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Okuyucu S, Demirbas U, Thesinga J, Edelmann M, Pergament M, Kärtner F. Diode-pumped passively mode-locked femtosecond Yb:YLF laser at 1.1 GHz. OPTICS EXPRESS 2024; 32:15555-15564. [PMID: 38859203 DOI: 10.1364/oe.518081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2024] [Accepted: 03/14/2024] [Indexed: 06/12/2024]
Abstract
We report femtosecond pulse generation at GHz repetition rates with the Yb:YLF gain medium for the first time. A simple, low-cost, and compact architecture is implemented for the potential usage of the system as a low-noise timing jitter source. The system is pumped by 250 mW, 960 nm single-mode diodes from both sides. The semiconductor saturable absorber mirror (SESAM) mode-locked laser is self-starting and generates transform-limited 210 fs long pulses near 1050 nm. The laser's average output power is 40 mW, corresponding to a pulse energy of 36 pJ at 1.1 GHz repetition rate. The measured laser relative intensity noise (RIN) from 1 Hz to 1 MHz is 0.42%. The performance obtained in this initial work is limited by the specifications of the available optics and could be improved significantly by employing custom-designed optical elements.
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Su X, Wang Y, Su L, Liu S, Zheng L, Zhang B, He J, Zhang B. Sub-50-fs Kerr-lens mode-locked Yb-doped fluoride laser with 44% optical efficiency. APPLIED OPTICS 2024; 63:912-916. [PMID: 38437387 DOI: 10.1364/ao.509994] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Accepted: 12/20/2023] [Indexed: 03/06/2024]
Abstract
Yb-doped fluoride has been demonstrated to be potential crystals for application in efficient ultrafast lasers. However, the trade-off between the shorter pulses with higher efficiencies is a challenge. In this work, using Y b,G d:C a S r F 2 crystal, we report on a sub-50-fs Kerr-lens mode-locked oscillator with an optical efficiency up to 44%. Pumped by a 976-nm diffraction-limited fiber laser and using chirped mirrors combined with prism pairs for the dispersion compensation, a pulse as short as 46 fs was obtained with 620-mW output power, corresponding to an optical efficiency more than 40%. Stable Kerr-lens mode-locking with RMS of output power lower than 0.3% and beam quality factors M 2<1.14 were achieved. Moreover, a maximum output power of 780 mW was obtained in continuous-wave operation with 55.3% optical efficiency. To the best of our knowledge, the results in this work represent the shortest pulses generated from Yb-doped fluoride lasers as well as the highest optical efficiencies ever reported in sub-100 fs Yb bulk lasers.
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Zhang P, Wu W, Lin ZL, Li ZQ, Loiko P, Normani S, Chen Z, Li Z, Elabedine GZ, Mateos X, Zeng HJ, Zhang G, Nie HY, Braud A, Camy P, Petrov V, Chen W. Growth, spectroscopy and SESAM mode-locking of a "mixed" Yb:Ca(Gd,Y)AlO 4 disordered crystal. OPTICS EXPRESS 2024; 32:3221-3233. [PMID: 38297548 DOI: 10.1364/oe.514436] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Accepted: 12/29/2023] [Indexed: 02/02/2024]
Abstract
We present the growth, spectroscopy, continuous-wave (CW) and passively mode-locked (ML) operation of a novel "mixed" tetragonal calcium rare-earth aluminate crystal, Yb3+:Ca(Gd,Y)AlO4. The absorption, stimulated-emission, and gain cross-sections are derived for π and σ polarizations. The laser performance of a c-cut Yb:Ca(Gd,Y)AlO4 crystal is studied using a spatially single-mode, 976-nm fiber-coupled laser diode as a pump source. A maximum output power of 347 mW is obtained in the CW regime with a slope efficiency of 48.9%. The emission wavelength is continuously tunable across 90 nm (1010 - 1100 nm) using a quartz-based Lyot filter. With a commercial SEmiconductor Saturable Absorber Mirror to initiate and maintain ML operation, soliton pulses as short as 35 fs are generated at 1059.8 nm with an average output power of 51 mW at ∼65.95 MHz. The average output power can be scaled to 105 mW for slightly longer pulses of 42 fs at 1063.5 nm.
