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Multi-spectral frequency selective mid-infrared microbolometers
摘要： Frequency selective detection of low energy photons is a scientific challenge using natural materials. A hypothetical surface which functions like a light funnel with very low thermal mass in order to enhance photon collection and suppress background thermal noise is the ideal solution to address both low temperature and frequency selective detection limitations of present detection systems. Here, we present a cavity-coupled quasi-three dimensional plasmonic crystal which induces impedance matching to the free space giving rise to extraordinary transmission through the sub-wavelength aperture array like a 'light funnel' in coupling low energy incident photons resulting in frequency selective perfect (~100%) absorption of the incident radiation and zero back reflection. The peak wavelength of absorption of the incident light is almost independent of the angle of incidence and remains within 20% of its maximum (100%) up to 45°. This perfect absorption results from the incident light-driven localized edge 'micro-plasma' currents on the lossy metallic surfaces. The wide-angle light funneling is validated with experimental measurements. Further, a super-lattice based electronic biasing circuit converts the absorbed narrow linewidth (Δλ/λ ~0.075) photon energy inside the sub-wavelength thick film (< λ/100) to voltage output with high signal to noise ratio close to the theoretical limit. Such artificial plasmonic surfaces enable flexible scaling of light funneling response to any wavelength range by simple dimensional changes paving the path towards room temperature frequency selective low energy photon detection.
关键词： microbolometers,plasmonic crystal,light funnel,perfect absorption,room temperature detection,mid-infrared,frequency selective detection
更新于2025-09-19 17:15:36
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Purcell-Enhanced Spontaneous Emission from Perovskite Quantum Dots Coupled to Plasmonic Crystal
摘要： Lead halide perovskite quantum dots (PQDs) have recently been proposed as scalable and color-tunable single emitters, but their slow spontaneous emission (1-10 ns) creates a mismatch with high-speed nanophotonic devices. Here we demonstrate Purcell enhanced emission rate in hybrid structure of PQDs coupled to plasmonic crystal at room temperature. A series of planar devices are produced in large scale via chemistry assembly using colloidal PQDs, Ag nanocubes and polyvinyl pyrrolidone (PVP) as building blocks. By varying the PVP spacer thickness as well as Ag nanocube surface density, a tunable photoluminescence enhancement is realized in both steady and time resolved measurements. We show a 3.5-fold enhancement in the total fluorescence intensity and simultaneously an increase in the emission rate of a factor of 4.5. Finally, a proof-of-concept tag using PVP spacer encoded inks is demonstrated, providing a promising approach for information security based on Purcell-enhanced emission.
关键词： perovskite quantum dots,plasmonic crystal,information security,spontaneous emission,Purcell-enhanced emission
更新于2025-09-16 10:30:52
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European Microscopy Congress 2016: Proceedings || Angle-resolved cathodoluminescence of plasmonic crystal waveguide
摘要： Slow-light manipulation in a photonic crystal (PhC) waveguide is expected to improve future optical information processing and communication technologies such as optical buffering and light compression [T. Baba, Nat. Photon. 2, 465-473 (2008)]. Waveguiding using bandgap of plasmonic crystal (PlC) has also been demonstrated [S. I. Bozhevolnyi et al. Phys. Rev. Lett. 86, 3008-3001 (2001)]. However, the dispersion characteristics of the guided modes, which are essential to control surface plasmon polariton (SPP) pulses, have not yet been understood. Electron beam spectroscopies at high spatial resolution are powerful characterization tools to observe electromagnetic modes nowadays. Momentum-resolved spectroscopy in electron microscopy is especially useful to investigate detailed optical properties of locally-modified structures introduced into a PhC [R. Sapienza et al. Nat. Mater. 11, 781-787 (2012)] and a PlC [H. Saito and N. Yamamoto, Nano Lett. 15, 5764-5769 (2015)]. We have studied the dispersion characteristics of SPPs in a PlC waveguide by angle-resolved chatodoluminescence performed in a STEM. The guided SPP modes were found to have two unique features : i) energy dependence of the phase shift at the wall, and ii) waveguide bandgap (WBG) due to the periodicity originating from PlC structure, which resulted in small group velocity of the guided SPP modes over a wide energy range.
关键词： Slow light,Plasmonic crystal,Cathodoluminescence,Waveguide,Momentum-resolved spectroscopy
更新于2025-09-11 14:15:04
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Hybridization of Gap Modes and Lattice Modes in a Plasmonic Resonator Array with a Metal-Insulator-Metal Structure
摘要： Plasmonic resonator arrays have attracted a great interest as a platform to enhance light-matter interaction, and have been examined for their applicability to various types of optical devices, such as sensors, light emitter, photocatalyst, to name a few. In a plasmonic resonator array, localized and propagating plasmon modes can hybridize, which is known to result in an anti-crossing of the plasmon bands in the dispersion curves. However, it was so far unclear how the modal symmetry affects such a hybridization, especially when it occurs at a specific reciprocal lattice point with a high degree of symmetry e.g. the Γ point. In this work, we used momentum-resolved cathodoluminescence-scanning transmission electron microscopy to comprehensively characterize the modal hybridization at the Γ point. Our study reveals theoretically and experimentally the existence of mode symmetry selection rules that specify hybrid pairs of the lattice mode and localized mode.
关键词： mode hybridization,plasmonic crystal,dispersion relation,triangular lattice,cathodoluminescence,momentum resolved spectroscopy
更新于2025-09-11 14:15:04