We report on the room-temperature cascade laser （QCL） at λ -4.7μm. cw operation of a surface grating Both grating design and material distributed feedback （DFB） quantum optimization are used to decrease the thre...We report on the room-temperature cascade laser （QCL） at λ -4.7μm. cw operation of a surface grating Both grating design and material distributed feedback （DFB） quantum optimization are used to decrease the threshold current density and to increase the output power. For a high-reflectivity-coated 13-μm-wide and 4- mm-long laser, high wall-plug efficiency of 6% is obtained at 20℃ from a single facet producing over I W of ew output power. The threshold current density of DFB QCL is as low as 1.13kA/cm^2 at 10℃ and 1.34kA/cm2 at 30℃ in cw mode. Stable single-mode emission with a side-mode suppression ratio of about 30 dB is observed in tile working temperature range of 20-50℃.展开更多
Silicon-air batteries(SABs)hold significant potential as efficient energy conversion devices due to their high theoretical energy density,theoretical discharge voltage,and favorable energy-to-cost ratios.However,their...Silicon-air batteries(SABs)hold significant potential as efficient energy conversion devices due to their high theoretical energy density,theoretical discharge voltage,and favorable energy-to-cost ratios.However,their applicability has been hindered by low output discharge potential,high discharge polarizations,and singular aqueous configuration.To address these,the catalyst with faster oxygen reduction reaction(ORR)kinetic rate,nitrogen-doped carbon materials functionalized with FeMo metal clusters(FeMo-NC),was designed in acid electrolyte and thus high output voltage and energy density SABs with asymmetric-electrolytes have been developed.This innovative design aligns the reaction rates of the cathode and anode in SABs,achieving stable discharge around 1.7 V for 188 h.Furthermore,an all-in-one quasisolid-state SAB(QSSSAB)was first developed using a suitable acid-base gel electrolyte.This all-in-one QSSSAB showcases good safety,low cost,and portability,with open-circuit voltage of 1.6 V and energy density of 300.2 Wh kg^(-1),surpassing the energy density of most previously reported aqueous SABs.In terms of application,these compact all-in-one QSSSABs can provide stable and reliable power support for portable small electronic devices(such as electronic players,diodes,and electronic watches).展开更多
W-band quartz based high output power fix-tuned doublers are analyzed and designed with planar Schot- tky diodes. Full-wave analysis is carried out to find diode embedding impedances with a lumped port to model the no...W-band quartz based high output power fix-tuned doublers are analyzed and designed with planar Schot- tky diodes. Full-wave analysis is carried out to find diode embedding impedances with a lumped port to model the nonlinear junction. Passive networks of the circuit, such as the low pass filter, the E-plane waveguide to strip transitions, input and output matching networks, and passive diode parts are analyzed by using electromagnetic simulators, and the different parts are then combined and optimized together. The exported S-parameters of the doubler circuit are used for multiply efficiency analysis. The highest measured output power is 29.5 mW at 80 GHz and higher than 15 mW in 76-94 GHz. The highest measured efficiency is 11.5% at 92.5 GHz, and the typical value is 6.0% in 70-100 GHz.展开更多
We fabricate the Tm-doped double cladding silica fiber by using the vapor-solution hybrid-doping method, then build up an all-fiber Tin-doped fiber laser which can provide the output power of up to 121 W, correspondin...We fabricate the Tm-doped double cladding silica fiber by using the vapor-solution hybrid-doping method, then build up an all-fiber Tin-doped fiber laser which can provide the output power of up to 121 W, corresponding to a slope efficiency of 51% and an optical-optical efficiency of 48%. By using the domestic Tin-doped fiber, it is the first time a hundred-watt level output at 1915nm has been achieved, to the best of our knowledge. The thermal effect of Tm-doped fiber laser is also analyzed.展开更多
This paper presents an output feedback design approach based on the adaptive control scheme developed for nonlinearly parameterized systems,to achieve global output regulation for a class of nonlinear systems in outpu...This paper presents an output feedback design approach based on the adaptive control scheme developed for nonlinearly parameterized systems,to achieve global output regulation for a class of nonlinear systems in output feedback form.We solve the output regulation problem without the knowledge of the sign and the value of the high frequency gain a priori.It is not necessary to have both the limiting assumptions that the exogenous signal co and the unknown parameter ju belong to a prior known compact set and the high frequency gain has a determinate lower and upper bounds.The effectiveness of the proposed algorithm is shown with the help of an example.展开更多
