm:LuF3-CaF2 crystal was mounted in water cooled (18°C) copper holder. For longitudinal pumping a fiber (core diameter 400 μm, NA = 0.22) coupled laser diode M1F4S22-765.3-30C-SS2.1 (DILAS) was used. The diode operated in pulse regime (10 ms pulse width, repetition rate f = 10 Hz) at wavelength λp = 763 nm (highest possible wavelength of the diode). Laser emission wavelength λe was measured with spectrometer StellarNet Red-Wave (sampling interval 1.4 nm). The absorption spectrum of Tm:LuF3-CaF2 crystal in pumping and lasing region is in Fig. 1a. The maximum absorption coefficient in pumping region 0.78 cm-1 was reached at 768 nm with linewidth 23.5 nm (FWHM) which is suitable for diode pumping. From 785 to 800 nm the absorption curve has a plateau with value 0.27 cm-1. In lasing region, the absorption coefficient has two maxima of 0.84 and 0.51 cm-1 at 1610 and 1667 nm respectively. The absorption spectrum in lasing region is smooth and broad and thus suitable for emission tuning and for short pulse generation. Measured laser performance with respect to absorbed pumped energy is shown in Fig. 1b. The slope efficiency σ and laser threshold Eth were calculated using linear fit. Maximum output energy of 4.2 mJ with slope efficiency σ = 30.3 % and laser threshold Eth = 12.5 mJ was achieved with 97.5 % OC. The wavelength of output radiation was 1887 nm. From the results follows that the new mixed Tm:LuF3-CaF2 crystal is suitable material for laser action with good efficiency. Further investigation needs to be done on material and spectroscopic properties to determine its laser performance in comparison with other thulium doped laser hosts.
关键词： diode pumped laser,1.9 μm region,thulium doped solid state lasers,Tm3+:LuF3-CaF2
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Nd,Gd:SrF <sub/>2</sub> Laser Generating 600 fs Pulses at 0.9 W of Pump Power
摘要： Fluoride crystals (CaF2, SrF2) doped with neodymium Nd3+ and codoped with non-active ions as Y3+, La3+, or Gd3+ for breaking clusters of active ions, have become recently interesting active media for the diode-pumped mode-locked lasers. They possess broader emission spectra as well as longer fluorescence lifetime in comparison with widely used crystals such as Nd:YAG or Nd:YVO4. The femtosecond Nd,Y:SrF2 laser generating 97 fs pulses was reported in the Ti:sapphire pumped system [1]. We have reported continuously mode-locked operation of this laser pumped by a 2 W multimode laser diode and mode-locked using a semiconductor saturable absorber generating pulses with the duration of 258 fs [2]. In laser systems with La3+ codoped crystals, which have wider tunability than Y3+ codoped crystals, passively mode-locked 354 to 1200 fs and continuous-wave 1044 to 1081 nm tunable operation was reported in the system pumped by 4 W laser diode [3]. Recently a new Nd,Gd:SrF2 crystal has been investigated and the dual wavelength mode-locked picosecond operation was reported for pump power higher than 3.8 W [4]. We reported femtosecond operation of laser with this crystal and obtained pulses as short as 228 fs with output power of 2 x 50 mW in system pumped by 2 W laser diode for absorbed pump power of 1320 mW [5]. In the present contribution we report on operation of this novel laser with a Brewster cut crystal in passively mode locked regime for extremely low pump power. Laser system schematic is similar as in ref. [5] and is shown in Fig. 1. A 5 mm long Brewster cut 0.5%Nd, 5%Gd:SrF2 crystal was pumped by a multimode 2 W laser diode at 796 nm and passively mode-locked using a semiconductor saturable absorber mirror (SAM). Using a chirped mirror M3 with GDD equal to -650 fs2 it was possible to achieve continuously mode locked regime at absorbed pump power of only 320 mW, with output power of 2 x 12 mW behind the mirror M4 in linearly polarized beams with nearly Gaussian spatial profile and pulse duration of 740 fs (assuming sech2 pulse shape). For higher absorbed pump power of 632 mW (905 mW incident on the crystal) the total output power of 2 x 20 mW was achieved with a pulse duration of 600 fs. The autocorrelation curve is shown in Fig. 2 together with the measured spectrum 3.3 nm wide, and centered at 1051.5 nm. The absorbed pump power is 2 - 4 times smaller in comparison with our previous results. The calculated time-bandwidth product of 0.536 gives potential to get shorter pulses (down to 352 fs) with optimum GVD compensation.
