In this paper, we have demonstrated an Er-doped ultrafast laser with a single mode fiber-gradient index multimode fiber-single mode fiber(SMF-GIMF-SMF, SMS) structure as saturable absorber(SA), which can generate not ...In this paper, we have demonstrated an Er-doped ultrafast laser with a single mode fiber-gradient index multimode fiber-single mode fiber(SMF-GIMF-SMF, SMS) structure as saturable absorber(SA), which can generate not only stable single-pulse state, but also special mode-locked pulses with the characteristics of high energy and noisy behaviors at proper pump power and cavity polarization state. In addition, we have deeply investigated the real-time spectral evolutions of the mode-locked pulses through the dispersive Fourier transformation(DFT) technique. It can be found that the pulse regime can actually consist of a lot of small noise pulses with randomly varying intensities. We believe that these results will further enrich the nonlinear dynamical processes in the ultrafast lasers.展开更多
Laser interferometry with higher resolution,faster update rate,and larger dynamic range is highly anticipated in the exploration of physics frontiers,advanced manufacturing,and precision sensing.Real-time dispersive s...Laser interferometry with higher resolution,faster update rate,and larger dynamic range is highly anticipated in the exploration of physics frontiers,advanced manufacturing,and precision sensing.Real-time dispersive spectral interferometry(DSI)shows promise for high-speed precision measurements,whereas the resolution of subnanometers has not yet been achieved.We present a comprehensive theoretical framework to analyze the limitations of real-time DSI based on the signal-to-noise ratio and data volume.A real-time orthogonal polarization spectral interferometry technique is proposed,which utilizes a pair of interferograms with the pi-phase shift to effectively mitigate the phase noise embedded in real-time spectral envelopes,thereby enabling the precise measurements with subnanometer resolution at megahertz frame rates.The recorded time series data are processed through interpolation,segmentation,time–frequency mapping,and de-enveloping to regain the typical cosine-shaped spectral evolution,followed by a fitting-based phase retrieval method to extract the interference phase.The phase resolution of 1.1 mrad(0.91 as for time delay and 0.3 nm for distance)is obtained at the update rate of 22.2 MHz even under the detection bandwidth of 500 MHz,and can be further enhanced to 0.29 mrad(0.24 as for time delay)after 500 times averaging(∼0.5 MHz).Our approach is validated through periodic phase modulations and applied to measure the rapid damped oscillations of a piezo stage,yielding results consistent with those obtained from a commercial picometer interferometer.展开更多
We have numerically and experimentally observed the soliton pulsation with obvious breathing behavior in the anomalous fiber laser mode-locked by a nonlinear polarization rotation technique.The numerical study of the ...We have numerically and experimentally observed the soliton pulsation with obvious breathing behavior in the anomalous fiber laser mode-locked by a nonlinear polarization rotation technique.The numerical study of the soliton pulsation with breathing behavior was analyzed through the split-step Fourier method at first,and it was found that the phase difference caused by the polarization controller would affect the breathing characteristics.Then,taking advantage of the dispersive Fourier transform technique,we confirmed the breathing characteristic of soliton pulsation in the same fiber laser as the simulation model experimentally.These results complement the research on the breathing characteristic of soliton pulsation.展开更多
We present experimental observations of soliton pulsations in the net normal-dispersion fiber laser by using the dispersive Fourier transform(DFT) technique. According to the pulsating characteristics, the soliton pul...We present experimental observations of soliton pulsations in the net normal-dispersion fiber laser by using the dispersive Fourier transform(DFT) technique. According to the pulsating characteristics, the soliton pulsations are classified as visible and invisible soliton pulsations. The visible soliton pulsation is converted from single-into dual-soliton pulsation with the common characteristics of energy oscillation and bandwidth breathing. The invisible soliton pulsation undergoes periodic variation in the spectral profile and peak power but remains invariable in pulse energy. The reason for invisible soliton pulsation behavior is periodic oscillation of the pulse inside the soliton molecule. These results could be helpful in deepening our understanding of the soliton pulsation phenomena.展开更多
