The wavelength-tunable and switchable narrow bandwidth mode-locking operation is demonstrated in an all fiber laser based on semiconductor-saturable absorber mirror (SESAM). Two narrow-band fiber Bragg gratings cent...The wavelength-tunable and switchable narrow bandwidth mode-locking operation is demonstrated in an all fiber laser based on semiconductor-saturable absorber mirror (SESAM). Two narrow-band fiber Bragg gratings centered at 1029.9nm and 1032nm respectively with a polarization controller inserted between them are used to realize the wavelength switchable between 1029.9nm and 1032nm. The laser delivers different pulse widths of 7.5ps for 1030nm and 20ps for 1032nm. The maximum output power for both could reach -6.5mW at single pulse operation. The output wavelength couM be tuned to about 0.gnm intervals ranging from 1030.2nm to 1031.1 nm and from 1032.15nm to 1033.7nm with the temperature change of the fiber Bragg grating, respectively.展开更多
We demonstrate a self-starting erbium fiber oscillator-amplifier system based on the nonlinear polarization rota- tion mode-locked mechanism. The direct output pulse from the amplifier is 47fs with an average power of...We demonstrate a self-starting erbium fiber oscillator-amplifier system based on the nonlinear polarization rota- tion mode-locked mechanism. The direct output pulse from the amplifier is 47fs with an average power of 1.22 W and a repetition rate of 50 MHz, corresponding to a pulse energy of 24 nJ. The full width at half-maximum of the spectrum of the output pulses is approximately 93nm at a central wavelength of 1572nm so that the transform- limited pulse duration is as short as 39 fs. Due to the imperfect dispersion compensation, we compress the pulses to 47fs in this experiment.展开更多
A theoretical analysis of noise in a high-power cascaded fiber amplifier is presented. Unlike the noise theory in low power communication, the noise of a high power system is redefined as the leaked output energy betw...A theoretical analysis of noise in a high-power cascaded fiber amplifier is presented. Unlike the noise theory in low power communication, the noise of a high power system is redefined as the leaked output energy between pulses with coherent beat noise uncounted. This definition is more appropriate for high power usage in which the pulse energy receives more attention than the pulse shape integrity. Then the low power pre-amplifying stages are considered as linear amplification and analyzed by linear theory. In the high-power amplification stages, the inversion is assumed to recover linearly in the time interval between pulses. The time shape of the output pulse is different from that of the input signal because of different gains at the front and back ends of the pulse. Then, a criterion is provided to distinguish the nonlinear and linear amplifications based on the signal-to-noise ratio (SNR) analysis. Then, an experiment that shows that the output SNR actually drops off in nonlinear amplification is performed. The change in the noise factor can be well evaluated by pulse shape distortion.展开更多
A harmonic dark pulse generation in an erbium-doped fiber laser is demonstrated based on a figure-of-eight configuration. It is found that the harmonic dark pulse can be shifted from the fundamental to the 5th order h...A harmonic dark pulse generation in an erbium-doped fiber laser is demonstrated based on a figure-of-eight configuration. It is found that the harmonic dark pulse can be shifted from the fundamental to the 5th order harmonic by increasing the pump power with an appropriate polarization controller orientation. The fundamental repetition rate of 2O kHz is obtained at the pump power of 29 m W. The highest pulse energy of 42.6 n3 is obtained at the fundamental repetition rate. The operating frequency of the dark pulse trains shifts to 2nd, 3rd, 4th and 5th harmonic as the pump powers are increased to 34mW, 50mW, 59mW and 137mW, respectively.展开更多
Using the reduced graphene oxide(rGO) as a saturable absorber(SA) in an Er-doped fiber(EDF) laser cavity,we obtain the Q-switching operation. The rGO SA is prepared by depositing the GO on fluorine mica(FM) us...Using the reduced graphene oxide(rGO) as a saturable absorber(SA) in an Er-doped fiber(EDF) laser cavity,we obtain the Q-switching operation. The rGO SA is prepared by depositing the GO on fluorine mica(FM) using the thermal reduction method. The modulation depth of rGO/FM is measured to be 3.2%. By incorporating the rGO/FM film into the EDF laser cavity, we obtain stable Q-switched pulses. The shortest pulse duration is3.53 μs, and the maximum single pulse energy is 48.19 nJ. The long-term stability of working is well exhibited.The experimental results show that the rGO possesses potential photonics applications.展开更多