关键词： diode-pumped,semiconductor saturable absorber mirror,femtosecond pulses,Nd,Gd:SrF2,mode-locked lasers
更新于2025-09-12 10:27:22
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[OSA CLEO: Science and Innovations - San Jose, California (2015..-..)] CLEO: 2015 - Novel Diode Pumped Sulfur Oxide Laser: DPSOL
摘要： The concept of a diode pumped molecular gas laser is introduced, with energy storing sulfur monoxide (SO) as the active molecule. Key spectroscopic and kinetic characteristics are presented, along with a kW-class laser point design.
关键词： molecular gas laser,DPSOL,sulfur monoxide,Diode pumped sulfur oxide laser
更新于2025-09-11 14:15:04
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Diode-Pumped Visible Laser Operation of Tb <sup>3+</sup> :LiLuF <sub/>4</sub>
摘要： Trivalent terbium-doped materials have been attracting the attention of the scientific community due to the capacity of Tb3+ to emit in the visible range. Efficient laser operation at green and yellow wavelengths has been demonstrated previously while laser operation in the orange and red ranges is not expected due to detrimental excited state absorption (ESA) processes [1-4]. Previous research on laser operation of Tb3+ doped materials was performed under pumping with frequency doubled optically pumped semiconductor laser (2ω-OPSL). These blue emitting pump sources exhibit an excellent beam quality at output powers up to 5 W, but they are complex, bulky, and expensive, and thus not well suited for power scaling. Diode-pumping presents a cost-efficient alternative with potential for power scaling and miniaturization. The availability of InGaN-based blue laser diodes makes it possible to match the peak absorption wavelength of the 7F6→5D4 transition of Tb3+ ions around 488 nm. Here, we present to the best of our knowledge, the first diode-pumped Tb3+ based laser. Under 200 mW of pump power at 488.3 nm, the laser operates in continuous wave (cw) at 542 or 544 nm with a maximum slope efficiency of 53% and up to 44 mW of output power.
关键词： visible laser,diode-pumped,Tb3+:LiLuF4,terbium-doped materials
更新于2025-09-11 14:15:04
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Efficient Tm:YAG and Tm:LuAG Lasers Pumped by Red Tapered Diodes
摘要： Eye-safe, diode-pumped all-solid-state lasers working in the 2 μm region are favourable for many applications including remote sensing, medicine, and gas sensing. Tm-doped crystals such as Tm:YAG and Tm:LuAG are among the commonly employed laser gain media for this purpose. These systems are usually pumped by laser diodes operating around 780 nm [1]. The corresponding stokes limit for laser slope efficiency is then about 39%. However, for highly-doped samples, the two-for-one cross-relaxation process enables laser efficiencies exceeding this limit, and a slope efficiency of 59% has been reported from a 785 nm Ti:Sapphire pumped Tm:YAG laser, indicating a cross-relaxation efficiency of around 1.5 (one 780 nm pump photon generating 1.5 laser photons around 2 μm) [2]. As an alternative pumping approach, Stoneman et al. pointed out the possibility to pump Tm-based lasers around 681 nm, due to the much stronger absorption line at this wavelength [3]. Compared to 785 nm pumping, using the stronger 681 nm line warrants utilization of shorter Tm-crystals, which minimizes self-absorption losses [3]. Moreover, 681 nm pumping could also facilitate usage of thinner crystals in thin-disk geometry and/or could decrease the required number of bounces on the thin-disk for sufficient absorption of the pump light [4]. Moreover, pumping at a wavelength with stronger absorption coefficient creates a more densely populated gain medium, which could increase the effectiveness of cross-relaxation process. As a drawback, the stokes limited slope efficiency reduces to around 34% for 681 nm pumping, and decreased absorption lengths might also induce stronger thermal effects. In their early work, Stoneman et al. used a Ti:Sapphire laser operating at 681 nm to pump a Tm:YAG crystal, but the obtained slope efficiency was only around 35%, indicating a weak cross-relaxation process [3]. In this work, we report highly efficient Tm:YAG and Tm:LuAG lasers pumped with high brightness tapered diodes operating around 681 nm [5]. The lasers crystals had a Tm-doping of 6%, a length of 7 mm, and absorbed around 98% of the incident TM polarized pump light. In the experiments, we have achieved slope efficiencies up to 52% and 51% in cw operation from Tm:YAG and Tm:LuAG lasers, respectively (Fig. 1). This efficiency indicates a cross-relaxation efficiency of around 1.55, which is similar to what was shown with the regular 785 nm diode pumping [2]. To the best of our knowledge, this is the first report of diode pumping of Tm-doped solid-state lasers at 681 nm, as well as the first usage of tapered diodes as pump sources in Tm-systems.
