REI3Fes4Cr3（RE=Ce, Pr, Tb, Er） and Pr13_XFes4Cr3Ti（x=0, 2, 4, 6） alloy powders were prepared by are smelting method and high energy ball milling technique. The phase structure and the morphology of the alloy powde...REI3Fes4Cr3（RE=Ce, Pr, Tb, Er） and Pr13_XFes4Cr3Ti（x=0, 2, 4, 6） alloy powders were prepared by are smelting method and high energy ball milling technique. The phase structure and the morphology of the alloy powders were investigated by X-ray diffraction （XRD） and scanning electron microscopy （SEM）, and their microwave absorbing properties were determined by a vector network analyzer. The results show that the alloys with light rare earths （Ce, Pr） have good low frequency absorbing property and those with heavy rare earths （Tb, Er） exhibit an improved high frequency absorbing property. The minimum refleetivity at the absorbing peak frequency of RE,FeuCr3（RE=Ce, Pr, Tb, Er） are -9.49 dB at 5.76 GHz, -22.38 dB at 7.92 GHz, -18.52 dB at 11.68 GHz and -17.59 dB at 10.24 GHz, respectively. The absorbing bandwidth under -10 dB of the Pr13FesaCr3 powder was widened from 1.91 GI-Iz to 3.89 GHz by adding 2% Ti, but the reflectivity of the alloy was increased from -22.38 dB to -14.91 riB.展开更多
The wavelength-tunable rectangular mode-locking operation is demonstrated in an all-fiber laser based on semi- conductor saturable absorber mirror. As the dissipative soliton resonance signature, the pulse duration va...The wavelength-tunable rectangular mode-locking operation is demonstrated in an all-fiber laser based on semi- conductor saturable absorber mirror. As the dissipative soliton resonance signature, the pulse duration varies from 5SOps to 2.1 ns as a function o~ the increasing pump power. Correspondingly, the maximum pulse energy is 9.11 n3. Moreover, it is found that the wavelength tunable operation with a range of approximately 10 nm could be obtained by properly adjusting the polarization controllers. The characteristics of the rectangular pulses at different wavelengths are similar to each other. The demonstration of the wavelength tunable rectangular pulses would be beneficial to some applications for many fields such as spectroscopy and sensing research.展开更多
We report on generation of a dual-wavelength, all-fiber, passively Q-switched ytterbium-doped fiber laser using aluminum oxide nanoparticle （Al2O3-NP） thin film. A thin film of Al2O3 was prepared by embedding Al2O3-...We report on generation of a dual-wavelength, all-fiber, passively Q-switched ytterbium-doped fiber laser using aluminum oxide nanoparticle （Al2O3-NP） thin film. A thin film of Al2O3 was prepared by embedding Al2O3-NPs into a polyvinyl alcohol （PVA） as a host polymer, and then inserted between two fiber ferrules to act as a saturable absorber （SA）. By incorporating the Al2O3-PVA SA into the laser cavity, a stable dual-wavelength pulse output centered at 1050 and 1060.7nm is observed at threshold pump power of 80mW. As the pump power is gradually increased from 80 to 300mW, the repetition rate of the generated pulse increases from 16.23 to 59 kHz, while the pulse width decreases from 19 to 6μs. To the best of our knowledge, this is the first demonstration for this type of SA operating in the 1 μm region.展开更多
The process models for an equilibrium CO_2 absorber and a rate based CO_2 absorber using potassium carbonate(K2 CO3) solvents were developed in Aspen Custom Modeller(ACM) to remove CO_2 from a flue gas. The process mo...The process models for an equilibrium CO_2 absorber and a rate based CO_2 absorber using potassium carbonate(K2 CO3) solvents were developed in Aspen Custom Modeller(ACM) to remove CO_2 from a flue gas. The process model utilised the Electrolyte Non-Random Two Liquid(ENRTL) thermodynamic model and various packing correlations. The results from the ACM equilibrium model shows good agreement with an inbuilt Aspen Plus?model when using the same input conditions. By further introducing a Murphree efficiency which is related to mass transfer and packing hydraulics, the equilibrium model can validate the experimental results from a pilot plant within a deviation of 10%. A more rigorous rate based model included mass and energy flux across the interface and the enhancement effect resulting from chemical reactions. The rate based model was validated using experimental data from pilot plants and was shown to predict the results to within 10%. A parametric sensitivity analysis showed that inlet flue gas flowrate and K2 CO3 concentration in the lean solvent has significant impact on CO_2 recovery. Although both models can provide reasonable predictions based on pilot plant results, the rate based model is more advanced as it can explain mass and heat transfer, transport phenomena and chemical reactions occurring inside the absorber without introducing an empirical Murphree efficiency.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
