In the last few years,research on advanced ultrafast photonic devices has attracted great interest from laser physicists.As a semiconductor material with excellent nonlinear saturation absorption characteristics,Ga As...In the last few years,research on advanced ultrafast photonic devices has attracted great interest from laser physicists.As a semiconductor material with excellent nonlinear saturation absorption characteristics,Ga As has been used in solidstate and fiber lasers as a mode-locker.However,the pulse widths that have been reported in the searchable published literature are all long and the shortest is tens of picoseconds.Femtosecond pulse widths,desired for a variety of applications,have not yet been reported in Ga As-based pulsed lasers.In this work,we further explore the nonlinear characteristics of Ga As that has been magnetron sputtered onto the surface of a tapered fiber and its application in the generation of femtosecond lasing via effective dispersion optimization and nonlinearity management.With the enhanced interaction between evanescent waves and Ga As nanosheets,mode-locked soliton pulses as short as 830 fs are generated at repetition rates of 4.64 MHz.As far as we know,this is the first time that femtosecond-level pulses have been generated with a Ga As-based saturable absorber.In addition,soliton molecules,including in the dual-pulse state,are also realized under stronger pumping.This work demonstrates that Ga As-based photonic devices have good application prospects in effective polymorphous ultrashort pulsed laser generation.展开更多
CsPbBr3 nanocrystal is used as the saturable absorber(SA) for mode-locking Tm-doped fiber laser in a ring fiber cavity.The modulation depth, saturable intensity, and non-saturable loss of the fabricated SA are 14.1%, ...CsPbBr3 nanocrystal is used as the saturable absorber(SA) for mode-locking Tm-doped fiber laser in a ring fiber cavity.The modulation depth, saturable intensity, and non-saturable loss of the fabricated SA are 14.1%, 2.5 MW/cm^2,and 5.9%, respectively.In the mode-locking operation, the mode-locked pulse train has a repetition rate of 16.6 MHz with pulse width of 24.2 ps.The laser wavelength is centered at 1992.9 nm with 3-dB spectrum width of 2.5 nm.The maximum output power is 110 mW with slope efficiency of 7.1%.Our experiment shows that CsPbBr3 nanocrystal can be used as an efficient SA in the 2-μm wavelength region.展开更多
Passive harmonic mode locking of an erbium-doped fiber laser based on few-layer molybdenum disulfide(MoS2)saturable absorber(SA) is demonstrated. The few-layer MoS2 is prepared by the chemical vapor deposition(CVD) me...Passive harmonic mode locking of an erbium-doped fiber laser based on few-layer molybdenum disulfide(MoS2)saturable absorber(SA) is demonstrated. The few-layer MoS2 is prepared by the chemical vapor deposition(CVD) method and then transferred onto the end face of a fiber connector to form a fiber-compatible Mo S2SA. The 20 th harmonic modelocked pulses at 216-MHz repetition rate are stably generated with a pulse duration of 1.42 ps and side-mode suppression ratio(SMSR) of 36.1dB. The results confirm that few-layer MoS2 can serve as an effective SA for mode-locked fiber lasers.展开更多
Using Langevin simulations, we study numerically the directional mode-locking of the dynamics of two- dimensional superpararnagnetic colloidal system in a periodic pinning array. When the colloidal particles are initi...Using Langevin simulations, we study numerically the directional mode-locking of the dynamics of two- dimensional superpararnagnetic colloidal system in a periodic pinning array. When the colloidal particles are initially commensurate with the pinning sites, there appear mode-locking steps in the average velocity of colloidal particles along certain directions of the external driving force. With an increase in the pinning strength, the width of the step increases linearly but the velocity at the step decreases parabolically.展开更多
The pulse generation from active mode-locking terahertz quantum cascade laser is studied by Maxwell-Bloch equations.It is shown that longer dephasing time will lead to multiple pulses generation from the laser.The dep...The pulse generation from active mode-locking terahertz quantum cascade laser is studied by Maxwell-Bloch equations.It is shown that longer dephasing time will lead to multiple pulses generation from the laser.The dependence of output field on modulation length and radio-frequency parameters is obtained.In order to achieve short pulse generation,the DC bias should close to threshold value and modulation length should be shorter than 0.256 mm.The output pulse is unstable and the envelope shows many oscillations in the presence of spatial hole burning,resulting destabilization of mode-locking.展开更多