A tightly synchronized fiber laser system composed of two mode-locked Yb-doped fiber lasers in a master-slave configuration is built.The synchronization could sustain for more than 6 h,and the maximum tolerance of cav...A tightly synchronized fiber laser system composed of two mode-locked Yb-doped fiber lasers in a master-slave configuration is built.The synchronization could sustain for more than 6 h,and the maximum tolerance of cavity length mismatch is measured to be about 210μm.Afterward,a time-stretch dispersive Fourier transform technique is introduced to analyze the synchronization process over multiple cycles.The pulse evolution,center wavelength shift,spectral reshaping,and broadening are all clearly detected.And the synchronization time is experimentally determined on the order of microseconds(hundreds of roundtrips).These results also show the seed pulse acting as a temporal gate for mode locking in some cases.To the best of our knowledge,this is the first time that pulse formation,spectral evolution,center wavelength shift,and synchronization time during the synchronization process are precisely revealed in experiment.These results would help to improve the performances of synchronized laser devices and deeply understand the mechanisms of the synchronization process and other light-light interactions in materials.展开更多
The dispersive Fourier transform technique provides feasibility of exploring non-repetitive events and the buildup process in ultrafast lasers.In this paper,we report a new buildup process of dissipative solitons in a...The dispersive Fourier transform technique provides feasibility of exploring non-repetitive events and the buildup process in ultrafast lasers.In this paper,we report a new buildup process of dissipative solitons in a simplified mode-locked Yb-doped fiber laser,which includes more complex physics stages such as the Q-switching stage,raised and damped relaxation oscillation stages,noise-like stage,successive soliton explosions stage,and soliton breathing stage.Complete evolution dynamics of noise-like pulse and double pulse are also investigated with dispersive Fourier transform.For the noise-like pulse dynamics process,it will only experience the Q-switching and relaxation oscillation stages.In the case of dissipative soliton and noise-like pulse,the double pulse buildup behavior is manifested as the replication of individual pulses.A weak energy migration occurs between two pulses before reaching steady state.Meanwhile,real-time mutual conversion of the dissipative soliton and noise-like pulse has been experimentally observed,which appears to be instantaneous without extra physical processes.To the best of our knowledge,this is the first report on these physical phenomena observed together in a mode-locked fiber laser.The results further enrich the dynamics of mode-locked fiber lasers and provide potential conditions for obtaining intelligent mode-locked lasers with controllable output.展开更多
The utilization of the dispersive Fourier transformation approach has enabled comprehensive observation of the birth process of dissipative solitons in fiber lasers.However,there is still a dearth of deep understandin...The utilization of the dispersive Fourier transformation approach has enabled comprehensive observation of the birth process of dissipative solitons in fiber lasers.However,there is still a dearth of deep understanding regarding the extinction process of dissipative solitons.In this study,we have utilized a combination of experimental and numerical techniques to thoroughly examine the breathing dynamics of dissipative solitons during the extinction process in an Er-doped mode-locked fiber laser.The results demonstrate that the transient breathing dynamics have a substantial impact on the extinction stage of both steady-state and breathing-state dissipative solitons.The duration of transient breathing exhibits a high degree of sensitivity to variations in pump power.Numerical simulations are utilized to produce analogous breathing dynamics within the framework of a model that integrates equations characterizing the population inversion in a mode-locked laser.These results corroborate the role of Q-switching instability in the onset of breathing oscillations.Furthermore,these findings offer new possibilities for the advancement of various operational frameworks for ultrafast lasers.展开更多
The evolution dynamics of mode locking for a solid-state femtosecond Yb:KGW laser is demonstrated and detected with time-stretch dispersive Fourier transform(DFT)technique for the first time,to the best of our knowled...The evolution dynamics of mode locking for a solid-state femtosecond Yb:KGW laser is demonstrated and detected with time-stretch dispersive Fourier transform(DFT)technique for the first time,to the best of our knowledge.The Yb:KGW laser is constructed first with a classical X-shaped cavity,and SESAM-assisted Kerr lens mode locking is obtained.Then,a DFT device is built to record the buildup and extinction dynamics of the mode-locked laser.The results suggest that the time of extinction is slightly shorter than the buildup time and both of them experience complex transitions.The results indicate that DFT could also be suitable to detect the transient buildup and extinction process in solid-state lasers,which would help investigate both the evolution of mode locking and characteristics determination for solid-state lasers.展开更多