We numerically study the pulse compression approaches based on atomic or molecular gases in a hollow-core fiber.From the perspective of self-phase modulation(SPM), we give the extensive study of the SPM influence on...We numerically study the pulse compression approaches based on atomic or molecular gases in a hollow-core fiber.From the perspective of self-phase modulation(SPM), we give the extensive study of the SPM influence on a probe pulse with molecular phase modulation(MPM) effect. By comparing the two compression methods, we summarize their advantages and drawbacks to obtain the few-cycle pulses with micro- or millijoule energies. It is also shown that the double pump-probe approach can be used as a tunable dual-color source by adjusting the time delay between pump and probe pulses to proper values.展开更多
From Maxwell's equations and Post's formalism, a generalized chiral nonlinear Schr6dinger equation (CNLSE) is obtained for the nonlinear chiral fiber. This equation governs light transmission through a dispersive ...From Maxwell's equations and Post's formalism, a generalized chiral nonlinear Schr6dinger equation (CNLSE) is obtained for the nonlinear chiral fiber. This equation governs light transmission through a dispersive nonlinear chiral fiber with joint action of chirality in linear and nonlinear ways. The generalized CNLSE shows a modu- lation of chirality to the effect of attenuation and nonlinearity compared with the case for a conventional fiber. Simulations based on the split-step beam propagation method reveal the role of nonlinearity with cooperation to chirality playing in the pulse evolution. By adjusting its strength the role of chirality in forming solitons is demonstrated for a given circularly polarized component. The application of nonlinear optical rotation is also discussed in an all-optical switch.展开更多
After a half century of development, fiber laser has evolved from a concept to a great family penetrating into various fields of applications. This paper reviews the history and current development of fiber lasers, wi...After a half century of development, fiber laser has evolved from a concept to a great family penetrating into various fields of applications. This paper reviews the history and current development of fiber lasers, with topics covering both continuous wave and short pulse fiber lasers. Important issues such as the major rare earth dopants, fiber laser brightness, polarization effects, clad pumping technology, beam combination, mode locking and pulse shaping are discussed in this paper.展开更多
In this paper, the theoretical rate equation model of an in-band pumped gain-switched thulium-doped fiber (TDF) laser is investigated. The analytical formulations of pump energy threshold, peak power extraction effi...In this paper, the theoretical rate equation model of an in-band pumped gain-switched thulium-doped fiber (TDF) laser is investigated. The analytical formulations of pump energy threshold, peak power extraction efficiency, and pulse extraction efficiency are derived through analyzing the interaction process between the pump pulse and the laser pulse. They are useful for understanding, designing, and optimizing the in-band pumped TDF lasers in a 1.9 μm-2.1 μm wavelength region. The experiment with an all-fiber gain-switched TDF laser pumped by a 1.558-μm pulse amplifier is conducted, and our experimental results show good agreement with theoretical analysis.展开更多
Silicon carbide particle reinforced aluminum matrix composites(SiCp/Al composites)are widely used in aviation,aerospace and electronic package.However,low machining efficiency,severe tool wear and poor surface quality...Silicon carbide particle reinforced aluminum matrix composites(SiCp/Al composites)are widely used in aviation,aerospace and electronic package.However,low machining efficiency,severe tool wear and poor surface quality are severe during the machining of SiCp/Al composites.Laser-induced oxidation is capable to improve the machinability of SiCp/Al composites.The material response of 55%(volume fraction)SiCp/Al composites induced by a nanosecond pulsed laser is studied.A metamorphic layer which is composed of an oxide layer and sub-layer is produced.The effects of reaction surrounding and laser average power on the microstructure and thickness of the oxide layer and sub-layer are investigated.Experimental results show that:A thicker oxide layer and a sub-layer are formed in an oxygen-rich atmosphere.The oxides are mainly composed of 2Al2O3·SiO2(mullite).A positive correlation between the laser average power and thicknesses of oxide layers and sub-layers is found.A loose oxide layer of 138μm and a sub-layer of 21μm are formed at the laser average power of 6 W,laser scanning pitch of 10μm,and laser scanning speed of 1 mm/s under an oxygen-rich atmosphere.The high efficient machining of Si Cp/Al composites can be realized by laser-induced oxidation.展开更多