We report on a Kerr-lens mode-locked(KLM)femtosecond Yb:CaYAlO_(4)(Yb:CYA)laser operating at a repetition rate of 1.04 GHz,pumped by a single-mode fiber laser.The laser delivers an average output power of 1.37 W with ...We report on a Kerr-lens mode-locked(KLM)femtosecond Yb:CaYAlO_(4)(Yb:CYA)laser operating at a repetition rate of 1.04 GHz,pumped by a single-mode fiber laser.The laser delivers an average output power of 1.37 W with a pulse duration of 109 fs.Potential improvements,including scaling the pump power,increasing the repetition rate,and further reducing the pulse duration,are discussed.This study contributes to the advancement of Watt-level GHz femtosecond laser generation and its applications.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
As a representative transition metal dichalcogenides(TMD),NiTe_(2)has an ultra-fast optical response,high carrier mobility,and excellent environmental stability.It has a broad application prospect in the fields of ene...As a representative transition metal dichalcogenides(TMD),NiTe_(2)has an ultra-fast optical response,high carrier mobility,and excellent environmental stability.It has a broad application prospect in the fields of ener-gy,biomedicine,optoelectronic devices,and so on.At present,there have been scant reports on the application of NiTe_(2)in the field of ultrafast photonics.In this work,NiTe_(2)was synthesized by chemical vapor deposition(CVD)and integrated with a tapered optical fiber to achieve mode-locking in an erbium-doped fiber laser(EDFL)and a thu-lium-doped fiber laser(TDFL).The mode-locked EDFL exhibited a pulse width of 678 fs and an output power of 3.92 mW.The pulse width of mode-locked TDFL was estimated to have a pulse width of 694 fs with an output power of 21.64 mW.These results demonstrate that NiTe_(2)is an effective saturable absorber material with potential applica-tions in the field of ultrafast optics.展开更多
Ultra-narrow bandwidth mode-locked lasers with tunable pulse duration can be versatile light sources for diverse applications.However,the spectral-temporal control of a narrow bandwidth mode-locked laser is challengin...Ultra-narrow bandwidth mode-locked lasers with tunable pulse duration can be versatile light sources for diverse applications.However,the spectral-temporal control of a narrow bandwidth mode-locked laser is challenging due to limited gain and nonlinearity,hindering practical applications of such lasers.We demonstrate a pulse duration widely tunable mode-locked ultra-narrow bandwidth laser using a composite filtering mechanism and a single-wall carbon nanotube.The laser pulse duration can be adjusted from 481 ps to 1.38 ns,which is the widest tuning range achieved in narrow-bandwidth passively mode-locked lasers.When the pulse duration is 1.38 ns,the corresponding spectral width reaches 4 pm(502 MHz).Numerical simulations support the experimental results and show that the evolution of long pulses in the laser cavity behaves similarly to a quasi-continuous wave with a low breathing ratio.We have not only designed a simple and flexible tunable scheme for the dilemma of spectral-temporal control in narrow-bandwidth mode-locked fiber lasers but also provided a unique and idealized light source for various applications that takes into account robust output.展开更多
With MoS2 as saturable absorber, passive Q-switching and Q-switched mode-locking operations of a Tm-doped calcium lithium niobium gallium garnet（Tm:CLNGG） laser were experimentally demonstrated. The Q-switched laser...With MoS2 as saturable absorber, passive Q-switching and Q-switched mode-locking operations of a Tm-doped calcium lithium niobium gallium garnet（Tm:CLNGG） laser were experimentally demonstrated. The Q-switched laser emitted a maximum average output power of 62 mW and highest pulse energy of 0.72 μJ. Q-switched mode locking was also obtained in the experiment. The research results will open up applications of MoS2 at the mid-infrared wavelength.展开更多