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4
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Su X, Wang Y, Yin Y, Wang M, Zhang B, He J, Zhang B. Sub-100-fs Kerr-lens mode-locked Yb:Lu 2O 3 laser with more than 60% optical efficiency. OPTICS LETTERS 2024; 49:145-148. [PMID: 38134173 DOI: 10.1364/ol.513788] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Accepted: 12/07/2023] [Indexed: 12/24/2023]
Abstract
Yb-doped sesquioxides represent one of the most excellent laser crystals applying for high-power ultrafast lasers owing to their very high thermal conductivities and broadband emission spectra. Pumped by a high-brightness Yb-fiber laser at 976 nm, the Yb:Lu2O3 laser delivers a maximum output power that amounts to 3.55 W in the continuous-wave regime with an optical efficiency of 75%. In the mode-locked regime, 90-fs pulses were generated via soft-aperture Kerr-lens mode-locking at 1080.6 nm with an average output power of 2.85 W, which corresponds to an optical efficiency of 60.3% and a slope efficiency of 68.8%. Average output power of the mode-locked Yb:Lu2O3 laser can be further scaled to 3.05 W at the expense of the pulse duration (178 fs), which corresponds to an optical efficiency as high as 64.5%. To the best of our knowledge, it is the highest optical efficiency ever reported from any solid-state Kerr-lens mode-locked Yb lasers.
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Ding H, Liu J, Wang Y, Zhang N, Wang Z, Zhao Y, Xu X, Xue Y, Xu J, Griebner U, Petrov V. Mode-locking of a Tm,Ho:CALYGO laser delivering 50 fs pulses at 2.08 µm. OPTICS LETTERS 2023; 48:6267-6270. [PMID: 38039243 DOI: 10.1364/ol.510740] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Accepted: 11/08/2023] [Indexed: 12/03/2023]
Abstract
We study the polarization-dependent laser performance of a novel, to the best of our knowledge, "mixed" Tm,Ho:CaYGdAlO4 crystal in the continuous-wave (CW) and mode-locked regimes. Both in terms of the CW tunability range (261 nm) and the minimum pulse duration (50 fs at 2078 nm, spectral width of 95 nm) in the mode-locked regime, σ-polarization is superior. With extended inhomogeneous spectral broadening due to structural and compositional disorder, Tm,Ho:CaYGdAlO4 is promising for few-optical-cycle pulse generation around 2 µm.
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Tian W, Tian X, Li Q, Wang G, Bai C, Yu Y, Xu X, Xu J, Wei Z, Zhu J. Kerr-lens mode-locked femtosecond Yb:CALYO oscillator with more than 20-W average power. OPTICS LETTERS 2023; 48:4789-4792. [PMID: 37707903 DOI: 10.1364/ol.501843] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Accepted: 08/22/2023] [Indexed: 09/15/2023]
Abstract
We report on the demonstration of a pure Kerr-lens mode-locked Yb:CALYO laser which can directly deliver sub-200 fs pulses with more than 20-W average power. With an incident pump power of 89 W, 153-fs pulses were generated with an average power of 21.5 W at a repetition rate of 77.9 MHz. The corresponding peak power and single pulse energy were 1.6 MW and 0.27 µJ, respectively. The stable operation of the mode-locking was confirmed by very small fluctuations in both spectrum and output power recorded over an hour. Second harmonic generation (SHG) was conducted with 59% conversion efficiency, which indicated that the high-power mode-locking pulses are of good quality. Stable Kerr-lens mode-locking (KLM) with 156-fs pulse duration and 27.2-W average power was also achieved with 109-W pump power. To the best of our knowledge, this is the highest average output power ever reported from a femtosecond mode-locked bulk oscillator.
