A simple rate equation model for 2μm Tm,Ho:YLF laser is given to study laser dynamics. Under low pump power, the explicit formulae for the threshold pump power and the relation between output power and incident power...A simple rate equation model for 2μm Tm,Ho:YLF laser is given to study laser dynamics. Under low pump power, the explicit formulae for the threshold pump power and the relation between output power and incident power are obtained. The present model provides a straightforward procedure to design the laser resonator and the optical coupling system for optimization. At the same time, the experimental results are reported. At room temperature the slope efficiency is 22.4% and the typical lasing threshold is about 328mW. The theory is in good agreement with experiment.展开更多
Photo-responsive room-temperature phosphorescent(RTP)materials have garnered significant interest due to the advantages of rapid response,spatiotemporal control,and contactless precision manipulation.However,the devel...Photo-responsive room-temperature phosphorescent(RTP)materials have garnered significant interest due to the advantages of rapid response,spatiotemporal control,and contactless precision manipulation.However,the development of such materials remains in its infancy,underscoring the importance of exploiting novel and efficient light-responsive RTP molecules.In this work,three phenothiazine derivatives of TPA-PTZ,TPA-2PTZ,and TPA-3PTZ were successfully synthesized via the Buchwald-Hartwig C—N coupling reaction.By embedding these molecules as RTP guests into polymethyl methacrylate(PMMA)matrix,photo-induced RTP properties were realized.Upon sustained UV irradiation,there was an enhancement of 19 times in the quantum yield to reach a value of 5.68%.Remarkably,these materials exhibit superior alongside robust light and thermal stability,maintaining high phosphorescence intensity even after prolonged UV exposure(irradiation for>200 s by a 365 nm UV lamp with the power of 500μW·cm-2)or at higher temperature up to 75℃.The outstanding properties of these photo-induced RTP materials make them promising candidates for applications in information encryption,anti-counterfeiting,and advanced optical materials.展开更多
Herein we report the room-temperature epitaxial growth of V203 films by laser molecule beam epitaxy. X-ray diffraction pro- files show the room-temperature epitaxial V2O3 films orient in the [ 110] direction on α-Al2...Herein we report the room-temperature epitaxial growth of V203 films by laser molecule beam epitaxy. X-ray diffraction pro- files show the room-temperature epitaxial V2O3 films orient in the [ 110] direction on α-Al2O3 （0001） substrates. Atomic force microscopy measurements reveal that the ultra-smooth surfaces with root-mean-square surface roughness of 0.11 nm and 0.28 nm for 10-nm-thick and 35-nm-thick V2O3 film, respectively. X-ray photoelectron spectroscopy results indicate the V3＋ oxida- tion state in the films. Typical metal-insulator transition is observed in films at about 135 K. The resistivities at 300 K are ap- proximately 0.8 mΩ cm and 0.5 mΩ cm for 10-rim-thick and 35-nm-thick V203 film, respectively.展开更多
Three types of a-C:Co/Si samples were fabricated using the pulsed laser deposition: Co2-C98/8i with Co dispersed in the a-C film, Co2-C98/Si with Co segregated at the interface, and a-C/Co/Si with Co continuously dist...Three types of a-C:Co/Si samples were fabricated using the pulsed laser deposition: Co2-C98/8i with Co dispersed in the a-C film, Co2-C98/Si with Co segregated at the interface, and a-C/Co/Si with Co continuously distributed at the a-C/Si interface. Both types of Co2-C98/Si samples had the positive bias-voltage-dependent magnetoresistance (MR) at 300 K, and all MRs had saturated behavior. The study on the electrotransport properties indicated that the MR appeared in the diffusion current region, and the mechanism of MR was proposed to be that the applied magnetic field and local random magnetic field caused by the superparamagnetic Co particles modulate the ratio of singlet and triplet spin states, resulting in the MR effect. In addition, the very different physical and structural properties of all samples revealed that Co played a crucial role in the room-temperature positive MR of a-C:Co/Si system.展开更多
文摘A simple rate equation model for 2μm Tm,Ho:YLF laser is given to study laser dynamics. Under low pump power, the explicit formulae for the threshold pump power and the relation between output power and incident power are obtained. The present model provides a straightforward procedure to design the laser resonator and the optical coupling system for optimization. At the same time, the experimental results are reported. At room temperature the slope efficiency is 22.4% and the typical lasing threshold is about 328mW. The theory is in good agreement with experiment.
文摘Photo-responsive room-temperature phosphorescent(RTP)materials have garnered significant interest due to the advantages of rapid response,spatiotemporal control,and contactless precision manipulation.However,the development of such materials remains in its infancy,underscoring the importance of exploiting novel and efficient light-responsive RTP molecules.In this work,three phenothiazine derivatives of TPA-PTZ,TPA-2PTZ,and TPA-3PTZ were successfully synthesized via the Buchwald-Hartwig C—N coupling reaction.By embedding these molecules as RTP guests into polymethyl methacrylate(PMMA)matrix,photo-induced RTP properties were realized.Upon sustained UV irradiation,there was an enhancement of 19 times in the quantum yield to reach a value of 5.68%.Remarkably,these materials exhibit superior alongside robust light and thermal stability,maintaining high phosphorescence intensity even after prolonged UV exposure(irradiation for>200 s by a 365 nm UV lamp with the power of 500μW·cm-2)or at higher temperature up to 75℃.The outstanding properties of these photo-induced RTP materials make them promising candidates for applications in information encryption,anti-counterfeiting,and advanced optical materials.
基金supported by the National Basic Research Program of China(Grant Nos.2010CB630704 and 2012CB921403)
文摘Herein we report the room-temperature epitaxial growth of V203 films by laser molecule beam epitaxy. X-ray diffraction pro- files show the room-temperature epitaxial V2O3 films orient in the [ 110] direction on α-Al2O3 （0001） substrates. Atomic force microscopy measurements reveal that the ultra-smooth surfaces with root-mean-square surface roughness of 0.11 nm and 0.28 nm for 10-nm-thick and 35-nm-thick V2O3 film, respectively. X-ray photoelectron spectroscopy results indicate the V3＋ oxida- tion state in the films. Typical metal-insulator transition is observed in films at about 135 K. The resistivities at 300 K are ap- proximately 0.8 mΩ cm and 0.5 mΩ cm for 10-rim-thick and 35-nm-thick V203 film, respectively.
基金support given by the National Natural Science Foundation of China (Grant Nos. U0734001 and 50772054)the Ministry of Science and Technology of China (Grant Nos. 2008CB617601 and 2009CB929202)
文摘Three types of a-C:Co/Si samples were fabricated using the pulsed laser deposition: Co2-C98/8i with Co dispersed in the a-C film, Co2-C98/Si with Co segregated at the interface, and a-C/Co/Si with Co continuously distributed at the a-C/Si interface. Both types of Co2-C98/Si samples had the positive bias-voltage-dependent magnetoresistance (MR) at 300 K, and all MRs had saturated behavior. The study on the electrotransport properties indicated that the MR appeared in the diffusion current region, and the mechanism of MR was proposed to be that the applied magnetic field and local random magnetic field caused by the superparamagnetic Co particles modulate the ratio of singlet and triplet spin states, resulting in the MR effect. In addition, the very different physical and structural properties of all samples revealed that Co played a crucial role in the room-temperature positive MR of a-C:Co/Si system.