We demonstrated a 2-μm passively mode-locked nanosecond fiber laser based on a MoS2 saturable absorber(SA).Owing to the effect of nonlinear absorption in the MoS2 SA, the pulse width decreased from 64.7 to 13.8 ns ...We demonstrated a 2-μm passively mode-locked nanosecond fiber laser based on a MoS2 saturable absorber(SA).Owing to the effect of nonlinear absorption in the MoS2 SA, the pulse width decreased from 64.7 to 13.8 ns with increasing pump power from 1.10 to 1.45 W. The use of a narrow-bandwidth fiber Bragg grating resulted in a central wavelength and 3-dB spectral bandwidth of 2010.16 and 0.15 nm, respectively. Experimental results show that MoS2 is a promising material for a 2-μm mode-locked fiber laser.展开更多
We reported on the generation of the dual-wavelength rectangular pulse in an erbium-doped fiber laser(EDFL)with a topological insulator saturable absorber.The rectangular pulse could be stably initiated with pulse wid...We reported on the generation of the dual-wavelength rectangular pulse in an erbium-doped fiber laser(EDFL)with a topological insulator saturable absorber.The rectangular pulse could be stably initiated with pulse width from 13.62 to 25.16 ns and fundamental repetition rate of 3.54 MHz by properly adjusting the pump power and the polarization state.In addition,we verified that the pulse shape of the dual-wavelength rectangular pulse can be affected by the total net cavity dispersion in the fiber laser.Furthermore,by properly rotating the polarization controllers,the harmonic mode-locking operation of the dual-wavelength rectangular pulse was also obtained.The dual-wavelength rectangular pulse EDFL would benefit some potential applications,such as spectroscopy,biomedicine,and sensing research.展开更多
We report on a grating-free fiber chirped pulse amplifier(CPA)at 2.8μm for the first time.The CPA system adopted Er:ZBLAN fiber with large anomalous dispersion as the stretcher and germanium(Ge)rods as the compressor...We report on a grating-free fiber chirped pulse amplifier(CPA)at 2.8μm for the first time.The CPA system adopted Er:ZBLAN fiber with large anomalous dispersion as the stretcher and germanium(Ge)rods as the compressor with a compact structure.High-energy picosecond pulses of 2.07μJ were generated at the repetition rate of 100 kHz.Using highly dispersive Ge rods,the amplified pulses were compressed to 408 fs with a pulse energy of 0.57μJ,resulting in a peak power of approximately 1.4 MW.A spectral broadening phenomenon in the main amplifier was observed,which was caused by the special gain shape of the Er:ZBLAN fiber amplifier in operation and confirmed by our numerical simulation.This compact fiber CPA system at 2.8μm will be practical and meaningful for application fields.展开更多
Switchable single and double Brillouin multiwavelength and pulsed laser is successfully demonstrated. Brillouin spacing can be switched from single(0.08 nm) to double spacing(0.16 nm) or vice versa by swapping the...Switchable single and double Brillouin multiwavelength and pulsed laser is successfully demonstrated. Brillouin spacing can be switched from single(0.08 nm) to double spacing(0.16 nm) or vice versa by swapping the ports of the coupler in the proposed configuration. The proposed configuration can also be used to produce pulsed laser by inserting a home-made carbon nanotubes saturable absorber into the laser cavity. The proposed system is very versatile and flexible as it can be used as a multiwavelength laser or pulsed laser to cater for different types of applications.展开更多
We demonstrate the generation of supercontinuum (SC) of over 1350 nm by injecting 790-nm, 15-fs, 74-MHz optical pulses into a 183-mm-long microstructured fiber with combination core and random cladding. The maximum to...We demonstrate the generation of supercontinuum (SC) of over 1350 nm by injecting 790-nm, 15-fs, 74-MHz optical pulses into a 183-mm-long microstructured fiber with combination core and random cladding. The maximum total power of SC is 73 mW with 290-mW pump power from 40x microscope objective. The wavelength and power ranging in SC as well as the polarization states and waveguide modes of the visible light can be tuned by adjusting the input end of MF.In particular, white light has been observed. To our knowledge, this is the first report of tunable properties in SC generation process using microstructured fiber with combination core and random cladding.展开更多
