In this paper, a novel method of a subwavelength binary simple periodic rectangular structure is presented to realize even beam splitting by combining the rigorous couple-wave analysis with the genetic algorithm. Seve...In this paper, a novel method of a subwavelength binary simple periodic rectangular structure is presented to realize even beam splitting by combining the rigorous couple-wave analysis with the genetic algorithm. Several even splitters in the terahertz region were designed and one of the silicon-based beam splitters designed to separate one incident beam into four emergent beams has total efficiency up to 92.23 %. Zero-order diffraction efficiency was reduced to less than 0.192 % and the error of uniformity decreased to 6.51 9 10-6. These results break the limitation of even beam splitting based on the traditional scalar theory. In addition, the effects of the incident angle, wavelength, as well as the polarizing angle on the diffraction efficiency and uniformity were also investigated.展开更多
We numerically investigate the seven-core photonic crystal fiber (PCF) with the zero dispersion wavelength designed in the range of 1000 - 1080 nm, particularly suitable for the ytterbium-doped fiber laser pumping. Al...We numerically investigate the seven-core photonic crystal fiber (PCF) with the zero dispersion wavelength designed in the range of 1000 - 1080 nm, particularly suitable for the ytterbium-doped fiber laser pumping. Also, the PCFs are well designed for obtaining a flat in-phase mode by carefully adjusting the diameter of inner layer six holes, and the corresponding empirical values of fiber structure are summarized and listed. The variations of inner six holes to the amplitude of in-phase mode are further investigated, and our results show that a better tolerance can be achieved in the fiber structures with lower filling ratio configuration.展开更多
MXenes have received extensive attention from scholars due to their unique layered structure,significant electrical conductivity,and excellent mechanical properties.In addition to their pristine forms,they could also ...MXenes have received extensive attention from scholars due to their unique layered structure,significant electrical conductivity,and excellent mechanical properties.In addition to their pristine forms,they could also be incorporated with other components for attaining hybrids and nanocomposites,accompanying with amplified functionalities.It has been widely used in lithium batteries,supercapacitors,electromagnetic shielding,tumor therapy,biosensors,photocatalysis,and other fields,and has shown great application potential in energy conversion and storage.The purpose of this article is to encyclopaedically overview the latest progress in synthesis and characterization of MXenes,while their potential applications in energy conversation such as water splitting and solar cells,as well as in energy storage such as Li-ion batteries,supercapacitors,and hydrogen energy will be comprehensively elaborated.Development opportunities and challenges are summarized.展开更多
High-power femtosecond mid-infrared(MIR)lasers are of vast importance to both fundamental research and applications.We report a high-power femtosecond master oscillator power amplifier laser system consisting of a sin...High-power femtosecond mid-infrared(MIR)lasers are of vast importance to both fundamental research and applications.We report a high-power femtosecond master oscillator power amplifier laser system consisting of a singlemode Er:ZBLAN fiber mode-locked oscillator and pre-amplifier followed by a large-mode-area Er:ZBLAN fiber main amplifier.The main amplifier is actively cooled and bidirectionally pumped at 976 nm,generating a slope efficiency of 26.9%.Pulses of 8.12 W,148 fs at 2.8μm with a repetition rate of 69.65 MHz are achieved.To the best of our knowledge,this is the highest average power ever achieved from a femtosecond MIR laser source.Such a compact ultrafast laser system is promising for a wide range of applications,such as medical surgery and material processing.展开更多
We demonstrate an integrated all-fiber mid-infrared(mid-IR)supercontinuum(SC)source generated by a 1.95μm master oscillator power amplifier system and a single-mode ZBLAN(ZrF_4–BaF_2–LaF_3–AlF_3–NaF)fiber.The max...We demonstrate an integrated all-fiber mid-infrared(mid-IR)supercontinuum(SC)source generated by a 1.95μm master oscillator power amplifier system and a single-mode ZBLAN(ZrF_4–BaF_2–LaF_3–AlF_3–NaF)fiber.The maximum average output power is 10.67 W with spectral bandwidth covering from～1.9 to 4.1μm.The single-mode ZBLAN fiber and silica fiber are thermal-spliced to enhance the robustness and practicability of the system.It is,to the best of our knowledge,the first high-power integrated compacted all-fiber mid-IR SC source based on thermal-spliced silica fiber and ZBLAN fiber.展开更多