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Dupont H, Loiko P, Tyazhev A, Giordano L, Pan Z, Chu H, Li D, Viana B, Hideur A, Guillemot L, Braud A, Camy P, Georges P, Druon F. Tm:CALGO lasers at 2.32 µm: cascade lasing and upconversion pumping. OPTICS EXPRESS 2023; 31:18751-18764. [PMID: 37381308 DOI: 10.1364/oe.487590] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Accepted: 04/07/2023] [Indexed: 06/30/2023]
Abstract
We report on the first laser operation of a disordered Tm:CaGdAlO4 crystal on the 3H4 → 3H5 transition. Under direct pumping at 0.79 µm, it generates 264 mW at 2.32 µm with a slope efficiency of 13.9% and 22.5% vs. incident and absorbed pump power, respectively, and a linear polarization (σ). Two strategies to overcome the bottleneck effect of the metastable 3F4 Tm3+ state leading to the ground-state bleaching are exploited: cascade lasing on the 3H4 → 3H5 and 3F4 → 3H6 transitions and dual-wavelength pumping at 0.79 and 1.05 µm combining the direct and upconversion pumping schemes. The cascade Tm-laser generates a maximum output power of 585 mW at 1.77 µm (3F4 → 3H6) and 2.32 µm (3H4 → 3H5) with a higher slope efficiency of 28.3% and a lower laser threshold of 1.43 W, out of which 332 mW are achieved at 2.32 µm. Under dual-wavelength pumping, further power scaling to 357 mW at at 2.32 µm is observed at the expense of increased laser threshold. To support the upconversion pumping experiment, excited-state absorption spectra of Tm3+ ions for the 3F4 → 3F2,3 and 3F4 → 3H4 transitions are measured for polarized light. Tm3+ ions in CaGdAlO4 exhibit broadband emission at 2.3 - 2.5 µm making this crystal promising for ultrashort pulse generation.
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Lin ZL, Loiko P, Zeng HJ, Xue WZ, Zhang G, Normani S, Camy P, Petrov V, Mateos X, Lin H, Yu H, Zhang H, Liu J, Wang L, Chen W. Kerr-lens mode-locking of an Yb:CLNGG laser. OPTICS EXPRESS 2023; 31:8575-8585. [PMID: 36859969 DOI: 10.1364/oe.480986] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Accepted: 02/06/2023] [Indexed: 06/18/2023]
Abstract
We report on a Kerr-lens mode-locked laser based on an Yb3+-doped disordered calcium lithium niobium gallium garnet (Yb:CLNGG) crystal. Pumping by a spatially single-mode Yb fiber laser at 976 nm, the Yb:CLNGG laser delivers soliton pulses as short as 31 fs at 1056.8 nm with an average output power of 66 mW and a pulse repetition rate of ∼77.6 MHz via soft-aperture Kerr-lens mode-locking. The maximum output power of the Kerr-lens mode-locked laser amounted to 203 mW for slightly longer pulses of 37 fs at an absorbed pump power of 0.74 W, which corresponds to a peak power of 62.2 kW and an optical efficiency of 20.3%.
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Wang S, Liu S, Liu D, Wang N, Zhao R, Liu Y, Li Z, Mao G, Chen F, Sheng Y, Xu T, Krolikowski W. Ferroelectric domain engineering with femtosecond pulses of different wavelengths. OPTICS EXPRESS 2023; 31:5843-5852. [PMID: 36823856 DOI: 10.1364/oe.483162] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Accepted: 01/23/2023] [Indexed: 06/18/2023]
Abstract
Direct femtosecond laser writing of ferroelectric domain structures has been an indispensable technique for engineering the second-order optical nonlinearity of materials in three dimensions. It utilizes localized thermoelectric field motivated by nonlinear absorption at the position of laser focus to manipulate domains. However, the impact of laser wavelengths, which is pivotal in nonlinear absorption, on the inverted domains is still sketchy. Herein, the light-induced ferroelectric domain inversion is experimentally studied. It is shown that the domain inversions can be achieved over a broad spectral range, but the optical threshold for domain inversion varies dramatically with the laser wavelength, which can be explained by considering the physical mechanism of femtosecond laser poling and nonlinear absorption properties of the crystal. Meanwhile, the effects of other laser processing parameters are also experimentally investigated. Our findings are useful to guide the fabrication of high-performance optical and electronic devices based on ferroelectric domains.