A mode-locked thulium-doped fiber laser(TDFL) based on nonlinear polarization rotation(NPR) with different net anomalous dispersion is demonstrated. When the cavity dispersion is-1.425 ps^2, the noise-like(NL) pulse w...A mode-locked thulium-doped fiber laser(TDFL) based on nonlinear polarization rotation(NPR) with different net anomalous dispersion is demonstrated. When the cavity dispersion is-1.425 ps^2, the noise-like(NL) pulse with coherence spike width of 406 fs and pulse energy of 12.342 nJ is generated at a center wavelength of 2003.2 nm with 3 dB spectral bandwidth of 23.20 nm. In the experimental period of 400 min, the 3 dB spectral bandwidth variation, the output power fluctuation, and the central wavelength shift are less than 0.06 nm, 0.04 d B, and0.4 nm, respectively, indicating that the NPR-based TDFL operating in the NL regime holds good long-term stability.展开更多
The pulse dynamics of harmonic mode-locking in a dissipative soliton resonance(DSR) region in an erbiumdoped fiber ring laser is investigated at different values of anomalous dispersion. The fiber laser is mode-locked...The pulse dynamics of harmonic mode-locking in a dissipative soliton resonance(DSR) region in an erbiumdoped fiber ring laser is investigated at different values of anomalous dispersion. The fiber laser is mode-locked by a nonlinear polarization rotation technique. By inserting 0–200 m anomalous dispersion single-mode fiber in the laser cavity, the cavity length is changed from 17.3 to 217.3 m, and the corresponding dispersion of the cavity ranges from -0.27 to-4.67 ps^2. The observed results show that the tuning range of repetition rate under a harmonic DSR condition is highly influenced by the cavity dispersion. Furthermore, it is found that, by automatically adjusting their harmonic orders, the lasers can work at certain values of repetition rate, which are independent of the cavity length and dispersion. The pulses at the same repetition rate in different laser configurations have similar properties, demonstrating that each achievable repetition rate represents an operation regime of harmonic DSR lasers.展开更多
Two-dimensional(2D) materials have emerged as attractive mediums for fabricating versatile optoelectronic devices. Recently, few-layer molybdenum disulfide(MoS2), as a shining 2D material, has been discovered to p...Two-dimensional(2D) materials have emerged as attractive mediums for fabricating versatile optoelectronic devices. Recently, few-layer molybdenum disulfide(MoS2), as a shining 2D material, has been discovered to possess both the saturable absorption effect and large nonlinear refractive index. Herein, taking advantage of the unique nonlinear optical properties of MoS2, we fabricated a highly nonlinear saturable absorption photonic device by depositing the few-layer MoS2 onto the microfiber. With the proposed MoS2 photonic device, apart from the conventional soliton patterns, the mode-locked pulses could be shaped into some new soliton patterns, namely,multiple soliton molecules, localized chaotic multipulses, and double-scale soliton clusters. Our findings indicate that the few-layer MoS2-deposited microfiber could operate as a promising highlynonlinear photonic device for the related nonlinear optics applications.展开更多
We experimentally show dark pulse generation in all-normal dispersion multiwavelength erbium-doped fiber laser(EDFL) with a long cavity of figure-of-eight configuration. The EDFL generates a stable multiwavelength l...We experimentally show dark pulse generation in all-normal dispersion multiwavelength erbium-doped fiber laser(EDFL) with a long cavity of figure-of-eight configuration. The EDFL generates a stable multiwavelength laser with 0.47 nm spacing at 24 m W threshold pump power, while the number of lines obtained increases with the pump power. A dark pulse emission is observed as the pump power is increased above 137 m W, with fundamental repetition rate of 29 k Hz and pulse width of 2.7 μs. It is observed that the dark pulse train can be shifted to second-, third-, and fourth-order harmonic dark pulses by carefully adjusting the polarization controller. For the fundamental dark pulse, the maximum pulse energy of 32.4 n J is obtained at pump power of 146.0 mW.展开更多