The pulse energy in the ultrafast soliton fiber laser oscillators is usually limited by the well-known wave-breaking phenomenon owing to the absence of a desirable real saturable absorber(SA) with high power tolerance...The pulse energy in the ultrafast soliton fiber laser oscillators is usually limited by the well-known wave-breaking phenomenon owing to the absence of a desirable real saturable absorber(SA) with high power tolerance and large modulation depth. Here, we report a type of microfiber-based MoTe_2 SA fabricated by the magnetron-sputtering deposition(MSD) method. High-energy wave-breaking free soliton pulses were generated with pulse duration/pulse energy/average output power of 229 fs/2.14 nJ/57 mW in the 1.5 μm regime and 1.3 ps/13.8 nJ/212 mW in the 2 μm regime, respectively. To our knowledge, the generated soliton pulses at 1.5 μm had the shortest pulse duration and the highest output power among the reported erbium-doped fiber lasers mode locked by transition metal dichalcogenides. Moreover, this was the first demonstration of a MoTe_2-based SA in fiber lasers in the 2 μm regime, and the pulse energy/output power are the highest in the reported thulium-doped fiber lasers mode locked by two-dimensional materials. Our results suggest that a microfiber-based MoTe_2 SA could be used as an excellent photonic device for ultrafast pulse generation, and the MSD technique opens a promising route to produce a high-performance SA with high power tolerance and large modulation depth, which are beneficial for high-energy wave-breaking free pulse generation.展开更多
Mid-infrared laser materials with low phonon energy have significant applications. However, the development of available glass systems for high-power laser gain medium have posed a great challenge.Therefore, we invest...Mid-infrared laser materials with low phonon energy have significant applications. However, the development of available glass systems for high-power laser gain medium have posed a great challenge.Therefore, we investigated the 2.7 μm spectroscopic properties of Er^(3+)/Yb^(3+) -codoped oxyfluoride glass containing gallium, which were prepared by typically melting and quenching methods. The 2.7 μm luminescence properties of the Er^(3+)/Yb^(3+)-codoped oxyfluoride glass containing gallium were recorded by a 980 nm laser diode. The Judde Ofelt parameters, decay curves, emission cross section, energy transfer efficiency and quantum efficiency were calculated. The maximum emission cross section of YbFGa-0.5 is 1.63 × 10^(-20) cm^2 by 980 nm excitation. The energy transfer efficiency is calculated to be77.8% for the YbFGa-0.5 glass around 2700 nm. The quantum efficiency at 1530 nm is 65.6%. The result reveals that the best doping concentration ratio of Er^(3+):Yb^(3+) ions is 1:0.5, and suggests an effective energy transfer from Yb^(3+) to Er^(3+) ions.展开更多
We demonstrate, for the first time, to the best of our knowledge, an all-fiber figure-of-9 double-clad Tm-doped fiber laser operating in the dissipative soliton resonance(DSR) regime. Stable mode-locked rectangular pu...We demonstrate, for the first time, to the best of our knowledge, an all-fiber figure-of-9 double-clad Tm-doped fiber laser operating in the dissipative soliton resonance(DSR) regime. Stable mode-locked rectangular pulses are obtained by using the nonlinear amplifying loop mirror(NALM) technique. A long spool of high-nonlinearity fiber(HNLF) and a segment of SMF-28 fiber are used to enhance the nonlinearity of the NALM loop and to obtain a large all-anomalous regime. Output power and pulse energy are further boosted by using a three-stage master oscillator power amplifier(MOPA) system. At the maximum pump power, average output power of up to 104.3 W with record pulse energy of 0.33 mJ is achieved with a 2 μm DSR-based MOPA system.展开更多
Near infrared light-controlled release of payloads from ultraviolet-sensitive(UV-sensitive) polymer hydrogels or nanocarriers is one of the most promising strategies for biotherapy. Here, we propose the concept of lig...Near infrared light-controlled release of payloads from ultraviolet-sensitive(UV-sensitive) polymer hydrogels or nanocarriers is one of the most promising strategies for biotherapy. Here, we propose the concept of light activation of NaYF_4:20%Yb, 2%Tm nanocrystals(NCs). NaYF_4:20%Yb, 2%Tm NCs are synthesized by a solvothermal method. Effective upconversion luminescence from NaYF_4:20%Yb, 2%Tm NCs excited by a continuous wave(CW) 980 nm laser is obtained. The NaYF_4:20%Yb, 2%Tm NCs are then used as a laser gain medium and sandwiched between Al and quartz reflectors to form laser microcavities. UV and blue upconverted random lasing is obtained from the laser microcavities. Hence, we verify explicitly that the NaYF_4:Yb, Tm NCs support UV and blue upconversion random lasing via a 980 nm nanosecond laser excitation. Our work provides what we believe is a new concept for precision and localized cancer therapy by external light excitation.展开更多
We report on a mid-infrared fiber laser that uses a single-walled carbon nanotube saturable absorber mirror to realize the mode-locking operation.The laser generates 3.5 μm ultra-short pulses from an erbium-doped flu...We report on a mid-infrared fiber laser that uses a single-walled carbon nanotube saturable absorber mirror to realize the mode-locking operation.The laser generates 3.5 μm ultra-short pulses from an erbium-doped fluoride fiber by utilizing a dual-wavelength pumping scheme.Stable mode-locking is achieved at the 3.5 μm band with a repetition rate of 25.2 MHz.The maximum average power acquired from the laser in the mode-locking regime is 25 mW.The experimental results indicate that the carbon nanotube is an effective saturable absorber for mode-locking in the mid-infrared spectral region.展开更多
