As a preferable material in the field of photo-detection and catalysis,the characteristics of FePS3 in broad wavelength range have been proven by many experimental studies.However,FePS3 has not been used as a saturabl...As a preferable material in the field of photo-detection and catalysis,the characteristics of FePS3 in broad wavelength range have been proven by many experimental studies.However,FePS3 has not been used as a saturable absorber(SA)in fiber lasers yet.We propose and demonstrate the generation of a single wavelength and dual-wavelength based on an Er-doped fiber laser(EDFL)at 1.5μm by using an innovative FePS3 saturable absorber for the first time.The result shows that a stable passively Q-switched pulse can be generated,which demonstrates that the new two-dimensional(2D)material FePS3 served as SA provides a valid method to realize passively Q-switched laser.In addition,we achieve the output of the dual-wavelength pulse by properly rotating the polarization controller.To the best of our knowledge,the dual-wavelength pulse EDFL could be applied in biomedicine,spectroscopy,and sensing research.展开更多
In this paper,we report a coherent beam combining(CBC)system that involves two thulium-doped all-polarization maintaining(PM)fiber chirped pulse amplifiers.Through phase-locking the two channels via a fiber stretcher ...In this paper,we report a coherent beam combining(CBC)system that involves two thulium-doped all-polarization maintaining(PM)fiber chirped pulse amplifiers.Through phase-locking the two channels via a fiber stretcher by using the stochastic parallel gradient descent(SPGD)algorithm,a maximum average power of 265 W is obtained,with a CBC efficiency of 81%and a residual phase error of λ/17.After de-chirping by a pair of diffraction gratings,the duration of the combined laser pulse is compressed to 690 fs.Taking into account the compression efficiency of 90%and the main peak energy proportion of 91%,the corresponding peak power is calculated to be 4 MW.The laser noise characteristics before and after CBC are examined,and the results indicate that the CBC would degrade the low frequency relative intensity noise(RIN),of which the integration is 1.74%in[100 Hz,2 MHz]at the maximum combined output power.In addition,the effects of the nonlinear spectrum broadening during chirped pulse amplification on the CBC efficiency are also investigated,showing that a higher extent of pulse stretching is effective in alleviating the spectrum broadening and realizing a higher output power with decent combining efficiency.展开更多
The power scaling on short wavelength(SW)fiber lasers operating around 1μm are in significant demand for applications in energy,environment and industry.The challenge for performance scalability of high-power SW lase...The power scaling on short wavelength(SW)fiber lasers operating around 1μm are in significant demand for applications in energy,environment and industry.The challenge for performance scalability of high-power SW lasers based on rare-earth-doped fiber primarily lies in the physical limitations,including reabsorption,amplified spontaneous emission and parasitic laser oscillation.Here,we demonstrate an all-fiberized,purely passive SW(1018 nm)randomdistributed-feedback Raman fiber laser(RRFL)to validate the capability of achieving high-power output at SWs based on multimode laser diodes(LDs)direct pumping.Directly pumped by multimode LDs,the high-brightness RRFL delivers over 656 W,with an electro-optical efficiency of 20%relative to the power.The slope efficiency is 94%.The beam quality M2factor is 2.9(which is~20 times that of the pump)at the maximum output signal power,achieving the highest brightness enhancement of 14.9 in RRFLs.To the best of our knowledge,this achievement also represents the highest power record of RRFLs utilizing multimode diodes for direct pumping.This work may not only provide a new insight into the realization of high-power,high-brightness RRFLs but also is a promising contender in the power scaling of SWs below 1μm.展开更多
Heat generated by the quantum defect(QD)in optically pumped lasers can result in detrimental effects such as mode instability,frequency noise,and even catastrophic damage.Previously,we demonstrated that boson-peakbase...Heat generated by the quantum defect(QD)in optically pumped lasers can result in detrimental effects such as mode instability,frequency noise,and even catastrophic damage.Previously,we demonstrated that boson-peakbased Raman fiber lasers have great potential in low QD laser generation.But their power scalability and heat load characteristics have yet to be investigated.Here,we demonstrate a boson-peak-based Raman fiber amplifier(RFA)with 815 W output power and a QD of 1.3%.The low heat generation characteristics of this low QD RFA are demonstrated.Both experimental and simulation results show that at this power level,the heat load of the low QD RFA is significantly lower than that of the conventional RFA with a QD of 4.8%.Thanks to its low heat generation characteristics,the proposed phosphosilicate-fiber-based low QD RFA provides an effective solution for the intractable thermal issue in optically pumped lasers,which is of significance in reducing the laser’s noise,improving the laser’s stability and safety,and solving the challenge of heat removing.展开更多
