In terahertz (THz) photonics, there is an ongoing effort to develop thin, compact devices such as dielectric photonic crystal (PhC) slabs with desirable light matter interactions. However, previous works in THz PhC slabs are limited to rigid substrates with thicknesses $\sim$ 100s of micrometers. Dielectric PhC slabs have been shown to possess in-plane modes that are excited by external radiation to produce sharp guided mode resonances with minimal absorption for applications in sensors, optics and lasers. Here, we confirm the existence of guided resonances in a membrane-type THz PhC slab with subwavelength ($λ_{0}$/6 - $λ_{0}$/12) thicknesses of flexible dielectric polyimide films. The transmittance of the guided resonances was measured for different structural parameters of the unit cell. Furthermore, we exploited the flexibility of the samples to modulate the linewidth of the guided modes down to 1.5 GHz for bend angle of $θ$ $\geq 5^{\circ}$; confirmed experimentally by the suppression of these modes. The mechanical flexibility of the device allows for an additional degree of freedom in system design for optical components for high-speed communications, soft wearable photonics and implantable medical devices.
Broadband electro-optic intensity modulators are essential to convert electrical signals to the optical domain. The growing interest in THz wireless applications demands modulators with frequency responses to the sub-THz range, high power handling and very low nonlinear distortions, simultaneously. However, a modulator with all those characteristics has not been demonstrated to date. Here we experimentally demonstrate that plasmonic modulators do not trade off any performance parameter, featuring - at the same time - a short length of 10s of micrometers, record-high flat frequency response bey…
The computing speeds in modern multi-core processors and big data servers are no longer limited by the on-chip transistor density that doubles every two years following the Moores law, but are limited by the on-chip data communication between memories and microprocessor cores. Realization of integrated, low-cost, and efficient solutions for high speed, on-chip data communications require terahertz (THz) interconnect waveguides with tremendous significance in future THz technology including THz-wave integrated circuits and THz communication. However, conventional approaches to THz waveguiding s…
Photonics might play a key role in future wireless communication systems that operate at THz carrier frequencies. A prime example is the generation of THz data streams by mixing optical signals in high-speed photodetectors. Over the previous years, this concept has enabled a series of wireless transmission experiments at record-high data rates. Reception of THz signals in these experiments, however, still relied on electronic circuits. In this paper, we show that wireless THz receivers can also greatly benefit from optoelectronic signal processing techniques, in particular when carrier frequen…
The efficiency of photo-conductive switches, which continue to be used for the generation and detection of THz waves, has been overlooked for a long time. The so far 'optics-dominated' devices are making their way through to new and emerging fields of research that require ultrafast picosecond voltage pulses, as well as to new applications where power efficiency is of uttermost importance. To address the efficiency problems, in this article we present a novel photo-conductive switch that is based on a 3-dimensional design. In contrast to conventional planar designs, our photo-conductive switch…
In this paper, a photonic crystal containing graphene and metamaterial layers is investigated. The absorption spectrum of the structure in the terahertz range is obtained using the transfer matrix method. The results show that by adding a Si, SiO2 or metamaterial layer between two graphene layers, the terahertz absorption increases significantly. The results also reveal that in wide range of physical parameters, the approximately complete absorption occurs. Furthermore, the results indicate that the structure with metamaterial layer has the highest absorption performance.
Targeted light delivery into biological tissue is needed in applications such as optogenetic stimulation of the brain and in vivo functional or structural imaging of tissue. These applications require very compact, soft, and flexible implants that minimize damage to tissue. Here, we demonstrate a novel implantable photonic platform based on a high-density, flexible array of ultracompact (30 $μ$m x 5 $μ$m), low-loss (3.2 dB/cm at $λ$ = 680 nm, 4.1 dB/cm at $λ$ = 633 nm, 4.9 dB/cm at $λ$ = 532 nm, 6.1 dB/cm at $λ$ = 450 nm) optical waveguides made of biocompatible polymers Parylene C and polydim…
Fabricating high-performance and/or high-density flexible electronics on plastic substrates is often limited by the poor dimensional stability of polymer substrates. This can be mitigated by using glass carriers during fabrication, but removing the plastic substrate from a large-area carrier without damaging the electronics remains challenging. Here we present a large-area photonic lift-off (PLO) process to rapidly separate polymer films from rigid carriers. PLO uses a 150 microsecond pulse of broadband light from flashlamps to lift off functional thin films from a glass carrier substrate coat…
We report the polarization-dependent electromagnetic response from a series of novel terahertz (THz) metasurfaces where asymmetry is introduced through the displacement of two adjacent metallic arms separated by a distance $δ$. For all polarization states, the symmetric metasurface exhibits a low quality (Q) factor fundamental dipole mode. By breaking the symmetry, we experimentally observe a secondary dipole-like mode with a Q factor nearly $9\times$ higher than the fundamental resonance. As $δ$ increases, the fundamental dipole mode $f_{1}$ redshifts and the secondary mode $f_{2}$ blueshifts…
Second-order Raman and anharmonic lattice dynamics in lead-halide perovskites
Institute of Science and Technology Austria（科学技术奥地利研究所）；King Fahd University of Petroleum and Minerals（法赫德国王石油与矿产大学）；Interdisciplinary Research Center (IRC) for Advanced Materials, King Fahd University of Petroleum and Minerals（法赫德国王石油与矿产大学先进材料跨学科研究中心）；King Abdullah University of Science and Technology（阿卜杜拉国王科技大学）；Center for Renewable Energy and Storage Technologies, Division of Physical Science and Engineering, King Abdullah University of Science and Technology（阿卜杜拉国王科技大学物理科学与工程学部可再生能源与储能技术中心）；Aarhus University（奥胡斯大学）
We use computational approaches to explore the role of a high-refractive-index dielectric TiO2 grating with deep subwavelength thickness on InSb as a tunable coupler for THz surface plasmons. We find a series of resonances as the grating couples a normally-incident THz wave to standing surface plasmon waves on both thin and thick InSb layers. In a marked contrast with previously-explored metallic gratings, we observe the emergence of a much stronger additional resonance. The mechanism of this giant plasmonic resonance is well interpreted by the dispersion of surface plasmon excited in the air\…