Perovskite quantum dots(QDs) are of great interest due to their outstanding optoelectronic properties and tremendous application potential. Improving photoluminescence(PL) spectra in all-inorganic perovskite QDs is of...Perovskite quantum dots(QDs) are of great interest due to their outstanding optoelectronic properties and tremendous application potential. Improving photoluminescence(PL) spectra in all-inorganic perovskite QDs is of great importance for performance enhancement. In this work, the PL quantum yield of the CsPbBr3 perovskite QDs is enhanced from 70% to 95% with increasing radiation pressure. Such enhancement is attributed to the increased binding energy of self-trapped excitons(STEs) upon radiation pressure, which is consistent with its blue-shifted PL and other characterization results. Furthermore, we study ultrafast absorption spectroscopy and find that the dynamics of relaxation from free excitons to STEs in radiation pressure CsPbBr3 QDs is ascribed to stronger electron–phonon coupling in the contracted octahedral structure. It is further demonstrated that radiation pressure can boost the PL efficiency and explore effectively the relationship between the structure and optical properties.展开更多
Carbon nanodots(C-dots) with a uniform size of about 2 nm are synthesized via in situ pyrolysis of n-propylamine that is confined in the nanochannels of zeolite Linde Type A(LTA). The as-synthesized C-dots@LTA composi...Carbon nanodots(C-dots) with a uniform size of about 2 nm are synthesized via in situ pyrolysis of n-propylamine that is confined in the nanochannels of zeolite Linde Type A(LTA). The as-synthesized C-dots@LTA composite shows nonlinear optical saturable absorption properties in a broad wavelength band and can be used as saturable absorber(SA) to generate ultrafast pulsed fiber lasers. By inserting a zeolite LTA single crystal hosting C-dots into the fiber laser cavity, mode-locked fiber lasers with long-term operation stability at 1.5 μm and 1 μm are achieved. These results show that the C-dots@LTA are a promising SA material for ultrafast pulsed fiber laser generation in a broad wavelength band. To the best of our knowledge, this is the first demonstration of a C-dots@LTA-based mode-locked fiber laser.展开更多
We experimentally demonstrate an all-fiber supercontinuum source that covers the spectral region ranging from visible to mid-infrared. The ultra-broadband supercontinuum is realized by pumping a cascaded photonic crys...We experimentally demonstrate an all-fiber supercontinuum source that covers the spectral region ranging from visible to mid-infrared. The ultra-broadband supercontinuum is realized by pumping a cascaded photonic crystal fiber and a highly nonlinear fiber with a 1/1.5 μm dual-band pump source. A maximum output power of 9.01 W is achieved using the system,which is the highest power ever achieved from a supercontinuum source spanning from the visible to mid-infrared.展开更多
This study develops a Yb:KGW dual-crystal based regenerative amplifier.The thermal lensing and gain-narrowing effects are compensated by the dual-crystal configuration.Sub-nanojoule pulses are amplified to 1.5 mJ with...This study develops a Yb:KGW dual-crystal based regenerative amplifier.The thermal lensing and gain-narrowing effects are compensated by the dual-crystal configuration.Sub-nanojoule pulses are amplified to 1.5 mJ with 9 nm spectral bandwidth and 1 kHz repetition rate using chirped pulse amplification technology.Consequently,1.2 m J pulses with a pulse duration of 227 fs are obtained after compression.Thanks to the cavity design,the output laser was a near diffraction limited beam with M2 around 1.1.The amplifier has the potential to boost energy above 2 m J after compression and act as a front end for a future kilohertz terawatt-class diode-pumped Yb:KGW laser system.展开更多
Short pulsed fiber lasers have been widely made using single-walled carbon nanotubes as a saturable absorber(SA). However, most of the currently used devices can only operate in one determined operation state with an ...Short pulsed fiber lasers have been widely made using single-walled carbon nanotubes as a saturable absorber(SA). However, most of the currently used devices can only operate in one determined operation state with an unchangeable modulation SA depth in the cavity, which significantly limits their application in photonic devices.In this paper, well-aligned carbon nanotube arrays are synthesized using zeolite AlPO_4-5 as a template, which features anisotropic optical absorption. The linear optical absorption of the as-synthesized carbon nanotube arrays can easily be tuned by adjusting a polarization controller, thus providing a tunable modulation depth for the carbon nanotube SA. By exploiting this SA in an erbium-doped fiber laser cavity, both Q-switched and modelocked pulsed lasers are achieved by simply adjusting a polarization controller under a fixed pump power of 330 mW. In addition, the repetition rate of the Q-switching and pulse duration of the mode-locking can be tuned according to the variation of modulation depth. Moreover, soliton molecules can be obtained when the modulation depth of the SA is 4.5%.展开更多
制备低成本的高效电催化剂是缓解目前面临的环境能源危机的重要方式.通过无定型化和构建异质结构可以有效地改变催化剂的电子结构,从而实现电催化性能的稳步提升.但是对于两者之间协同作用的研究则相对较少.在本文中,我们构建了富含异...制备低成本的高效电催化剂是缓解目前面临的环境能源危机的重要方式.通过无定型化和构建异质结构可以有效地改变催化剂的电子结构,从而实现电催化性能的稳步提升.但是对于两者之间协同作用的研究则相对较少.在本文中,我们构建了富含异质结构的无定型FeMo基(a-FeMo)电催化剂,并系统评估了该催化剂的氮气还原和析氧反应性能.得益于无定型结构引起的活性位点数目的增多和异质结构引发的电子的重新分布,a-FeMo催化剂表现出优异的电化学催化性能.在-0.1 V vs.RHE的电势下,a-FeMo催化剂表现出29.15%的法拉第效率和71.78μg_(NH_(3)) mg_(cat.)^(-1) h^(-1)的氨气产率.这为合理设计具有低成本优势、高活性和长时间稳定性的优异催化剂提供了有益的参考.展开更多