44.6 fs pulses from a 257 MHz, mode-locked non-polarization maintaining Er-doped fiber laser based on a biased nonlinear amplifying loop mirror are reported. The output power is 104 mW and the single-pulse energy is 0...44.6 fs pulses from a 257 MHz, mode-locked non-polarization maintaining Er-doped fiber laser based on a biased nonlinear amplifying loop mirror are reported. The output power is 104 mW and the single-pulse energy is 0.4 nJ. The minimum pulse duration of the direct output is 44.6 fs, which is the shortest in this kind of laser.展开更多
基金Supported by the National High Technology Research and Development Program of China under Grant No 2014AA041901NSAF Foundation of the National Natural Science Foundation of China under Grant No U1330134+1 种基金the Opening Project of Shanghai Key Laboratory of All Solid-State Laser and Applied Techniques under Grant No 2012ADL02the National Natural Science Foundation of China under Grant Nos 61308024 and 11174305
文摘The wavelength-tunable and switchable narrow bandwidth mode-locking operation is demonstrated in an all fiber laser based on semiconductor-saturable absorber mirror (SESAM). Two narrow-band fiber Bragg gratings centered at 1029.9nm and 1032nm respectively with a polarization controller inserted between them are used to realize the wavelength switchable between 1029.9nm and 1032nm. The laser delivers different pulse widths of 7.5ps for 1030nm and 20ps for 1032nm. The maximum output power for both could reach -6.5mW at single pulse operation. The output wavelength couM be tuned to about 0.gnm intervals ranging from 1030.2nm to 1031.1 nm and from 1032.15nm to 1033.7nm with the temperature change of the fiber Bragg grating, respectively.
基金Supported by the National Key Research and Development Program of China under Grant No 2017YFB1104500the Science and Technology Project of Guangdong Province under Grant Nos 20148090903014,20158090920003,20168090917002 and20168090926004
文摘We demonstrate a self-starting erbium fiber oscillator-amplifier system based on the nonlinear polarization rota- tion mode-locked mechanism. The direct output pulse from the amplifier is 47fs with an average power of 1.22 W and a repetition rate of 50 MHz, corresponding to a pulse energy of 24 nJ. The full width at half-maximum of the spectrum of the output pulses is approximately 93nm at a central wavelength of 1572nm so that the transform- limited pulse duration is as short as 39 fs. Due to the imperfect dispersion compensation, we compress the pulses to 47fs in this experiment.
基金Project supported by the National High Technology Research and Development Program of China(Grant No.2011AA8042032)the National Natural Science Foundation of China(Grant Nos.61077034 and 61301190)
文摘A theoretical analysis of noise in a high-power cascaded fiber amplifier is presented. Unlike the noise theory in low power communication, the noise of a high power system is redefined as the leaked output energy between pulses with coherent beat noise uncounted. This definition is more appropriate for high power usage in which the pulse energy receives more attention than the pulse shape integrity. Then the low power pre-amplifying stages are considered as linear amplification and analyzed by linear theory. In the high-power amplification stages, the inversion is assumed to recover linearly in the time interval between pulses. The time shape of the output pulse is different from that of the input signal because of different gains at the front and back ends of the pulse. Then, a criterion is provided to distinguish the nonlinear and linear amplifications based on the signal-to-noise ratio (SNR) analysis. Then, an experiment that shows that the output SNR actually drops off in nonlinear amplification is performed. The change in the noise factor can be well evaluated by pulse shape distortion.
文摘A harmonic dark pulse generation in an erbium-doped fiber laser is demonstrated based on a figure-of-eight configuration. It is found that the harmonic dark pulse can be shifted from the fundamental to the 5th order harmonic by increasing the pump power with an appropriate polarization controller orientation. The fundamental repetition rate of 2O kHz is obtained at the pump power of 29 m W. The highest pulse energy of 42.6 n3 is obtained at the fundamental repetition rate. The operating frequency of the dark pulse trains shifts to 2nd, 3rd, 4th and 5th harmonic as the pump powers are increased to 34mW, 50mW, 59mW and 137mW, respectively.