A compact saturable absorber mirror（SAM） based on few-layer molybdenum disulfide（MoS2） nanoplatelets was fabricated and successfully used as an efficient saturable absorber（SA） for the passively Q-switched solid...A compact saturable absorber mirror（SAM） based on few-layer molybdenum disulfide（MoS2） nanoplatelets was fabricated and successfully used as an efficient saturable absorber（SA） for the passively Q-switched solid-state laser at 1 μm wavelength. Pulses as short as 182 ns were obtained from a ytterbium-doped（Yb:LGGG） bulk laser Q-switched by the MoS2 SAM, which we believe to be the shortest one ever achieved from the MoS2 SAs-based Q-switched bulk lasers. A maximum average output power of 0.6 W was obtained with a slope efficiency of 24%,corresponding to single pulse energy up to 1.8 μJ. In addition, the simultaneous dual-wavelength Q-switching at 1025.2 and 1028.1 nm has been successfully achieved. The results indicate the promising potential of few-layer MoS2 nanoplatelets as nonlinear optical switches for achieving efficient pulsed bulk lasers.展开更多
A tunable plasmonic perfect absorber with a tuning range of 650 nm is realized by introducing a 20 nm thick phase-change material Ge2Sb2Te5 layer into the metal–dielectric–metal configuration.The absorption at the p...A tunable plasmonic perfect absorber with a tuning range of 650 nm is realized by introducing a 20 nm thick phase-change material Ge2Sb2Te5 layer into the metal–dielectric–metal configuration.The absorption at the plasmonic resonance is kept above 0.96 across the whole tuning range.In this work we study this extraordinary optical response numerically and reveal the geometric conditions which support this phenomenon.This work shows a promising route to achieve tunable plasmonic devices for multi-band optical modulation,communication,and thermal imaging.展开更多
By using the ultrasound-assisted liquid phase exfoliation method, Bi_2Te_3 nanosheets are synthesized and deposited onto a quartz plate to form a kind of saturable absorber(SA), in which nonlinear absorption propertie...By using the ultrasound-assisted liquid phase exfoliation method, Bi_2Te_3 nanosheets are synthesized and deposited onto a quartz plate to form a kind of saturable absorber(SA), in which nonlinear absorption properties around 2 μm are analyzed with a home-made mode-locked laser. With the as-prepared Bi_2Te_3 SA employed,a stable passively Q-switched all-solid-state 2 μm laser is successfully realized. Q-switched pulses with a maximum average output power of 2.03 W are generated under an output coupling of 5%, corresponding to the maximum single-pulse energy of 18.4 μJ and peak power of 23 W. The delivered shortest pulse duration and maximum repetition rate are 620 ns and 118 k Hz under an output coupling of 2%, respectively. It is the first presentation of such Bi_2Te_3 SA employed in a solid-state Q-switched crystalline laser at 2 μm, to the best of our knowledge. In comparison with other 2 D materials suitable for pulsed 2 μm lasers, the saturable absorption performance of Bi_2Te_3 SA is proved to be promising in generating high power and high-repetition-rate 2 μm laser pulses.展开更多
Solar selective absorbing coatings(SSACs)are required to have not only excellent optical property but also outstanding thermal stability for high temperature applications.The optical properties of Mo/ZrSiN/ZrSiON/SiO_...Solar selective absorbing coatings(SSACs)are required to have not only excellent optical property but also outstanding thermal stability for high temperature applications.The optical properties of Mo/ZrSiN/ZrSiON/SiO_(2) SSAC had been optimized successfully before.Herein,we are focusing on the evaluation and mechanism of thermal stability of this multilayer coating for its potential applications in concentrated solar power(CSP)systems.Fortunately,the coating exhibits excellent thermal stability after aging at 400℃ for 1500 h in vacuum.At aging temperature of 500℃ for 1000 h or 600℃ for 300 h in vacuum,the slight inter-diffusion between Mo layer and stainless steel(SS)substrate occurs.At higher aging temperature of 700℃ for 100 h in vacuum,the serious inter-diffusion between Mo layer and SS substrate leads to invalidation of the coating,which has been evidenced by Rutherford backscattering spectrometry(RBS)and X-ray diffraction(XRD)technologies.Additionally,this coating also has an outstanding thermal stability after aging at 400℃for 300 h in air.A heating-cooling cycling(HCC)treatment evidences the good thermal stability of this coating working in cold environment(60℃).The results reveal that this coating can be a promising candidate not only for CSP system in high temperatures but also for usage in cold environment.展开更多