A set of semiconductor laser pulse seed sources based on an embedded chip is proposed.The greatest feature is that the optical pulse frequency and width can be independently adjusted in real time.The pulse seed source...A set of semiconductor laser pulse seed sources based on an embedded chip is proposed.The greatest feature is that the optical pulse frequency and width can be independently adjusted in real time.The pulse seed sources can be switched independently and online from the gain-switched mode to the quasi-continuous wave mode to obtain optimal optical parameters for specific applications.To explore the physical mechanism of the semiconductor laser source,the rate equation that describes the carrier-photon transient change in a semiconductor laser cavity is numerically derived and solved.Subsequently,problems that need to be considered while designing the drive circuit are identified.The system evaluation indicates that the optical pulse frequency adjustment range is 250 Hz to 42 MHz,and the narrowest optical pulse output width is 80 ps.The pulse seed source can drive semiconductor lasers with different central wavelengths(1064,1550,and 1970 nm),and can also simultaneously drive two semiconductor lasers and output dual-band optical pulses.It can be used as a seed source for general high-power optical systems,and exhibits good application value and extensive market prospects.展开更多
We report on mode-locked thulium-doped fiber lasers with high-energy nanosecond pulses,relying on the transmission in a semiconductor saturable absorber(SESA)and a carbon nanotube(CNTs-PVA)film separately.A section of...We report on mode-locked thulium-doped fiber lasers with high-energy nanosecond pulses,relying on the transmission in a semiconductor saturable absorber(SESA)and a carbon nanotube(CNTs-PVA)film separately.A section of an SMF-MMF-SMF structure multimode interferometer with a transmission peak wavelength of^2003 nm was used as a wavelength selector to fix the laser wavelength.When the SESA acted as a saturable absorber(SA),the mode-locked fiber laser had a maximum output power of^461 mW with a pulse energy of^0.14µJ and a pulse duration of^9.14 ns.In a CNT-film-based mode-locked fiber laser,stable mode-locked pulses with the maximum output power of^46 mW,pulse energy of^26.8 nJ and pulse duration of^9.3 ns were obtained.To the best of our knowledge,our experiments demonstrated the first 2µm region‘real’SA-based dissipative soliton resonance with the highest mode-locked pulse energy from a‘real’SA-based all-fiberized resonator.展开更多
High-power tunable femtosecond mid-infrared(MIR)pulses are of great interest for many scientific and industrial applications.Here we demonstrate a compact fluoride-fiber-based system that generates single solitons tun...High-power tunable femtosecond mid-infrared(MIR)pulses are of great interest for many scientific and industrial applications.Here we demonstrate a compact fluoride-fiber-based system that generates single solitons tunable from 3 to 3.8μm.The system is composed of an Er:ZBLAN fiber oscillator and amplifier followed by a fusion-spliced Dy:ZBLAN fiber amplifier.The Er:ZBLAN fiber amplifier acts as a power booster as well as a frequency shifter to generate Raman solitons up to 3μm.The Dy:ZBLAN fiber amplifier transfers the energy from the residual 2.8μm radiation into the Raman solitons using an in-band pumping scheme,and further extends the wavelength up to 3.8μm.Common residual pump radiation and secondary solitons accompanying the soliton self-frequency shift(SSFS)are recycled to amplify Raman solitons,consequently displaying a higher output power and pulse energy,a wider shifting range,and an excellent spectral purity.Stable 252 fs pulses at3.8μm with a record average power of 1.6 W and a pulse energy of 23 n J are generated.This work provides an effective way to develop high-power widely tunable ultrafast single-soliton MIR laser sources,and this method can facilitate the design of other SSFS-based laser systems for single-soliton generation.展开更多
基金supported by grants from the Natural Science Foundation of China(Nos.61275167,60878036and 60178023)the Basic Research Project of Shenzhen(Nos.JCYJ20130329103020637,JCYJ20120613112628842,JCYJ20140418095735591 and JC201005280533A)
文摘In this paper, a novel method of a subwavelength binary simple periodic rectangular structure is presented to realize even beam splitting by combining the rigorous couple-wave analysis with the genetic algorithm. Several even splitters in the terahertz region were designed and one of the silicon-based beam splitters designed to separate one incident beam into four emergent beams has total efficiency up to 92.23 %. Zero-order diffraction efficiency was reduced to less than 0.192 % and the error of uniformity decreased to 6.51 9 10-6. These results break the limitation of even beam splitting based on the traditional scalar theory. In addition, the effects of the incident angle, wavelength, as well as the polarizing angle on the diffraction efficiency and uniformity were also investigated.
文摘We numerically investigate the seven-core photonic crystal fiber (PCF) with the zero dispersion wavelength designed in the range of 1000 - 1080 nm, particularly suitable for the ytterbium-doped fiber laser pumping. Also, the PCFs are well designed for obtaining a flat in-phase mode by carefully adjusting the diameter of inner layer six holes, and the corresponding empirical values of fiber structure are summarized and listed. The variations of inner six holes to the amplitude of in-phase mode are further investigated, and our results show that a better tolerance can be achieved in the fiber structures with lower filling ratio configuration.