Dissipative Kerr cavity solitons(CSs) are localized temporal structures generated in coherently driven Kerr resonators which have attracted widespread attention for their rich nonlinear dynamics and key role in the ge...Dissipative Kerr cavity solitons(CSs) are localized temporal structures generated in coherently driven Kerr resonators which have attracted widespread attention for their rich nonlinear dynamics and key role in the generation of optical frequency combs. Akin to the complexity of the dissipative solitons in mode-locked lasers, the nonlinear dynamics of the CSs present distinctive evolutionary behaviors that may create new potential for understanding interdisciplinary nonlinear problems. Here, we leverage real-time spectroscopy to study the transient behaviors of the CSs in a Kerr fiber cavity with coherent driving. The real-time spectroscopy is implemented with the emerging dispersive Fourier transform(DFT) technology with a large dispersion of-10.2 ns/nm, which provides a sampling spectral resolution of ~1 pm. Under perturbations,the complete birth-to-annihilation process of the CS is visualized in real time as the Kerr fiber cavity specifically locked around the boundary of modulation instability(MI) and bistable regimes. Fruitful transient dynamics are observed, including MI, soliton breathing, stationary CS, and its annihilation. The mechanism of the observed transient dynamics is theoretically studied through numerical simulation, and we find that the cavity detuning variation resulting from the external perturbation plays a dominant role in the evolution of the CS. More importantly, there exists a visible energy drop accompanied by the CS breathing, wherein the collision between the solitons triggers the subsequent drift and annihilation of the CS. The spectral interferograms of multiple CSs that are analyzed by their field autocorrelation also verify the annihilation of the CS.展开更多
基金supported by the Guangdong Basic and Applied Basic Research Foundation (No.2023A1515010093)the Shenzhen Fundamental Research Program (Stable Support Plan Program)(Nos.JCYJ20220809170611004, 20231121110828001 and 20231121113641002)the National Taipei University of Technology-Shenzhen University Joint Research Program (No.2024001)。
文摘In this paper, we have demonstrated an Er-doped ultrafast laser with a single mode fiber-gradient index multimode fiber-single mode fiber(SMF-GIMF-SMF, SMS) structure as saturable absorber(SA), which can generate not only stable single-pulse state, but also special mode-locked pulses with the characteristics of high energy and noisy behaviors at proper pump power and cavity polarization state. In addition, we have deeply investigated the real-time spectral evolutions of the mode-locked pulses through the dispersive Fourier transformation(DFT) technique. It can be found that the pulse regime can actually consist of a lot of small noise pulses with randomly varying intensities. We believe that these results will further enrich the nonlinear dynamical processes in the ultrafast lasers.
基金supported by the National Natural Science Foundation of China(Grant No.61705193)the Natural Science Foundation of Zhejiang Province(Grant No.LGG20F050002)the Jinhua Science and Technology Plan(Project No.2024-1-064).
文摘Laser interferometry with higher resolution,faster update rate,and larger dynamic range is highly anticipated in the exploration of physics frontiers,advanced manufacturing,and precision sensing.Real-time dispersive spectral interferometry(DSI)shows promise for high-speed precision measurements,whereas the resolution of subnanometers has not yet been achieved.We present a comprehensive theoretical framework to analyze the limitations of real-time DSI based on the signal-to-noise ratio and data volume.A real-time orthogonal polarization spectral interferometry technique is proposed,which utilizes a pair of interferograms with the pi-phase shift to effectively mitigate the phase noise embedded in real-time spectral envelopes,thereby enabling the precise measurements with subnanometer resolution at megahertz frame rates.The recorded time series data are processed through interpolation,segmentation,time–frequency mapping,and de-enveloping to regain the typical cosine-shaped spectral evolution,followed by a fitting-based phase retrieval method to extract the interference phase.The phase resolution of 1.1 mrad(0.91 as for time delay and 0.3 nm for distance)is obtained at the update rate of 22.2 MHz even under the detection bandwidth of 500 MHz,and can be further enhanced to 0.29 mrad(0.24 as for time delay)after 500 times averaging(∼0.5 MHz).Our approach is validated through periodic phase modulations and applied to measure the rapid damped oscillations of a piezo stage,yielding results consistent with those obtained from a commercial picometer interferometer.