Stable mode-locking in a diode-pumped Yb:YAG laser was obtained with a very fast semiconductor sat-urable absorber mirror (SESAM). The pulse width was measured to be 4 ps at the central wavelength of 1047 nm. The aver...Stable mode-locking in a diode-pumped Yb:YAG laser was obtained with a very fast semiconductor sat-urable absorber mirror (SESAM). The pulse width was measured to be 4 ps at the central wavelength of 1047 nm. The average power was 200 mW and the repetition rate was 200 MHz.展开更多
The paper summarizes the recent achievements in the area of ultrafast fiber lasers mode-locked with so-called lowdimensional nanomaterials: graphene, topological insulators（Bi2Te3, Bi2Se3, Sb2Te3）, and transition me...The paper summarizes the recent achievements in the area of ultrafast fiber lasers mode-locked with so-called lowdimensional nanomaterials: graphene, topological insulators（Bi2Te3, Bi2Se3, Sb2Te3）, and transition metal sulfide semiconductors, like molybdenum disulfide（MoS2）. The most important experimental achievements are described and compared. Additionally, new original results on ultrashort pulse generation at 1.94 μm wavelength using graphene are presented. The designed Tm-doped fiber laser utilizes multilayer graphene as a saturable absorber and generates 654 fs pulses at 1940 nm wavelength, which are currently the shortest pulses generated from a Tm-doped fiber laser with a graphene-based saturable absorber.展开更多
In this paper, we demonstrated a series of short-living mode-locking(ML) states(each lasting a few to a hundred microseconds) that happened before a fiber laser reached a steady ML state.With time-stretched dispersion...In this paper, we demonstrated a series of short-living mode-locking(ML) states(each lasting a few to a hundred microseconds) that happened before a fiber laser reached a steady ML state.With time-stretched dispersion Fourier transform spectroscopy, a rich diversity of transient multi-pulse dynamics were revealed spectrally and temporally.As a result, we found that the formation of the short-living ML states was related to abundant pump power, and their decaying evolution dynamics were possibly governed by gain depletion and recovery.Our results revealed unexpected transient lasing behaviors of a soliton laser and thus might be useful to understand the complex dynamics of mode-locked lasers.展开更多
Graphene oxide carboxylic acid（COOH）, a novel two-dimensional（2D） layered material with its unique optical and electronic properties, is discovered to exhibit the saturation of optical absorption under laser illum...Graphene oxide carboxylic acid（COOH）, a novel two-dimensional（2D） layered material with its unique optical and electronic properties, is discovered to exhibit the saturation of optical absorption under laser illumination.Applying the liquid-phase exfoliation method, we prepare graphene oxide-COOH dispersions with deionized water and fabricate graphene oxide-COOH polyvinyl alcohol polymer composite film. We further obtain stable Q-switching pulse and mode-locked laser operation with a 22.7 MHz repetition rate and a 1.5 ps pulse duration by incorporating the graphene oxide-COOH-based saturable absorbers into the all-fiber erbium-doped fiber laser cavity. The experimental results show that the proposed graphene oxide-COOH material can act as an effective absorber for pulsed fiber lasers, which demonstrate potential applications in the area of ultrafast optics.展开更多
An all-fiber acousto-optic modulator(AOM), which features a compact structure and a low-driving voltage, is experimentally demonstrated for the active mode-locking of a fiber laser. The proposed AOM is based on the sh...An all-fiber acousto-optic modulator(AOM), which features a compact structure and a low-driving voltage, is experimentally demonstrated for the active mode-locking of a fiber laser. The proposed AOM is based on the short length of the cladding-etched fiber, the ends of which are fixed on a slide glass. On top of the cladding-etched fiber, a piezoelectric transducer was overlaid. A chemical wet-etching technique, which is based on a mixed solution of NH_4F and (NH_4)2SO_4, is used to reduce the fiber diameter down to ～25 μm, and the length of the etched section is only 0.5 cm. The fabricated device exhibited a modulation depth of 73.10% at an acoustic frequency of 918.9 kHz and a peak-to-peak electrical voltage of 10 V, while a laser beam was coupled at 1560 nm.By using the prepared AOM within an erbium-doped-fiber ring cavity, the mode-locked pulses with a temporalwidth of 2.66 ps were readily obtained at a repetition rate of 1.838 MHz.展开更多