We propose and demonstrate a dual-wavelength single-longitudinal-mode(SLM) fiber laser with switchable wavelength spacing based on a graphene saturable absorber(GSA) and a Wave Shaper. By virtue of the excellent satur...We propose and demonstrate a dual-wavelength single-longitudinal-mode(SLM) fiber laser with switchable wavelength spacing based on a graphene saturable absorber(GSA) and a Wave Shaper. By virtue of the excellent saturable absorption ability of graphene, the linewidths of the lasing wavelengths can be effectively reduced and eventually SLM operation can be obtained. The linewidths of both wavelengths are measured to be narrower than 7.3 kHz. The obtained results suggest that the graphene would be a good candidate nonlinear optical material for applications in related photonic fields, such as SLM oscillation generation for microwave generation and optical sensing.展开更多
We demonstrate a femtosecond mode-locked erbium-doped fiber laser（EDFL） using a nickel oxide（Ni O） as a saturable absorber（SA）. Ni O nanoparticles are hosted into polyethylene oxide film and attached to fiber fe...We demonstrate a femtosecond mode-locked erbium-doped fiber laser（EDFL） using a nickel oxide（Ni O） as a saturable absorber（SA）. Ni O nanoparticles are hosted into polyethylene oxide film and attached to fiber ferrule in the laser cavity. The Ni O-SA shows a 39% modulation depth with a 0.04 MW∕cm^2 saturation intensity. Our ring laser cavity based on erbium-doped active fiber with managed intracavity dispersion has the ability to generate ultrashort pulses with a full width at half-maximum（FWHM） of around 2.85 nm centered at 1561.8 nm.The pulses repeat at a frequency of 0.96 MHz and duration of 950 fs.展开更多
基金Funded by National Natural Science Foundation of China(Nos.50961005 and 51361007)National Natural Science Foundation of Guangxi(Nos.2012 GXNSFGA06002 and 2013GXNSFAA019295)
文摘REI3Fes4Cr3（RE=Ce, Pr, Tb, Er） and Pr13_XFes4Cr3Ti（x=0, 2, 4, 6） alloy powders were prepared by are smelting method and high energy ball milling technique. The phase structure and the morphology of the alloy powders were investigated by X-ray diffraction （XRD） and scanning electron microscopy （SEM）, and their microwave absorbing properties were determined by a vector network analyzer. The results show that the alloys with light rare earths （Ce, Pr） have good low frequency absorbing property and those with heavy rare earths （Tb, Er） exhibit an improved high frequency absorbing property. The minimum refleetivity at the absorbing peak frequency of RE,FeuCr3（RE=Ce, Pr, Tb, Er） are -9.49 dB at 5.76 GHz, -22.38 dB at 7.92 GHz, -18.52 dB at 11.68 GHz and -17.59 dB at 10.24 GHz, respectively. The absorbing bandwidth under -10 dB of the Pr13FesaCr3 powder was widened from 1.91 GI-Iz to 3.89 GHz by adding 2% Ti, but the reflectivity of the alloy was increased from -22.38 dB to -14.91 riB.
基金Supported by the National High-Technology Research and Development Program of China under Grant No 2014AA041901the NSAF Foundation of 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 No 61308024
文摘The wavelength-tunable rectangular mode-locking operation is demonstrated in an all-fiber laser based on semi- conductor saturable absorber mirror. As the dissipative soliton resonance signature, the pulse duration varies from 5SOps to 2.1 ns as a function o~ the increasing pump power. Correspondingly, the maximum pulse energy is 9.11 n3. Moreover, it is found that the wavelength tunable operation with a range of approximately 10 nm could be obtained by properly adjusting the polarization controllers. The characteristics of the rectangular pulses at different wavelengths are similar to each other. The demonstration of the wavelength tunable rectangular pulses would be beneficial to some applications for many fields such as spectroscopy and sensing research.