A review on the progress of powerful 2 μm silica fiber sources in past decades is presented. We review the state-of-the-art records and representative achievements of 2 μm high-average-power continuous- wave, pulsed...A review on the progress of powerful 2 μm silica fiber sources in past decades is presented. We review the state-of-the-art records and representative achievements of 2 μm high-average-power continuous- wave, pulsed fiber lasers and amplifiers, and powerful superfluorescent sources. Challenges which limit the further power scaling of 2 μm silica fiber sources are discussed, including pumping brightness limitation, thermal problem and nonlinear effects. Potential and promising roadmaps to go beyond these limitations, like tandem pumping and beam combining, are discussed. Prospects of powerful 2 μm silica fiber sources are also presented in the end of paper.展开更多
An all-fiber high-power linearly polarized chirped pulse amplification(CPA)system is experimentally demonstrated.Through stretching the pulse duration to a full width of approximately 2 ns with two cascaded chirped fi...An all-fiber high-power linearly polarized chirped pulse amplification(CPA)system is experimentally demonstrated.Through stretching the pulse duration to a full width of approximately 2 ns with two cascaded chirped fiber Bragg gratings(CFBGs),a maximum average output power of 612 W is achieved from a high-gain Yb-doped fiber that has a core diameter of 20μm with a slope efficiency of approximately 68%at the repetition rate of 80 MHz.At the maximum output power,the polarization degree is 92.5%and the M^(2)factor of the output beam quality is approximately 1.29;the slight performance degradations are attributed to the thermal effects in the main amplifier.By optimizing the B-integral of the amplifier and finely adjusting the higher-order dispersion of one of the CFBGs,the pulse width is compressed to 863 fs at the highest power with a compression efficiency of 72%,corresponding to a maximum compressed average power of 440.6 W,single pulse energy of 5.5μJ and peak power of about 4.67 MW.To the best of our knowledge,this is the highest average power of a femtosecond laser directly generated from an all-fiber linearly polarized CPA system.展开更多
In this work,a high-energy and high peak power chirped pulse amplifcation system with near difraction-limited beam quality based on tapered confned-doped fber(TCF)is experimentally demonstrated.The TCF has a core nume...In this work,a high-energy and high peak power chirped pulse amplifcation system with near difraction-limited beam quality based on tapered confned-doped fber(TCF)is experimentally demonstrated.The TCF has a core numerical aperture of 0.07 with core/cladding diameter of 35/250µm at the thin end and 56/400μm at the thick end.With a backward-pumping confguration,a maximum single pulse energy of 177.9μJ at a repetition rate of 504 kHz is realized,corresponding to an average power of 89.7 W.Through partially compensating for the accumulated nonlinear phase during the amplifcation process via adjusting the high order dispersion of the stretching chirped fber Bragg grating,the duration of the amplifed pulse is compressed to 401 fs with a pulse energy of 126.3μJ and a peak power of 207 MW,which to the best of our knowledge represents the highest peak power ever reported from a monolithic ultrafast fber laser.At the highest energy,the polarization extinction ratio and the M2 factor were respectively measured to be~19 dB and 1.20.In addition,the corresponding intensity noise properties as well as the short-and long-term stability were also examined,verifying a stable operation of the system.It is believed that the demonstrated laser source could fnd important applications in,for example,advanced manufacturing and photomedicine.展开更多
A high-power all polarization-maintaining(PM) chirped pulse amplification(CPA) system operating in the 2.0 μm range is experimentally demonstrated.Large mode area(LMA) thulium-doped fiber(TDF) with a core/cladding di...A high-power all polarization-maintaining(PM) chirped pulse amplification(CPA) system operating in the 2.0 μm range is experimentally demonstrated.Large mode area(LMA) thulium-doped fiber(TDF) with a core/cladding diameter of25/400 μm is employed to construct the main amplifier.Through dedicated coiling and cooling of the LMA-TDF to manage the loss of the higher order mode and thermal effect,a maximum average power of 314 W with a slope efficiency of 52% and polarization extinction ratio of 20 dB is realized.The pulse duration is compressed to 283 fs with a grating pair,corresponding to a calculated peak power of 10.8 MW,considering the compression efficiency of 88% and the estimated Strehl ratio of 89%.Moreover,through characterizing the noise properties of the laser,an integrated relative intensity noise of 0.11% at 100 Hz-1 MHz is obtained at the maximum output power,whereas the laser timing jitter is degraded by the final amplifier from 318 to 410 fs at an integration frequency of 5 kHz to 1 MHz,owing to the self-phase modulation effect-induced spectrum broadening.The root-mean-square of long-term power fluctuation is tested to be0.6%,verifying the good stability of the laser operation.To the best of our knowledge,this is the highest average power of an ultrafast laser realized from an all-PM-fiber TDF-CPA system ever reported.展开更多
It is well-established that waves are inhomogeneous in a lossy isotropic medium, and the validation of the classical Snell's law is still questionable for light refraction at the dissipative and dispersive interfa...It is well-established that waves are inhomogeneous in a lossy isotropic medium, and the validation of the classical Snell's law is still questionable for light refraction at the dissipative and dispersive interface. With high absorption, direct experimental investigation is rather difficult due to the extremely short penetration depth; i.e., the skin depth. In this paper, a simple and unified description of this issue is proposed, which can be applied to both materials with anomalous dispersion and in the Drude region. The gradient ▽_k~ω is found to be incident angle θ_i-dependent, and the direction of the group velocity may deviate significantly from the phase velocity due to the loss induced permittivity structure. The physics behind the negative refraction effect is explained, and a novel loss induced super-prism effect is also predicted.展开更多