A feedback controlled mode-locking in Nd: YAG oscillator has been successfully demonstrated by a novel mode-locking technique. The ultrafast response time of the switch without any avalanche is essential to the mode-l...A feedback controlled mode-locking in Nd: YAG oscillator has been successfully demonstrated by a novel mode-locking technique. The ultrafast response time of the switch without any avalanche is essential to the mode-locking. For photoconductors in common use, the intrinsic monocrystalline silicon and the GaAs are very familiar to us. Although Si has very fast response and high sensitivity, its dark resistance is not large enough(only about (20—30)×10~3Ω)to stand very high voltage. The Cr-doped GaAs has fast re-展开更多
Based on the Nd-doped single-mode fiber as the gain medium,an all-fiber 12th harmonic mode-locked(HML)laser operating at the 0.9μm waveband was obtained for the first time,to the best of our knowledge.A mandrel with ...Based on the Nd-doped single-mode fiber as the gain medium,an all-fiber 12th harmonic mode-locked(HML)laser operating at the 0.9μm waveband was obtained for the first time,to the best of our knowledge.A mandrel with a diameter of 10 mm was employed to introduce bending losses to suppress mode competition at 1.06μm,which resulted in a suppression ratio of up to 54 dB.The 1st–12th order HML pulses with the tunable repetition rate of 494.62 kHz–5.94 MHz were obtained in the mode-locked laser with a center wavelength of∼904 nm.In addition,the laser has an extremely low threshold pump power of 88 mW.To the best of our knowledge,this is the first time that an HML pulse has been achieved in a 0.9μm Nd-doped single-mode all-fiber mode-locked laser with the advantages of low cost,simple structure,and compactness,which could be an ideal light source for two-photon microscopy.展开更多
This study reports a passive mode-locked Thulium-Holmium co-doped fiber laser featuring a figure-9 shaped resonator structure.The laser utilizes a nonlinear amplifying loop mirror(NALM)as the mode-locking device.By in...This study reports a passive mode-locked Thulium-Holmium co-doped fiber laser featuring a figure-9 shaped resonator structure.The laser utilizes a nonlinear amplifying loop mirror(NALM)as the mode-locking device.By increasing pump power,the laser’s output evolution was experimentally observed,showing that bright-dark pulse pairs first split into double pulses and then into a second harmonic state.Additionally,the time intervals between bright and dark pulses and between double pulses increased with higher pump power.The RF spectrum of the bright-dark pulse pairs exhibited envelope modulation,with a modulation frequency approximately equal to the reciprocal of the time interval between bright and dark pulses.When the pump power increased from 0.46 W to 0.72 W,the reciprocal of the modulation frequency showed a linear growth trend.These findings contribute to understanding the evolution patterns of bright-dark pulse pairs in passive mode-locked fiber lasers.展开更多
A 980-nm semiconductor saturable absorber mirror（SESAM） mode-locked Yb-doped phosphate fiber laser is demonstrated by using an all-fiber linear cavity configuration. Two different kinds of cavity lengths are introdu...A 980-nm semiconductor saturable absorber mirror（SESAM） mode-locked Yb-doped phosphate fiber laser is demonstrated by using an all-fiber linear cavity configuration. Two different kinds of cavity lengths are introduced into the oscillator to obtain a robust and stable mode-locked seed source. When the cavity length is chosen to be 6 m, the oscillator generates an average output power of 3.5 m W and a pulse width of 76.27 ps with a repetition rate of 17.08 MHz. As the cavity length is optimized to short, 4.4-m W maximum output power and 61.15-ps pulse width are produced at a repetition rate of 20.96 MHz. The output spectrum is centered at 980 nm with a narrow spectral bandwidth of 0.13 nm. In the experiment, no undesired amplified spontaneous emission（ASE） nor harmful oscillation around 1030 nm is observed. Moreover,through a two-stage all-fiber-integrated amplifier, an output power of 740 m W is generated with a pulse width of 200 ps.展开更多