基金Supported by the National Natural Science Foundation of China under Grant No 61705183the Central University Special Fund Basic Research and Operating Expenses under Grant No GK201702005+1 种基金the Natural Science Foundation of Shaanxi Province under Grant No 2017JM6091the Fundamental Research Funds for the Central Universities under Grant No 2017TS011
文摘Using the reduced graphene oxide(rGO) as a saturable absorber(SA) in an Er-doped fiber(EDF) laser cavity,we obtain the Q-switching operation. The rGO SA is prepared by depositing the GO on fluorine mica(FM) using the thermal reduction method. The modulation depth of rGO/FM is measured to be 3.2%. By incorporating the rGO/FM film into the EDF laser cavity, we obtain stable Q-switched pulses. The shortest pulse duration is3.53 μs, and the maximum single pulse energy is 48.19 nJ. The long-term stability of working is well exhibited.The experimental results show that the rGO possesses potential photonics applications.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11204328,61221064,61078037,11127901,11134010,and 61205208)the National Basic Research Program of China(Grant No.2011CB808101)the Natural Science Foundation of Shanghai,China(Grant No.13ZR1414800)
文摘We numerically study the pulse compression approaches based on atomic or molecular gases in a hollow-core fiber.From the perspective of self-phase modulation(SPM), we give the extensive study of the SPM influence on a probe pulse with molecular phase modulation(MPM) effect. By comparing the two compression methods, we summarize their advantages and drawbacks to obtain the few-cycle pulses with micro- or millijoule energies. It is also shown that the double pump-probe approach can be used as a tunable dual-color source by adjusting the time delay between pump and probe pulses to proper values.
基金Supported by the National Natural Science Foundation of China under Grant No 60977032the Program for Innovation Research of Science of Harbin Institute of Technology(PIRS-HIT)under Grant No T201407
文摘From Maxwell's equations and Post's formalism, a generalized chiral nonlinear Schr6dinger equation (CNLSE) is obtained for the nonlinear chiral fiber. This equation governs light transmission through a dispersive nonlinear chiral fiber with joint action of chirality in linear and nonlinear ways. The generalized CNLSE shows a modu- lation of chirality to the effect of attenuation and nonlinearity compared with the case for a conventional fiber. Simulations based on the split-step beam propagation method reveal the role of nonlinearity with cooperation to chirality playing in the pulse evolution. By adjusting its strength the role of chirality in forming solitons is demonstrated for a given circularly polarized component. The application of nonlinear optical rotation is also discussed in an all-optical switch.
文摘After a half century of development, fiber laser has evolved from a concept to a great family penetrating into various fields of applications. This paper reviews the history and current development of fiber lasers, with topics covering both continuous wave and short pulse fiber lasers. Important issues such as the major rare earth dopants, fiber laser brightness, polarization effects, clad pumping technology, beam combination, mode locking and pulse shaping are discussed in this paper.
基金supported by the National Natural Science Foundation of China (Grant Nos. 60878011 and 61078008)the Program for New Century ExcellentTalents in University,China (Grant No. NCET-10-0067)
文摘In this paper, the theoretical rate equation model of an in-band pumped gain-switched thulium-doped fiber (TDF) laser is investigated. The analytical formulations of pump energy threshold, peak power extraction efficiency, and pulse extraction efficiency are derived through analyzing the interaction process between the pump pulse and the laser pulse. They are useful for understanding, designing, and optimizing the in-band pumped TDF lasers in a 1.9 μm-2.1 μm wavelength region. The experiment with an all-fiber gain-switched TDF laser pumped by a 1.558-μm pulse amplifier is conducted, and our experimental results show good agreement with theoretical analysis.
基金supported by the National Natural Science Foundation of China(Nos.51705249, 52075255)the China Postdoctoral Science Foundation (No.2019M661823)
文摘Silicon carbide particle reinforced aluminum matrix composites(SiCp/Al composites)are widely used in aviation,aerospace and electronic package.However,low machining efficiency,severe tool wear and poor surface quality are severe during the machining of SiCp/Al composites.Laser-induced oxidation is capable to improve the machinability of SiCp/Al composites.The material response of 55%(volume fraction)SiCp/Al composites induced by a nanosecond pulsed laser is studied.A metamorphic layer which is composed of an oxide layer and sub-layer is produced.The effects of reaction surrounding and laser average power on the microstructure and thickness of the oxide layer and sub-layer are investigated.Experimental results show that:A thicker oxide layer and a sub-layer are formed in an oxygen-rich atmosphere.The oxides are mainly composed of 2Al2O3·SiO2(mullite).A positive correlation between the laser average power and thicknesses of oxide layers and sub-layers is found.A loose oxide layer of 138μm and a sub-layer of 21μm are formed at the laser average power of 6 W,laser scanning pitch of 10μm,and laser scanning speed of 1 mm/s under an oxygen-rich atmosphere.The high efficient machining of Si Cp/Al composites can be realized by laser-induced oxidation.
