A full-duplex radiant energy converter based on both betavoltaic and photovoltaic effects in an easyto-implement way is an attractive alternative for the autonomous wireless sensor microsystem.Here,we report a novel b...A full-duplex radiant energy converter based on both betavoltaic and photovoltaic effects in an easyto-implement way is an attractive alternative for the autonomous wireless sensor microsystem.Here,we report a novel beta/photovoltaic cell based on free-standing Zn O nanorod arrays(ZNRAs)modified with metallic single-walled carbon nanotubes(m-SWCNTs),using radioisotope63 Ni as beta-emitting source.The ZNRAs were grown on Al-doped Zn O(AZO)conductive glass using hydrothermal method.The optimum length and diameter of Zn O nanorods were determined by Monte Carlo simulation for beta energy deposition in ZNRAs.The m-SWCNTs were anchored into the ZNRAs to form a three-dimensional(3-D)Schottky junction structure for effectively separating the beta/photo-excited electron-hole pairs.Experimentally,the betavoltaic and photovoltaic effects were confirmed through the I-V measurements of beta/photovoltaic cells under beta/UV/Vis irradiations,respectively.It is suggested that the m-SWCNTs play key role for the enhancement of beta/photovoltaic performance through the formation of extensive3-D Schottky junction,the conductive network for hole transport,and the surface plasmon resonance exciton absorption for visible light.展开更多
Lichen vegetation reacts very sensitively to a variety of air pollutants including increased nitrogen concentrations as well as to traffic exhaust in general, which makes lichens reliable monitoring organisms for atmo...Lichen vegetation reacts very sensitively to a variety of air pollutants including increased nitrogen concentrations as well as to traffic exhaust in general, which makes lichens reliable monitoring organisms for atmospheric pollution. Recent environmental studies have shown that decreasing abundance of acidophytic lichen species and the increase of nitrophytic lichens can be explained by elevated levels of atmospheric nitric-compounds adsorbed onto nanoparticles. One major source of these atmospheric compounds amongst a wider pollution inventory is diesel exhaust—a mixture of gases and particle matter. This study aimed to shed light on the impact of diesel exhaust on the viability of six differently sensitive lichen species. Diesel exhaust particle concentrations in the laboratory experiments resembled those at a local highway during rush hour. By incubation in a closed stainless steel chamber we could exclude influences from other pollutants than diesel exhaust providing explicit data about the effects of diesel exhaust on lichens. The investigations revealed effects on the photosynthesis of the lichen photobionts and hence the lichen vitality. The conclusions of this study are that 1) the photobiont is affected stronger as the mycobiont and 2) older parts of the lichen are damaged first. Another remarkable result of this study is that 3) these lichens are regenerating to some extent during incubation-free periods—unless the organism is not damaged too much to restore photosynthetic activity. To our knowledge this is the first study evaluating the impact of diesel exhaust on lichens under laboratory conditions separate from other interfering pollutants.展开更多
Semiconductor vertical-cavity surface-emitting lasers(VCSELs)with wavelengths from 491.8 to 565.7 nm,covering most of the‘green gap’,are demonstrated.For these lasers,the same quantum dot(QD)active region was used,w...Semiconductor vertical-cavity surface-emitting lasers(VCSELs)with wavelengths from 491.8 to 565.7 nm,covering most of the‘green gap’,are demonstrated.For these lasers,the same quantum dot(QD)active region was used,whereas the wavelength was controlled by adjusting the cavity length,which is difficult for edge-emitting lasers.Compared with reports in the literature for green VCSELs,our lasers have set a few world records for the lowest threshold,longest wavelength and continuous-wave(CW)lasing at room temperature.The nanoscale QDs contribute dominantly to the low threshold.The emitting wavelength depends on the electron–photon interaction or the coupling between the active layer and the optical field,which is modulated by the cavity length.The green VCSELs exhibit a low-thermal resistance of 915 kW^(−1),which benefits the CW lasing.Such VCSELs are important for small-size,low power consumption full-color displays and projectors.展开更多
Single-mode, long-wavelength vertical-cavity surface-emitting lasers （VCSELs） in the near- to mid-infrared covering the wavelength range from 1.3 to 2.3 μm are presented. This wide spectral emission range opens app...Single-mode, long-wavelength vertical-cavity surface-emitting lasers （VCSELs） in the near- to mid-infrared covering the wavelength range from 1.3 to 2.3 μm are presented. This wide spectral emission range opens applications in gas sensing and optical interconnects. All these lasers are monolithically grown in the InGaAlAs-InP material system utilizing a buried tunnel junction （BTJ） as current aperture. Fabricated with a novel high-speed design with reduced parasitics, bandwidths in excess of 10 GHz at 1.3 and 1.55 μm have been achieved. Therefore, the coarse wavelength division multiplexing （CWDM） wavelength range of 1.3 to 1.6 μm at 10 Gb/s can be accomplished with one technology. Error-free data-transmission at 10 Gb/s over a fiber link of 20 km is demonstrated. One-dimensional arrays have been fabricated with emission wavelengths addressable by current tuning. Micro-electro-mechanical system （MEMS） tunable devices provide an extended tuning range in excess of 50 nm with high spectral purity. All these devices feature continuous-wave （CW） operation with typical single-mode output powers exceeding 1 mW. The operation voltage is around 1 - 1.5 V and power consumption is as low as 10 - 20 mW. Furthermore, we have also developed VCSELs based on GaSb, targeting functionality of tunable diode laser spectroscopy （TDLS） applying a 1.84-μm VCSEL. at the wavelength range from 2.3 to 3.0 μm. The systems is shown by presenting a laser hygrometer展开更多
基金the financial support of the project from the National Natural Science Foundation of China(Grant No.61574117)the Natural Science Foundation of Guangdong Province(Grant No.2018B030311002)the China Scholarship Council(Grant No.201806310044)。
文摘A full-duplex radiant energy converter based on both betavoltaic and photovoltaic effects in an easyto-implement way is an attractive alternative for the autonomous wireless sensor microsystem.Here,we report a novel beta/photovoltaic cell based on free-standing Zn O nanorod arrays(ZNRAs)modified with metallic single-walled carbon nanotubes(m-SWCNTs),using radioisotope63 Ni as beta-emitting source.The ZNRAs were grown on Al-doped Zn O(AZO)conductive glass using hydrothermal method.The optimum length and diameter of Zn O nanorods were determined by Monte Carlo simulation for beta energy deposition in ZNRAs.The m-SWCNTs were anchored into the ZNRAs to form a three-dimensional(3-D)Schottky junction structure for effectively separating the beta/photo-excited electron-hole pairs.Experimentally,the betavoltaic and photovoltaic effects were confirmed through the I-V measurements of beta/photovoltaic cells under beta/UV/Vis irradiations,respectively.It is suggested that the m-SWCNTs play key role for the enhancement of beta/photovoltaic performance through the formation of extensive3-D Schottky junction,the conductive network for hole transport,and the surface plasmon resonance exciton absorption for visible light.
