Compact on-Chip Temperature Sensors Based on Dielectric-Loaded Plasmonic Waveguide-Ring Resonators

The application of a waveguide-ring resonator based on dielectric-loaded surface plasmon-polariton waveguides as a temperature sensor is demonstrated in this paper and the influence of temperature change to the transmission through the waveguide-ring resonator system is comprehensively analyzed. The results show that the roundtrip phase change in the ring resonator due to the temperature change is the major reason for the transmission variation. The performance of the temperature sensor is also discussed and it is shown that for a waveguide-ring resonator with the resonator radius around 5 μm and waveguide-ring gap of 500 nm which gives a footprint around 140 μm2, the temperature sensitivity at the order of 10−2 K can be achieved with the input power of 100 μW within the measurement sensitivity limit of a practical optical detector

Detection of internal fields in double-metal terahertz resonators

Terahertz (THz) double-metal plasmonic resonators enable enhanced light-matter coupling by exploiting strong field confinement. The double-metal design however restricts access to the internal fields. We propose and demonstrate a method for spatial mapping and spectroscopic analysis of the internal electromagnetic fields in double-metal plasmonic resonators. We use the concept of image charges and aperture-type scanning near-field THz time-domain microscopy to probe the fields confined within the closed resonator. The experimental method opens doors to studies of light-matter coupling in deeply sub-wavelength volumes at THz frequencies

Efficient and broadband Terahertz plasmonic absorbers using highly doped Si as the plasmonic material

The design of efficient and broadband Terahertz plasmonic absorbers with highly doped Si as the plasmonic material is proposed and the performance of these absorbers are numerically investigated. The plasmonic properties of highly doped Si are first analyzed, based on which resonant plasmonic structures consisting of HDSi-SiO2-HDSi are presented. Numerical results  demonstrate that these structures exhibit high absorption in the terahertz frequencies with large bandwidth and tenability

Efficient and broadband Terahertz plasmonic absorbers with highly doped Si as the plasmonic material

The design of efficient and broadband Terahertz plasmonic absorbers with highly doped Si as the plasmonic material is proposed and the performance of these absorbers are numerically investigated. The plasmonic properties of highly doped Si are first analyzed, based on which resonant plasmonic structures consisting of HDSi-SiO2-HDSi are presented. Numerical results  demonstrate that these structures exhibit high absorption in the terahertz frequencies with large bandwidth and tenability

Quasi-Guided Modes Supported by a Composite Grating Structure with Alternating Element Widths

The efficiency of many optical processes is significantly dependent on the magnitude of the electric field. In this context, many artificially made resonating structures have been investigated to enhance light–matter interactions and facilitate the creation of practical applications. While metal–based terahertz metamaterials have been extensively investigated for this purpose, their performances are mainly limited by the poor confinement of terahertz waves on metal surfaces, exhibiting low resonance quality factors. In this work, we propose and investigate a simple yet novel scheme of enhancing wave–matter interactions in the terahertz region by exploiting the phenomenon of quasi–guided modes. The quasi-guided modes with ultra–high quality factors and huge local field enhancement can be achieved by manipulating the guided modes supported by a slab waveguide. The guided modes with the dispersion lines below the light line have infinite Q factors and can not be accessed from external space. By using a new type of composite grating composed of two ridge grating arrays with alternating ridge widths, the grating period is doubled, leading to a folding of the first Brillouin Zone and the flipping of the dispersion lines to be above the light line. Then, the guided modes will be transitioned into new quasi–guided modes with the possibility of free–space excitation while the Q factors are determined by the level of period–doubling perturbation. The presented results of realizing quasi–guided modes can be extended to other structures, providing a novel means of manipulating light–matter interactions

Efficient and broadband Terahertz plasmonic absorbers using highly doped Si as the plasmonic material

The property of highly doped Si as the plasmonic material in the THz regime is analyzed, based on which the design of efficient and broadband Terahertz plasmonic absorbers is proposed and the performance of these absorbers is numerically investigated. Numerical results from the reflection spectra demonstrate that these structures exhibit high absorption in the terahertz frequencies with large bandwidth and high tunability. It is also shown that the same level of absorptivity and bandwidth can be achieved when the top layer of highly dopes Si stripes are replaced with regular metal materials e.g. copper, highly facilitating the fabrication and practical use of the proposed structure in real Terahertz applications