基金Project supported by the National Natural Science Foundation of China(Grant No.11304409)the Natural Science Foundation of Chongqing City,China(Grant No.CSTC2013jcyj A4004)+1 种基金the Scientific and Technological Research Program of Chongqing Municipal Education Commission,China(Grant No.KJ1500422)the Special Theme Projects on LCD Industrial Generic Technology Innovation of Chongqing City,China(Grant No.CSTC2015zdcyztzx40003)
文摘We demonstrated a 2-μm passively mode-locked nanosecond fiber laser based on a MoS2 saturable absorber(SA).Owing to the effect of nonlinear absorption in the MoS2 SA, the pulse width decreased from 64.7 to 13.8 ns with increasing pump power from 1.10 to 1.45 W. The use of a narrow-bandwidth fiber Bragg grating resulted in a central wavelength and 3-dB spectral bandwidth of 2010.16 and 0.15 nm, respectively. Experimental results show that MoS2 is a promising material for a 2-μm mode-locked fiber laser.
基金supported by National Natural Science Foundation of China (No.612050346)the Shenzhen Municipal Science and Technology Plan (Nos.2010B090400306,JC201105160592A,and JCYJ 20120613150130014)
文摘We reported on the generation of the dual-wavelength rectangular pulse in an erbium-doped fiber laser(EDFL)with a topological insulator saturable absorber.The rectangular pulse could be stably initiated with pulse width from 13.62 to 25.16 ns and fundamental repetition rate of 3.54 MHz by properly adjusting the pump power and the polarization state.In addition,we verified that the pulse shape of the dual-wavelength rectangular pulse can be affected by the total net cavity dispersion in the fiber laser.Furthermore,by properly rotating the polarization controllers,the harmonic mode-locking operation of the dual-wavelength rectangular pulse was also obtained.The dual-wavelength rectangular pulse EDFL would benefit some potential applications,such as spectroscopy,biomedicine,and sensing research.
基金partially supported by the National Natural Science Foundation of China(Nos.62075126 and 62005161)the Chenguang Program。
文摘We report on a grating-free fiber chirped pulse amplifier(CPA)at 2.8μm for the first time.The CPA system adopted Er:ZBLAN fiber with large anomalous dispersion as the stretcher and germanium(Ge)rods as the compressor with a compact structure.High-energy picosecond pulses of 2.07μJ were generated at the repetition rate of 100 kHz.Using highly dispersive Ge rods,the amplified pulses were compressed to 408 fs with a pulse energy of 0.57μJ,resulting in a peak power of approximately 1.4 MW.A spectral broadening phenomenon in the main amplifier was observed,which was caused by the special gain shape of the Er:ZBLAN fiber amplifier in operation and confirmed by our numerical simulation.This compact fiber CPA system at 2.8μm will be practical and meaningful for application fields.
文摘Switchable single and double Brillouin multiwavelength and pulsed laser is successfully demonstrated. Brillouin spacing can be switched from single(0.08 nm) to double spacing(0.16 nm) or vice versa by swapping the ports of the coupler in the proposed configuration. The proposed configuration can also be used to produce pulsed laser by inserting a home-made carbon nanotubes saturable absorber into the laser cavity. The proposed system is very versatile and flexible as it can be used as a multiwavelength laser or pulsed laser to cater for different types of applications.
基金This work was supPorted by the Henan Cultivatlon Project for University Innovatlon Thlents.
文摘We demonstrate the generation of supercontinuum (SC) of over 1350 nm by injecting 790-nm, 15-fs, 74-MHz optical pulses into a 183-mm-long microstructured fiber with combination core and random cladding. The maximum total power of SC is 73 mW with 290-mW pump power from 40x microscope objective. The wavelength and power ranging in SC as well as the polarization states and waveguide modes of the visible light can be tuned by adjusting the input end of MF.In particular, white light has been observed. To our knowledge, this is the first report of tunable properties in SC generation process using microstructured fiber with combination core and random cladding.