In this work, we investigate suppressing mode instability in detail by varying the seed power in a large mode area all-fiber amplifier with a fiber core diameter of 25 μm. The transverse mode instability(TMI) thresho...In this work, we investigate suppressing mode instability in detail by varying the seed power in a large mode area all-fiber amplifier with a fiber core diameter of 25 μm. The transverse mode instability(TMI) thresholds are systematically measured for different seed power. Our experimental results reveal that increasing the seed power has a positive influence on enhancing the output power before the TMI effect appears, and finally the TMI threshold is approximately doubled from1030 W to 2280 W when the seed power is increased from 27 W to 875 W. Almost 84.7% slope efficiency is reached with different seed power before the TMI threshold power. During our operation, we also find that in this type of LMA fiber the beam quality of the amplifier is degraded gradually instead of a sudden change as the pump power increases.展开更多
Anall-fiber Mamyshevoscillator witha single amplification arm is experimentally demonstrated to achieve high-energy and high-average-power ultrafast pulse output,with the initiating of an external seed pulse.In the hi...Anall-fiber Mamyshevoscillator witha single amplification arm is experimentally demonstrated to achieve high-energy and high-average-power ultrafast pulse output,with the initiating of an external seed pulse.In the high-energy operation,a maximum single-pulse energy of 153 nJ is achieved at a repetition rate of 9.77 MHz.After compression with a pair of diffraction gratings,a measured pulse width of 73 fs witha record energy of 122.1 nJ and a peak power of 1.7 MW is obtained.In the high-average-power operation,up to 5th harmonic mode locking of the oscillator is realized via slightly adjusting the output coupling ratio and the cavity length.The achieved maximum output power is 3.4 W at a repetition rate of 44.08 MHz,while the corresponding pulse width is compressed to around~10o fs.Meanwhile,the system is verified to be operated reliability in both high-energy and-average-power operation regimes through assessing its short-and long-term stabilities.To the best of our knowledge,these are the highest records in pulse energy and average power delivered from a single all-fiberultrafast laser oscillator withpicosecond/femtosecond pulse duration It is believed that even higher-energy and-average-power ultrafast laser can be realized with the proposed laser scheme through further increasing the core diameter of the all-fiber cavity,providing promising sources for advancedfabrication,biomedical imaging,laser micromachining,andother practical applications,as well as an unprecedented platformfor exploring undiscovered nonlinear dynamics.展开更多
Development of a high power fiber laser at special waveband,which is difficult to achieve by conventional rare-earth-doped fibers,is a significant challenge.One of the most common methods for achieving lasing at speci...Development of a high power fiber laser at special waveband,which is difficult to achieve by conventional rare-earth-doped fibers,is a significant challenge.One of the most common methods for achieving lasing at special wavelength is Raman conversion.Phosphorus-doped fiber(PDF),due to the phosphorus-related large frequency shift Raman peak at 40 THz,is a great choice for large frequency shift Raman conversion.Here,by adopting 150 m large mode area triple-clad PDF as Raman gain medium,and a novel wavelength-selective feedback mechanism to suppress the silica-related Raman emission,we build a high power cladding-pumped Raman fiber laser at 1.2μm waveband.A Raman signal with power up to 735.8 W at 1252.7 nm is obtained.To the best of our knowledge,this is the highest output power ever reported for fiber lasers at 1.2μm waveband.Moreover,by tuning the wavelength of the pump source,a tunable Raman output of more than 450 W over a wavelength range of 1240.6–1252.7 nm is demonstrated.This work proves PDF’s advantage in high power large frequency shift Raman conversion with a cladding pump scheme,thus providing a good solution for a high power laser source at special waveband.展开更多
Laser state active controlling is challenging under the influence of inherent loss and other nonlinear effects in ultrafast systems.Seeking an extension of degree of freedom in optical devices based on low-dimensional...Laser state active controlling is challenging under the influence of inherent loss and other nonlinear effects in ultrafast systems.Seeking an extension of degree of freedom in optical devices based on low-dimensional materials may be a way forward.Herein,the anisotropic quasi-one-dimensional layered material Ta2PdS6 was utilized as a saturable absorber to modulate the nonlinear parameters effectively in an ultrafast system by polarization-dependent absorption.The polarization-sensitive nonlinear optical response facilitates the Ta2PdS6-based mode-lock laser to sustain two types of laser states,i.e.,conventional soliton and noise-like pulse.The laser state was switchable in the single fiber laser with a mechanism revealed by numerical simulation.Digital coding was further demonstrated in this platform by employing the laser as a codable light source.This work proposed an approach for ultrafast laser state active controlling with low-dimensional material,which offers a new avenue for constructing tunable on-fiber devices.展开更多
