The noise feature of a single-mode class-A laser amplifier is investigated by solving the Maxwell–Bloch equations of motion in the presence of the fluctuation force of cavity Langevin.The aim is to calculate the simu...The noise feature of a single-mode class-A laser amplifier is investigated by solving the Maxwell–Bloch equations of motion in the presence of the fluctuation force of cavity Langevin.The aim is to calculate the simultaneous fluctuations that are superimposed on the amplitude and phase of the cavity electric field, as well as the atomic population inversion. The correlation function of these fluctuations yields the amplitude, phase, and spontaneous emission noise fluxes, respectively. The amplitude and spontaneous emission noise fluxes exhibit the Lorentzian profiles in both the below-threshold state and the injection-locking region of the above-threshold state. While noise is typically viewed negatively in science and engineering, this research highlights its positive role as a valuable tool for measuring the optical properties of a laser amplifier. For instance, the degree of first-order temporal coherence(DFOTC) is derived by taking the Fourier transform of the amplitude noise flux. The damping rate of DFOTC is associated with the coherence time of the light emitted by the laser amplifier. Furthermore, the uncertainty relation between noise bandwidth and coherence time is confirmed. Finally, it is demonstrated that the input pumping noise flux, together with the output amplitude and spontaneous emission noise fluxes, satisfy the principle of flux conservation.展开更多
<div style="text-align:justify;"> A new planar waveguide laser was demonstrated. The output energy of 400 mW was achieved by a single waveguide laser;the slope efficiency was 61%. The single waveguide ...<div style="text-align:justify;"> A new planar waveguide laser was demonstrated. The output energy of 400 mW was achieved by a single waveguide laser;the slope efficiency was 61%. The single waveguide laser can expand to waveguide laser group and waveguide laser array to produce higher energy. </div>展开更多
A high efficiency compact Yb:KGW regenerative amplifier using an all-fiber laser seed source was comprehensively studied.With thermal lensing effect compensated by the cavity design,the compressed pulses with energy o...A high efficiency compact Yb:KGW regenerative amplifier using an all-fiber laser seed source was comprehensively studied.With thermal lensing effect compensated by the cavity design,the compressed pulses with energy of 1 mJ at 1 kHz and 0.4 mJ at 10 kHz in sub-400-fs pulse duration using chirped fiber Bragg grating(CFBG)stretcher were demonstrated.A modified Frantz-Nodvik equation was developed to emulate the dynamic behavior of the regenerative amplifier.The simulation results were in good agreement with the experiment.Numerical simulations and experimental results show that the scheme can be scalable to higher energy of multi-mJ,sub-300 fs pulses.展开更多
This paper presents an investigation of specific optical fiber core mode leakage behavior that occurs in high-power double-clad fiber lasers as a result of thermally-induced refractive index variations. A model of the...This paper presents an investigation of specific optical fiber core mode leakage behavior that occurs in high-power double-clad fiber lasers as a result of thermally-induced refractive index variations. A model of the power transfer between the core modes and the cladding modes during thermally-induced refractive index variations is established based on the mode coupling theory. The results of numerical simulations based on actual laser parameters are presented. Experimental measurements were also carried out, the results showed good agreement with the corresponding simulation results.展开更多
After considering Kerr nonlinear effect, group velocity dispersion of host and gain distribution of active particle in laser amplifying medium, a basic equation describing propagation of the coupling optical pulse und...After considering Kerr nonlinear effect, group velocity dispersion of host and gain distribution of active particle in laser amplifying medium, a basic equation describing propagation of the coupling optical pulse under the multi-photon nonlinear Compton scattering in the laser amplifying medium has been deduced. Besides, the profile and power spectrum of a picosecond-level super-Gaussian coupling pulse in the laser amplifying medium have been discussed when its central frequency coincides with the gain peak frequency of the laser amplifying medium.展开更多