1064 nm semiconductor lasers are crucial for optical communication,but the multitransverse‐mode nature of vertical‐cavity surface‐emitting laser(VCSEL)degrades beam quality over long distances.Traditional methods t...1064 nm semiconductor lasers are crucial for optical communication,but the multitransverse‐mode nature of vertical‐cavity surface‐emitting laser(VCSEL)degrades beam quality over long distances.Traditional methods to achieve fundamental transverse mode often limit power output and modulation band-width.We propose a two‐junction 1064 nm VCSEL with double embedded antiresonant oxide islands embedded in the top distributed Bragg reflector(DBR).By varying the oxide island count,aperture size,and position,we explore the behaviors of threshold current and output power for different transverse modes.This simulation‐based design achieves a maximum funda-mental transverse mode output power of 36.2 mW,a power conversion effi-ciency of 54.8%,and a 3 dB bandwidth of 33.06 GHz using oxide islands with 4 and 6μm radii at the second and eighth pairs of the top DBR.The enhanced modal discrimination raises the threshold current for higher‐order modes,thereby improving the fundamental mode output power,making this VCSEL structure promising for long‐distance optical communication.展开更多
Electrode materials have an important effect on the property of microbial fuel cell(MFC). Carbon foam is utilized as an anode and further modified by urea to improve its performance in marine benthic microbial fuel ce...Electrode materials have an important effect on the property of microbial fuel cell(MFC). Carbon foam is utilized as an anode and further modified by urea to improve its performance in marine benthic microbial fuel cell(BMFC) with higher voltage and output power. The electrochemical properties of plain carbon foam(PC) and urea-modified carbon foam(UC) are measured respectively. Results show that the UC obtains better wettability after its modification and higher anti-polarization ability than the PC. A novel phenomenon has been found that the electrical potential of the modified UC anode is nearly 100 m V lower than that of the PC, reaching-570 ±10 m V(vs. SCE), and that it also has a much higher electron transfer kinetic activity, reaching 9399.4 m W m-2, which is 566.2-fold higher than that from plain graphite anode(PG). The fuel cell containing the UC anode has the maximum power density(256.0 m W m-2) among the three different BMFCs. Urea would enhance the bacteria biofilm formation with a more diverse microbial community and maintain more electrons, leading to a lower anodic redox potential and higher power output. The paper primarily analyzes why the electrical potential of the modified anode becomes much lower than that of others after urea modification. These results can be utilized to construct a novel BMFC with higher output power and to design the conditioner of voltage booster with a higher conversion ratio. Finally, the carbon foam with a bigger pore size would be a potential anodic material in conventional MFC.展开更多
基金Supported by the National Basic Research Program of China under Grant Nos 2013CB632801 and 2013CB632803the National Natural Science Foundation of China under Grant Nos 61435014,61306058 and 61274094the Beijing Natural Science Foundation under Grant No 4144086
文摘We report on the room-temperature cascade laser （QCL） at λ -4.7μm. cw operation of a surface grating Both grating design and material distributed feedback （DFB） quantum optimization are used to decrease the threshold current density and to increase the output power. For a high-reflectivity-coated 13-μm-wide and 4- mm-long laser, high wall-plug efficiency of 6% is obtained at 20℃ from a single facet producing over I W of ew output power. The threshold current density of DFB QCL is as low as 1.13kA/cm^2 at 10℃ and 1.34kA/cm2 at 30℃ in cw mode. Stable single-mode emission with a side-mode suppression ratio of about 30 dB is observed in tile working temperature range of 20-50℃.
基金National Natural Science Foundation of China,Grant/Award Number:62264006。
文摘Silicon-air batteries(SABs)hold significant potential as efficient energy conversion devices due to their high theoretical energy density,theoretical discharge voltage,and favorable energy-to-cost ratios.However,their applicability has been hindered by low output discharge potential,high discharge polarizations,and singular aqueous configuration.To address these,the catalyst with faster oxygen reduction reaction(ORR)kinetic rate,nitrogen-doped carbon materials functionalized with FeMo metal clusters(FeMo-NC),was designed in acid electrolyte and thus high output voltage and energy density SABs with asymmetric-electrolytes have been developed.This innovative design aligns the reaction rates of the cathode and anode in SABs,achieving stable discharge around 1.7 V for 188 h.Furthermore,an all-in-one quasisolid-state SAB(QSSSAB)was first developed using a suitable acid-base gel electrolyte.This all-in-one QSSSAB showcases good safety,low cost,and portability,with open-circuit voltage of 1.6 V and energy density of 300.2 Wh kg^(-1),surpassing the energy density of most previously reported aqueous SABs.In terms of application,these compact all-in-one QSSSABs can provide stable and reliable power support for portable small electronic devices(such as electronic players,diodes,and electronic watches).
文摘W-band quartz based high output power fix-tuned doublers are analyzed and designed with planar Schot- tky diodes. Full-wave analysis is carried out to find diode embedding impedances with a lumped port to model the nonlinear junction. Passive networks of the circuit, such as the low pass filter, the E-plane waveguide to strip transitions, input and output matching networks, and passive diode parts are analyzed by using electromagnetic simulators, and the different parts are then combined and optimized together. The exported S-parameters of the doubler circuit are used for multiply efficiency analysis. The highest measured output power is 29.5 mW at 80 GHz and higher than 15 mW in 76-94 GHz. The highest measured efficiency is 11.5% at 92.5 GHz, and the typical value is 6.0% in 70-100 GHz.