文摘Lichen vegetation reacts very sensitively to a variety of air pollutants including increased nitrogen concentrations as well as to traffic exhaust in general, which makes lichens reliable monitoring organisms for atmospheric pollution. Recent environmental studies have shown that decreasing abundance of acidophytic lichen species and the increase of nitrophytic lichens can be explained by elevated levels of atmospheric nitric-compounds adsorbed onto nanoparticles. One major source of these atmospheric compounds amongst a wider pollution inventory is diesel exhaust—a mixture of gases and particle matter. This study aimed to shed light on the impact of diesel exhaust on the viability of six differently sensitive lichen species. Diesel exhaust particle concentrations in the laboratory experiments resembled those at a local highway during rush hour. By incubation in a closed stainless steel chamber we could exclude influences from other pollutants than diesel exhaust providing explicit data about the effects of diesel exhaust on lichens. The investigations revealed effects on the photosynthesis of the lichen photobionts and hence the lichen vitality. The conclusions of this study are that 1) the photobiont is affected stronger as the mycobiont and 2) older parts of the lichen are damaged first. Another remarkable result of this study is that 3) these lichens are regenerating to some extent during incubation-free periods—unless the organism is not damaged too much to restore photosynthetic activity. To our knowledge this is the first study evaluating the impact of diesel exhaust on lichens under laboratory conditions separate from other interfering pollutants.
基金supported by the National Natural Science Foundation of China(Grant Nos.61274052,11474235,U1505253)the Major Scientific and Technological Special Project of Guangdong Province(No.2014B010119004)the Science Challenge Project(No.JCKY2016212A503).
文摘Semiconductor vertical-cavity surface-emitting lasers(VCSELs)with wavelengths from 491.8 to 565.7 nm,covering most of the‘green gap’,are demonstrated.For these lasers,the same quantum dot(QD)active region was used,whereas the wavelength was controlled by adjusting the cavity length,which is difficult for edge-emitting lasers.Compared with reports in the literature for green VCSELs,our lasers have set a few world records for the lowest threshold,longest wavelength and continuous-wave(CW)lasing at room temperature.The nanoscale QDs contribute dominantly to the low threshold.The emitting wavelength depends on the electron–photon interaction or the coupling between the active layer and the optical field,which is modulated by the cavity length.The green VCSELs exhibit a low-thermal resistance of 915 kW^(−1),which benefits the CW lasing.Such VCSELs are important for small-size,low power consumption full-color displays and projectors.
基金the German Research Council(DFG)the National Natural Science Foundation of China(No.60510173 and 60506006)+1 种基金the European Union via NEMIS(No.FP6-2005-IST-5-031845)the German Federal Ministry of Education and Research via NOSE(No.13N8772).
文摘Single-mode, long-wavelength vertical-cavity surface-emitting lasers （VCSELs） in the near- to mid-infrared covering the wavelength range from 1.3 to 2.3 μm are presented. This wide spectral emission range opens applications in gas sensing and optical interconnects. All these lasers are monolithically grown in the InGaAlAs-InP material system utilizing a buried tunnel junction （BTJ） as current aperture. Fabricated with a novel high-speed design with reduced parasitics, bandwidths in excess of 10 GHz at 1.3 and 1.55 μm have been achieved. Therefore, the coarse wavelength division multiplexing （CWDM） wavelength range of 1.3 to 1.6 μm at 10 Gb/s can be accomplished with one technology. Error-free data-transmission at 10 Gb/s over a fiber link of 20 km is demonstrated. One-dimensional arrays have been fabricated with emission wavelengths addressable by current tuning. Micro-electro-mechanical system （MEMS） tunable devices provide an extended tuning range in excess of 50 nm with high spectral purity. All these devices feature continuous-wave （CW） operation with typical single-mode output powers exceeding 1 mW. The operation voltage is around 1 - 1.5 V and power consumption is as low as 10 - 20 mW. Furthermore, we have also developed VCSELs based on GaSb, targeting functionality of tunable diode laser spectroscopy （TDLS） applying a 1.84-μm VCSEL. at the wavelength range from 2.3 to 3.0 μm. The systems is shown by presenting a laser hygrometer