A low-repetition-rate, all-polarization-maintaining（PM）-fiber sub-nanosecond oscillator is presented, which is simple and low-cost, composed of standard components. The ring cavity is elongated by 114-m-long standar...A low-repetition-rate, all-polarization-maintaining（PM）-fiber sub-nanosecond oscillator is presented, which is simple and low-cost, composed of standard components. The ring cavity is elongated by 114-m-long standard PM fiber, and passively mode-locked by a fiber pigtailed semiconductor saturable absorber. Linearly polarized pulses with 1.66 MHz repetition rate and 22 dB polarization extinction ratio are generated at a wavelength of 1030 nm, which is determined by an intracavity filter. In addition, to demonstrate that the oscillator is a good seed for high energy pulse generation, an all-fiber master oscillator power amplifier is built and amplified pulses with energy about 2 μJ are obtained.展开更多
We report a diode-pumped rod-type Yb:YAG laser amplifier operating at 1 kHz.Cryogenic cooling method was adopted to make the Yb:YAG crystal work with four-level behavior.A single-frequency fiber laser acts as the seed...We report a diode-pumped rod-type Yb:YAG laser amplifier operating at 1 kHz.Cryogenic cooling method was adopted to make the Yb:YAG crystal work with four-level behavior.A single-frequency fiber laser acts as the seed in an actively Q-switched Yb:YAG oscillator.The resonator delivers 5.75-mJ pulses at 1 kHz with a pulse duration of approximately 40 ns.The pulses were amplified to 61 mJ in a four-pass rod-type Yb:YAG amplifier with optical-to-optical efficiency of 24%in the main amplifier.The M^(2)parameter of the output laser is<1.4.展开更多
We report the generation of 207-fs pulses with 1.2 mW average power at 1036 nm directly from a passively modelocked Yb-doped fibre laser with a nonlinear optical loop mirror for mode-locking and pairs of diffraction g...We report the generation of 207-fs pulses with 1.2 mW average power at 1036 nm directly from a passively modelocked Yb-doped fibre laser with a nonlinear optical loop mirror for mode-locking and pairs of diffraction gratings for intracavity dispersion compensation. These results imply a 4-fold reduction in pulse duration over previously reported figure-of-eight cavity passively mode-locked Yb-doped fibre lasers. Stable pulse trains are produced at the fundamental repetition rate of the resonator, 24.0 MHz. On the other hand, this laser offers a cleaner spectrum and greater stability and is completely self-starting.展开更多
A high power Nd：YAG end-pumped slab amplifier chain with a Nd：YVO4 innoslab laser as the master oscillator is demonstrated. A chain output power of 5210 W with beam quality of 4 times the diffraction limit is achiev...A high power Nd：YAG end-pumped slab amplifier chain with a Nd：YVO4 innoslab laser as the master oscillator is demonstrated. A chain output power of 5210 W with beam quality of 4 times the diffraction limit is achieved by double-passing the first amplifier stage and single-passing the second stage with an optical efficiency of 29% while working at a frequency of 1kHz and pulse width of 200 μs.展开更多
In this paper,to reduce the damage or absorption caused by radiation to optical fibers,we study lightweight and flexible anti-radiation films based on optical precision deposition technology.At first,anti-radiation co...In this paper,to reduce the damage or absorption caused by radiation to optical fibers,we study lightweight and flexible anti-radiation films based on optical precision deposition technology.At first,anti-radiation composite thin films based on Kapton,ITO,and Cu(or Al)are designed and homemade with different structures.Subsequently,polarization-maintaining(PM)Yb-doped fiber(Yb-fiber)samples protected by these different kinds of anti-radiation films are irradiated with a dose of∼150 kGy.At last,we comparatively investigate(1)the radiation-induced attenuation(RIA)of these PM Yb-fiber samples and(2)the lasing performance(threshold and slope efficiency)and gain performance of a 1064 nm fiber laser and amplifier using these irradiated PM Yb-fibers as the gain medium,respectively.The results show that such a film can reduce the RIA of the irradiated Yb-fiber by up to 2.84 dB/m and increase the output power by up to 75.3%at most.In addition,we also study the optical recovery of the PM Yb-fibers after radiation.展开更多