基金Supported by the Iraqi Ministry of Higher Education and Scientific Research and University of Baghdad
文摘We report on generation of a dual-wavelength, all-fiber, passively Q-switched ytterbium-doped fiber laser using aluminum oxide nanoparticle （Al2O3-NP） thin film. A thin film of Al2O3 was prepared by embedding Al2O3-NPs into a polyvinyl alcohol （PVA） as a host polymer, and then inserted between two fiber ferrules to act as a saturable absorber （SA）. By incorporating the Al2O3-PVA SA into the laser cavity, a stable dual-wavelength pulse output centered at 1050 and 1060.7nm is observed at threshold pump power of 80mW. As the pump power is gradually increased from 80 to 300mW, the repetition rate of the generated pulse increases from 16.23 to 59 kHz, while the pulse width decreases from 19 to 6μs. To the best of our knowledge, this is the first demonstration for this type of SA operating in the 1 μm region.
基金financial support from Peter Cook Centre for CCS Research
文摘The process models for an equilibrium CO_2 absorber and a rate based CO_2 absorber using potassium carbonate(K2 CO3) solvents were developed in Aspen Custom Modeller(ACM) to remove CO_2 from a flue gas. The process model utilised the Electrolyte Non-Random Two Liquid(ENRTL) thermodynamic model and various packing correlations. The results from the ACM equilibrium model shows good agreement with an inbuilt Aspen Plus?model when using the same input conditions. By further introducing a Murphree efficiency which is related to mass transfer and packing hydraulics, the equilibrium model can validate the experimental results from a pilot plant within a deviation of 10%. A more rigorous rate based model included mass and energy flux across the interface and the enhancement effect resulting from chemical reactions. The rate based model was validated using experimental data from pilot plants and was shown to predict the results to within 10%. A parametric sensitivity analysis showed that inlet flue gas flowrate and K2 CO3 concentration in the lean solvent has significant impact on CO_2 recovery. Although both models can provide reasonable predictions based on pilot plant results, the rate based model is more advanced as it can explain mass and heat transfer, transport phenomena and chemical reactions occurring inside the absorber without introducing an empirical Murphree efficiency.
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supported by the National Natural Science Foundation of China (Grant Nos. 51321091, 61275142, 61308042, and 91022003)China Postdoctoral Science Foundation (Grant Nos. 2013M531594, 2014T70633)
文摘A compact saturable absorber mirror（SAM） based on few-layer molybdenum disulfide（MoS2） nanoplatelets was fabricated and successfully used as an efficient saturable absorber（SA） for the passively Q-switched solid-state laser at 1 μm wavelength. Pulses as short as 182 ns were obtained from a ytterbium-doped（Yb:LGGG） bulk laser Q-switched by the MoS2 SAM, which we believe to be the shortest one ever achieved from the MoS2 SAs-based Q-switched bulk lasers. A maximum average output power of 0.6 W was obtained with a slope efficiency of 24%,corresponding to single pulse energy up to 1.8 μJ. In addition, the simultaneous dual-wavelength Q-switching at 1025.2 and 1028.1 nm has been successfully achieved. The results indicate the promising potential of few-layer MoS2 nanoplatelets as nonlinear optical switches for achieving efficient pulsed bulk lasers.
基金the support from the National Research Foundation,Prime Minister’s Office,Singapore under its Competitive Research Program (CRP Award No.NRF-CRP10-2012-04)funding from the Leverhulme trust and the EPSRC Active Plasmonics Programm+1 种基金funding provided by the 973 Program of China (No.2013CBA01700)the Chinese Natural Sciences Grant (61138002 and 61307043)
文摘A tunable plasmonic perfect absorber with a tuning range of 650 nm is realized by introducing a 20 nm thick phase-change material Ge2Sb2Te5 layer into the metal–dielectric–metal configuration.The absorption at the plasmonic resonance is kept above 0.96 across the whole tuning range.In this work we study this extraordinary optical response numerically and reveal the geometric conditions which support this phenomenon.This work shows a promising route to achieve tunable plasmonic devices for multi-band optical modulation,communication,and thermal imaging.