We report on a diode-pumped passively continuous wave （cw） mode-locked Tm：YAP laser with a double-wall carbon nanotube （DWCNT） absorber operating at a wavelength of 2023 nm for the first time, to the best our kno...We report on a diode-pumped passively continuous wave （cw） mode-locked Tm：YAP laser with a double-wall carbon nanotube （DWCNT） absorber operating at a wavelength of 2023 nm for the first time, to the best our knowledge. The DWCNT absorber is fabricated on a hydrophilic quartz substrate by using the vertical evaporation technique. The output power is as high as 375 mW. A stable pulse train with a repetition rate of 72.26 MHz is generated with a highest single pulse energy of 5.2 μJ.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.12164030)Young Science and Technology Talents of Inner Mongolia,China(Grant No.NJYT22101)+1 种基金the Central Government Guides Local Science,the Technology Development Fund Projects(Grant No.2023ZY0005)the Science and Technology Plan Projects of Inner Mongolia Autonomous Region of China(Grant No.2023KYPT0012)。
文摘In the last few years,research on advanced ultrafast photonic devices has attracted great interest from laser physicists.As a semiconductor material with excellent nonlinear saturation absorption characteristics,Ga As has been used in solidstate and fiber lasers as a mode-locker.However,the pulse widths that have been reported in the searchable published literature are all long and the shortest is tens of picoseconds.Femtosecond pulse widths,desired for a variety of applications,have not yet been reported in Ga As-based pulsed lasers.In this work,we further explore the nonlinear characteristics of Ga As that has been magnetron sputtered onto the surface of a tapered fiber and its application in the generation of femtosecond lasing via effective dispersion optimization and nonlinearity management.With the enhanced interaction between evanescent waves and Ga As nanosheets,mode-locked soliton pulses as short as 830 fs are generated at repetition rates of 4.64 MHz.As far as we know,this is the first time that femtosecond-level pulses have been generated with a Ga As-based saturable absorber.In addition,soliton molecules,including in the dual-pulse state,are also realized under stronger pumping.This work demonstrates that Ga As-based photonic devices have good application prospects in effective polymorphous ultrashort pulsed laser generation.
基金Project supported by the National Key R&D Program of China(Grant No.2018YFB0504500)the National Natural Science Foundation of China(Grant Nos.51472162,51672177,and 61475171)the Talent Introduction Research Project of Shanghai Institute of Technology,China(Grant No.YJ 2018-8)
文摘CsPbBr3 nanocrystal is used as the saturable absorber(SA) for mode-locking Tm-doped fiber laser in a ring fiber cavity.The modulation depth, saturable intensity, and non-saturable loss of the fabricated SA are 14.1%, 2.5 MW/cm^2,and 5.9%, respectively.In the mode-locking operation, the mode-locked pulse train has a repetition rate of 16.6 MHz with pulse width of 24.2 ps.The laser wavelength is centered at 1992.9 nm with 3-dB spectrum width of 2.5 nm.The maximum output power is 110 mW with slope efficiency of 7.1%.Our experiment shows that CsPbBr3 nanocrystal can be used as an efficient SA in the 2-μm wavelength region.
基金supported by the National Natural Science Foundation of China(Grant Nos.61378028,61421002,61475030,and 61377042)the National Basic Research Program of China(Grant No.2012CB315701)the New Century Excellent Talents Program in University,China(Grant No.NCET-13-0092)
文摘Passive harmonic mode locking of an erbium-doped fiber laser based on few-layer molybdenum disulfide(MoS2)saturable absorber(SA) is demonstrated. The few-layer MoS2 is prepared by the chemical vapor deposition(CVD) method and then transferred onto the end face of a fiber connector to form a fiber-compatible Mo S2SA. The 20 th harmonic modelocked pulses at 216-MHz repetition rate are stably generated with a pulse duration of 1.42 ps and side-mode suppression ratio(SMSR) of 36.1dB. The results confirm that few-layer MoS2 can serve as an effective SA for mode-locked fiber lasers.
基金Supported by the Scientific Research Foundation of Graduate School of Zhengzhou Universitythe Natural Science Research Foundation of Henan Provincial Department of Science and Technology under Grant No. 112300410151
文摘Using Langevin simulations, we study numerically the directional mode-locking of the dynamics of two- dimensional superpararnagnetic colloidal system in a periodic pinning array. When the colloidal particles are initially commensurate with the pinning sites, there appear mode-locking steps in the average velocity of colloidal particles along certain directions of the external driving force. With an increase in the pinning strength, the width of the step increases linearly but the velocity at the step decreases parabolically.