基金the Jilin Province Science and Technology Development Plan Project,China(Grant Nos.20190201128JC and 20200401125GX)the National Natural Science Foundation of China(Grant No.62105209)+1 种基金Foundation and Applied Foundation Research Fund of Guangdong Province,China(Grant No.2019A1515111060)Science and Technology Project of the 13th Five-Year Plan of Jilin Provincial Department of Education,China(Grant Nos.JJKH20190157KJ and JJKH20190169KJ)。
文摘We have numerically and experimentally observed the soliton pulsation with obvious breathing behavior in the anomalous fiber laser mode-locked by a nonlinear polarization rotation technique.The numerical study of the soliton pulsation with breathing behavior was analyzed through the split-step Fourier method at first,and it was found that the phase difference caused by the polarization controller would affect the breathing characteristics.Then,taking advantage of the dispersive Fourier transform technique,we confirmed the breathing characteristic of soliton pulsation in the same fiber laser as the simulation model experimentally.These results complement the research on the breathing characteristic of soliton pulsation.
基金supported by the National Natural Science Foundation of China (Grant No. 41875040)the Natural Science Foundation of Anhui Province, China (Grant No. 2008085MF211)+1 种基金the Foundation for Young Talents in College of Anhui Province, China (Grant No. gxyqZD2019034)the Innovation Fund for Postgraduates of Huaibei Normal University, China (Grant No. CX2022035)。
文摘We present experimental observations of soliton pulsations in the net normal-dispersion fiber laser by using the dispersive Fourier transform(DFT) technique. According to the pulsating characteristics, the soliton pulsations are classified as visible and invisible soliton pulsations. The visible soliton pulsation is converted from single-into dual-soliton pulsation with the common characteristics of energy oscillation and bandwidth breathing. The invisible soliton pulsation undergoes periodic variation in the spectral profile and peak power but remains invariable in pulse energy. The reason for invisible soliton pulsation behavior is periodic oscillation of the pulse inside the soliton molecule. These results could be helpful in deepening our understanding of the soliton pulsation phenomena.
基金Natural Science Foundation of Beijing Municipality(4192015)National Natural Science Foundation of China(61975003)。
文摘A tightly synchronized fiber laser system composed of two mode-locked Yb-doped fiber lasers in a master-slave configuration is built.The synchronization could sustain for more than 6 h,and the maximum tolerance of cavity length mismatch is measured to be about 210μm.Afterward,a time-stretch dispersive Fourier transform technique is introduced to analyze the synchronization process over multiple cycles.The pulse evolution,center wavelength shift,spectral reshaping,and broadening are all clearly detected.And the synchronization time is experimentally determined on the order of microseconds(hundreds of roundtrips).These results also show the seed pulse acting as a temporal gate for mode locking in some cases.To the best of our knowledge,this is the first time that pulse formation,spectral evolution,center wavelength shift,and synchronization time during the synchronization process are precisely revealed in experiment.These results would help to improve the performances of synchronized laser devices and deeply understand the mechanisms of the synchronization process and other light-light interactions in materials.
基金This work was supported by the Beijing Natural Science Foundation(No.4192015)the National Natural Science Foundation of China(No.61975003).
文摘The dispersive Fourier transform technique provides feasibility of exploring non-repetitive events and the buildup process in ultrafast lasers.In this paper,we report a new buildup process of dissipative solitons in a simplified mode-locked Yb-doped fiber laser,which includes more complex physics stages such as the Q-switching stage,raised and damped relaxation oscillation stages,noise-like stage,successive soliton explosions stage,and soliton breathing stage.Complete evolution dynamics of noise-like pulse and double pulse are also investigated with dispersive Fourier transform.For the noise-like pulse dynamics process,it will only experience the Q-switching and relaxation oscillation stages.In the case of dissipative soliton and noise-like pulse,the double pulse buildup behavior is manifested as the replication of individual pulses.A weak energy migration occurs between two pulses before reaching steady state.Meanwhile,real-time mutual conversion of the dissipative soliton and noise-like pulse has been experimentally observed,which appears to be instantaneous without extra physical processes.To the best of our knowledge,this is the first report on these physical phenomena observed together in a mode-locked fiber laser.The results further enrich the dynamics of mode-locked fiber lasers and provide potential conditions for obtaining intelligent mode-locked lasers with controllable output.
