The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
Surface wave provides unique applications ranging from biological sensing, deep-subwavelength lasing to plasmonic circuits. Seeking new approaches for controlling surface wave is highly desired in future integrated photonic devices. Here, we develop a versatile platform based on metasurfaces for the launch and control of propagating surface wave in the terahertz frequency regime.
We demonstrate that a nanostructured terahertz (THz) photoconductive detector enables sampling of THz fields localized on micrometer scale. The nanostructure, consisting of an optical nanoantenna array and a distributed Bragg reflector, acts as a hybrid cavity, which traps optical gate pulses within an optically thin photoconductive layer of the THz detector. This allows us to detect highly confined...
A conventional bull's eye antenna has a great potential to terahertz technologies, while its narrow band nature limits its ability for multi-frequency applications. Here we proposed an split-joint bull's eye (SJBE) structure with optimized aperture, which can achieve multi-frequency transmission and high concentration.
A kind of ultra-wide band-pass terahertz filter constructed by drilling annular holes on the metallic strips is proposed. The dispersion curves and S-parameters of the proposed filter are investigated in detail. Compared with the rectangular grooves, the results of the proposed structure demonstrate stronger field confinement and more excellent propagation performance in frequency range from 0.12THz...
Graphene's plasmons are extremely confined, with velocities as low as c/200, yet with long lifetimes exceeding 200 fs at room temperature. I will discuss recent experimental results in graphene plasmons in the frequency range 2–50 THz: how to engineer and understand their spatiotemporal dispersion, how to improve the lifetimes, and how plasmons may be optoelectronically detected using the graphene...
One of the main objectives of the THz-ARTE project is the construction of a portable THz imaging scanner, specifically designed to investigate mural paintings. Making of such a device and its use on an artwork will be presented.
To push the development of surface plasmonic devices (SPDs), a practical characterization means is essential for accurately observing a THz surface wave (TSW). In this work, a THz digital holographic imaging system is employed to coherently characterize temporal variations and spectral properties of TSWs excited by metallic sub-wavelength structures. Numerical simulations of experimental procedures...
We have developed a passive THz s-SNOM (scattering-type scanning near-field optical microscope) equipped with a helium-free cryostat. The mechanical vibration from the compressor is reduced for accurately controlling the probe-sample distance. Besides, the confocal system with a solid immersion lens leads to gather higher signal-to-noise ratio. To demonstrate the capability of the s-SNOM, we measured...
The recent discovery of anisotropic 2D materials introduces new horizons to implement miniaturized devices based on 2D materials. Black Phosphorous (BP) as a thermodynamically stable state of phosphorous is a multilayer material, which exhibits strong anisotropy due to its particular atomic lattice. The anisotropy in this material offers implementation of ultrathin polarization rotators in THz regime,...
A method to extract terahertz radiation from surface plasmon polaritons excited in the surface of a uniform graphene structure by an electron beam is presented. A sidewall configuration is proposed to lift the surface plasmon mode to be close to the light line, so that some of its harmonics have chances to go above the light line and become radiative. The harmonics are considered to be excited by...
We performed time-resolved terahertz (THz) near-field imaging of perfect electric conductor (PEC) disks with sub-wavelength periodic grooves. We successfully observed spoof localized surface plasmons (LSPs) whose resonance frequencies are solely determined by the groove depth. Controllable selective excitation method is demonstrated with orbital angular momentum of light. Our results pave the way...
Terahertz imaging solutions for industrial non-destructive testing applications receive an increasing attention. Besides the need for real-time acquisition and image processing, 3D feature localization and large field of views of several tenths to a few meters are in the focus of interest. For this purposes sparse line arrays of transmitters (Tx) and receivers (Rx) offer an optimal approach to reduce...
We present a feasibility study of THz surface emission from semiconductors as a mapping tool for magnetic field distribution. Using a standard THz time-domain spectroscopy setup, the THz emission of indium antimonide (InSb) was systematically measured at different points of an external magnetic field. The initial results suggest promising directions in developing a THz emission-based magnetic field...
We study the dependence of extraordinary optical transmission (EOT) on the input excitation mode by placing a metal screen with a 1D array of holes inside a parallel-plate waveguide (PPWG) operating at terahertz (THz) frequencies. We demonstrate that the output resonant frequency depends strongly on the input mode of the waveguide. We show that the surface plasmon theoretical description is invalid...
We report on terahertz radiation from topological insulator (TI) Sb2Te3 thin film under ultrafast optical excitation with different helicity. Polarity-reversals of the emitted THz radiation were observed as the helicity of optical pulses reversed. The observed phenomena are coincident with the characteristics of the helicity-dependent photocurrent on TIs. Our work demonstrates the potential applications...
We performed time-resolved terahertz (THz) near-field imaging of the perfect electric conductor (PEC) disk with sub-wavelength periodic grooves. The results strongly indicate the quadrupole spoof localized surface plasmon (LSP) is excited by vortex beam excitation. Our results pave the way for plasmonic applications in the THz frequency region.
The passive near-field microscope probes thermal evanescent waves derived from local dynamics on surfaces. Here we study dielectric samples, whose surface phonon resonances are close to the detection wavelength. GaAs and SiC show finite near-field signals due to thermal phonons, which decay rapidly from the surface. On the other hand, GaN and AlN show very unique characteristics, derived from phonon...
Monte Carlo simulations of photoexcited carrier dynamics combined with time domain electromagnetic modeling of the radiated field reveal different roles of the photocurrent vector components in the process of THz pulse generation upon ultrashort optical excitation of semiconductor surfaces. We find that only low frequency components (below 0.3 THz) are generated mainly by the initial transient current...
A kind of single-mode graphene loaded double ridge plasmon waveguide (GDRW) is proposed here, it demonstrates excellent mode confinement and long propagation length. Tunable propagation properties can be realized by changing either Fermi energy level or geometrical parameters, the structure of GDRW can efficiently suppress interference between adjacent devices. So, it can qualify the integration application...
Experiments with terahertz surface plasmons (SPs) excited by a free electron laser demonstrated that SPs are totally reflected from a plain mirror slightly inclined to the normal of the guiding surface. With larger angles, the SP reflection decreases gradually, which indicates that the wave vector of SPs on a real metal surface is not constant but is spread over a rather wide interval due to SP scattering...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.