基金supported by the National Natural Science Foundation of China(52172070 and 51962013)Key R&D Program of Jiangxi Province(20223AAE02010,20192ACB80007,20201BBE51011,20232ACB204009 and jxsq2019201036)+2 种基金Guangdong Basic and Applied Basic Research Foundation(2020B1515120002)General Projects of Shenzhen Stable Development(SZWD2021003)the University Engineering Research Center of Crystal Growth and Applications of Guangdong Province(2020GCZX005).
文摘MXenes have received extensive attention from scholars due to their unique layered structure,significant electrical conductivity,and excellent mechanical properties.In addition to their pristine forms,they could also be incorporated with other components for attaining hybrids and nanocomposites,accompanying with amplified functionalities.It has been widely used in lithium batteries,supercapacitors,electromagnetic shielding,tumor therapy,biosensors,photocatalysis,and other fields,and has shown great application potential in energy conversion and storage.The purpose of this article is to encyclopaedically overview the latest progress in synthesis and characterization of MXenes,while their potential applications in energy conversation such as water splitting and solar cells,as well as in energy storage such as Li-ion batteries,supercapacitors,and hydrogen energy will be comprehensively elaborated.Development opportunities and challenges are summarized.
基金the National Natural Science Foundation of China(61975136,61935014,62105222,61775146,61905151)the Basic and Applied Basic Research Foundation of Guangdong Province(2019A1515010699)+1 种基金the Shenzhen Science and Technology Innovation Program(CJGJZD20200617103003009,JCYJ20210324094400001,GJHZ20210705141801006)the Beijing Natural Science Foundation(JQ21019).
文摘High-power femtosecond mid-infrared(MIR)lasers are of vast importance to both fundamental research and applications.We report a high-power femtosecond master oscillator power amplifier laser system consisting of a singlemode Er:ZBLAN fiber mode-locked oscillator and pre-amplifier followed by a large-mode-area Er:ZBLAN fiber main amplifier.The main amplifier is actively cooled and bidirectionally pumped at 976 nm,generating a slope efficiency of 26.9%.Pulses of 8.12 W,148 fs at 2.8μm with a repetition rate of 69.65 MHz are achieved.To the best of our knowledge,this is the highest average power ever achieved from a femtosecond MIR laser source.Such a compact ultrafast laser system is promising for a wide range of applications,such as medical surgery and material processing.
基金National High-tech R&D Program of China(863 Program)(2015AA021102)Innovative Research and Development Project of Nanshan District(KC2013JSCX0013A)+3 种基金China Postdoctoral Science Foundation(2015M572353,2015M582407)Natural Science Foundation of SZU(201457)National Natural Science Foundation of China(NSFC)(61275144,61308049)Science and Technology Projects of Shenzhen City(JCYJ20130329103213543,JCYJ20140418091413568,JCYJ20150324140036862)
文摘We demonstrate an integrated all-fiber mid-infrared(mid-IR)supercontinuum(SC)source generated by a 1.95μm master oscillator power amplifier system and a single-mode ZBLAN(ZrF_4–BaF_2–LaF_3–AlF_3–NaF)fiber.The maximum average output power is 10.67 W with spectral bandwidth covering from～1.9 to 4.1μm.The single-mode ZBLAN fiber and silica fiber are thermal-spliced to enhance the robustness and practicability of the system.It is,to the best of our knowledge,the first high-power integrated compacted all-fiber mid-IR SC source based on thermal-spliced silica fiber and ZBLAN fiber.
基金National Natural Science Foundation of China(NSFC)(11704260,61405126,61605122,61775146)Shenzhen Science and Technology Project(JCY20150324141711695,JCYJ20160427105041864,JSGG20160429114438287,KQJSCX20160226194031,JCYJ20160422103744090)+1 种基金Beijing University of Posts and Telecommunications(BUPT)(IPOC2015B003)Natural Science Foundation of Guangdong Province(2016A030310049,2016A030310059)
文摘The pulse energy in the ultrafast soliton fiber laser oscillators is usually limited by the well-known wave-breaking phenomenon owing to the absence of a desirable real saturable absorber(SA) with high power tolerance and large modulation depth. Here, we report a type of microfiber-based MoTe_2 SA fabricated by the magnetron-sputtering deposition(MSD) method. High-energy wave-breaking free soliton pulses were generated with pulse duration/pulse energy/average output power of 229 fs/2.14 nJ/57 mW in the 1.5 μm regime and 1.3 ps/13.8 nJ/212 mW in the 2 μm regime, respectively. To our knowledge, the generated soliton pulses at 1.5 μm had the shortest pulse duration and the highest output power among the reported erbium-doped fiber lasers mode locked by transition metal dichalcogenides. Moreover, this was the first demonstration of a MoTe_2-based SA in fiber lasers in the 2 μm regime, and the pulse energy/output power are the highest in the reported thulium-doped fiber lasers mode locked by two-dimensional materials. Our results suggest that a microfiber-based MoTe_2 SA could be used as an excellent photonic device for ultrafast pulse generation, and the MSD technique opens a promising route to produce a high-performance SA with high power tolerance and large modulation depth, which are beneficial for high-energy wave-breaking free pulse generation.