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Chen W, Lin ZL, Xue WZ, Zeng HJ, Zhang G, Loiko P, Zhao Y, Xu X, Xu J, Mateos X, Lin H, Wang L, Petrov V. Kerr-lens mode-locked Yb:YAlO 3 laser generating 24-fs pulses at 1085 nm. OPTICS LETTERS 2022; 47:4728-4731. [PMID: 36107073 DOI: 10.1364/ol.471504] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Accepted: 08/18/2022] [Indexed: 06/15/2023]
Abstract
We report on a Kerr-lens mode-locked Yb:YAlO3 laser generating soliton pulses as short as 24 fs at 1085 nm with an average output power of 186 mW and a pulse repetition rate of 87.5 MHz, representing the shortest pulses ever achieved from any mode-locked laser based on Yb3+-doped structurally ordered crystal. Optimized for power-scalable operation, the Yb:YAlO3 laser delivers 1.9 W at 1060 nm at the expense of a longer pulse duration of 44 fs, corresponding to a peak power of 462 kW and an optical efficiency of 43.2%.
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11
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Lin ZL, Xue WZ, Zeng HJ, Zhang G, Zhao Y, Xu X, Xu J, Loiko P, Mateos X, Lin H, Petrov V, Wang L, Chen W. Semiconductor saturable absorber mirror mode-locked Yb:YAP laser. OPTICS EXPRESS 2022; 30:31986-31997. [PMID: 36242269 DOI: 10.1364/oe.464815] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Accepted: 08/09/2022] [Indexed: 06/16/2023]
Abstract
We report on sub-30 fs pulse generation from a semiconductor saturable absorber mirror mode-locked Yb:YAP laser. Pumping by a spatially single-mode Yb fiber laser at 979 nm, soliton pulses as short as 29 fs were generated at 1091 nm with an average output power of 156 mW and a pulse repetition rate of 85.1 MHz. The maximum output power of the mode-locked Yb:YAP laser amounted to 320 mW for slightly longer pulses (32 fs) at an incident pump power of 1.52 W, corresponding to a peak power of 103 kW and an optical efficiency of 20.5%. To the best of our knowledge, this result represents the shortest pulses ever achieved from any solid-state Yb laser mode-locked by a slow, i.e., physical saturable absorber.
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12
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Lin ZL, Xue WZ, Zeng HJ, Zhang G, Zhang P, Chen Z, Li Z, Petrov V, Loiko P, Mateos X, Lin H, Wang L, Chen W. Kerr-lens mode-locked ytterbium-activated orthoaluminate laser. OPTICS LETTERS 2022; 47:3027-3030. [PMID: 35709041 DOI: 10.1364/ol.460701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Accepted: 05/10/2022] [Indexed: 06/15/2023]
Abstract
We report on the first, to the best of our knowledge, Kerr-lens mode-locked laser based on an Yb3+-doped perovskite-type orthoaluminate crystal exploiting two different principal light polarizations. The Yb:(Y,Gd)AlO3 laser delivers soliton pulses as short as 32 fs at 1067 nm with an average output power of 328 mW and a pulse repetition rate of ∼84.6 MHz for E || a polarization. For the orthogonal E || b polarization, 33-fs pulses are generated at 1057 nm with an average output power of 305 mW. Power scaling to a maximum average output power reaching 2.07 W is achieved at the expense of longer pulse duration (72 fs for E || b), corresponding to an optical efficiency of 43.9% and a peak power of 303 kW.
