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Small mode volume plasmonic film-coupled nanostar resonators
摘要： Confining and controlling light in extreme subwavelength scales are tantalizing tasks. In this work, we report a study of individual plasmonic film-coupled nanostar resonators where polarized plasmonic optical modes are trapped in ultrasmall volumes. Individual gold nanostars, separated from a flat gold film by a thin dielectric spacer layer, exhibit a strong light confinement between the sub-10 nm volume of the nanostar’s tips and the film. Through dark field scattering measurements of many individual nanostars, a statistical observation of the scattered spectra is obtained and compared with extensive simulation data to reveal the origins of the resonant peaks. We observe that an individual nanostar on a flat gold film can result in a resonant spectrum with single, double or multiple peaks. Further, these resonant peaks are strongly polarized under white light illumination. Our simulation data revealed that the resonant spectrum of an individual film-coupled nanostar resonator is related to the symmetry of the nanostar, as well as the orientation of the nanostar relative to its placement on the gold substrate. Our results demonstrate a simple new method to create an ultrasmall mode volume and polarization sensitive plasmonic platform which could be useful for applications in sensing or enhanced light-matter interactions.
关键词： polarization,light confinement,resonators,plasmonic,film-coupled,nanostar
更新于2025-09-23 15:21:01
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Unique Design Strategy for Laser‐Driven Color Converters Enabling Superhigh‐Luminance and High‐Directionality White Light
摘要： Robust ceramic color converters withstanding strong laser irradiations have recently drawn great attention for laser-driven white lighting. However, the local emission within the incident laser spot usually expands to the whole surface area of the ceramics, which definitely makes it hard to achieve white light with high luminance and high directionality. Herein, a new strategy is proposed to solve the problem by elaborately introducing uniform spherical pores (diameter of ≈2 μm) into the phosphor ceramics with controlled contents from 8 to 24.6 vol%. The well-distributed pores, acting as light scattering centers, enable reduction of the luminescent spot size greatly but without any losses in conversion efficiency. By using the high-scattering ceramic color converters with 15% porosity, the light spot diameter is decreased by 46% and the central illuminance is increased by 156%. Moreover, laser-driven white light with an enhanced beam directionality and uniformity is also achieved. A superhigh luminous flux of 7199 lm is realized by using this promising color converter in a rotary mode. The designed high-scattering ceramics with controllable microstructures show great potential for use in extra-high luminance laser-driven lighting and projection.
关键词： light confinement,phosphor ceramics,phosphor wheel,laser-driven lighting,color converters,scattering
更新于2025-09-19 17:13:59
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Efficient coupling of light from dielectric to HIMI plasmonic waveguide
摘要： This is the ?rst report on the investigation of a hybrid plasmonic tapered coupler injecting light ef?ciently from conventional dielectric waveguide to a hybrid insulator–metal–insulator (HIMI) plasmonic waveguide. The proposed structure gives high transmission ef?ciency and suppresses the re?ection losses signi?cantly. With this tapered coupling mechanism, maximum transmittance and return loss of 98% and 26 dB have been observed, respectively. The coupler also offers very good propagation length (274 μm) along with minimal mode propagation losses (0.016 dB/μm). Apart from that, it offers decent con?nement of light in low dielectric regions up to 32%. The proposed structure is designed in an ultra-short tapered length of 1.0 μm, and the entire structure occupies a footprint area of 1.4 × 2.4 μm2. Proposed hybrid waveguide coupler could be useful for several chip scale applications.
关键词： chip scale applications,light confinement,hybrid plasmonic tapered coupler,propagation length,mode propagation losses,reflection losses,HIMI plasmonic waveguide,transmission efficiency
更新于2025-09-16 10:30:52