We theoretically discuss 40 Gb/s semiconductor optical amplifier （SOA）-based wavelength conversion （WC） using a detuning optical bandpass Jilter based on ultrafast dynamic characteristics of SOA. Both the inverted...We theoretically discuss 40 Gb/s semiconductor optical amplifier （SOA）-based wavelength conversion （WC） using a detuning optical bandpass Jilter based on ultrafast dynamic characteristics of SOA. Both the inverted and noninverted WCs are obtained by shifting the filter central wavelength with respect to the probe wavelength when input data signal is in return-to-zero （RZ） format. However, we can obtain format conversion from nonreturn- to-zero （NRZ） to pseudo-return-to-zero （PRZ） and inverted WC when the input signal is in NRZ format.展开更多
A review on the progress of powerful 2 μm silica fiber sources in past decades is presented. We review the state-of-the-art records and representative achievements of 2 μm high-average-power continuous- wave, pulsed...A review on the progress of powerful 2 μm silica fiber sources in past decades is presented. We review the state-of-the-art records and representative achievements of 2 μm high-average-power continuous- wave, pulsed fiber lasers and amplifiers, and powerful superfluorescent sources. Challenges which limit the further power scaling of 2 μm silica fiber sources are discussed, including pumping brightness limitation, thermal problem and nonlinear effects. Potential and promising roadmaps to go beyond these limitations, like tandem pumping and beam combining, are discussed. Prospects of powerful 2 μm silica fiber sources are also presented in the end of paper.展开更多
A series of 2,5-diaminoterephthalates with a simple structure were synthesized through one-step reaction, and their bar-shaped single crystals with a large size and a smooth surface have been obtained via the solvent-...A series of 2,5-diaminoterephthalates with a simple structure were synthesized through one-step reaction, and their bar-shaped single crystals with a large size and a smooth surface have been obtained via the solvent-evaporation method. These crystals exhibit bright emission with fluorescence quantum yields higher than 0.2. They display the waveguide property, and low optical loss coefficients for waveguide have been determined for the crystal of one compound. In addition, the crystal can cause linear polarization of the light emitted from it, with a high polarization contrast of 0.70. Most importantly, these crystals can realize amplified spontaneous emission （ASE）, including the red ASE, with appreciable energy thresholds of 72-198 kW/cm^2 and high gain coefficients, which suggests the potential of these crystals for the application in organic solid-state lasers.展开更多
Theoretical and experimental studies of the influence of the mode competition on the output beam quality of fiber amplifiers are presented. Rate equations and modal decomposition method are used in the theoretical mod...Theoretical and experimental studies of the influence of the mode competition on the output beam quality of fiber amplifiers are presented. Rate equations and modal decomposition method are used in the theoretical model. In the experiment, the output beam-quality factor of a fiber amplifier, which is based on a Yb-doped double-clad large mode area fiber as a function of the seed beam quality and the pump power of the amplifier, is measured. The experimental results are consistent with the theoretical analysis.展开更多
Side-pumping fibre combiners offer several advantages in fibre laser design,including distributed pump absorption,reduced heat load,and improved flexibility and reliability.These benefits are particularly important fo...Side-pumping fibre combiners offer several advantages in fibre laser design,including distributed pump absorption,reduced heat load,and improved flexibility and reliability.These benefits are particularly important for all-fibre lasers and amplifiers operating in the mid-IR wavelength range and based on soft-glass optical fibres.However,conventional fabrication methods face limitations due to significant differences in the thermal properties of pump-delivering silica fibres and signal-guiding fluoride-based fibres.To address these challenges,this work introduces a design for a fuse-less side-polished(D-shaped)fibre-based pump combiner comprising multimode silica and double-clad fluoride-based fibres.The results demonstrate stable coupling efficiency exceeding 80%at a 980-nm wavelength over 8 hours of continuous operation under active thermal control.The developed pump combiner has also been successfully integrated into a linear Er-doped fibre laser cavity,showing continuous-wave generation at 2731 or 2781-nm central wavelength with an output power of 0.87 W.Overall,this innovative approach presents a simple,repeatable,and reproducible pump combiner design that opens up new possibilities for leveraging fibre-based component technology in soft glass matrices and other emerging fibres with unique compositions.展开更多
