One-step direct patterning of high definition conductive tracks in textiles is realized through l... more One-step direct patterning of high definition conductive tracks in textiles is realized through laser direct writing in combination with a silver organometallic ink developed in-house. Photoreduction, nano-crystallization, and sintering are accomplished in one pass under the irradiation of a CW green laser light (λ = 532 nm) at moderate intensities (I ≥ 95 mW/mm2). By tailoring the surface tension and viscosity of the ink, high-definition conductive tracks are formed in weft-knitted polyester-Spandex composite fabrics, well-following the laser’s profile with negligible coffee stain effect. Length resistance as low as 4 Ω/cm is measured and anisotropy of the gauge factor as high as 25 is achieved. The metallized fabric exhibits reversible and hysteresis-free electromechanical responses subject to high strains. Durability assessment qualifies that the as-metallized strain sensors are able to sustain their performance for over 5000 stretch/release cycles, demonstrating its potential ap...
We report the spectral transmission of a rib waveguide side-coupled to a self-assembled polystyre... more We report the spectral transmission of a rib waveguide side-coupled to a self-assembled polystyrene microsphere array. A transmission stopband was observed at lambda ~ 1590nm, showing the potential for realising wavelength-selective devices.
The fabrication, spectroscopic properties, and laser performance of Nd 3+-doped Ta 2 O 5 channel ... more The fabrication, spectroscopic properties, and laser performance of Nd 3+-doped Ta 2 O 5 channel waveguide lasers are described. Lasing is obtained at both 1.066 and 1.375 m with threshold pump powers as low as 2.7 mW. The rib waveguides are reactive-ion-etched into Nd:Ta 2 O 5 layers formed by reactive magnetron sputtering. These high-index low-loss rare-earth-doped waveguides are fabricated on silicon substrates and offer the potential for integration with photonic crystal structures for compact optical circuits.
Comprehensive studies were carried out to understand the origin of the current hysteresis effects... more Comprehensive studies were carried out to understand the origin of the current hysteresis effects in highly efficient C60-CH3NH3PbI3(MAPbI3) heterojunction solar cells, using atomic-force microscopy, transmittance spectra, photoluminescence spectra, X-ray diffraction patterns and a femtosecond time-resolved pump-probe technique. The power conversion efficiency (PCE) of C60-MAPbI3 solar cells can be increased to 18.23% by eliminating the point (lattice) defects in the MAPbI3 thin film which is fabricated by using the one-step spin-coating method with toluene washing treatment. The experimental results show that the point defects and surface defects of the MAPbI3 thin films can be minimized by varying the dropping time of the washing solvent. The point defects (surface defects) can be reduced with an (a) increase (decrease) in the dropping time, resulting in an optimized dropping time for obtaining the defect-minimized MAPbI3 thin film deposited on top of the C60 thin film. Consequent...
We demonstrate an as yet unused method to sieve, localize, and steer plasmonic hot spot within me... more We demonstrate an as yet unused method to sieve, localize, and steer plasmonic hot spot within metallic nano-interstices close to percolation threshold. Multicolor superlocalization of plasmon mode within 60 nm was constantly achieved by chirp-manipulated superresolved four wave mixing (FWM) images. Since the percolated film is strongly plasmonic active and structurally multiscale invariant, the present method provides orders of magnitude enhanced light localization within single metallic nano-interstice, and can be universally applied to any region of the random film. The result, verified by the maximum likelihood estimation (MLE) and deconvolution stochastic optical reconstruction microscopy (deconSTORM) algorithm, may contribute to label-free multiplex superlocalized spectroscopy of single molecule and sub-cellular activity monitoring combining hot spot steering capability.
Germanium antimony sulphide (Ge-Sb-S) amorphous thin films have been deposited directly onto SiO2... more Germanium antimony sulphide (Ge-Sb-S) amorphous thin films have been deposited directly onto SiO2-on-silicon substrates by means of chemical vapour deposition. The Ge-Sb-S films have been characterized by micro-Raman, scanning electron microscopy, energy dispersive X-ray analysis and static tester techniques. Ge-Sb-S nano wires have been patterned and fabricated by e-beam lithography and dry etching techniques. Modeling results show the potential for
we develop a precise modelling where nonlocal electro-opto-thermal interactions are comprehensive... more we develop a precise modelling where nonlocal electro-opto-thermal interactions are comprehensively included for the analysis of nonlinear Raman enhancement and plasmonic heating. An interaction enhancement factor G(IEF) is introduced to quantify the coupling between the electromagnetic field and the temperature field which is rarely considered in the estimation of Raman enhancement. For the case of isolated single nanosphere, G(IEF) can be up to ten, indicating a thermal origin which well explains the observed temperature rise, shortened blinking period, and the nonlinearly enhanced Raman cross-section. For the case of nanodimer, the suppression of plasmon heating was analyzed, demonstrating the great capability to mitigate biomolecular degradation and blinking.