A spectral programmable,continuous-wave mid-infrared(MIR)optical parametric oscillator(OPO),enabled by a self-developed high-power spectral tailorable fiber laser,was proposed and realized.While operating at a singlew...A spectral programmable,continuous-wave mid-infrared(MIR)optical parametric oscillator(OPO),enabled by a self-developed high-power spectral tailorable fiber laser,was proposed and realized.While operating at a singlewavelength,the maximum idler power reached 5.53 W at 3028 nm,with a corresponding pump-to-idler conversion efficiency of 14.7%.The wavelength number switchable output was available from one to three.The single idler was tunable in a range of 528 nm(2852–3380 nm).In a dual-wavelength operation,the interval between two idlers could be flexibly tuned for 470 nm(53–523 nm),and the intensity of each channel was controllable.Triplewavelength idler emission was realized,meanwhile exhibiting spectral custom-tailored characteristics.Furthermore,we balanced the parametric gain through the pre-modulating broadband multi-peak pump spectra,enabling a 10 d B bandwidth adjustment of the idler emission from 20 to 125 nm.This versatile mid-infrared laser,simultaneously featuring wide tuning,multi-wavelength operation,and broad bandwidth manipulation,has great application potential in composition detection,terahertz generation,and speckle-free imaging.展开更多
An all-fiberized and narrow-bandwidth master oscillator power amplification(MOPA) system with record output power of 4 kW level and slope efficiency of 78% is demonstrated. Tandem pumping strategy is tentatively intro...An all-fiberized and narrow-bandwidth master oscillator power amplification(MOPA) system with record output power of 4 kW level and slope efficiency of 78% is demonstrated. Tandem pumping strategy is tentatively introduced into the narrow-bandwidth MOPA system for thermally induced mode instability(TMI) suppression. The stimulated Brillouin scattering(SBS) effect is balanced by simply using one-stage phase modulation technique. With different phase modulation signals, SBS limited output powers of 336 W, 1.2 kW and 3.94 kW are respectively achieved with spectral bandwidths accounting for 90% power of ～0.025, 0.17 and ～0.89 nm. Compared with our previous 976 nm pumping system, TMI threshold is overall boosted to be >5 times in which tandem pumping increases the TMI threshold of >3times. The beam quality(M～2 factor) of the output laser is well within 1.5 below the TMI threshold while it is ultimately saturated to be 1.86 with the influence of TMI at maximal output power. Except for SBS and TMI, stimulated Raman scattering(SRS) effect will be another challenge for further power scaling. In such a high power MOPA system, multidetrimental effects(SBS, SRS and TMI) will coexist and may be mutual-coupled, which could provide a well platform for further comprehensively investigating and optimizing the high power, narrow-bandwidth fiber amplifiers.展开更多
In this paper, we propose and experimentally investigate a linearly polarized narrow-linewidth random fiber laser(RFL) operating at 1080 nm and boost the output power to kilowatt level with near-diffraction-limited be...In this paper, we propose and experimentally investigate a linearly polarized narrow-linewidth random fiber laser(RFL) operating at 1080 nm and boost the output power to kilowatt level with near-diffraction-limited beam quality using a master oscillation power amplifier. The RFL based on a half-opened cavity, which is composed of a linearly polarized narrow-linewidth fiber Bragg grating and a 500 m piece of polarization-maintained Ge-doped fiber, generates a 0.71 W seed laser with an 88 pm full width at half-maximum(FWHM) linewidth and a 22.5 dB polarization extinction ratio(PER) for power scaling. A two-stage fiber amplifier enhances the seed laser to the maximal 1.01 k W with a PER value of 17 dB and a beam quality of M_x^2=1.15 and M_y^2=1.13. No stimulated Brillouin scattering effect is observed at the ultimate power level, and the FWHM linewidth of the amplified random laser broadens linearly as a function of the output power with a coefficient of about 0.1237 pm∕W.To the best of our knowledge, this is the first demonstration of a linearly polarized narrow-linewidth RFL with even kilowatt-level near-diffraction-limited output, and further performance scaling is ongoing.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61875223 and 11574349)the Natural Science Foundation of Hunan Province,China(Grant No.2018JJ3610)+1 种基金the Natural Science Foundation of Jiangsu Province,China(Grant Nos.BK20150365 and BK20170424)the Natural Science Foundation of Hainan Province,China(Grant No.117111)
文摘As a preferable material in the field of photo-detection and catalysis,the characteristics of FePS3 in broad wavelength range have been proven by many experimental studies.However,FePS3 has not been used as a saturable absorber(SA)in fiber lasers yet.We propose and demonstrate the generation of a single wavelength and dual-wavelength based on an Er-doped fiber laser(EDFL)at 1.5μm by using an innovative FePS3 saturable absorber for the first time.The result shows that a stable passively Q-switched pulse can be generated,which demonstrates that the new two-dimensional(2D)material FePS3 served as SA provides a valid method to realize passively Q-switched laser.In addition,we achieve the output of the dual-wavelength pulse by properly rotating the polarization controller.To the best of our knowledge,the dual-wavelength pulse EDFL could be applied in biomedicine,spectroscopy,and sensing research.