High gain greater than 106 is crucial for the preamplifiers of joule-class high-energy lasers.In this work,we present a specially designed compact amplifier using 0.5%Nd,5%Gd:SrF_(2)and 0.5%Nd,5%Y:SrF_(2)crystals.The ...High gain greater than 106 is crucial for the preamplifiers of joule-class high-energy lasers.In this work,we present a specially designed compact amplifier using 0.5%Nd,5%Gd:SrF_(2)and 0.5%Nd,5%Y:SrF_(2)crystals.The irregular crystal shape enhances the gain length of the laser beam and helps suppress parasitic oscillations.The amplified spontaneous emission(ASE)induced by the high gain is analyzed through ray tracing.The balance between gain and ASE is estimated via numerical simulation.The gain spectral characteristics of the two-stage two-pass amplifier are examined,demonstrating the advantages of using different crystals,with bandwidths up to 8 nm and gains over 106.In addition,the temperature and stress distributions in the Nd,Gd:SrF_(2)crystal are simulated.This work is expected to contribute to the development of high-peak-power(≥terawatt-class)high-energy(joule-class)laser devices.展开更多
This paper presents an innovative eight-pass laser amplifier design that effectively utilizes polarization and angular multiplexing,enjoying high gain,high extraction efficiency and compact layout.To optimize the desi...This paper presents an innovative eight-pass laser amplifier design that effectively utilizes polarization and angular multiplexing,enjoying high gain,high extraction efficiency and compact layout.To optimize the design parameters,a general spatiotemporal model for a multi-pass amplifier is established that accounts for beam passages in different angles,and the predicted output energy and gain distribution agree well with the experimental results.The multi-pass amplifier scales the seed energy of 120 mJ to 5 J at 10 Hz and 3 J at 50 Hz,with the beam quality within three times the diffraction limit.展开更多
This work investigates spatial evolution characteristics during second-harmonic generation(SHG)through numerical and experimental study by employing a dual-pass Nd:YLF amplifier chain.Through simultaneous monitoring o...This work investigates spatial evolution characteristics during second-harmonic generation(SHG)through numerical and experimental study by employing a dual-pass Nd:YLF amplifier chain.Through simultaneous monitoring of conversion efficiency dynamics and beam profile evolution,we demonstrate that the spatial uniformity follows deterministic transformation patterns during nonlinear frequency conversion.Notably,optimization of beam uniformity was achieved at the fundamental power density of 0.478 GW/cm2in our configuration,while maintaining conversion efficiency exceeding 85%.展开更多
We present a lamp-pumped Nd： phosphate glass laser amplifier delivering up to 1 J of pulse energy at 1053 nm with a repetition rate of 1 Hz and an injected pulse energy of 2.5 mJ. The amplifier system employs a beams...We present a lamp-pumped Nd： phosphate glass laser amplifier delivering up to 1 J of pulse energy at 1053 nm with a repetition rate of 1 Hz and an injected pulse energy of 2.5 mJ. The amplifier system employs a beamshaping module and a four-pass, lamp-pumped amplifier. The thermally induced wavefront distortion is mitigated and a uniform gain distribution is obtained by a four-lamp-pmnped laser head in the amplifier. Thus, an excellent beam quality is obtained.展开更多
High-power fiber lasers have experienced a dramatic development over the last decade.Further increasing the output power needs an upscaling of the fiber mode area,while maintaining a single-mode output.Here,we propose...High-power fiber lasers have experienced a dramatic development over the last decade.Further increasing the output power needs an upscaling of the fiber mode area,while maintaining a single-mode output.Here,we propose an all-solid anti-resonant fiber(ARF)structure,which ensures single-mode operation in broadband by resonantly coupling higherorder modes into the cladding.A series of fibers with core sizes ranging from 40 to 100µm are proposed exhibiting maximum mode area exceeding 5000µm2.Numerical simulations show this resonant coupling scheme provides a higher-order mode(mainly TE01,TM01,and HE21)suppression ratio of more than 20 dB,while keeping the fundamental mode loss lower than 1 dB/m.The proposed structure also exhibits high tolerance for core index depression.展开更多