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Su X, Wang Y, Li G, Su L, Liu S, Zheng L, Zhang B, Zhang B. Sub-60-fs ultralow threshold and efficient Kerr-lens mode-locked Yb,Gd:CaSrF 2 laser. OPTICS LETTERS 2022; 47:2362-2365. [PMID: 35486800 DOI: 10.1364/ol.457120] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Accepted: 04/09/2022] [Indexed: 06/14/2023]
Abstract
In this Letter, using a Yb,Gd:CaSrF2 co-doping mixed crystal, an ultra-low threshold and efficient Kerr-lens mode-locked femtosecond oscillator is realized with a mode-locking threshold as low as 150 mW. With a 200-mW pump power, the shortest pulses are obtained with a pulse duration of 57 fs. A maximum mode-locked output power of 185 mW is observed under a 500-mW pump power, corresponding to an optical-to-optical efficiency of up to 37%. To the best of our knowledge, the 150-mW threshold is the lowest pump power to realize Kerr-lens mode-locking operation in Yb-doped bulk lasers. Furthermore, an optical efficiency of 37% is the highest efficiency in Yb-doped fluoride bulk lasers to date. Our results provide a new basis for high-efficiency and low-threshold Yb-doped ultrafast bulk lasers.
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Demirbas U, Thesinga J, Kellert M, Reuter S, Pergament M, Kärtner FX. Broadly tunable (993-1110 nm) Yb:YLF laser. APPLIED OPTICS 2022; 61:3702-3710. [PMID: 36256411 DOI: 10.1364/ao.456316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Accepted: 04/10/2022] [Indexed: 06/08/2023]
Abstract
We have investigated room-temperature continuous-wave (cw) lasing performance of Yb:YLF oscillators in detail using rod-type crystals with low Yb-doping (2%). The laser is pumped by a low-cost, high brightness, 10 W, 960 nm single-emitter multimode diode. Laser performance is acquired in both E//a and E//c configurations, using 12 different output couplers with transmission ranging from 0.015% to 70%. We have estimated the passive loss of the Yb:YLF crystal as 0.06% per cm, corresponding to an impressive crystal figure of merit above 4000. The low-doping level not only reduces the system losses but also minimizes the thermal load as the low doped crystals enable distribution of heat load in a greater volume. Using the advantages of lower loss and improved thermal behavior, we have achieved cw output power above 4 W, cw slope efficiencies up to 78%, and a record cw tuning range covering the 993-1110 nm region (117 nm). The output power performance achieved in this initial work is limited by the available pump power, and future room-temperature Yb:YLF systems have the potential to produce higher output power levels.
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Wang Y, Loiko P, Zhao Y, Pan Z, Chen W, Mero M, Xu X, Xu J, Mateos X, Major A, Guina M, Petrov V, Griebner U. Polarized spectroscopy and SESAM mode-locking of Tm,Ho:CALGO. OPTICS EXPRESS 2022; 30:7883-7893. [PMID: 35299541 DOI: 10.1364/oe.449626] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Accepted: 02/03/2022] [Indexed: 06/14/2023]
Abstract
A Tm,Ho:CALGO laser passively mode-locked by a GaSb-based SESAM generated pulses as short as 52 fs at a central wavelength of 2015 nm with a broad spectral bandwidth of 82 nm (full width at half maximum) owing to the combined gain profiles of both dopants for σ-polarized light. The average output power reached 376 mW at a repetition rate of 85.65 MHz. In the continuous-wave regime, the laser was power scaled up to 1.01 W at 2080.6 nm with a slope efficiency of 32.0%, a laser threshold of 155 mW and π-polarized emission. Polarized spectroscopic properties of Ho3+ ions in singly doped and codoped CALGO crystals were revisited to explain the observed laser performance.