基金Project supported by the National Key Research and Development Program of China(Grant No.2017YFF0106302)the National Natural Science Foundation of China(Grant Nos.61975225 and 61927813)Shanghai International Cooperation Project,China(Grant No.18590780100).
文摘The pulse generation from active mode-locking terahertz quantum cascade laser is studied by Maxwell-Bloch equations.It is shown that longer dephasing time will lead to multiple pulses generation from the laser.The dependence of output field on modulation length and radio-frequency parameters is obtained.In order to achieve short pulse generation,the DC bias should close to threshold value and modulation length should be shorter than 0.256 mm.The output pulse is unstable and the envelope shows many oscillations in the presence of spatial hole burning,resulting destabilization of mode-locking.
基金supported by the National Key Research and Development Program of China(Grant No.2022YFB4600158)。
文摘We report on a Kerr-lens mode-locked(KLM)femtosecond Yb:CaYAlO_(4)(Yb:CYA)laser operating at a repetition rate of 1.04 GHz,pumped by a single-mode fiber laser.The laser delivers an average output power of 1.37 W with a pulse duration of 109 fs.Potential improvements,including scaling the pump power,increasing the repetition rate,and further reducing the pulse duration,are discussed.This study contributes to the advancement of Watt-level GHz femtosecond laser generation and its applications.
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 Guangdong Basic and Applied Basic Research Fund,China(2024A1515012429)。
文摘As a representative transition metal dichalcogenides(TMD),NiTe_(2)has an ultra-fast optical response,high carrier mobility,and excellent environmental stability.It has a broad application prospect in the fields of ener-gy,biomedicine,optoelectronic devices,and so on.At present,there have been scant reports on the application of NiTe_(2)in the field of ultrafast photonics.In this work,NiTe_(2)was synthesized by chemical vapor deposition(CVD)and integrated with a tapered optical fiber to achieve mode-locking in an erbium-doped fiber laser(EDFL)and a thu-lium-doped fiber laser(TDFL).The mode-locked EDFL exhibited a pulse width of 678 fs and an output power of 3.92 mW.The pulse width of mode-locked TDFL was estimated to have a pulse width of 694 fs with an output power of 21.64 mW.These results demonstrate that NiTe_(2)is an effective saturable absorber material with potential applica-tions in the field of ultrafast optics.
基金supported by the National Natural Science Foundation of China(Grant No.61975107)the Natural Science Foundation of Shanghai(Grant Nos.24ZR1422000 and 20ZR1471500),and the“111”Project(Grant No.D20031).
文摘Ultra-narrow bandwidth mode-locked lasers with tunable pulse duration can be versatile light sources for diverse applications.However,the spectral-temporal control of a narrow bandwidth mode-locked laser is challenging due to limited gain and nonlinearity,hindering practical applications of such lasers.We demonstrate a pulse duration widely tunable mode-locked ultra-narrow bandwidth laser using a composite filtering mechanism and a single-wall carbon nanotube.The laser pulse duration can be adjusted from 481 ps to 1.38 ns,which is the widest tuning range achieved in narrow-bandwidth passively mode-locked lasers.When the pulse duration is 1.38 ns,the corresponding spectral width reaches 4 pm(502 MHz).Numerical simulations support the experimental results and show that the evolution of long pulses in the laser cavity behaves similarly to a quasi-continuous wave with a low breathing ratio.We have not only designed a simple and flexible tunable scheme for the dilemma of spectral-temporal control in narrow-bandwidth mode-locked fiber lasers but also provided a unique and idealized light source for various applications that takes into account robust output.
基金supported by the National Natural Science Foundation of China (Grant Nos. 61008018 and 11421064)the National Basic Research Program of China (Grant No. 2013CBA01505)
文摘With MoS2 as saturable absorber, passive Q-switching and Q-switched mode-locking operations of a Tm-doped calcium lithium niobium gallium garnet（Tm:CLNGG） laser were experimentally demonstrated. The Q-switched laser emitted a maximum average output power of 62 mW and highest pulse energy of 0.72 μJ. Q-switched mode locking was also obtained in the experiment. The research results will open up applications of MoS2 at the mid-infrared wavelength.