基金Fundamental Research Funds for the Central Universities(2016YJS034)
文摘A mode-locked thulium-doped fiber laser(TDFL) based on nonlinear polarization rotation(NPR) with different net anomalous dispersion is demonstrated. When the cavity dispersion is-1.425 ps^2, the noise-like(NL) pulse with coherence spike width of 406 fs and pulse energy of 12.342 nJ is generated at a center wavelength of 2003.2 nm with 3 dB spectral bandwidth of 23.20 nm. In the experimental period of 400 min, the 3 dB spectral bandwidth variation, the output power fluctuation, and the central wavelength shift are less than 0.06 nm, 0.04 d B, and0.4 nm, respectively, indicating that the NPR-based TDFL operating in the NL regime holds good long-term stability.
基金National Natural Science Foundation of China(NSFC)(61435003,61421002,61327004,61377042,61505024,61378028)Science and Technology Project of Sichuan Province(2016JY0102)
文摘The pulse dynamics of harmonic mode-locking in a dissipative soliton resonance(DSR) region in an erbiumdoped fiber ring laser is investigated at different values of anomalous dispersion. The fiber laser is mode-locked by a nonlinear polarization rotation technique. By inserting 0–200 m anomalous dispersion single-mode fiber in the laser cavity, the cavity length is changed from 17.3 to 217.3 m, and the corresponding dispersion of the cavity ranges from -0.27 to-4.67 ps^2. The observed results show that the tuning range of repetition rate under a harmonic DSR condition is highly influenced by the cavity dispersion. Furthermore, it is found that, by automatically adjusting their harmonic orders, the lasers can work at certain values of repetition rate, which are independent of the cavity length and dispersion. The pulses at the same repetition rate in different laser configurations have similar properties, demonstrating that each achievable repetition rate represents an operation regime of harmonic DSR lasers.
基金supported in part by the National Natural Science Foundation of China (Grant Nos. 11474108, 61378036, 61307058, 11304101, 11074078)the PhD Start-up Fund of Natural Science Foundation of Guangdong Province, China (Grant No. S2013040016320)+2 种基金the Scientific and Technological Innovation Project of Higher Education Institute, Guangdong, China (Grant No. 2013KJCX0051)the financial support from the Guangdong Natural Science Funds for Distinguished Young Scholarthe Zhujiang New-star Plan of Science & Technology in Guangzhou City (Grant No. 2014J2200008)
文摘Two-dimensional(2D) materials have emerged as attractive mediums for fabricating versatile optoelectronic devices. Recently, few-layer molybdenum disulfide(MoS2), as a shining 2D material, has been discovered to possess both the saturable absorption effect and large nonlinear refractive index. Herein, taking advantage of the unique nonlinear optical properties of MoS2, we fabricated a highly nonlinear saturable absorption photonic device by depositing the few-layer MoS2 onto the microfiber. With the proposed MoS2 photonic device, apart from the conventional soliton patterns, the mode-locked pulses could be shaped into some new soliton patterns, namely,multiple soliton molecules, localized chaotic multipulses, and double-scale soliton clusters. Our findings indicate that the few-layer MoS2-deposited microfiber could operate as a promising highlynonlinear photonic device for the related nonlinear optics applications.
文摘We experimentally show dark pulse generation in all-normal dispersion multiwavelength erbium-doped fiber laser(EDFL) with a long cavity of figure-of-eight configuration. The EDFL generates a stable multiwavelength laser with 0.47 nm spacing at 24 m W threshold pump power, while the number of lines obtained increases with the pump power. A dark pulse emission is observed as the pump power is increased above 137 m W, with fundamental repetition rate of 29 k Hz and pulse width of 2.7 μs. It is observed that the dark pulse train can be shifted to second-, third-, and fourth-order harmonic dark pulses by carefully adjusting the polarization controller. For the fundamental dark pulse, the maximum pulse energy of 32.4 n J is obtained at pump power of 146.0 mW.
基金supported in part by the National Natural Science Foundation of China(Nos.1162780027,31327901,and 61761136002)the Major National Basic Research Program of China(No.2013CB922401)the National Key Scientific Instrument and Equipment Development Program(No.2012YQ140005)
文摘44.6 fs pulses from a 257 MHz, mode-locked non-polarization maintaining Er-doped fiber laser based on a biased nonlinear amplifying loop mirror are reported. The output power is 104 mW and the single-pulse energy is 0.4 nJ. The minimum pulse duration of the direct output is 44.6 fs, which is the shortest in this kind of laser.