基金Supported by the National High-Technology Research and Development Program of China under Grant No 2013AA031501the National Natural Science Foundation of China for Director Fund of WNLO
文摘We fabricate the Tm-doped double cladding silica fiber by using the vapor-solution hybrid-doping method, then build up an all-fiber Tin-doped fiber laser which can provide the output power of up to 121 W, corresponding to a slope efficiency of 51% and an optical-optical efficiency of 48%. By using the domestic Tin-doped fiber, it is the first time a hundred-watt level output at 1915nm has been achieved, to the best of our knowledge. The thermal effect of Tm-doped fiber laser is also analyzed.
基金supported by the National Natural Science Foundation of China(61663030,61663032)the Natural Science Foundation of Jiangxi Province(20142BAB207021)+4 种基金the Foundation of Jiangxi Educational Committee(GJJ150753)the Open Fund of Key Laboratory of Image Processing and Pattern Recognition of Jiangxi Province(Nanchang Hangkong University)(TX201404003)the Key Laboratory of Nondestructive Testing(Nanchang Hangkong University)Ministry of Education(ZD29529005)the Reform Project of Degree and Postgraduate Education in Jiangxi(JXYJG-2017-131)
文摘This paper presents an output feedback design approach based on the adaptive control scheme developed for nonlinearly parameterized systems,to achieve global output regulation for a class of nonlinear systems in output feedback form.We solve the output regulation problem without the knowledge of the sign and the value of the high frequency gain a priori.It is not necessary to have both the limiting assumptions that the exogenous signal co and the unknown parameter ju belong to a prior known compact set and the high frequency gain has a determinate lower and upper bounds.The effectiveness of the proposed algorithm is shown with the help of an example.
基金Supported by National Natural Science Foundation of China（60774010 10971256） Natural Science Foundation of Jiangsu Province（BK2009083）+1 种基金 Program for Fundamental Research of Natural Sciences in Universities of Jiangsu Province（07KJB510114） Shandong Provincial Natural Science Foundation of China（ZR2009GM008 ZR2009AL014）
基金National Key Research and Development Program of China,Grant/Award Number:2021YFA1401100National Natural Science Foundation of China,Grant/Award Numbers:52202165,52472148,62304031Natural Science Foundation of Sichuan Province,Grant/Award Number:2025ZNSFSC0351。
文摘1064 nm semiconductor lasers are crucial for optical communication,but the multitransverse‐mode nature of vertical‐cavity surface‐emitting laser(VCSEL)degrades beam quality over long distances.Traditional methods to achieve fundamental transverse mode often limit power output and modulation band-width.We propose a two‐junction 1064 nm VCSEL with double embedded antiresonant oxide islands embedded in the top distributed Bragg reflector(DBR).By varying the oxide island count,aperture size,and position,we explore the behaviors of threshold current and output power for different transverse modes.This simulation‐based design achieves a maximum funda-mental transverse mode output power of 36.2 mW,a power conversion effi-ciency of 54.8%,and a 3 dB bandwidth of 33.06 GHz using oxide islands with 4 and 6μm radii at the second and eighth pairs of the top DBR.The enhanced modal discrimination raises the threshold current for higher‐order modes,thereby improving the fundamental mode output power,making this VCSEL structure promising for long‐distance optical communication.
基金supported by the Key Project of Natural Science Fund of Shandong Province,China(ZR2011 BZ008)the Special Fund of Marine Renewable Energy from State Ocean Bureau,China(GHME2011GD 04)
文摘Electrode materials have an important effect on the property of microbial fuel cell(MFC). Carbon foam is utilized as an anode and further modified by urea to improve its performance in marine benthic microbial fuel cell(BMFC) with higher voltage and output power. The electrochemical properties of plain carbon foam(PC) and urea-modified carbon foam(UC) are measured respectively. Results show that the UC obtains better wettability after its modification and higher anti-polarization ability than the PC. A novel phenomenon has been found that the electrical potential of the modified UC anode is nearly 100 m V lower than that of the PC, reaching-570 ±10 m V(vs. SCE), and that it also has a much higher electron transfer kinetic activity, reaching 9399.4 m W m-2, which is 566.2-fold higher than that from plain graphite anode(PG). The fuel cell containing the UC anode has the maximum power density(256.0 m W m-2) among the three different BMFCs. Urea would enhance the bacteria biofilm formation with a more diverse microbial community and maintain more electrons, leading to a lower anodic redox potential and higher power output. The paper primarily analyzes why the electrical potential of the modified anode becomes much lower than that of others after urea modification. These results can be utilized to construct a novel BMFC with higher output power and to design the conditioner of voltage booster with a higher conversion ratio. Finally, the carbon foam with a bigger pore size would be a potential anodic material in conventional MFC.