文摘The noise feature of a single-mode class-A laser amplifier is investigated by solving the Maxwell–Bloch equations of motion in the presence of the fluctuation force of cavity Langevin.The aim is to calculate the simultaneous fluctuations that are superimposed on the amplitude and phase of the cavity electric field, as well as the atomic population inversion. The correlation function of these fluctuations yields the amplitude, phase, and spontaneous emission noise fluxes, respectively. The amplitude and spontaneous emission noise fluxes exhibit the Lorentzian profiles in both the below-threshold state and the injection-locking region of the above-threshold state. While noise is typically viewed negatively in science and engineering, this research highlights its positive role as a valuable tool for measuring the optical properties of a laser amplifier. For instance, the degree of first-order temporal coherence(DFOTC) is derived by taking the Fourier transform of the amplitude noise flux. The damping rate of DFOTC is associated with the coherence time of the light emitted by the laser amplifier. Furthermore, the uncertainty relation between noise bandwidth and coherence time is confirmed. Finally, it is demonstrated that the input pumping noise flux, together with the output amplitude and spontaneous emission noise fluxes, satisfy the principle of flux conservation.
文摘<div style="text-align:justify;"> A new planar waveguide laser was demonstrated. The output energy of 400 mW was achieved by a single waveguide laser;the slope efficiency was 61%. The single waveguide laser can expand to waveguide laser group and waveguide laser array to produce higher energy. </div>
基金Project supported by Major Program of the National Natural Science Foundation of China (Grant No. 12034020)the National Natural Science Foundation of China (Grant No. 61805274)+1 种基金the National Key R&D Program of China (Grant No. 2018YFB1107201)the Synergic Extreme Condition User Facility
文摘A high efficiency compact Yb:KGW regenerative amplifier using an all-fiber laser seed source was comprehensively studied.With thermal lensing effect compensated by the cavity design,the compressed pulses with energy of 1 mJ at 1 kHz and 0.4 mJ at 10 kHz in sub-400-fs pulse duration using chirped fiber Bragg grating(CFBG)stretcher were demonstrated.A modified Frantz-Nodvik equation was developed to emulate the dynamic behavior of the regenerative amplifier.The simulation results were in good agreement with the experiment.Numerical simulations and experimental results show that the scheme can be scalable to higher energy of multi-mJ,sub-300 fs pulses.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61307057 and 61675114)
文摘This paper presents an investigation of specific optical fiber core mode leakage behavior that occurs in high-power double-clad fiber lasers as a result of thermally-induced refractive index variations. A model of the power transfer between the core modes and the cladding modes during thermally-induced refractive index variations is established based on the mode coupling theory. The results of numerical simulations based on actual laser parameters are presented. Experimental measurements were also carried out, the results showed good agreement with the corresponding simulation results.
文摘After considering Kerr nonlinear effect, group velocity dispersion of host and gain distribution of active particle in laser amplifying medium, a basic equation describing propagation of the coupling optical pulse under the multi-photon nonlinear Compton scattering in the laser amplifying medium has been deduced. Besides, the profile and power spectrum of a picosecond-level super-Gaussian coupling pulse in the laser amplifying medium have been discussed when its central frequency coincides with the gain peak frequency of the laser amplifying medium.
基金Project supported by the Initiative Research Program of State Key Laboratory of Precision Measurement Technology and Instruments,Chinathe National Natural Science Foundation of China(Grant No.51527901)
文摘A low-repetition-rate, all-polarization-maintaining（PM）-fiber sub-nanosecond oscillator is presented, which is simple and low-cost, composed of standard components. The ring cavity is elongated by 114-m-long standard PM fiber, and passively mode-locked by a fiber pigtailed semiconductor saturable absorber. Linearly polarized pulses with 1.66 MHz repetition rate and 22 dB polarization extinction ratio are generated at a wavelength of 1030 nm, which is determined by an intracavity filter. In addition, to demonstrate that the oscillator is a good seed for high energy pulse generation, an all-fiber master oscillator power amplifier is built and amplified pulses with energy about 2 μJ are obtained.