基金This work was supported by the National Key Basic Research Special Foundation of China (No. G1999075201-2) the National Natural Science Foundation of China (No. 69978016, 60178008) the Foundation of the Optoelectronic United Center of Tianjin, the Na
文摘Stable mode-locking in a diode-pumped Yb:YAG laser was obtained with a very fast semiconductor sat-urable absorber mirror (SESAM). The pulse width was measured to be 4 ps at the central wavelength of 1047 nm. The average power was 200 mW and the repetition rate was 200 MHz.
基金supported by the National Science Centre (NCN, Poland) under the research project entitled “Passive mode-locking in dispersion-managed ultrafast thulium-doped fiber lasers” (decision no. DEC-2013/11/D/ST7/03138)
文摘The paper summarizes the recent achievements in the area of ultrafast fiber lasers mode-locked with so-called lowdimensional nanomaterials: graphene, topological insulators（Bi2Te3, Bi2Se3, Sb2Te3）, and transition metal sulfide semiconductors, like molybdenum disulfide（MoS2）. The most important experimental achievements are described and compared. Additionally, new original results on ultrashort pulse generation at 1.94 μm wavelength using graphene are presented. The designed Tm-doped fiber laser utilizes multilayer graphene as a saturable absorber and generates 654 fs pulses at 1940 nm wavelength, which are currently the shortest pulses generated from a Tm-doped fiber laser with a graphene-based saturable absorber.
基金supported by the National Key Research and Development Program (No.2018YFB0504400)National Natural Science Foundation of China (NSFC)(Nos.61875243and 11804100)+1 种基金Shanghai Municipal Science and Technology Major Project (No.2019SHZDZX01)Science and Technology Innovation Program of Basic Science Foundation of Shanghai (No.18JC1412000)。
文摘In this paper, we demonstrated a series of short-living mode-locking(ML) states(each lasting a few to a hundred microseconds) that happened before a fiber laser reached a steady ML state.With time-stretched dispersion Fourier transform spectroscopy, a rich diversity of transient multi-pulse dynamics were revealed spectrally and temporally.As a result, we found that the formation of the short-living ML states was related to abundant pump power, and their decaying evolution dynamics were possibly governed by gain depletion and recovery.Our results revealed unexpected transient lasing behaviors of a soliton laser and thus might be useful to understand the complex dynamics of mode-locked lasers.
基金supported by the National Natural Science Foundation of China(No.61690222)the CAS/SAFEA international Partnership Program for creative Research Teams
文摘Graphene oxide carboxylic acid（COOH）, a novel two-dimensional（2D） layered material with its unique optical and electronic properties, is discovered to exhibit the saturation of optical absorption under laser illumination.Applying the liquid-phase exfoliation method, we prepare graphene oxide-COOH dispersions with deionized water and fabricate graphene oxide-COOH polyvinyl alcohol polymer composite film. We further obtain stable Q-switching pulse and mode-locked laser operation with a 22.7 MHz repetition rate and a 1.5 ps pulse duration by incorporating the graphene oxide-COOH-based saturable absorbers into the all-fiber erbium-doped fiber laser cavity. The experimental results show that the proposed graphene oxide-COOH material can act as an effective absorber for pulsed fiber lasers, which demonstrate potential applications in the area of ultrafast optics.
基金National Research Foundation of Korea(NRF)(2015R1A2A2A04006979,2015R1A2A2A11000907)Institute for Information and Communications Technology Promotion(IITP-2017-2015-0-00385)
文摘An all-fiber acousto-optic modulator(AOM), which features a compact structure and a low-driving voltage, is experimentally demonstrated for the active mode-locking of a fiber laser. The proposed AOM is based on the short length of the cladding-etched fiber, the ends of which are fixed on a slide glass. On top of the cladding-etched fiber, a piezoelectric transducer was overlaid. A chemical wet-etching technique, which is based on a mixed solution of NH_4F and (NH_4)2SO_4, is used to reduce the fiber diameter down to ～25 μm, and the length of the etched section is only 0.5 cm. The fabricated device exhibited a modulation depth of 73.10% at an acoustic frequency of 918.9 kHz and a peak-to-peak electrical voltage of 10 V, while a laser beam was coupled at 1560 nm.By using the prepared AOM within an erbium-doped-fiber ring cavity, the mode-locked pulses with a temporalwidth of 2.66 ps were readily obtained at a repetition rate of 1.838 MHz.
