We report the use of a terahertz(THz)transparent material,cyclic olefin copolymer(COC or TOPAS),for fabricating a hollow-core antiresonant fiber that provides an electromagnetic wave guidance in the THz regime.A novel...We report the use of a terahertz(THz)transparent material,cyclic olefin copolymer(COC or TOPAS),for fabricating a hollow-core antiresonant fiber that provides an electromagnetic wave guidance in the THz regime.A novel fabrication technique to realize a hollow-core antiresonant polymer optical fiber(HC-ARPF)for THz guidance is proposed and demonstrated.The fiber is directly extruded in a single-step procedure using a conventional fused deposition modeling 3 D printer.The fiber geometry is defined by a structured nozzle manufactured with a metal 3 D printer,which allows tailoring of the nozzle design to the various geometries of microstructured optical fibers.The possibility to use the HC-ARPF made from TOPAS for guiding in the THz region is theoretically and experimentally assessed through the profile of mode simulation and time-frequency diagram(spectrogram)analysis.展开更多
Random scattering of light in disordered media can be used for highly sensitive speckle-based wavemeters and spectrometers. However, the multiple scattering events that fold long optical paths within a compact space a...Random scattering of light in disordered media can be used for highly sensitive speckle-based wavemeters and spectrometers. However, the multiple scattering events that fold long optical paths within a compact space also make such devices exceedingly sensitive to vibrations and small disturbances to the disordered media. Here, we show how scattering can be engineered so that it can be used for a compact computational spectrometer that is largely insensitive to environmental factors. We designed and fabricated a three-dimensional pseudo-random nano-void pattern with 62% scattering efficiency. The controlled amount of multiple scattering ensured a sufficiently long optical path for the target resolution of 100 pm, with optimal long-term stability. The 200-μm-thick scattering silica substrate was integrated in a compact assembly with a low-cost camera sensor. The target resolution was achieved for full spectrum measurements while single wavelengths could be determined with 50 pm resolution. Such tailored scattering systems can improve the trade-off among cost, size, stability, and spectral resolution in computational spectrometers.展开更多
A novel fluorescence lifetime imaging microscopy(FLIM) working with deep UV 240–280 nm wavelength excitations has been developed. UV-FLIM is used for measurement of defect-related fluorescence and its changes upon an...A novel fluorescence lifetime imaging microscopy(FLIM) working with deep UV 240–280 nm wavelength excitations has been developed. UV-FLIM is used for measurement of defect-related fluorescence and its changes upon annealing from femtosecond laser-induced modifications in fused silica. This FLIM technique can be used with microfluidic and biosamples to characterize temporal characteristics of fluorescence upon UV excitation, a capability easily added to a standard microscope-based FLIM. UV-FLIM was tested to show annealing of the defects induced by silica structuring with ultrashort laser pulses. Frequency-domain fluorescence measurements were converted into the time domain to extract long fluorescence lifetimes from defects in silica.展开更多
文摘We report the use of a terahertz(THz)transparent material,cyclic olefin copolymer(COC or TOPAS),for fabricating a hollow-core antiresonant fiber that provides an electromagnetic wave guidance in the THz regime.A novel fabrication technique to realize a hollow-core antiresonant polymer optical fiber(HC-ARPF)for THz guidance is proposed and demonstrated.The fiber is directly extruded in a single-step procedure using a conventional fused deposition modeling 3 D printer.The fiber geometry is defined by a structured nozzle manufactured with a metal 3 D printer,which allows tailoring of the nozzle design to the various geometries of microstructured optical fibers.The possibility to use the HC-ARPF made from TOPAS for guiding in the THz region is theoretically and experimentally assessed through the profile of mode simulation and time-frequency diagram(spectrogram)analysis.
基金European Research Council(804626)UK Research and Innovation(MR/S034900/1)+1 种基金Royal Academy of EngineeringEngineering and Physical Sciences Research Council(EP/N00762X/1).
文摘Random scattering of light in disordered media can be used for highly sensitive speckle-based wavemeters and spectrometers. However, the multiple scattering events that fold long optical paths within a compact space also make such devices exceedingly sensitive to vibrations and small disturbances to the disordered media. Here, we show how scattering can be engineered so that it can be used for a compact computational spectrometer that is largely insensitive to environmental factors. We designed and fabricated a three-dimensional pseudo-random nano-void pattern with 62% scattering efficiency. The controlled amount of multiple scattering ensured a sufficiently long optical path for the target resolution of 100 pm, with optimal long-term stability. The 200-μm-thick scattering silica substrate was integrated in a compact assembly with a low-cost camera sensor. The target resolution was achieved for full spectrum measurements while single wavelengths could be determined with 50 pm resolution. Such tailored scattering systems can improve the trade-off among cost, size, stability, and spectral resolution in computational spectrometers.
基金support via the Australian Research Council Discovery DP130101205 and DP120102980 grantsproject with Altechna Ltd
文摘A novel fluorescence lifetime imaging microscopy(FLIM) working with deep UV 240–280 nm wavelength excitations has been developed. UV-FLIM is used for measurement of defect-related fluorescence and its changes upon annealing from femtosecond laser-induced modifications in fused silica. This FLIM technique can be used with microfluidic and biosamples to characterize temporal characteristics of fluorescence upon UV excitation, a capability easily added to a standard microscope-based FLIM. UV-FLIM was tested to show annealing of the defects induced by silica structuring with ultrashort laser pulses. Frequency-domain fluorescence measurements were converted into the time domain to extract long fluorescence lifetimes from defects in silica.