基金Project supported by the National National Science Foundation of China(Grant Nos.12004262 and 62005184)the Natural Science Foundation of Top Talent of SZTU(Grant No.202024555101039)。
文摘We report a diode-pumped rod-type Yb:YAG laser amplifier operating at 1 kHz.Cryogenic cooling method was adopted to make the Yb:YAG crystal work with four-level behavior.A single-frequency fiber laser acts as the seed in an actively Q-switched Yb:YAG oscillator.The resonator delivers 5.75-mJ pulses at 1 kHz with a pulse duration of approximately 40 ns.The pulses were amplified to 61 mJ in a four-pass rod-type Yb:YAG amplifier with optical-to-optical efficiency of 24%in the main amplifier.The M^(2)parameter of the output laser is<1.4.
基金Project supported by the National Natural Science Foundation of China （Grant Nos 60537060 and 10390160）.
文摘We report the generation of 207-fs pulses with 1.2 mW average power at 1036 nm directly from a passively modelocked Yb-doped fibre laser with a nonlinear optical loop mirror for mode-locking and pairs of diffraction gratings for intracavity dispersion compensation. These results imply a 4-fold reduction in pulse duration over previously reported figure-of-eight cavity passively mode-locked Yb-doped fibre lasers. Stable pulse trains are produced at the fundamental repetition rate of the resonator, 24.0 MHz. On the other hand, this laser offers a cleaner spectrum and greater stability and is completely self-starting.
文摘A high power Nd：YAG end-pumped slab amplifier chain with a Nd：YVO4 innoslab laser as the master oscillator is demonstrated. A chain output power of 5210 W with beam quality of 4 times the diffraction limit is achieved by double-passing the first amplifier stage and single-passing the second stage with an optical efficiency of 29% while working at a frequency of 1kHz and pulse width of 200 μs.
基金supported by the National Key Research and Development Program of China(No.2020YFC2200403)the National Natural Science Foundation of China(No.62375231)the Fujian Province Science and Technology Planning Project of China(No.2022H6015).
文摘In this paper,to reduce the damage or absorption caused by radiation to optical fibers,we study lightweight and flexible anti-radiation films based on optical precision deposition technology.At first,anti-radiation composite thin films based on Kapton,ITO,and Cu(or Al)are designed and homemade with different structures.Subsequently,polarization-maintaining(PM)Yb-doped fiber(Yb-fiber)samples protected by these different kinds of anti-radiation films are irradiated with a dose of∼150 kGy.At last,we comparatively investigate(1)the radiation-induced attenuation(RIA)of these PM Yb-fiber samples and(2)the lasing performance(threshold and slope efficiency)and gain performance of a 1064 nm fiber laser and amplifier using these irradiated PM Yb-fibers as the gain medium,respectively.The results show that such a film can reduce the RIA of the irradiated Yb-fiber by up to 2.84 dB/m and increase the output power by up to 75.3%at most.In addition,we also study the optical recovery of the PM Yb-fibers after radiation.
基金Supported by the National High Technology Developing Programme of China under Grant No 2006AA03Z0414, the National Natural Science Foundation of China under Grant No 60407001, and the New Century Excellent Talent Project in the Ministry of Education of China under Grant No NCET-04-0715.
文摘We theoretically discuss 40 Gb/s semiconductor optical amplifier （SOA）-based wavelength conversion （WC） using a detuning optical bandpass Jilter based on ultrafast dynamic characteristics of SOA. Both the inverted and noninverted WCs are obtained by shifting the filter central wavelength with respect to the probe wavelength when input data signal is in return-to-zero （RZ） format. However, we can obtain format conversion from nonreturn- to-zero （NRZ） to pseudo-return-to-zero （PRZ） and inverted WC when the input signal is in NRZ format.