基金National Natural Science Foundation of China(NSFC)(61475088,61775119,61378022,61422511)Young Scholars Program of Shandong University(2015WLJH38)Open Research Fund of the State Key Laboratory of Pulsed Power Laser Technology,Electronic Engineering Institute,Hefei,China(SLK2016KF01)
文摘By using the ultrasound-assisted liquid phase exfoliation method, Bi_2Te_3 nanosheets are synthesized and deposited onto a quartz plate to form a kind of saturable absorber(SA), in which nonlinear absorption properties around 2 μm are analyzed with a home-made mode-locked laser. With the as-prepared Bi_2Te_3 SA employed,a stable passively Q-switched all-solid-state 2 μm laser is successfully realized. Q-switched pulses with a maximum average output power of 2.03 W are generated under an output coupling of 5%, corresponding to the maximum single-pulse energy of 18.4 μJ and peak power of 23 W. The delivered shortest pulse duration and maximum repetition rate are 620 ns and 118 k Hz under an output coupling of 2%, respectively. It is the first presentation of such Bi_2Te_3 SA employed in a solid-state Q-switched crystalline laser at 2 μm, to the best of our knowledge. In comparison with other 2 D materials suitable for pulsed 2 μm lasers, the saturable absorption performance of Bi_2Te_3 SA is proved to be promising in generating high power and high-repetition-rate 2 μm laser pulses.
基金the financial support by the National Natural Science Foundation of China(NSFC)(Nos.51732001,U1832219 and 51972013)Beijing Natural Science Foundation(No.2182035)the Fundamental Research Funds for the Central Universities.
文摘Solar selective absorbing coatings(SSACs)are required to have not only excellent optical property but also outstanding thermal stability for high temperature applications.The optical properties of Mo/ZrSiN/ZrSiON/SiO_(2) SSAC had been optimized successfully before.Herein,we are focusing on the evaluation and mechanism of thermal stability of this multilayer coating for its potential applications in concentrated solar power(CSP)systems.Fortunately,the coating exhibits excellent thermal stability after aging at 400℃ for 1500 h in vacuum.At aging temperature of 500℃ for 1000 h or 600℃ for 300 h in vacuum,the slight inter-diffusion between Mo layer and stainless steel(SS)substrate occurs.At higher aging temperature of 700℃ for 100 h in vacuum,the serious inter-diffusion between Mo layer and SS substrate leads to invalidation of the coating,which has been evidenced by Rutherford backscattering spectrometry(RBS)and X-ray diffraction(XRD)technologies.Additionally,this coating also has an outstanding thermal stability after aging at 400℃for 300 h in air.A heating-cooling cycling(HCC)treatment evidences the good thermal stability of this coating working in cold environment(60℃).The results reveal that this coating can be a promising candidate not only for CSP system in high temperatures but also for usage in cold environment.
基金supported by the National Natural Science Foundation of China (No. 61475065)
文摘We propose and demonstrate a dual-wavelength single-longitudinal-mode(SLM) fiber laser with switchable wavelength spacing based on a graphene saturable absorber(GSA) and a Wave Shaper. By virtue of the excellent saturable absorption ability of graphene, the linewidths of the lasing wavelengths can be effectively reduced and eventually SLM operation can be obtained. The linewidths of both wavelengths are measured to be narrower than 7.3 kHz. The obtained results suggest that the graphene would be a good candidate nonlinear optical material for applications in related photonic fields, such as SLM oscillation generation for microwave generation and optical sensing.
文摘We demonstrate a femtosecond mode-locked erbium-doped fiber laser（EDFL） using a nickel oxide（Ni O） as a saturable absorber（SA）. Ni O nanoparticles are hosted into polyethylene oxide film and attached to fiber ferrule in the laser cavity. The Ni O-SA shows a 39% modulation depth with a 0.04 MW∕cm^2 saturation intensity. Our ring laser cavity based on erbium-doped active fiber with managed intracavity dispersion has the ability to generate ultrashort pulses with a full width at half-maximum（FWHM） of around 2.85 nm centered at 1561.8 nm.The pulses repeat at a frequency of 0.96 MHz and duration of 950 fs.