基金Project supported by National Natural Science Foundation of China(51502176)Shenzhen Science and Technology Project(JCYJ20150324141711618,JCYJ 20160427105041864,JSGG20160429114438287)Natural Science Foundation of SZU(827-000130,836-00008322)
文摘Mid-infrared laser materials with low phonon energy have significant applications. However, the development of available glass systems for high-power laser gain medium have posed a great challenge.Therefore, we investigated the 2.7 μm spectroscopic properties of Er^(3+)/Yb^(3+) -codoped oxyfluoride glass containing gallium, which were prepared by typically melting and quenching methods. The 2.7 μm luminescence properties of the Er^(3+)/Yb^(3+)-codoped oxyfluoride glass containing gallium were recorded by a 980 nm laser diode. The Judde Ofelt parameters, decay curves, emission cross section, energy transfer efficiency and quantum efficiency were calculated. The maximum emission cross section of YbFGa-0.5 is 1.63 × 10^(-20) cm^2 by 980 nm excitation. The energy transfer efficiency is calculated to be77.8% for the YbFGa-0.5 glass around 2700 nm. The quantum efficiency at 1530 nm is 65.6%. The result reveals that the best doping concentration ratio of Er^(3+):Yb^(3+) ions is 1:0.5, and suggests an effective energy transfer from Yb^(3+) to Er^(3+) ions.
基金National Natural Science Foundation of China(NSFC)(11704260,61575129,61605122,61775146)Natural Science Foundation of Guangdong Province(2016A030310049)+1 种基金Major Science and Technology Project of Guangdong Province(2014B010131006)Shenzhen Science and Technology Project(JCYJ20160427105041864,JSGG20160429114438287,KQJSCX20160226194031)
文摘We demonstrate, for the first time, to the best of our knowledge, an all-fiber figure-of-9 double-clad Tm-doped fiber laser operating in the dissipative soliton resonance(DSR) regime. Stable mode-locked rectangular pulses are obtained by using the nonlinear amplifying loop mirror(NALM) technique. A long spool of high-nonlinearity fiber(HNLF) and a segment of SMF-28 fiber are used to enhance the nonlinearity of the NALM loop and to obtain a large all-anomalous regime. Output power and pulse energy are further boosted by using a three-stage master oscillator power amplifier(MOPA) system. At the maximum pump power, average output power of up to 104.3 W with record pulse energy of 0.33 mJ is achieved with a 2 μm DSR-based MOPA system.
基金Natural Science Foundation of SZU(827-000130)National Natural Science Foundation of China(NSFC)(51502176,61378071)Science and Technology Projects of Shenzhen(JCYJ20150324141711618,JCYJ20160427105041864,JCYJ20170818101651195,JSGG20160429114438287)
文摘Near infrared light-controlled release of payloads from ultraviolet-sensitive(UV-sensitive) polymer hydrogels or nanocarriers is one of the most promising strategies for biotherapy. Here, we propose the concept of light activation of NaYF_4:20%Yb, 2%Tm nanocrystals(NCs). NaYF_4:20%Yb, 2%Tm NCs are synthesized by a solvothermal method. Effective upconversion luminescence from NaYF_4:20%Yb, 2%Tm NCs excited by a continuous wave(CW) 980 nm laser is obtained. The NaYF_4:20%Yb, 2%Tm NCs are then used as a laser gain medium and sandwiched between Al and quartz reflectors to form laser microcavities. UV and blue upconverted random lasing is obtained from the laser microcavities. Hence, we verify explicitly that the NaYF_4:Yb, Tm NCs support UV and blue upconversion random lasing via a 980 nm nanosecond laser excitation. Our work provides what we believe is a new concept for precision and localized cancer therapy by external light excitation.
基金supported by the National Natural Science Foundation of China (NSFC) (Nos. 61975136, 61935014, 61775146, and 61905151)Guangdong Basic and Applied Basic Research Foundation (No. 2019A1515010699)+2 种基金Shenzhen Science and Technology Project (Nos. JCYJ20160520161351540, JCYJ20170817100639177,JCYJ20170302151146995, JCYJ20180305125352956,JCYJ20160328144942069,and JCYJ20190808141011530)State Key Laboratory of Information Photonics and Optical Communications (No. IPOC2019ZZ01)State Key Laboratory of Pulsed Power Laser Technology (No. SKL2018KF04)
文摘We report on a mid-infrared fiber laser that uses a single-walled carbon nanotube saturable absorber mirror to realize the mode-locking operation.The laser generates 3.5 μm ultra-short pulses from an erbium-doped fluoride fiber by utilizing a dual-wavelength pumping scheme.Stable mode-locking is achieved at the 3.5 μm band with a repetition rate of 25.2 MHz.The maximum average power acquired from the laser in the mode-locking regime is 25 mW.The experimental results indicate that the carbon nanotube is an effective saturable absorber for mode-locking in the mid-infrared spectral region.
