- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Insulator-Metal Transition in CaTiO<sub>3</sub> Quantum Dots induced by Ultrafast Laser Pulses
摘要： Based on time dependent density functional theory (TDDFT), we have studied the interaction between ultra-fast laser pulses and two kinds of calcium titanate quantum dots (PCTO-QDs and MCTO-QDs). Under the action of localized field effect, ultrafast lasers can induce quantum dots to make the transition from insulator to metal. PCTO-QDs are ultimately metallic, while MCTO-QDs are still insulator after experiencing metal state. This is bacause the stability of the unsaturated atoms in the outermost layer of PCTO-QDs is weak and the geometric configuration of MCTO-QDs as a potential well will also reduce the damage of laser. Moreover, laser waveforms approaching the intrinsic frequency of quantum dots tend to cause the highest electron levels to cross the Fermi surface. In this paper, it is reported that the insulating quantum dots can be transformed into metal by adjusting the intensity and frequency of laser. It emphasizes the importance of local morphology by comparing the difference about two kinds of CTO-QDs. More importantly, it is a step to identify the potential properties of perovskite materials.
关键词： CaTiO3 QDs,metallic transformation,ultra-fast laser
更新于2025-09-23 15:19:57
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Ultra-fast laser-based surface engineering of conductive thin films
摘要： Modern electronics facilitate the need for fast, efficient, and reliable methods for direct laser-based surface engineering of conductive thin film materials on flexible substrates. Recent advances in pulsed laser source development only incrementally increased the processing speeds, as those are limited by the available scanning systems. Our goal was to combine a high pulse repetition frequency high-power pulse-on-demand fiber laser source with an ultra-fast resonant scanner to achieve high throughput surface engineering. The enabling factor to compensate a resonant scanner’s sinusoidal movement were the laser’s intrinsic pulse-on-demand capabilities beyond simple pulse picking solutions. The high temporal resolution at full laser power was exploited for spatially controlled surface texturing, allowing a minimally 3 μm positioning accuracy throughout the scanner’s range at up to 60 m/s scan speed with a 10 μm laser spot size. We applied the setup to processing of ITO and metallic films on flexible substrates for touchscreens, position sensors, or EM shielding. Surface modification and patterning of the conductive layer was successfully demonstrated while keeping the underlying surface intact. We employed a simple laser ablation model in comparison to the experimental data to improve the understanding of the ablation process. The resulting surface topography was observed and analysed.
关键词： ultra-fast laser processing,resonant scanning,intrinsic pulse-on-demand,surface engineering
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - A Multiple-Waveguide Mode-Locked Chip-Laser Architecture
摘要： Frequency combs and analogue to digital sampling are emerging applications that can benefit from advances in elegant, compact, and high performance miniature mode-locked lasers. By virtue of their ‘chip-scale’, and multiplicity of adjacent waveguides, compact cavity planar waveguide devices are suited to efficiently operate in the ~0.5 GHz to 10 GHz pulse regimes. The ultra-fast chip laser platform we have pioneered is based on direct inscription of sub-surface large mode-area waveguides into rare-earth doped fluorozirconate (ZBLAN) glass chips. Multiple waveguides per chip are rapidly written via computer numerically controlled (CNC) ultra-fast laser inscription (ULI); a flexible and advancing waveguide fabrication technique. The guided-wave confinement of these fiber like structures in this bulk gain media ensures efficient pump and cavity mode overlap, robust alignment, and single transverse mode operation. Our initial mode-locking experiments focused on erbium doped ZBLAN chips (sensitized by Yb). These lasers display reasonable cw laser performance, a large single transverse-mode, a wide tunable range covering 1510-1590 nm, and a zero-dispersion wavelength of 1650 nm, thereby reducing the requirement for dispersion compensation. The erbium ytterbium cerium co-doped ZBLAN chips have been demonstrated to produce transform limited mode-locked output near 1.55 μm, with pulse lengths down to 180 fs, and operation up to 3 GHz. In recent work we have also demonstrated cw mode-locking near 1 μm based on Yb doped ZBLAN chip lasers. This talk will provide an overview of chip fabrication, cavity design, mode-locking configuration, and mode-locking results we have achieved. By taking advantage of the multiple waveguide channels, we have demonstrated a cavity that could simultaneously operate adjacent mode-locked erbium lasers using all common cavity components. By slightly modifying one of the cavity lengths, the dual mode-locked laser was shown to operate as an ultra-stable dual frequency comb. This laser possessed the highest mutual coherence reported to date for a passively stabilised dual-comb laser.
关键词： waveguide,ZBLAN glass,frequency combs,ultra-fast laser inscription,mode-locked lasers
更新于2025-09-12 10:27:22