基金supported by the National Natural Science Foundation of China(Grant Nos.62305299 and 62205296)the Zhejiang Provincial Natural Science Foundation of China(Nos.LQ22F050007 and LQ23F050004)+1 种基金the Open Project Program of Wuhan National Laboratory for Optoelectronics(No.2020WNLOKF008)the“Pioneer”and“Leading Goose”R&D Program of Zhejiang(No.2022C03084).
文摘The utilization of the dispersive Fourier transformation approach has enabled comprehensive observation of the birth process of dissipative solitons in fiber lasers.However,there is still a dearth of deep understanding regarding the extinction process of dissipative solitons.In this study,we have utilized a combination of experimental and numerical techniques to thoroughly examine the breathing dynamics of dissipative solitons during the extinction process in an Er-doped mode-locked fiber laser.The results demonstrate that the transient breathing dynamics have a substantial impact on the extinction stage of both steady-state and breathing-state dissipative solitons.The duration of transient breathing exhibits a high degree of sensitivity to variations in pump power.Numerical simulations are utilized to produce analogous breathing dynamics within the framework of a model that integrates equations characterizing the population inversion in a mode-locked laser.These results corroborate the role of Q-switching instability in the onset of breathing oscillations.Furthermore,these findings offer new possibilities for the advancement of various operational frameworks for ultrafast lasers.
基金supported by the National Natural Science Foundation of China(No.61975003)the Beijing Natural Science Foundation(No.4192015)。
文摘The evolution dynamics of mode locking for a solid-state femtosecond Yb:KGW laser is demonstrated and detected with time-stretch dispersive Fourier transform(DFT)technique for the first time,to the best of our knowledge.The Yb:KGW laser is constructed first with a classical X-shaped cavity,and SESAM-assisted Kerr lens mode locking is obtained.Then,a DFT device is built to record the buildup and extinction dynamics of the mode-locked laser.The results suggest that the time of extinction is slightly shorter than the buildup time and both of them experience complex transitions.The results indicate that DFT could also be suitable to detect the transient buildup and extinction process in solid-state lasers,which would help investigate both the evolution of mode locking and characteristics determination for solid-state lasers.
基金supported by the National Natural Science Foundation of China (NSFC) (Nos.62375087 and 12374304)the Key-Area Research and Development Program of Guangdong Province (No.2023B0909010002)+3 种基金the NSFC DevelopmentofNationalMajorScientificResearch Instrument (No.61927816)the Mobility Programme of the Sino-German (No.M-0296)the Introduced Innovative Team Project of Guangdong Pearl River Talents Program (No.2021ZT09Z109)the Natural Science Foundation of Guangdong Province (No.2021B1515020074)。
文摘Dissipative Kerr cavity solitons(CSs) are localized temporal structures generated in coherently driven Kerr resonators which have attracted widespread attention for their rich nonlinear dynamics and key role in the generation of optical frequency combs. Akin to the complexity of the dissipative solitons in mode-locked lasers, the nonlinear dynamics of the CSs present distinctive evolutionary behaviors that may create new potential for understanding interdisciplinary nonlinear problems. Here, we leverage real-time spectroscopy to study the transient behaviors of the CSs in a Kerr fiber cavity with coherent driving. The real-time spectroscopy is implemented with the emerging dispersive Fourier transform(DFT) technology with a large dispersion of-10.2 ns/nm, which provides a sampling spectral resolution of ~1 pm. Under perturbations,the complete birth-to-annihilation process of the CS is visualized in real time as the Kerr fiber cavity specifically locked around the boundary of modulation instability(MI) and bistable regimes. Fruitful transient dynamics are observed, including MI, soliton breathing, stationary CS, and its annihilation. The mechanism of the observed transient dynamics is theoretically studied through numerical simulation, and we find that the cavity detuning variation resulting from the external perturbation plays a dominant role in the evolution of the CS. More importantly, there exists a visible energy drop accompanied by the CS breathing, wherein the collision between the solitons triggers the subsequent drift and annihilation of the CS. The spectral interferograms of multiple CSs that are analyzed by their field autocorrelation also verify the annihilation of the CS.