基金National Key R&D Program of China(2016YFA041100)China Postdoctoral Science Foundation(2016M592528)+2 种基金Natural Science Foundation of Guangdong Province(2017A030310130)National Natural Science Foundation of China(NSFC)(11704285,61575129,61805156)Science Technology Innovation Committee Foundation of Shenzhen(JCYJ20160328144942069)
文摘Perovskite quantum dots(QDs) are of great interest due to their outstanding optoelectronic properties and tremendous application potential. Improving photoluminescence(PL) spectra in all-inorganic perovskite QDs is of great importance for performance enhancement. In this work, the PL quantum yield of the CsPbBr3 perovskite QDs is enhanced from 70% to 95% with increasing radiation pressure. Such enhancement is attributed to the increased binding energy of self-trapped excitons(STEs) upon radiation pressure, which is consistent with its blue-shifted PL and other characterization results. Furthermore, we study ultrafast absorption spectroscopy and find that the dynamics of relaxation from free excitons to STEs in radiation pressure CsPbBr3 QDs is ascribed to stronger electron–phonon coupling in the contracted octahedral structure. It is further demonstrated that radiation pressure can boost the PL efficiency and explore effectively the relationship between the structure and optical properties.
基金National Key Research and Development Program of China(2016YFA0401100)National Natural Science Foundation of China(61575129,61705134)Shenzhen Science and Technology Innovation Commission(JCYJ20160328144942069,JCYJ20180305124706833).
文摘Carbon nanodots(C-dots) with a uniform size of about 2 nm are synthesized via in situ pyrolysis of n-propylamine that is confined in the nanochannels of zeolite Linde Type A(LTA). The as-synthesized C-dots@LTA composite shows nonlinear optical saturable absorption properties in a broad wavelength band and can be used as saturable absorber(SA) to generate ultrafast pulsed fiber lasers. By inserting a zeolite LTA single crystal hosting C-dots into the fiber laser cavity, mode-locked fiber lasers with long-term operation stability at 1.5 μm and 1 μm are achieved. These results show that the C-dots@LTA are a promising SA material for ultrafast pulsed fiber laser generation in a broad wavelength band. To the best of our knowledge, this is the first demonstration of a C-dots@LTA-based mode-locked fiber laser.
基金supported by the National Natural Science Foundation of China (NSFC) (Nos. 61975136, 61935014, 61775146, and 61905151)the Outstanding Young Teacher Cultivation Projects in Guangdong Province (No. YQ2015142)+3 种基金the Guangdong Basic and Applied Basic Research Foundation (No. 2019A1515010699)the Shenzhen Science and Technology Project (Nos. JCYJ20160520161351540, JCYJ20170817100639177, JCYJ20170302151146995, and JCYJ20160328144942069)the Engineering Applications of Artificial Intelligence Technology Laboratory Project (No. PT201701)the National Key Research and Development Program of China (No. 2016YFA0401100)。
文摘We experimentally demonstrate an all-fiber supercontinuum source that covers the spectral region ranging from visible to mid-infrared. The ultra-broadband supercontinuum is realized by pumping a cascaded photonic crystal fiber and a highly nonlinear fiber with a 1/1.5 μm dual-band pump source. A maximum output power of 9.01 W is achieved using the system,which is the highest power ever achieved from a supercontinuum source spanning from the visible to mid-infrared.
基金supported by the Natural Science Foundation of Top Talent of SZTU(Nos.2019010801001 and 202024555101039)。
文摘This study develops a Yb:KGW dual-crystal based regenerative amplifier.The thermal lensing and gain-narrowing effects are compensated by the dual-crystal configuration.Sub-nanojoule pulses are amplified to 1.5 mJ with 9 nm spectral bandwidth and 1 kHz repetition rate using chirped pulse amplification technology.Consequently,1.2 m J pulses with a pulse duration of 227 fs are obtained after compression.Thanks to the cavity design,the output laser was a near diffraction limited beam with M2 around 1.1.The amplifier has the potential to boost energy above 2 m J after compression and act as a front end for a future kilohertz terawatt-class diode-pumped Yb:KGW laser system.
基金National Key Research and Development Program of China(2016YFA0401100)National Natural Science Foundation of China(NSFC)(61575129,61705134)+1 种基金Shenzhen Science and Technology Project(JCYJ20160328144942069)China Postdoctoral Science Foundation(2017M612723)
文摘Short pulsed fiber lasers have been widely made using single-walled carbon nanotubes as a saturable absorber(SA). However, most of the currently used devices can only operate in one determined operation state with an unchangeable modulation SA depth in the cavity, which significantly limits their application in photonic devices.In this paper, well-aligned carbon nanotube arrays are synthesized using zeolite AlPO_4-5 as a template, which features anisotropic optical absorption. The linear optical absorption of the as-synthesized carbon nanotube arrays can easily be tuned by adjusting a polarization controller, thus providing a tunable modulation depth for the carbon nanotube SA. By exploiting this SA in an erbium-doped fiber laser cavity, both Q-switched and modelocked pulsed lasers are achieved by simply adjusting a polarization controller under a fixed pump power of 330 mW. In addition, the repetition rate of the Q-switching and pulse duration of the mode-locking can be tuned according to the variation of modulation depth. Moreover, soliton molecules can be obtained when the modulation depth of the SA is 4.5%.