基金supported in part by the National Key Research and Development Program of China(No.2022YFB3606000)in part by State Key Laboratory of Pulsed Power Laser Technology(No.SKL2020ZR02).
文摘In this paper,we report a coherent beam combining(CBC)system that involves two thulium-doped all-polarization maintaining(PM)fiber chirped pulse amplifiers.Through phase-locking the two channels via a fiber stretcher by using the stochastic parallel gradient descent(SPGD)algorithm,a maximum average power of 265 W is obtained,with a CBC efficiency of 81%and a residual phase error of λ/17.After de-chirping by a pair of diffraction gratings,the duration of the combined laser pulse is compressed to 690 fs.Taking into account the compression efficiency of 90%and the main peak energy proportion of 91%,the corresponding peak power is calculated to be 4 MW.The laser noise characteristics before and after CBC are examined,and the results indicate that the CBC would degrade the low frequency relative intensity noise(RIN),of which the integration is 1.74%in[100 Hz,2 MHz]at the maximum combined output power.In addition,the effects of the nonlinear spectrum broadening during chirped pulse amplification on the CBC efficiency are also investigated,showing that a higher extent of pulse stretching is effective in alleviating the spectrum broadening and realizing a higher output power with decent combining efficiency.
基金supported by the National Natural Science Foundation of China(Nos.62061136013 and 12174445)。
文摘The power scaling on short wavelength(SW)fiber lasers operating around 1μm are in significant demand for applications in energy,environment and industry.The challenge for performance scalability of high-power SW lasers based on rare-earth-doped fiber primarily lies in the physical limitations,including reabsorption,amplified spontaneous emission and parasitic laser oscillation.Here,we demonstrate an all-fiberized,purely passive SW(1018 nm)randomdistributed-feedback Raman fiber laser(RRFL)to validate the capability of achieving high-power output at SWs based on multimode laser diodes(LDs)direct pumping.Directly pumped by multimode LDs,the high-brightness RRFL delivers over 656 W,with an electro-optical efficiency of 20%relative to the power.The slope efficiency is 94%.The beam quality M2factor is 2.9(which is~20 times that of the pump)at the maximum output signal power,achieving the highest brightness enhancement of 14.9 in RRFLs.To the best of our knowledge,this achievement also represents the highest power record of RRFLs utilizing multimode diodes for direct pumping.This work may not only provide a new insight into the realization of high-power,high-brightness RRFLs but also is a promising contender in the power scaling of SWs below 1μm.
基金National Postdoctoral Program for Innovative Talents(BX20190063)National Natural Science Foundation of China(61635005,61905284,62305391)。
文摘Heat generated by the quantum defect(QD)in optically pumped lasers can result in detrimental effects such as mode instability,frequency noise,and even catastrophic damage.Previously,we demonstrated that boson-peakbased Raman fiber lasers have great potential in low QD laser generation.But their power scalability and heat load characteristics have yet to be investigated.Here,we demonstrate a boson-peak-based Raman fiber amplifier(RFA)with 815 W output power and a QD of 1.3%.The low heat generation characteristics of this low QD RFA are demonstrated.Both experimental and simulation results show that at this power level,the heat load of the low QD RFA is significantly lower than that of the conventional RFA with a QD of 4.8%.Thanks to its low heat generation characteristics,the proposed phosphosilicate-fiber-based low QD RFA provides an effective solution for the intractable thermal issue in optically pumped lasers,which is of significance in reducing the laser’s noise,improving the laser’s stability and safety,and solving the challenge of heat removing.
