Spatially twisted light with femtosecond temporal structure is of particular interest in strong-field physics and light–matter interactions.However,present femtosecond vortex sources exhibit limited power handling ca...Spatially twisted light with femtosecond temporal structure is of particular interest in strong-field physics and light–matter interactions.However,present femtosecond vortex sources exhibit limited power handling capabilities,and their amplification remains an ongoing challenge particularly for high-order orbital angular momentum(OAM)states due to several inherent technical difficulties.Here,we exploit a straightforward approach to directly amplify a femtosecond optical vortex(FOV,OAM=-8?)by using a two-stage single-crystal fiber(SCF)amplifier system without pulse stretching and compression in the time domain,delivering 23-W,163-fs pulses at a repetition rate of1 MHz.The spatial and temporal features are well-conserved during the amplification,as well as the high modal purity(>96%).The results indicate that the multi-stage SCF amplifier system is particularly suited for direct amplification of high-order FOVs.The generated high-power femtosecond OAM laser beams are expected to help reveal complex physical phenomena in light–matter interactions and pave the way for practical applications in attoscience,laser plasma acceleration,and high-dimension micromachining.展开更多
We report on a high-power Ho:YAG single-crystal fiber(SCF)laser inband pumped by a high-brightness Tm-fiber laser at 1908 nm.The Ho:YAG SCF grown by the micro-pulling-down technique exhibits a propagation loss of 0.05...We report on a high-power Ho:YAG single-crystal fiber(SCF)laser inband pumped by a high-brightness Tm-fiber laser at 1908 nm.The Ho:YAG SCF grown by the micro-pulling-down technique exhibits a propagation loss of 0.05±0.005 cm^-1 at 2.09μm.A continuous-wave output power of 35.2 W is achieved with a slope efficiency of 42.7%,which is to the best of our knowledge the highest power ever reported from an SCF-based laser in the 2µm spectral range.展开更多
A mode-locked laser based on a Tm:CNNGG disordered crystal as an active medium and a single-walled carbon nanotube saturable absorber is demonstrated, operating at a central wavelength of 2018 nm. Transformlimited 84 ...A mode-locked laser based on a Tm:CNNGG disordered crystal as an active medium and a single-walled carbon nanotube saturable absorber is demonstrated, operating at a central wavelength of 2018 nm. Transformlimited 84 fs pulses are generated with an average output power of 22 mW at a repetition rate of ~90 MHz.A maximum output power of 98 mW is obtained at a slightly longer pulse duration of 114 fs.展开更多
Structured ultrashort-pulse laser beams, and in particular eigenmodes of the paraxial Helmholtz equation, are currently extensively studied for novel potential applications in various fields, e.g., laser plasma accele...Structured ultrashort-pulse laser beams, and in particular eigenmodes of the paraxial Helmholtz equation, are currently extensively studied for novel potential applications in various fields, e.g., laser plasma acceleration,attosecond science, and fine micromachining. To extend these prospects further, in the present work we push forward the advancement of such femtosecond structured laser sources into the 2-μm spectral region. Ultrashortpulse Hermite– and Laguerre–Gaussian laser modes both with a pulse duration around 100 fs are successfully produced from a compact solid-state laser in combination with a simple single-cylindrical-lens converter. The negligible beam astigmatism, the broad optical spectra, and the almost chirp-free pulses emphasize the high reliability of this laser source. This work, as a proof of principle study, paves the way toward few-cycle pulse generation of optical vortices at 2 μm. The presented light source can enable new research in the fields of interaction with organic materials, next generation optical detection, and optical vortex infrared supercontinuum.展开更多