基金supported by the National Natural Science Foundation of China(U2032149)Shenzhen Science and Technology Project(JCYJ20180507182246321)+3 种基金Hunan Provincial Natural Science Foundation of China(2020JJ2001)Hefei National Laboratory for Physical Sciences at the Microscale(KF2020108)the Fundamental Research Funds for the Central UniversitiesChina Postdoctoral Science Foundation(2019M663058 and 2019M652749).
文摘制备低成本的高效电催化剂是缓解目前面临的环境能源危机的重要方式.通过无定型化和构建异质结构可以有效地改变催化剂的电子结构,从而实现电催化性能的稳步提升.但是对于两者之间协同作用的研究则相对较少.在本文中,我们构建了富含异质结构的无定型FeMo基(a-FeMo)电催化剂,并系统评估了该催化剂的氮气还原和析氧反应性能.得益于无定型结构引起的活性位点数目的增多和异质结构引发的电子的重新分布,a-FeMo催化剂表现出优异的电化学催化性能.在-0.1 V vs.RHE的电势下,a-FeMo催化剂表现出29.15%的法拉第效率和71.78μg_(NH_(3)) mg_(cat.)^(-1) h^(-1)的氨气产率.这为合理设计具有低成本优势、高活性和长时间稳定性的优异催化剂提供了有益的参考.
基金Project supported by the Basic Research Foundation of Knowledge Innovation Program of Shenzhen City,China(No.JCYJ20180301-171044707)the University-Enterprise Cooperation Research and Development Project of Shenzhen Technology University,China(Nos.2018010802002,2018010802005,and 2019310103001)。
文摘A set of semiconductor laser pulse seed sources based on an embedded chip is proposed.The greatest feature is that the optical pulse frequency and width can be independently adjusted in real time.The pulse seed sources can be switched independently and online from the gain-switched mode to the quasi-continuous wave mode to obtain optimal optical parameters for specific applications.To explore the physical mechanism of the semiconductor laser source,the rate equation that describes the carrier-photon transient change in a semiconductor laser cavity is numerically derived and solved.Subsequently,problems that need to be considered while designing the drive circuit are identified.The system evaluation indicates that the optical pulse frequency adjustment range is 250 Hz to 42 MHz,and the narrowest optical pulse output width is 80 ps.The pulse seed source can drive semiconductor lasers with different central wavelengths(1064,1550,and 1970 nm),and can also simultaneously drive two semiconductor lasers and output dual-band optical pulses.It can be used as a seed source for general high-power optical systems,and exhibits good application value and extensive market prospects.
基金This work was supported by the National Natural Science Foundation of China(NSFC)(No.61575129).
文摘We report on mode-locked thulium-doped fiber lasers with high-energy nanosecond pulses,relying on the transmission in a semiconductor saturable absorber(SESA)and a carbon nanotube(CNTs-PVA)film separately.A section of an SMF-MMF-SMF structure multimode interferometer with a transmission peak wavelength of^2003 nm was used as a wavelength selector to fix the laser wavelength.When the SESA acted as a saturable absorber(SA),the mode-locked fiber laser had a maximum output power of^461 mW with a pulse energy of^0.14µJ and a pulse duration of^9.14 ns.In a CNT-film-based mode-locked fiber laser,stable mode-locked pulses with the maximum output power of^46 mW,pulse energy of^26.8 nJ and pulse duration of^9.3 ns were obtained.To the best of our knowledge,our experiments demonstrated the first 2µm region‘real’SA-based dissipative soliton resonance with the highest mode-locked pulse energy from a‘real’SA-based all-fiberized resonator.
基金National Natural Science Foundation of China(61775146,61905151,61935014,61975136,62105222)Basic and Applied Basic Research Foundation of Guangdong Province(2019A1515010699)+1 种基金Natural Science Basic Research Program of Shaanxi(2020JQ-204)Shenzhen Science and Technology Program(CJGJZD20200617103003009,JCYJ20210324094400001)。
文摘High-power tunable femtosecond mid-infrared(MIR)pulses are of great interest for many scientific and industrial applications.Here we demonstrate a compact fluoride-fiber-based system that generates single solitons tunable from 3 to 3.8μm.The system is composed of an Er:ZBLAN fiber oscillator and amplifier followed by a fusion-spliced Dy:ZBLAN fiber amplifier.The Er:ZBLAN fiber amplifier acts as a power booster as well as a frequency shifter to generate Raman solitons up to 3μm.The Dy:ZBLAN fiber amplifier transfers the energy from the residual 2.8μm radiation into the Raman solitons using an in-band pumping scheme,and further extends the wavelength up to 3.8μm.Common residual pump radiation and secondary solitons accompanying the soliton self-frequency shift(SSFS)are recycled to amplify Raman solitons,consequently displaying a higher output power and pulse energy,a wider shifting range,and an excellent spectral purity.Stable 252 fs pulses at3.8μm with a record average power of 1.6 W and a pulse energy of 23 n J are generated.This work provides an effective way to develop high-power widely tunable ultrafast single-soliton MIR laser sources,and this method can facilitate the design of other SSFS-based laser systems for single-soliton generation.