基金supported by the National Nature Science Foundation of China under Grant No.61322505Innovation Foundation for Graduates of National University of Defense Technology under Grant No.B130704
文摘A review on the progress of powerful 2 μm silica fiber sources in past decades is presented. We review the state-of-the-art records and representative achievements of 2 μm high-average-power continuous- wave, pulsed fiber lasers and amplifiers, and powerful superfluorescent sources. Challenges which limit the further power scaling of 2 μm silica fiber sources are discussed, including pumping brightness limitation, thermal problem and nonlinear effects. Potential and promising roadmaps to go beyond these limitations, like tandem pumping and beam combining, are discussed. Prospects of powerful 2 μm silica fiber sources are also presented in the end of paper.
基金This work was supported by the National Natural Science Foundation of China(No.62005316)Director Fund of State Key Laboratory of Pulsed Power Laser Technology(No.SKL2020ZR02).
文摘An all-fiber high-power linearly polarized chirped pulse amplification(CPA)system is experimentally demonstrated.Through stretching the pulse duration to a full width of approximately 2 ns with two cascaded chirped fiber Bragg gratings(CFBGs),a maximum average output power of 612 W is achieved from a high-gain Yb-doped fiber that has a core diameter of 20μm with a slope efficiency of approximately 68%at the repetition rate of 80 MHz.At the maximum output power,the polarization degree is 92.5%and the M^(2)factor of the output beam quality is approximately 1.29;the slight performance degradations are attributed to the thermal effects in the main amplifier.By optimizing the B-integral of the amplifier and finely adjusting the higher-order dispersion of one of the CFBGs,the pulse width is compressed to 863 fs at the highest power with a compression efficiency of 72%,corresponding to a maximum compressed average power of 440.6 W,single pulse energy of 5.5μJ and peak power of about 4.67 MW.To the best of our knowledge,this is the highest average power of a femtosecond laser directly generated from an all-fiber linearly polarized CPA system.
基金the Director Fund of State Key Laboratory of Pulsed Power Laser Technology(No.SKL2020ZR02)the Postgraduate Scientifc Research Innovation Project of Hunan Province(No.QL20220007).
文摘In this work,a high-energy and high peak power chirped pulse amplifcation system with near difraction-limited beam quality based on tapered confned-doped fber(TCF)is experimentally demonstrated.The TCF has a core numerical aperture of 0.07 with core/cladding diameter of 35/250µm at the thin end and 56/400μm at the thick end.With a backward-pumping confguration,a maximum single pulse energy of 177.9μJ at a repetition rate of 504 kHz is realized,corresponding to an average power of 89.7 W.Through partially compensating for the accumulated nonlinear phase during the amplifcation process via adjusting the high order dispersion of the stretching chirped fber Bragg grating,the duration of the amplifed pulse is compressed to 401 fs with a pulse energy of 126.3μJ and a peak power of 207 MW,which to the best of our knowledge represents the highest peak power ever reported from a monolithic ultrafast fber laser.At the highest energy,the polarization extinction ratio and the M2 factor were respectively measured to be~19 dB and 1.20.In addition,the corresponding intensity noise properties as well as the short-and long-term stability were also examined,verifying a stable operation of the system.It is believed that the demonstrated laser source could fnd important applications in,for example,advanced manufacturing and photomedicine.
基金supported by the Director Fund of State Key Laboratory of Pulsed Power Laser Technology(No.SKL2020ZR02)the Postgraduate Scientific Research Innovation Project of Hunan Province(No.QL20210015).
文摘A high-power all polarization-maintaining(PM) chirped pulse amplification(CPA) system operating in the 2.0 μm range is experimentally demonstrated.Large mode area(LMA) thulium-doped fiber(TDF) with a core/cladding diameter of25/400 μm is employed to construct the main amplifier.Through dedicated coiling and cooling of the LMA-TDF to manage the loss of the higher order mode and thermal effect,a maximum average power of 314 W with a slope efficiency of 52% and polarization extinction ratio of 20 dB is realized.The pulse duration is compressed to 283 fs with a grating pair,corresponding to a calculated peak power of 10.8 MW,considering the compression efficiency of 88% and the estimated Strehl ratio of 89%.Moreover,through characterizing the noise properties of the laser,an integrated relative intensity noise of 0.11% at 100 Hz-1 MHz is obtained at the maximum output power,whereas the laser timing jitter is degraded by the final amplifier from 318 to 410 fs at an integration frequency of 5 kHz to 1 MHz,owing to the self-phase modulation effect-induced spectrum broadening.The root-mean-square of long-term power fluctuation is tested to be0.6%,verifying the good stability of the laser operation.To the best of our knowledge,this is the highest average power of an ultrafast laser realized from an all-PM-fiber TDF-CPA system ever reported.