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Labaye F, Wittwer VJ, Hamrouni M, Modsching N, Cormier E, Südmeyer T. Efficient few-cycle Yb-doped laser oscillator with Watt-level average power. OPTICS EXPRESS 2022; 30:2528-2538. [PMID: 35209390 DOI: 10.1364/oe.446047] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Accepted: 12/10/2021] [Indexed: 06/14/2023]
Abstract
So far, the operation of ultrafast bulk laser oscillators based on Yb-doped gain materials and directly emitting few-cycle pulses have been restricted to low optical-to-optical efficiencies and average output powers of only a few milliwatt. This performance limitation can be attributed to the commonly-applied standard collinear pumping scheme in which the optical pump is transmitted through a dichroic mirror whose spectral transmission and dispersion properties severely perturb the oscillating pulse when its optical spectrum extends towards the pump wavelength. In this study, we report on a novel pumping scheme relying on cross polarization that overcomes this challenge. In our concept, the pump transmitting mirror is highly transmissive for the pump light in p-polarization, while it is highly reflective for the laser light in s-polarization over a broad wavelength range, even covering the pump wavelength and beyond. In contrast to a standard thin-film polarizer featuring similar polarization dependent properties, it provides a low and flat dispersion profile over a broad spectral range for the s-polarization. Implementing this pumping scheme in a soft-aperture Kerr-lens mode-locked bulk laser oscillator based on the gain material Yb:CALGO, we achieve clean 22-fs soliton pulses at 729 mW of average output power and an optical-to-optical efficiency of 25%. In a second configuration optimized for the highest average output power, we demonstrate a high optical-to-optical efficiency of 36.6%, which was obtained for 31-fs pulses at 1.63 W of average output power. In a third configuration we experimentally confirm the limiting effect of a dichroic mirror commonly used in the standard collinear pumping scheme. All the results presented here and obtained in the first and second configuration generate pulses with a center wavelength ranging from 1030 nm to 1056 nm, well within the spectral region of high gain cross sections of Yb:CALGO. While this initial demonstration was realized using a commercial diffraction-limited fiber laser as pump source, the pump geometry appears also well suited for pumping with laser diodes coupled into multimode fibers. This novel approach opens up new opportunities for compact and cost-efficient high-power few-cycle bulk laser oscillators based on Yb-doped gain materials and can be applied to any gain material with small quantum defect.
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Wang Y, Tomilov S, Saraceno CJ. High-power modelocked thin-disk oscillators as potential technology for high-rate material processing. ADVANCED OPTICAL TECHNOLOGIES 2021; 10:247-261. [PMID: 35881661 PMCID: PMC9113671 DOI: 10.1515/aot-2021-0045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Accepted: 09/11/2021] [Indexed: 06/15/2023]
Abstract
High average power femtosecond lasers have made spectacular progress in the last decades - moving from laboratory-based systems with maximum average powers of tens of watts to kilowatt-class mature industrial systems in a short time. The availability of such systems opens new possibilities in many fields; one of the most prominent ones that have driven many of these technological advances is precise high-speed material processing, where ultrashort pulses have long been recognized to provide highest precision processing of virtually any material, and high average power extends these capabilities to highest processing rates. Here, we focus our attention on one high-average power technology with large unexplored potential for this specific application: directly modelocked multi-MHz repetition frequency high-power thin-disk oscillators. We review their latest state-of-the-art and discuss future directions and challenges, specifically with this application field in mind.
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Affiliation(s)
- Yicheng Wang
- Photonics and Ultrafast Laser Science, Ruhr Universität Bochum, Universitätsstrasse 150, 44801 Bochum, Germany
| | - Sergei Tomilov
- Photonics and Ultrafast Laser Science, Ruhr Universität Bochum, Universitätsstrasse 150, 44801 Bochum, Germany
| | - Clara J. Saraceno
- Photonics and Ultrafast Laser Science, Ruhr Universität Bochum, Universitätsstrasse 150, 44801 Bochum, Germany
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Hao Q, Ye K, Dong M, Liu J, Liu Z. Nonlinear optical response of a monolayer WS 2 and the application of a hundred-MHz nanosecond laser. OPTICS EXPRESS 2021; 29:36634-36643. [PMID: 34809070 DOI: 10.1364/oe.441281] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Accepted: 10/12/2021] [Indexed: 06/13/2023]
Abstract
High quality monolayer WS2 was successfully fabricated by chemical vapor deposition method. The nonlinear optical response of monolayer WS2 is demonstrated for the first time. Due to the relatively low modulation depth of 1.4% and saturable intensity of 68.6 kW/cm2 of monolayer WS2, a robust continuous-wave mode-locked (CWML) nanosecond laser with a repetition rate of 93.1 MHz is obtained. To the best of our knowledge, this is the highest repetition rate of nanosecond pulses generated from CWML lasers. This work provides an effective approach to obtaining nanosecond pulsed lasers with repetition rates of hundred-megahertz.
