Pei-En Chang

Emission properties of Ag/dielectric/Ag plasmonic thermal emitter with different lattice type, hole shape, and dielectric material

The emission spectra of the trilayer Ag/dielectric/Ag plasmonic thermal emitter (PTE) with different lattice type, hole shape, and dielectric material were investigated. It is found that the position and number of thermal emission peak of the PTE are determined by the lattice type not by the hole shape and dielectric materials. The PTE with hexagonal lattice generates only one strong (1,0) Ag/dielectric emission peak, whereas a similar PTE with square lattice generates two strong (1,0) and (1,1) Ag/dielectric emission peaks, their relative intensities follow the blackbody radiation law. This phenomenon suggests the coupling of Ag/dielectric and Ag/air modes.

Wavelength selective plasmonic thermal emitter by polarization utilizing Fabry-Pérot type resonances

The experimental results of dispersion relations and thermal emittance spectra of a metal/insulator/metal (MIM) structure with rectangle metallic patch arrays as top layer are demonstrated. The structure exhibits wide-angle, multipeak and polarized emission characteristics caused by Fabry-Perot type resonances of surface plasmons. Emission modes in x- and y-polarization are totally distinct, and their position depends on the width and length of the rectangular metallic patch. Therefore the designing of mode positions has two degrees of freedom and could be applied to wavelength selective light sources.

Narrow Bandwidth Midinfrared Waveguide Thermal Emitters

This work describes innovative waveguide thermal emitters with top metal perforated with subwavelength holes arranged in a short period to eliminate Bragg scattered waveguide modes (WMs) and surface plasmon polariton (SPP) modes. A metal-dielectric-metal parallel-plate waveguide with top metal perforated with subwavelength holes arranged in a short period exhibits high output intensities and emission peaks (WMs) with a narrow bandwidth in the midinfrared region under heat treatment. The redundant SPP modes and Bragg scattered WMs are filtered automatically by shifting them to the short wavelength due to a short period where blackbody radiations are too weak to appear.

Narrow bandwidth and highly polarized ratio infrared thermal emitter

Polarized infrared thermal emitters consisting of a waveguide thermal emitter combined with silver grating structure were studied. For a device containing a perforated silver film under the grating, polarized infrared light was emitted only when the wavelength satisfied the standing wave condition, therefore the broad bandwidth SiO2 phonon vibration modes were suppressed in the thermal radiation spectrum. The polarized ratio with different grating thickness was investigated and the highly polarized ratio up to 0.875 was achieved. This study demonstrated that the integrated structure can be used as a narrow bandwidth and highly polarized ratio infrared light source.

Characteristics of a waveguide mode in a trilayer Ag/SiO 2 /Au plasmonic thermal emitter

A suitably designed trilayer Ag/SiO(2)/Au thermal emitter can be used as the narrow bandwidth infrared light source. The thermal radiation generated in the SiO(2) layer resonates between the two metal films and results in not only the Ag/SiO(2) surface plasmon polaritons but also the waveguide mode (WM) in the Ag/SiO(2)/Au structure owing to the thick SiO(2) layer. This study investigated the influence of dielectric thickness on energy dispersion relations and derived the theoretical dispersion relation, which fit well with experimental results. This WM light source can be applied in the area of gas sensing and probing the response of the animal cells and plants to infrared radiation.

Triple peaks plasmonic thermal emitter with selectable wavelength using periodic block pattern as top layer

A plasmonic thermal emitter (PTE) with periodic block pattern as top layer was investigated. It is found that by adjusting the length and orientation of the rectangle metallic islands inside the block, three polarization-dependent peaks can be obtained in the thermal radiation spectra. The individual mode can be extracted according to different polarization by an external polarizer. Thus, a triple - spectral response PTE can be designed by tuning the appropriate dimensions of the block pattern.

Extraordinary Transmission Through Ag–Si Structure Perforated With Rhombus Lattice Hole Arrays

This investigation elucidates the transmission characteristics of an Ag-Si structure on which an Ag film is perforated with a rhombus-shape of lattice holes. The transmission in the Ag-Si mode depends approximately linearly on the numbers of degenerate modes at long wavelengths at which the couplings between Ag-Si and Ag-air modes are weak. At the shorter wavelengths where Ag-Si and Ag-air modes are coupled together, the transmission intensities are approximately constant without an apparent peak at wavelengths longer than those of the Ag-air modes. The intensities decay rapidly at lower wavelengths owing the asymmetric slope of the Ag-air mode in the spectra.

Electrical and optoelectronic characterization of a ZnO nanowire contacted by focused-ion-beam-deposited Pt

We report on the transport properties of single ZnO nanowires measured as a function of the length/square of radius ratio via transmission line method. The specific contact resistance of the FIB Pt contacts to the ZnO nanowires is determined as low as 1.1×10−5 Ωcm2. The resistivity of the ZnO nanowires is measured to be 2.2×10−2 Ωcm. ZnO nanowire-based UV photodetectors contacted by the FIB-Pt with the photoconductive gain as high as µ108 have been fabricated and characterized.

Optical characteristics of Al/Si structure and Ag/Al 2 O 3 /Ag plasmonic thermal emitter with square and hexagonal lattice

Optical emission spectra of the tri-layer Ag/Al2O3/Ag plasmonic thermal emitter with square and hexagonal lattice are consistent with the extraordinary transmission through Ag/Si structure with similar lattices. The plasmonic thermal emitter with hexagonal periodic lattice emits only one strong (1,0)Ag/Al2O3 peak, tends to suppress the (1,0)Ag/air and (1,1)Ag/Al2O3 SP modes, whereas a similar plasmonic thermal emitter with square periodic lattice emits two strong (1,0) and (1,1)Ag/Al2O3 peaks, their relative intensities follow the blackbody radiation law. Its fits well to the transmission spectra of the Ag/Si structure with square and hexagonal lattice, the (1,0)Ag/air and high order Ag/Si Rayleigh-woods anomaly, the (1,0)Ag/air and (2,0), (2,1)Ag/Si SP modes were excited when the holes cover more than 12.6%or 14.5%of the total area of the Ag film, respectively.