基金Project supported by the China Postdoctoral Science Foundation(Grant No.2016M601586)the National Natural Science Foundation of China(Grant No.11404092)the Opening Funding of Hunan Provincial Key Laboratory of High Energy Laser Technology,China(Grant No.GNJGJS07)
文摘It is well-established that waves are inhomogeneous in a lossy isotropic medium, and the validation of the classical Snell's law is still questionable for light refraction at the dissipative and dispersive interface. With high absorption, direct experimental investigation is rather difficult due to the extremely short penetration depth; i.e., the skin depth. In this paper, a simple and unified description of this issue is proposed, which can be applied to both materials with anomalous dispersion and in the Drude region. The gradient ▽_k~ω is found to be incident angle θ_i-dependent, and the direction of the group velocity may deviate significantly from the phase velocity due to the loss induced permittivity structure. The physics behind the negative refraction effect is explained, and a novel loss induced super-prism effect is also predicted.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61735007 and 61505260)
文摘In this work, we investigate suppressing mode instability in detail by varying the seed power in a large mode area all-fiber amplifier with a fiber core diameter of 25 μm. The transverse mode instability(TMI) thresholds are systematically measured for different seed power. Our experimental results reveal that increasing the seed power has a positive influence on enhancing the output power before the TMI effect appears, and finally the TMI threshold is approximately doubled from1030 W to 2280 W when the seed power is increased from 27 W to 875 W. Almost 84.7% slope efficiency is reached with different seed power before the TMI threshold power. During our operation, we also find that in this type of LMA fiber the beam quality of the amplifier is degraded gradually instead of a sudden change as the pump power increases.
基金supported by the National Natural Science Foundation of China under grant 62005316Director Fund of State Key Laboratory of Pulsed Power Laser Technology under grant SKL2020ZR02.
文摘Anall-fiber Mamyshevoscillator witha single amplification arm is experimentally demonstrated to achieve high-energy and high-average-power ultrafast pulse output,with the initiating of an external seed pulse.In the high-energy operation,a maximum single-pulse energy of 153 nJ is achieved at a repetition rate of 9.77 MHz.After compression with a pair of diffraction gratings,a measured pulse width of 73 fs witha record energy of 122.1 nJ and a peak power of 1.7 MW is obtained.In the high-average-power operation,up to 5th harmonic mode locking of the oscillator is realized via slightly adjusting the output coupling ratio and the cavity length.The achieved maximum output power is 3.4 W at a repetition rate of 44.08 MHz,while the corresponding pulse width is compressed to around~10o fs.Meanwhile,the system is verified to be operated reliability in both high-energy and-average-power operation regimes through assessing its short-and long-term stabilities.To the best of our knowledge,these are the highest records in pulse energy and average power delivered from a single all-fiberultrafast laser oscillator withpicosecond/femtosecond pulse duration It is believed that even higher-energy and-average-power ultrafast laser can be realized with the proposed laser scheme through further increasing the core diameter of the all-fiber cavity,providing promising sources for advancedfabrication,biomedical imaging,laser micromachining,andother practical applications,as well as an unprecedented platformfor exploring undiscovered nonlinear dynamics.
基金supported by the National Natural Science Foundation of China(NSFC)(Grant Nos.61635005,61905284,and 62305391)the National Postdoctoral Program for Innovative Talents(No.BX20190063).
文摘Development of a high power fiber laser at special waveband,which is difficult to achieve by conventional rare-earth-doped fibers,is a significant challenge.One of the most common methods for achieving lasing at special wavelength is Raman conversion.Phosphorus-doped fiber(PDF),due to the phosphorus-related large frequency shift Raman peak at 40 THz,is a great choice for large frequency shift Raman conversion.Here,by adopting 150 m large mode area triple-clad PDF as Raman gain medium,and a novel wavelength-selective feedback mechanism to suppress the silica-related Raman emission,we build a high power cladding-pumped Raman fiber laser at 1.2μm waveband.A Raman signal with power up to 735.8 W at 1252.7 nm is obtained.To the best of our knowledge,this is the highest output power ever reported for fiber lasers at 1.2μm waveband.Moreover,by tuning the wavelength of the pump source,a tunable Raman output of more than 450 W over a wavelength range of 1240.6–1252.7 nm is demonstrated.This work proves PDF’s advantage in high power large frequency shift Raman conversion with a cladding pump scheme,thus providing a good solution for a high power laser source at special waveband.
基金the Jiangsu Province Key Research and Development Program(Grant No.BE2021007-3,BE2023009-5)the National Natural Science Foundation of China(Grant No.62035015,62061136013)+4 种基金the Postgraduate Scientific Research Innovation Project of Hunan Province(Grant No.QL20230006)the Hubei Province Key Laboratory of Systems Science in Metallurgical Process(Grant No.Y202208)the Open Fund of Key Laboratory for Intelligent Nano Materials and Devices of the Ministry of Education NJ2023002(Grant No.INMD-2023M06)J.W.acknowledges the support from the CAS Young Talent program under Grant No.E3291305the Vacuum Interconnected Nanotech Workstation(Nano-X)of Suzhou Institute of Nano-tech and Nano-bionics(SINANO),Chinese Academy of Sciences is also acknowledged.