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Drs J, Fischer J, Modsching N, Labaye F, Wittwer VJ, Südmeyer T. Sub-30-fs Yb:YAG thin-disk laser oscillator operating in the strongly self-phase modulation broadened regime. OPTICS EXPRESS 2021; 29:35929-35937. [PMID: 34809016 DOI: 10.1364/oe.440196] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Accepted: 10/06/2021] [Indexed: 06/13/2023]
Abstract
We experimentally investigate the limits of pulse duration in a Kerr-lens mode-locked Yb:YAG thin-disk laser (TDL) oscillator. Thanks to its excellent mechanical and optical properties, Yb:YAG is one of the most used gain materials for continuous-wave and pulsed TDLs. In mode-locked operation, its 8-nm wide gain bandwidth only directly supports pulses with a minimum duration of approximately 140 fs. For achieving shorter pulses, a Kerr-lens mode-locked TDL oscillator can be operated in the strongly self-phase modulation (SPM) broadened regime. Here, the spectral bandwidth of the oscillating pulse exceeds the available gain bandwidth by generating additional frequencies via SPM inside the Kerr medium. In this work, we study and compare different laser configurations in the strongly SPM-broadened regime. Starting with a configuration providing 84-fs pulses at 69 W average power at 17 MHz repetition rate, we reduce the pulse duration by optimizing various mode-locking parameters. One crucial parameter is the dispersion control which was provided by in-house-developed dispersive mirrors produced by ion-beam sputtering (IBS). We discuss trade-offs in average power, pulse duration, efficiency, and intra-cavity peak power. For the configuration operating at the highest SPM-broadening, we achieve a minimum pulse duration of 27 fs, which represents the shortest pulse duration directly generated by any ultrafast TDL oscillator. The corresponding full width at half maximum (FWHM) spectral bandwidth exceeds more than five times the FWHM gain bandwidth. The average output power of 3.3 W is moderate for ultrafast TDL oscillators, but higher than other Yb-based laser oscillators operating at this pulse duration. Additionally, the corresponding intra-cavity peak power of 0.8 GW is highly attractive for implementing intra-cavity extreme nonlinear optical interactions such as high harmonic generation.
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Abstract
Yb:CaGdAlO4, or Yb:CALGO, a new laser crystal, has been attracting increasing attention recently in a myriad of laser technologies. This crystal features salient thermal, spectroscopic and mechanical properties, which enable highly efficient and safe generation of continuous-wave radiations and ultrafast pulses with ever short durations. More specifically, its remarkable thermal-optic property and its high conversion efficiency allow high-power operation. Its high nonlinear coefficient facilitates study of optimized mode locking lasers. Besides, its ultrabroad and flat-top emission band benefits the generation of complex structured light with outstanding tunability. In this paper, we review the recent advances in the study of Yb:CALGO, covering its physical properties as well as its growing applications in various fields and prospect for future development.
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Zhang Y, Li S, Du X, Guo J, Gong Q, Tao S, Zhang P, Fang Q, Pan S, Zhao C, Liang X, Hang Y. Yb:GdScO 3 crystal for efficient ultrashort pulse lasers. OPTICS LETTERS 2021; 46:3641-3644. [PMID: 34329246 DOI: 10.1364/ol.431243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2021] [Accepted: 06/18/2021] [Indexed: 06/13/2023]
Abstract
We present, to the best of our knowledge, the first demonstration of thermal, optical, and laser properties of Yb:GdScO3 for potentially efficient ultrashort pulse lasers. The stimulated emission cross section at 1025 nm (E//c) is 0.46×10-20cm2 with the emission band width of 85 nm, even broader than the well-known Yb:CaGdAlO4. It has quite a high thermal conductivity of 5.54W/(m⋅K) at 50°C, comparable with Yb:YAG. In the continuous-wave regime, the maximum output power of 13.45 W at 1063.9 nm was generated with the optical-to-optical efficiency of 63.3%. These results suggest that the Yb:GdScO3 crystal is a promising candidate for ultrashort pulse lasers.