基金supported by the National Nature Science Foundation of China under Grant No.61322505Innovation Foundation for Graduates of National University of Defense Technology under Grant No.B130704
文摘A review on the progress of powerful 2 μm silica fiber sources in past decades is presented. We review the state-of-the-art records and representative achievements of 2 μm high-average-power continuous- wave, pulsed fiber lasers and amplifiers, and powerful superfluorescent sources. Challenges which limit the further power scaling of 2 μm silica fiber sources are discussed, including pumping brightness limitation, thermal problem and nonlinear effects. Potential and promising roadmaps to go beyond these limitations, like tandem pumping and beam combining, are discussed. Prospects of powerful 2 μm silica fiber sources are also presented in the end of paper.
基金supported by the National Natural Science Foundation of China (Nos. 51622304, 51603082)Open Research Fund of State Key Laboratory of Polymer Physics and Chemistry,Changchun Institute of Applied Chemistry,Chinese Academy of Sciences (No. 201631)
文摘A series of 2,5-diaminoterephthalates with a simple structure were synthesized through one-step reaction, and their bar-shaped single crystals with a large size and a smooth surface have been obtained via the solvent-evaporation method. These crystals exhibit bright emission with fluorescence quantum yields higher than 0.2. They display the waveguide property, and low optical loss coefficients for waveguide have been determined for the crystal of one compound. In addition, the crystal can cause linear polarization of the light emitted from it, with a high polarization contrast of 0.70. Most importantly, these crystals can realize amplified spontaneous emission （ASE）, including the red ASE, with appreciable energy thresholds of 72-198 kW/cm^2 and high gain coefficients, which suggests the potential of these crystals for the application in organic solid-state lasers.
基金Project supported by the National Natural Science Foundation of China(Grant No.61307057)the State Key Laboratory of Tribology,Tsinghua University,China(Grant No.SKLT12B08)and the China Postdoctoral Science Foundation(Grant Nos.2012M520258 and 2013T60109)
文摘Theoretical and experimental studies of the influence of the mode competition on the output beam quality of fiber amplifiers are presented. Rate equations and modal decomposition method are used in the theoretical model. In the experiment, the output beam-quality factor of a fiber amplifier, which is based on a Yb-doped double-clad large mode area fiber as a function of the seed beam quality and the pump power of the amplifier, is measured. The experimental results are consistent with the theoretical analysis.
基金funded by the German Federal Ministry of Education and Research(BMBF)and supervised by the VDI Technology Center under number 13N15464"Leibniz Center for Photonics in Infection Research(LPI):Multidimensional,multimodal,intelligent imaging platforms"The authors also acknowledge the support from the European Regional Development Fund.
文摘Side-pumping fibre combiners offer several advantages in fibre laser design,including distributed pump absorption,reduced heat load,and improved flexibility and reliability.These benefits are particularly important for all-fibre lasers and amplifiers operating in the mid-IR wavelength range and based on soft-glass optical fibres.However,conventional fabrication methods face limitations due to significant differences in the thermal properties of pump-delivering silica fibres and signal-guiding fluoride-based fibres.To address these challenges,this work introduces a design for a fuse-less side-polished(D-shaped)fibre-based pump combiner comprising multimode silica and double-clad fluoride-based fibres.The results demonstrate stable coupling efficiency exceeding 80%at a 980-nm wavelength over 8 hours of continuous operation under active thermal control.The developed pump combiner has also been successfully integrated into a linear Er-doped fibre laser cavity,showing continuous-wave generation at 2731 or 2781-nm central wavelength with an output power of 0.87 W.Overall,this innovative approach presents a simple,repeatable,and reproducible pump combiner design that opens up new possibilities for leveraging fibre-based component technology in soft glass matrices and other emerging fibres with unique compositions.