文摘A feedback controlled mode-locking in Nd: YAG oscillator has been successfully demonstrated by a novel mode-locking technique. The ultrafast response time of the switch without any avalanche is essential to the mode-locking. For photoconductors in common use, the intrinsic monocrystalline silicon and the GaAs are very familiar to us. Although Si has very fast response and high sensitivity, its dark resistance is not large enough(only about (20—30)×10~3Ω)to stand very high voltage. The Cr-doped GaAs has fast re-
基金supported by the Natural Science Foundation of Shandong Province(Nos.ZR2019MF047,ZR2020MF126,and ZR2019MF043).
文摘Based on the Nd-doped single-mode fiber as the gain medium,an all-fiber 12th harmonic mode-locked(HML)laser operating at the 0.9μm waveband was obtained for the first time,to the best of our knowledge.A mandrel with a diameter of 10 mm was employed to introduce bending losses to suppress mode competition at 1.06μm,which resulted in a suppression ratio of up to 54 dB.The 1st–12th order HML pulses with the tunable repetition rate of 494.62 kHz–5.94 MHz were obtained in the mode-locked laser with a center wavelength of∼904 nm.In addition,the laser has an extremely low threshold pump power of 88 mW.To the best of our knowledge,this is the first time that an HML pulse has been achieved in a 0.9μm Nd-doped single-mode all-fiber mode-locked laser with the advantages of low cost,simple structure,and compactness,which could be an ideal light source for two-photon microscopy.
文摘This study reports a passive mode-locked Thulium-Holmium co-doped fiber laser featuring a figure-9 shaped resonator structure.The laser utilizes a nonlinear amplifying loop mirror(NALM)as the mode-locking device.By increasing pump power,the laser’s output evolution was experimentally observed,showing that bright-dark pulse pairs first split into double pulses and then into a second harmonic state.Additionally,the time intervals between bright and dark pulses and between double pulses increased with higher pump power.The RF spectrum of the bright-dark pulse pairs exhibited envelope modulation,with a modulation frequency approximately equal to the reciprocal of the time interval between bright and dark pulses.When the pump power increased from 0.46 W to 0.72 W,the reciprocal of the modulation frequency showed a linear growth trend.These findings contribute to understanding the evolution patterns of bright-dark pulse pairs in passive mode-locked fiber lasers.
基金supported by the National Natural Science Foundation of China(Grant No.61205047)
文摘A 980-nm semiconductor saturable absorber mirror（SESAM） mode-locked Yb-doped phosphate fiber laser is demonstrated by using an all-fiber linear cavity configuration. Two different kinds of cavity lengths are introduced into the oscillator to obtain a robust and stable mode-locked seed source. When the cavity length is chosen to be 6 m, the oscillator generates an average output power of 3.5 m W and a pulse width of 76.27 ps with a repetition rate of 17.08 MHz. As the cavity length is optimized to short, 4.4-m W maximum output power and 61.15-ps pulse width are produced at a repetition rate of 20.96 MHz. The output spectrum is centered at 980 nm with a narrow spectral bandwidth of 0.13 nm. In the experiment, no undesired amplified spontaneous emission（ASE） nor harmful oscillation around 1030 nm is observed. Moreover,through a two-stage all-fiber-integrated amplifier, an output power of 740 m W is generated with a pulse width of 200 ps.
基金Project supported by the National Natural Science Foundation of China (Grant No. 61078032)the Science and Technology Funds on Solide-State Laser Laboratory of China (Grant No. 9140C0403011106)
文摘We report on a diode-pumped passively continuous wave （cw） mode-locked Tm：YAP laser with a double-wall carbon nanotube （DWCNT） absorber operating at a wavelength of 2023 nm for the first time, to the best our knowledge. The DWCNT absorber is fabricated on a hydrophilic quartz substrate by using the vertical evaporation technique. The output power is as high as 375 mW. A stable pulse train with a repetition rate of 72.26 MHz is generated with a highest single pulse energy of 5.2 μJ.