Surface channel waveguides(WGs) were fabricated in a monoclinic Tm^(3+):KLu(WO_4)_2 crystal by femtosecond direct laser writing(fs-DLW). The WGs consisted of a half-ring cladding with diameters of 50 and 60 μm locate...Surface channel waveguides(WGs) were fabricated in a monoclinic Tm^(3+):KLu(WO_4)_2 crystal by femtosecond direct laser writing(fs-DLW). The WGs consisted of a half-ring cladding with diameters of 50 and 60 μm located just beneath the crystal surface. They were characterized by confocal laser microscopy and μ-Raman spectroscopy,indicating a reduced crystallinity and stress-induced birefringence of the WG cladding. In continuous-wave(CW)mode, under Ti:sapphire laser pumping at 802 nm, the maximum output power reached 171.1 mW at 1847.4 nm,corresponding to a slope efficiency η of 37.8% for the 60 μm diameter WG. The WG propagation loss was0.7 0.3 d B∕cm. The top surface of the WGs was spin-coated by a polymethyl methacrylate film containing randomly oriented(spaghetti-like) arc-discharge single-walled carbon nanotubes serving as a saturable absorber based on evanescent field coupling. Stable passively Q-switched(PQS) operation was achieved. The PQS60 μm diameter WG laser generated a record output power of 150 m W at 1846.8 nm with η = 34.6%. The conversion efficiency with respect to the CW mode was 87.6%. The best pulse characteristics(energy/duration)were 105.6 nJ/98 ns at a repetition rate of 1.42 MHz.展开更多
We report on a power-scalable sub-100-fs laser in the 2-μm spectral range using a Tm;-doped‘mixed’(Lu,Sc);O;sesquioxide ceramic as an active medium.Pulses as short as 58 fs at 2076 nm with an average output power o...We report on a power-scalable sub-100-fs laser in the 2-μm spectral range using a Tm;-doped‘mixed’(Lu,Sc);O;sesquioxide ceramic as an active medium.Pulses as short as 58 fs at 2076 nm with an average output power of 114 mW at a pulse repetition rate of approximately 82.9 MHz are generated by employing single-walled carbon nanotubes as a saturable absorber.A higher average power of 350 m W at 2075 nm is obtained at the expense of the pulse duration(65 fs).A maximum average power of 486 mW is achieved for a pulse duration of 98 fs and an optical conversion efficiency of 22.3%,representing the highest value ever reported from sub-100-fs mode-locked Tm lasers.展开更多
基金National Natural Science Foundation of China(52032009,62075090)。
文摘Spatially twisted light with femtosecond temporal structure is of particular interest in strong-field physics and light–matter interactions.However,present femtosecond vortex sources exhibit limited power handling capabilities,and their amplification remains an ongoing challenge particularly for high-order orbital angular momentum(OAM)states due to several inherent technical difficulties.Here,we exploit a straightforward approach to directly amplify a femtosecond optical vortex(FOV,OAM=-8?)by using a two-stage single-crystal fiber(SCF)amplifier system without pulse stretching and compression in the time domain,delivering 23-W,163-fs pulses at a repetition rate of1 MHz.The spatial and temporal features are well-conserved during the amplification,as well as the high modal purity(>96%).The results indicate that the multi-stage SCF amplifier system is particularly suited for direct amplification of high-order FOVs.The generated high-power femtosecond OAM laser beams are expected to help reveal complex physical phenomena in light–matter interactions and pave the way for practical applications in attoscience,laser plasma acceleration,and high-dimension micromachining.
基金Foundation of Deutscher Akademischer Austauschdienst(DAAD)–Research Stays for University Academics and Scientists(57381327)Natural Science Foundation of Jiangsu Province,China(SBK2019030177)+1 种基金China Scholarship Council(201704910363)Foundation of the Government of the Russian Federation(074-U01).
文摘We report on a high-power Ho:YAG single-crystal fiber(SCF)laser inband pumped by a high-brightness Tm-fiber laser at 1908 nm.The Ho:YAG SCF grown by the micro-pulling-down technique exhibits a propagation loss of 0.05±0.005 cm^-1 at 2.09μm.A continuous-wave output power of 35.2 W is achieved with a slope efficiency of 42.7%,which is to the best of our knowledge the highest power ever reported from an SCF-based laser in the 2µm spectral range.
基金National Natural Science Foundation of China(NSFC)(51402268,61505072)Institute of Chemical Materials,China Academy of Engineering Physics(CAEP)(32203)China Scholarship Council(CSC)(201704890003)
文摘A mode-locked laser based on a Tm:CNNGG disordered crystal as an active medium and a single-walled carbon nanotube saturable absorber is demonstrated, operating at a central wavelength of 2018 nm. Transformlimited 84 fs pulses are generated with an average output power of 22 mW at a repetition rate of ~90 MHz.A maximum output power of 98 mW is obtained at a slightly longer pulse duration of 114 fs.