文摘Laser state active controlling is challenging under the influence of inherent loss and other nonlinear effects in ultrafast systems.Seeking an extension of degree of freedom in optical devices based on low-dimensional materials may be a way forward.Herein,the anisotropic quasi-one-dimensional layered material Ta2PdS6 was utilized as a saturable absorber to modulate the nonlinear parameters effectively in an ultrafast system by polarization-dependent absorption.The polarization-sensitive nonlinear optical response facilitates the Ta2PdS6-based mode-lock laser to sustain two types of laser states,i.e.,conventional soliton and noise-like pulse.The laser state was switchable in the single fiber laser with a mechanism revealed by numerical simulation.Digital coding was further demonstrated in this platform by employing the laser as a codable light source.This work proposed an approach for ultrafast laser state active controlling with low-dimensional material,which offers a new avenue for constructing tunable on-fiber devices.
基金Project 2019-JCJQ(JJ-202)National Postdoctoral Program for Innovative Talents(BX20190063)+1 种基金Hunan Innovative Province Construction Project(2019RS3017)National Natural Science Foundation of China(61975236,62061136013,62035015)。
文摘A spectral programmable,continuous-wave mid-infrared(MIR)optical parametric oscillator(OPO),enabled by a self-developed high-power spectral tailorable fiber laser,was proposed and realized.While operating at a singlewavelength,the maximum idler power reached 5.53 W at 3028 nm,with a corresponding pump-to-idler conversion efficiency of 14.7%.The wavelength number switchable output was available from one to three.The single idler was tunable in a range of 528 nm(2852–3380 nm).In a dual-wavelength operation,the interval between two idlers could be flexibly tuned for 470 nm(53–523 nm),and the intensity of each channel was controllable.Triplewavelength idler emission was realized,meanwhile exhibiting spectral custom-tailored characteristics.Furthermore,we balanced the parametric gain through the pre-modulating broadband multi-peak pump spectra,enabling a 10 d B bandwidth adjustment of the idler emission from 20 to 125 nm.This versatile mid-infrared laser,simultaneously featuring wide tuning,multi-wavelength operation,and broad bandwidth manipulation,has great application potential in composition detection,terahertz generation,and speckle-free imaging.
基金sponsored by the National Natural Science Foundation of China (Nos. 61705264 and 61705265)
文摘An all-fiberized and narrow-bandwidth master oscillator power amplification(MOPA) system with record output power of 4 kW level and slope efficiency of 78% is demonstrated. Tandem pumping strategy is tentatively introduced into the narrow-bandwidth MOPA system for thermally induced mode instability(TMI) suppression. The stimulated Brillouin scattering(SBS) effect is balanced by simply using one-stage phase modulation technique. With different phase modulation signals, SBS limited output powers of 336 W, 1.2 kW and 3.94 kW are respectively achieved with spectral bandwidths accounting for 90% power of ～0.025, 0.17 and ～0.89 nm. Compared with our previous 976 nm pumping system, TMI threshold is overall boosted to be >5 times in which tandem pumping increases the TMI threshold of >3times. The beam quality(M～2 factor) of the output laser is well within 1.5 below the TMI threshold while it is ultimately saturated to be 1.86 with the influence of TMI at maximal output power. Except for SBS and TMI, stimulated Raman scattering(SRS) effect will be another challenge for further power scaling. In such a high power MOPA system, multidetrimental effects(SBS, SRS and TMI) will coexist and may be mutual-coupled, which could provide a well platform for further comprehensively investigating and optimizing the high power, narrow-bandwidth fiber amplifiers.
基金National Natural Science Foundation of China(NSFC)(61322505,61635005)
文摘In this paper, we propose and experimentally investigate a linearly polarized narrow-linewidth random fiber laser(RFL) operating at 1080 nm and boost the output power to kilowatt level with near-diffraction-limited beam quality using a master oscillation power amplifier. The RFL based on a half-opened cavity, which is composed of a linearly polarized narrow-linewidth fiber Bragg grating and a 500 m piece of polarization-maintained Ge-doped fiber, generates a 0.71 W seed laser with an 88 pm full width at half-maximum(FWHM) linewidth and a 22.5 dB polarization extinction ratio(PER) for power scaling. A two-stage fiber amplifier enhances the seed laser to the maximal 1.01 k W with a PER value of 17 dB and a beam quality of M_x^2=1.15 and M_y^2=1.13. No stimulated Brillouin scattering effect is observed at the ultimate power level, and the FWHM linewidth of the amplified random laser broadens linearly as a function of the output power with a coefficient of about 0.1237 pm∕W.To the best of our knowledge, this is the first demonstration of a linearly polarized narrow-linewidth RFL with even kilowatt-level near-diffraction-limited output, and further performance scaling is ongoing.