基金supported by the National Major Project of China (Grant No.GFZX020503.10)the National Natural Science Foundation of China (Grant Nos.12074353,62405298 and 61925508)the CAS Project for Young Scientists in Basic Research (Grant No.YSBR-024)
文摘High gain greater than 106 is crucial for the preamplifiers of joule-class high-energy lasers.In this work,we present a specially designed compact amplifier using 0.5%Nd,5%Gd:SrF_(2)and 0.5%Nd,5%Y:SrF_(2)crystals.The irregular crystal shape enhances the gain length of the laser beam and helps suppress parasitic oscillations.The amplified spontaneous emission(ASE)induced by the high gain is analyzed through ray tracing.The balance between gain and ASE is estimated via numerical simulation.The gain spectral characteristics of the two-stage two-pass amplifier are examined,demonstrating the advantages of using different crystals,with bandwidths up to 8 nm and gains over 106.In addition,the temperature and stress distributions in the Nd,Gd:SrF_(2)crystal are simulated.This work is expected to contribute to the development of high-peak-power(≥terawatt-class)high-energy(joule-class)laser devices.
基金supported by the National Key Research and Development Program of China(Grant No.2022YFB3606300)the Tsinghua University(Department of Precision Instrument)-North Laser Research Institute Co.,Ltd.Joint Research Center for Advanced Laser Technology(Grant No.20216701004)。
文摘This paper presents an innovative eight-pass laser amplifier design that effectively utilizes polarization and angular multiplexing,enjoying high gain,high extraction efficiency and compact layout.To optimize the design parameters,a general spatiotemporal model for a multi-pass amplifier is established that accounts for beam passages in different angles,and the predicted output energy and gain distribution agree well with the experimental results.The multi-pass amplifier scales the seed energy of 120 mJ to 5 J at 10 Hz and 3 J at 50 Hz,with the beam quality within three times the diffraction limit.
基金supported by the National Key R&D Program of China(Nos.2024YFB3613605,2022YFA160440,and 2019YFF01014401)the National Natural Science Foundation of China(Nos.61925507,12388102,62075227,and U21A20138)+3 种基金the National Major Scientific Research Instrument Development Project(No.22227901)the XDB(No.0890101)the Shanghai Rising-Star Program(No.21QA1410200)the Shanghai Science and Technology Committee Program(Nos.22DZ1100300,22560780100,and 23560750200)。
文摘This work investigates spatial evolution characteristics during second-harmonic generation(SHG)through numerical and experimental study by employing a dual-pass Nd:YLF amplifier chain.Through simultaneous monitoring of conversion efficiency dynamics and beam profile evolution,we demonstrate that the spatial uniformity follows deterministic transformation patterns during nonlinear frequency conversion.Notably,optimization of beam uniformity was achieved at the fundamental power density of 0.478 GW/cm2in our configuration,while maintaining conversion efficiency exceeding 85%.
文摘We present a lamp-pumped Nd： phosphate glass laser amplifier delivering up to 1 J of pulse energy at 1053 nm with a repetition rate of 1 Hz and an injected pulse energy of 2.5 mJ. The amplifier system employs a beamshaping module and a four-pass, lamp-pumped amplifier. The thermally induced wavefront distortion is mitigated and a uniform gain distribution is obtained by a four-lamp-pmnped laser head in the amplifier. Thus, an excellent beam quality is obtained.
基金the National Research and Development Program of China(No.2017YFB0405200)National Natural Science Foundation of China(Nos.61675011,61827820,61527822,and 61535009)+2 种基金Beijing Nova Program(No.Z181100006218097)Research Program of Beijing Municipal Education Commission(No.KZ201810005003)State Key Laboratory of Advanced Optical Communication Systems and Networks,China.
文摘High-power fiber lasers have experienced a dramatic development over the last decade.Further increasing the output power needs an upscaling of the fiber mode area,while maintaining a single-mode output.Here,we propose an all-solid anti-resonant fiber(ARF)structure,which ensures single-mode operation in broadband by resonantly coupling higherorder modes into the cladding.A series of fibers with core sizes ranging from 40 to 100µm are proposed exhibiting maximum mode area exceeding 5000µm2.Numerical simulations show this resonant coupling scheme provides a higher-order mode(mainly TE01,TM01,and HE21)suppression ratio of more than 20 dB,while keeping the fundamental mode loss lower than 1 dB/m.The proposed structure also exhibits high tolerance for core index depression.