One-step direct patterning of high definition conductive tracks in textiles is realized through l... more One-step direct patterning of high definition conductive tracks in textiles is realized through laser direct writing in combination with a silver organometallic ink developed in-house. Photoreduction, nano-crystallization, and sintering are accomplished in one pass under the irradiation of a CW green laser light (λ = 532 nm) at moderate intensities (I ≥ 95 mW/mm2). By tailoring the surface tension and viscosity of the ink, high-definition conductive tracks are formed in weft-knitted polyester-Spandex composite fabrics, well-following the laser’s profile with negligible coffee stain effect. Length resistance as low as 4 Ω/cm is measured and anisotropy of the gauge factor as high as 25 is achieved. The metallized fabric exhibits reversible and hysteresis-free electromechanical responses subject to high strains. Durability assessment qualifies that the as-metallized strain sensors are able to sustain their performance for over 5000 stretch/release cycles, demonstrating its potential ap...
We report the spectral transmission of a rib waveguide side-coupled to a self-assembled polystyre... more We report the spectral transmission of a rib waveguide side-coupled to a self-assembled polystyrene microsphere array. A transmission stopband was observed at lambda ~ 1590nm, showing the potential for realising wavelength-selective devices.
The fabrication, spectroscopic properties, and laser performance of Nd 3+-doped Ta 2 O 5 channel ... more The fabrication, spectroscopic properties, and laser performance of Nd 3+-doped Ta 2 O 5 channel waveguide lasers are described. Lasing is obtained at both 1.066 and 1.375 m with threshold pump powers as low as 2.7 mW. The rib waveguides are reactive-ion-etched into Nd:Ta 2 O 5 layers formed by reactive magnetron sputtering. These high-index low-loss rare-earth-doped waveguides are fabricated on silicon substrates and offer the potential for integration with photonic crystal structures for compact optical circuits.
Comprehensive studies were carried out to understand the origin of the current hysteresis effects... more Comprehensive studies were carried out to understand the origin of the current hysteresis effects in highly efficient C60-CH3NH3PbI3(MAPbI3) heterojunction solar cells, using atomic-force microscopy, transmittance spectra, photoluminescence spectra, X-ray diffraction patterns and a femtosecond time-resolved pump-probe technique. The power conversion efficiency (PCE) of C60-MAPbI3 solar cells can be increased to 18.23% by eliminating the point (lattice) defects in the MAPbI3 thin film which is fabricated by using the one-step spin-coating method with toluene washing treatment. The experimental results show that the point defects and surface defects of the MAPbI3 thin films can be minimized by varying the dropping time of the washing solvent. The point defects (surface defects) can be reduced with an (a) increase (decrease) in the dropping time, resulting in an optimized dropping time for obtaining the defect-minimized MAPbI3 thin film deposited on top of the C60 thin film. Consequent...
We demonstrate an as yet unused method to sieve, localize, and steer plasmonic hot spot within me... more We demonstrate an as yet unused method to sieve, localize, and steer plasmonic hot spot within metallic nano-interstices close to percolation threshold. Multicolor superlocalization of plasmon mode within 60 nm was constantly achieved by chirp-manipulated superresolved four wave mixing (FWM) images. Since the percolated film is strongly plasmonic active and structurally multiscale invariant, the present method provides orders of magnitude enhanced light localization within single metallic nano-interstice, and can be universally applied to any region of the random film. The result, verified by the maximum likelihood estimation (MLE) and deconvolution stochastic optical reconstruction microscopy (deconSTORM) algorithm, may contribute to label-free multiplex superlocalized spectroscopy of single molecule and sub-cellular activity monitoring combining hot spot steering capability.
Germanium antimony sulphide (Ge-Sb-S) amorphous thin films have been deposited directly onto SiO2... more Germanium antimony sulphide (Ge-Sb-S) amorphous thin films have been deposited directly onto SiO2-on-silicon substrates by means of chemical vapour deposition. The Ge-Sb-S films have been characterized by micro-Raman, scanning electron microscopy, energy dispersive X-ray analysis and static tester techniques. Ge-Sb-S nano wires have been patterned and fabricated by e-beam lithography and dry etching techniques. Modeling results show the potential for
we develop a precise modelling where nonlocal electro-opto-thermal interactions are comprehensive... more we develop a precise modelling where nonlocal electro-opto-thermal interactions are comprehensively included for the analysis of nonlinear Raman enhancement and plasmonic heating. An interaction enhancement factor G(IEF) is introduced to quantify the coupling between the electromagnetic field and the temperature field which is rarely considered in the estimation of Raman enhancement. For the case of isolated single nanosphere, G(IEF) can be up to ten, indicating a thermal origin which well explains the observed temperature rise, shortened blinking period, and the nonlinearly enhanced Raman cross-section. For the case of nanodimer, the suppression of plasmon heating was analyzed, demonstrating the great capability to mitigate biomolecular degradation and blinking.
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Papers by Chao-Yi Tai