基金National Natural Science Foundation of China(51761135115, 52032009, 61975208, 62075090)Deutsche Forschungsgemeinschaft (PE 607/14-1)+3 种基金Laserlab-Europe(654148)Natural Science Foundation of Jiangsu Province(BK20190104)Sino-German Scientist Cooperation and Exchanges Mobility Programme (M-0040)Alexander von Humboldt-Stiftung。
文摘Structured ultrashort-pulse laser beams, and in particular eigenmodes of the paraxial Helmholtz equation, are currently extensively studied for novel potential applications in various fields, e.g., laser plasma acceleration,attosecond science, and fine micromachining. To extend these prospects further, in the present work we push forward the advancement of such femtosecond structured laser sources into the 2-μm spectral region. Ultrashortpulse Hermite– and Laguerre–Gaussian laser modes both with a pulse duration around 100 fs are successfully produced from a compact solid-state laser in combination with a simple single-cylindrical-lens converter. The negligible beam astigmatism, the broad optical spectra, and the almost chirp-free pulses emphasize the high reliability of this laser source. This work, as a proof of principle study, paves the way toward few-cycle pulse generation of optical vortices at 2 μm. The presented light source can enable new research in the fields of interaction with organic materials, next generation optical detection, and optical vortex infrared supercontinuum.
基金Ministerio de Economía y Competitividad(MINECO)(FIS2013-44174-P,FIS2015-71933-REDT,MAT2016-75716-C2-1-R(AEI/FEDER,UE),TEC2014-55948-R)Agència de Gestiód’Ajuts Universitaris i de Recerca(AGAUR)(2017SGR755)+1 种基金Consejería de Educación,Junta de Castilla y León(SA046U16,UIC016)Generalitat de Catalunya(2016FI_B00844,2017FI_B100158,2018FI_B2 00123)
文摘Surface channel waveguides(WGs) were fabricated in a monoclinic Tm^(3+):KLu(WO_4)_2 crystal by femtosecond direct laser writing(fs-DLW). The WGs consisted of a half-ring cladding with diameters of 50 and 60 μm located just beneath the crystal surface. They were characterized by confocal laser microscopy and μ-Raman spectroscopy,indicating a reduced crystallinity and stress-induced birefringence of the WG cladding. In continuous-wave(CW)mode, under Ti:sapphire laser pumping at 802 nm, the maximum output power reached 171.1 mW at 1847.4 nm,corresponding to a slope efficiency η of 37.8% for the 60 μm diameter WG. The WG propagation loss was0.7 0.3 d B∕cm. The top surface of the WGs was spin-coated by a polymethyl methacrylate film containing randomly oriented(spaghetti-like) arc-discharge single-walled carbon nanotubes serving as a saturable absorber based on evanescent field coupling. Stable passively Q-switched(PQS) operation was achieved. The PQS60 μm diameter WG laser generated a record output power of 150 m W at 1846.8 nm with η = 34.6%. The conversion efficiency with respect to the CW mode was 87.6%. The best pulse characteristics(energy/duration)were 105.6 nJ/98 ns at a repetition rate of 1.42 MHz.
基金partly supported by the National Natural Science Foundation of China(NSFC)(52032009,61975208,62075090,51761135115,61575199,61850410533,and 52072351)Deutsche Forschungsgemeinschaft(PE 607/14-1)+6 种基金Sino-German Scientist Cooperation and Exchanges Mobility Program(M-0040)Natural Science Foundation of Jiangsu Province(BK20190104)National Research Foundation of Korea(2020R1A4A2002828)CAS Key Laboratory of Optoelectronic Materials Chemistry and Physics,FJIRSM CAS(2008DP173016)Foundation of the President of China Academy of Engineering Physics(YZJJLX2018005)State Key Laboratory of Crystal Materials(SKLCM),SDU(KF2001)financial support from the Alexander von Humboldt Foundation through a Humboldt fellowship。
文摘We report on a power-scalable sub-100-fs laser in the 2-μm spectral range using a Tm;-doped‘mixed’(Lu,Sc);O;sesquioxide ceramic as an active medium.Pulses as short as 58 fs at 2076 nm with an average output power of 114 mW at a pulse repetition rate of approximately 82.9 MHz are generated by employing single-walled carbon nanotubes as a saturable absorber.A higher average power of 350 m W at 2075 nm is obtained at the expense of the pulse duration(65 fs).A maximum average power of 486 mW is achieved for a pulse duration of 98 fs and an optical conversion efficiency of 22.3%,representing the highest value ever reported from sub-100-fs mode-locked Tm lasers.