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Yin X, Wu G, Fan S, Yu F, Li Y, Liu Z, Zhang X, Zhao X, Fang J. All-solid-state widely wavelength-tunable and high-efficiency Yb:YSr 3(PO 4) 3 laser. APPLIED OPTICS 2021; 60:6713-6718. [PMID: 34612915 DOI: 10.1364/ao.432579] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Accepted: 07/05/2021] [Indexed: 06/13/2023]
Abstract
We demonstrate an all-solid-state widely wavelength-tunable Yb:YSr3(PO4)3 (Yb:YSP) laser with high efficiency. The free-running Yb:YSP laser oscillating at multiple wavelengths in the range of 1024-1054 nm is realized with different crystal lengths and output coupler transmittances. The maximum output power of 2.72 W is obtained under the absorption pump power of 7.30 W. The highest slope efficiency is 66.9%, using the crystal of 6.5-mm-length. Simultaneous dual-wavelength operation can be realized as well. Furthermore, the widely wavelength-tunable Yb:YSP laser with a range of more than 60 nm (from 1004 to 1066 nm) is achieved using a birefringent filter. The experimental results indicate that the Yb:YSP crystal can be a promising candidate for ultrafast lasers in the 1 µm region.
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Liang S, Wang S, Hua J, Li S, Xia H. Laser digital manufacturing of high-performance photodetectors based on a semiconductor microwire. OPTICS LETTERS 2021; 46:3472-3475. [PMID: 34264241 DOI: 10.1364/ol.434263] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Accepted: 06/22/2021] [Indexed: 06/13/2023]
Abstract
Digital manufacturing technology meets the needs of today's technological development. However, the post-processing is essential for some digital fabrication methods, such as annealing and ultraviolet (UV) exposure. Femtosecond laser direct writing (FsLDW) has gained considerable attention, because it is a non-photolithographic, non-vacuum, and no heat fabrication method. The photodetectors based on a semiconductor microwire were fabricated via FsLDW. Finally, the responsivity of the fabricated photodetectors based on zinc oxide (ZnO), titanium dioxide (TiO2), and tin oxide (SnO2) can reach 14.27, 1.3, and 81 A/W, respectively. The enhanced performance is attributed to the rough and porous surface of ZnO, TiO2, and SnO2 microwires. The whole preparation process is realized by the programmed control femtosecond laser scanning path. This Letter demonstrates that the fabrication method has potential in the digital manufacturing of high-performance UV photodetectors.
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Ma J, Yang F, Gao W, Xiaodong X, Jun X, Shen D, Tang D. Sub-five-optical-cycle pulse generation from a Kerr-lens mode-locked Yb:CaYAlO 4 laser. OPTICS LETTERS 2021; 46:2328-2331. [PMID: 33988575 DOI: 10.1364/ol.424846] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Accepted: 04/16/2021] [Indexed: 06/12/2023]
Abstract
Direct generation of ultrashort few-optical-cycle pulses in various wavelength regions has attracted great attention in recent decades. In this paper, generation of less than five-optical-cycle pulses from a Kerr-lens mode-locked ${\rm Yb}{:}{\rm CaYAlO}_4$ laser is demonstrated. Pumped by a 976 nm fiber laser, stable near-Fourier-transform-limited ultrashort soliton pulses centered around 1080 nm with a repetition rate of ${\sim}{113.7}\;{\rm MHz}$ were obtained. The obtained pulses have a pulse duration as short as 17 fs if a ${{\rm Sech}^2}$-shaped pulse profile is assumed, corresponding to about 4.68 optical cycles. To the best of our knowledge, this is the shortest pulse directly generated from mode-locked rare-earth-doped solid-state oscillators.
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