关键词： diode-pumped,681 nm,Tm:YAG,Tm:LuAG,lasers,tapered diodes
更新于2025-09-11 14:15:04
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Growth and laser performance of Tm:SrGdGa3O7 crystal
摘要： The Tm:SrGdGa3O7 crystal was grown by the Czochralski (CZ) method. Continuous-wave, Q-switched, and tunable laser performance are demonstrated based on Tm:SrGdGa3O7 crystal for the first time. The maximum continuous-wave output power was 0.49 W under the absorbed pump power of 8.6 W. Using a commercial WS2 as the saturable absorber, the passively Q-switched laser was successfully achieved. The maximum output power of Q-switched reached up to 0.13 W with the repetition rate of 21.4 kHz and the pulse width of 1.1 μs. A tunable laser was obtained with the whole tuning range of 60.8 nm from 1907.0 to 1967.8 nm.
关键词： Diode-pumped,Tm-doped crystal,Tunable laser,Q-switched
更新于2025-09-11 14:15:04
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260?W of average green beam generation by intracavity frequency-doubled acousto-optic Q-Switched Nd:YAG laser
摘要： We developed an intracavity frequency-doubled acousto-optic Q-switched Nd:YAG laser generating * 260 W of average green power using two identical diode-pumped gain modules with ?vefold pumping symmetry in a simple two mirror linear cavity con?guration. The corresponding optical to optical conversion ef?ciency was estimated to be * 16.8%. At maximum output power, individual green pulse duration (FWHM) was measured to be * 73 ns with a pulse repetition rate of 18 kHz. The output average green power was highly stable with measured ?uctuation in average green power ± 0.83 W over 5 h of continuous operation. The jitter in pulse delay time and pulse to pulse amplitude ?uctuation was measured to be within ± 4.25 ns and ± 5%, respectively. The maximum beam drift recorded at 5 m distance away from the laser system was * 14 micron corresponding to beam pointing stability of ± 2.8 micro-rad.
关键词： Acousto-optic Q-switching,Intracavity frequency conversion,Diode-pumped solid-state lasers,High-power green laser
更新于2025-09-11 14:15:04
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[IEEE 2019 IEEE Photonics Conference (IPC) - San Antonio, TX, USA (2019.9.29-2019.10.3)] 2019 IEEE Photonics Conference (IPC) - High-Power Ultrafast Industrial Thin-Disk Lasers
摘要： Ultrafast amplifiers using industrial thin-disk technology from TRUMPF deliver record pulse energies of 200 mJ at 5 kHz. In addition, multipass amplifiers to increase the average power and pulse energy and concepts for nonlinear compression to reach pulse durations below 50 fs will be discussed.
关键词： diode-pumped,ultrafast,high-energy,Thin-disk laser,amplification,high-power,laser amplifier,X-ray
更新于2025-09-11 14:15:04
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Low-cost multimode diode-pumped Tm:YAG and Tm:LuAG lasers
摘要： We report a continuous-wave operation of Tm:YAG and Tm:LuAG lasers pumped with a low-cost, multimode AlGaAs laser diode. First, the lifetime and the absorbance behavior of 5 mm, 6% Tm 3+ -doped YAG and LuAG crystals were thoroughly investigated. A low-cost multimode 3W laser diode at 781 nm was then used as a pump source for the Tm 3+ -doped laser systems. Using three different output couplers, up to 636 mW of output power was obtained from Tm:YAG laser, with a slope efficiency of 29% at 2017 nm. The maximum output power was 637 mW in the Tm:LuAG laser, with a slope efficiency of 28% at 2023 nm. The lasing performances showed a decreasing slope efficiency with an increasing level of output coupling, which leads to a high upconversion. Furthermore, using a birefringent filter in the resonators, the laser outputs were tuned from 1942 to 2086 nm in the Tm:YAG resonator and from 1931 to 2107 nm in the Tm:LuAG case.
关键词： diode-pumped lasers,infrared lasers,Tm:LuAG laser,Tm:YAG laser,tunable lasers,solid-state lasers,Lasers
更新于2025-09-11 14:15:04