Wenxiong Xu 1†Yuanyuan Li 2†Qiannan Cui 1,5,*He Zhang 1[ ... ]Chunxiang Xu 1,6,*
Author Affiliations
1 State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast Universityhttps://ror.org/04ct4d772, Nanjing 210096, China
2 School of Electronic and Information Engineering, Nanjing University of Information Science and Technology, Nanjing 210044, China
3 Department of Physics and Astronomy, The University of Kansas, Lawrence, Kansas 66045, USA
4 Laboratory of Micro-Nano Optoelectronic Materials and Devices, Key Laboratory of Materials for High-Power Laser, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China
5 e-mail: qiannan@seu.edu.cn
6 e-mail: xcxseu@seu.edu.cn
Launching, tracking, and controlling picosecond acoustic (PA) pulses are fundamentally important for the construction of ultrafast hypersonic wave sources, ultrafast manipulation of matter, and spatiotemporal imaging of interfaces. Here, we show that GHz PA pulses can be all-optically generated, detected, and manipulated in a 2D layered MoS2/glass heterostructure using femtosecond laser pump–probe. Based on an interferometric model, PA pulse signals in glass are successfully decoupled from the coexisting temperature and photocarrier relaxation and coherent acoustic phonon (CAP) oscillation signals of MoS2 lattice in both time and frequency domains. Under selective interface excitations, temperature-mediated interfacial phonon scatterings can compress PA pulse widths by about 50%. By increasing the pump fluences, anharmonic CAP oscillations of MoS2 lattice are initiated. As a result, the increased interatomic distance at the MoS2/glass interface that reduces interfacial energy couplings can markedly broaden the PA pulse widths by about 150%. Our results open new avenues to obtain controllable PA pulses in 2D semiconductor/dielectric heterostructures with femtosecond laser pump–probe, which will enable many investigations and applications.
Photonics Research
2023, 11(12): 2000
东南大学 生物科学与医学工程学院 生物电子学国家重点实验室,南京 210096
飞秒激光 生物表界面 超快光谱 相干声学声子 声速 Femtosecond laser Bio-surface/interface Ultrafast spectroscopy Coherent acoustic phonon Acoustic velocity 
2022, 51(10): 1032001
Author Affiliations
State Key Laboratory of Bioelectronics, School of Biological Sciences & Medical Engineering, Southeast University, Nanjing 210096, China
Interface emission from heterojunction is a shortcoming for electroluminescent devices. A buffer layer introduced in the heterojunctional interfaces is a potential solution for the challenge. However, the dynamics for carrier tunneling to control the interface emission is still a mystery. Herein, the low-refractive HfO2 with a proper energy band configuration is employed as the buffer layer in achieving ZnO-microwire/HfO2/GaN heterojunctional light-emitting diodes (LEDs). The optically pumped lasing threshold and lifetime of the ZnO microwire are reduced with the introduced HfO2 layer. As a result, the interface emission is of blue-shift from visible wavelengths to 394 nm whereas the ultraviolet (UV) emission is enhanced. To regulate the interface recombination between electrons in the conduction band of ZnO and holes in the valence band of GaN, the tunneling electrons with higher conduction band are employed to produce a higher tunneling current through regulation of thin HfO2 film causing blue shift and interface emission enhancement. Our results provide a method to control the tunneling electrons in heterojunction for high-performance LEDs.
tunneling electron light-emitting diode heterojunctional interface nano HfO2 buffer 
Opto-Electronic Advances
2021, 4(9): 09200064
Author Affiliations
1 State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China
2 School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189, China
Microlasers based on high quality (Q) whispering-gallery mode (WGM) resonance are promising low threshold laser sources for bio-sensing and imaging applications. In this Letter, dye-doped polymer microspheres were fabricated by a controlling emulsion solvent evaporation method. WGM lasing with low threshold and high Q factors was realized in an individual microsphere under femtosecond laser pumping. The slight change of environmental relative humidity (RH) can be monitored by measuring the shift of the lasing modes at the exposure of water molecules, which demonstrates the sensitivity is as high as 6 pm/RH%. The results would offer an insight into employing microlasers as sensors.
140.2020 Diode lasers 160.2540 Fluorescent and luminescent materials 
Chinese Optics Letters
2018, 16(8): 081401
Author Affiliations
Advanced Photonics Center, School of Electronic Science and Engineering, Southeast University, Nanjing 210096
The synthesis of zinc oxide (ZnO) nanowires is achieved by vapor phase transportation (VPT) method. The designed quartz tube, whose both ends are narrow and the middle is wider, is used to control the growth of ZnO nanowires. Dielectrophoresis (DEP) method is employed to align and manipulate ZnO nanowires which are ultrasonic dispersed and suspended in ethanol solution. Under the dielectrophoretic force, the nanowires are trapped on the pre-patterned electrodes, and further aligned along the electric field and bridge the electrode gap. The dependence of the alignment yield on the applied voltage and frequency is investigated.
电泳 ZnO纳米线 排列 160.4236 Nanomaterials 160.5335 Photosensitive materials 160.6000 Semiconductor materials 
Chinese Optics Letters
2009, 7(3): 03235
Author Affiliations
Advanced Photonics Center, School of Electronic Science and Engineering, Southeast University, Nanjing 2100962 School of Chemistry and Chemical Engineering, Southeast University, Nanjing 210096
A simple method is adopted to grow ZnO nanofibers laterally among the patterned seeds designed in advance on silicon substrate. The preparation of seed lattices is carried out by lithographing the metal zinc film evaporated on the substrate. A layer of aluminum is covered on the zinc layer to prevent the ZnO nanorods vertically growing on the top surface. After oxidation, the patterned ZnO/Al2O3 spots are formed at the sites for the horizontal growth of ZnO nanofibers by the vapor phase transportation (VPT) method using the zinc powders as source material.
氧化锌 图案化 纳米纤维 160.0160 Materials 220.0220 Optical design and fabrication 250.0250 Optoelectronics 
Chinese Optics Letters
2009, 7(3): 03238
Author Affiliations
Adavnced Photonics Center, Southeast University, Nanjing 210096
A triple-layer light-emitting diode based on an organic salt ASPT (trans-4-[p-[N-methyl-N-(hydroxyethyl)amino]styryl]-N-methylpyridinium tetraphenylborate), in which TPD and Alq3 were employed as hole and electron transporting materials respectively, exhibits variable electroluminescence (EL) spectra under different applied voltage. At lower voltage, the EL spectrum peaks at 560 nm, which emanates from the TPD/ASPT interface; when the voltage is further increased, the peak at 610 nm, which is originated from ASPT, increases; at higher applied voltage, the device yields green light with a peak at 530 nm and a shoulder at 610 nm. The stronger emission peaking at 530 nm stems from the Alq3. It reveals the hole-electron recombination zone depends on the applied voltage, so the color-variable EL can be observed by adjusting the applied voltage.
250.0250 Optoelectronics 310.3840 Materials and process characterization 310.6870 Thin films, other properties 
Chinese Optics Letters
2005, 3(0s): 293

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