Long-Range Uniform SiCO Beaded Carbon Fibers for Efficient Microwave Absorption.

SiCO beaded carbon fibers were successfully fabricated for the first time using a facile and stable electrospinning and temperature process. The resulting fibers showcase a unique micro-nanocomposite structure, in which β-SiC beads with a silica-enriched surface are strung together with defect carbon fibers, as confirmed by XRD, XPS, and HRTEM investigation. The SiCO beaded carbon fibers display efficient microwave absorption performance, with a minimum reflection loss of -58.

Colossal Room-Temperature Terahertz Topological Response in Type-II Weyl Semimetal NbIrTe.

The electromagnetic spectrum between microwave and infrared light is termed the "terahertz (THz) gap," of which there is an urgent lack of feasible and efficient room-temperature (RT) THz detectors. Type-II Weyl semimetals (WSMs) have been predicted to host significant RT topological photoresponses in low-frequency regions, especially in the THz gap, well addressing the shortcomings of THz detectors. However, such devices have not been experimentally realized yet.

Bionic Scarfskin-Inspired Hierarchy Configuration toward Tunable Microwave-Absorbing Performance.

Maintaining the dynamical microwave synchronization between a target and its background is the key to electromagnetical invisibility in real environment. Herein, we introduce an archetypical paradigm for ultraelastic films of graphene-functionalized ionic gel with tunable microwave-absorbing behaviors. Inspired by the local structural changes during the wing-spreading process of vespertilionids, the experimental and finite element simulations have revealed that proper shape changing of 3D wrinkled structure containing ridge walls with moderate impedance is the effective way to minimize reflected wave and promote energy attenuation.

Surface plasmon enhanced GeSn photodetectors operating at 2 µm.

Au-hole array and Au-GeSn grating structures were designed and incorporated in GeSn metal-semiconductor-metal (MSM) photodetectors for enhanced photo detection at 2 µm. Both plasmonic structures are beneficial for effective optical confinement near the surface due to surface plasmon resonance (SPR), contributing to an enhanced responsivity. The responsivity enhancement for Au hole-array structure is insensitive to the polarization direction, while the enhancement for Au-GeSn grating structure depends on the polarization direction.

Hole array enhanced dual-band infrared photodetection.

Photonic structures have been attracting more attention due to their ability to capture, concentrate and propagate optical energy. In this work, we propose a photon-trapping hole-array structure integrated in a nip InAsSb-GaSb heterostructure for the enhancement of the photoresponse in both near- and mid-infrared regions. The proposed symmetrical hole array can increase the photon lifetime inside the absorption layer and reduce reflection without polarization dependence.

Plasmonic semiconductor nanogroove array enhanced broad spectral band millimetre and terahertz wave detection.

High-performance uncooled millimetre and terahertz wave detectors are required as a building block for a wide range of applications. The state-of-the-art technologies, however, are plagued by low sensitivity, narrow spectral bandwidth, and complicated architecture. Here, we report semiconductor surface plasmon enhanced high-performance broadband millimetre and terahertz wave detectors which are based on nanogroove InSb array epitaxially grown on GaAs substrate for room temperature operation.

Ternary Ta PdS Atomic Layers for an Ultrahigh Broadband Photoresponsive Phototransistor.

2D noble-transition-metal chalcogenides (NTMCs) are emerging as a promising class of optoelectronic materials due to ultrahigh air stability, large bandgap tunability, and high photoresponse. Here, a new set of 2D NTMC: Ta PdS atomic layers is developed, displaying the excellent comprehensive optoelectronic performance with an ultrahigh photoresponsivity of 1.42 × 10 A W , detectivity of 7.

Photo detection and modulation from 1,550 to 2,000 nm realized by a GeSn/Ge multiple-quantum-well photodiode on a 300-mm Si substrate.

A GeSn/Ge multiple-quantum-well (MQW) p-i-n photodiode structure was proposed for simultaneously realizing high detectivity photo detection with low dark current and effective optical modulation based on the quantum confined Stark (QCSE) effect. The MQW stacks were grown on a 300-mm Ge-buffered Si substrate using reduced pressure chemical vapor deposition (RPCVD). GeSn/Ge MQW p-i-n photodiodes with varying mesa diameters were fabricated and characterized.

Rotated fourfold U-shape metasurface for polarization-insensitive strong enhancement of mid-infrared photodetection.

Metasurface with thin planar resonant elements offers great capability in manipulating electromagnetic waves and their interaction with semiconductors. Split-ring resonator (SRR), as the basic building block, has been extensively investigated for myriad applications owing to its multiple electric and magnetic resonant modes. In this work, we report a rotated fourfold U-shape SRR metasurface for polarization-insensitive strong enhancement of mid-infrared photodetection.

High Order Magnetic and Electric Resonant Modes of Split Ring Resonator Metasurface Arrays for Strong Enhancement of Mid-Infrared Photodetection.

Integration of photonic nanostructures with optoelectrical semiconductors offers great potential of developing high sensitivity and multifunctional photodetectors enabled by enhanced light-matter interactions. Split ring resonator (SRR) array which resonates at different resonant modes, including fundamental magnetic mode (m), high order magnetic mode (m), and electric (e) mode has been investigated because of the high potential for different applications. In this work, we study photodetection enhancement of these resonant modes of U-shape SRR arrays in the mid-infrared (2-5 μm) range and report, for the first time, the strong enhancement of photodetection by superimposition of m and e modes in an integrated photodetector consisting of a U-shape SRR array and an InAsSb-based heterojunction photodiode.

Indium antimonide uncooled photodetector with dual band photoresponse in the infrared and millimeter wave range.

All-InSb film-based and spiral antenna-assisted Au-InSb-Au metal-semiconductor-metal detector is reported with dual-band photoresponse in the infrared (IR) and millimeter wave range. At IR, the detector exhibits a long wavelength 100% cut-off at 7.3 µm.

Plasmon-exciton systems with high quantum yield using deterministic aluminium nanostructures with rotational symmetries.

The abundance and corrosion-resistant properties of aluminium, coupled with its compatibility to silicon processing make aluminium an excellent plasmonic material for light-matter interaction in the ultraviolet-visible spectrum. We investigate the interplay of the excitation and emission enhancements of quantum dots coupled with ultra-small aluminium nanoantennae with varying rotational symmetries, where emission enhancements of ∼8 and ∼6 times have been directly measured for gammadion and star-shaped structures. We observed spontaneous emission modification in the Al antenna with a C symmetry and deduce a Purcell factor in the range of 68.

CMOS-compatible all-Si metasurface polarizing bandpass filters on 12-inch wafers.

The implementation of polarization controlling components enables additional functionalities of short-wave infrared (SWIR) imagers. The high-performance and mass-producible polarization controller based on Si metasurface is in high demand for the next-generation SWIR imaging system. In this work, we report the first demonstration of all-Si metasurface based polarizing bandpass filters (PBFs) on 12-inch wafers.

Nanobridges formed through electron beam image reversal lithography for plasmonic mid-infrared resonators with high aspect ratio nanogaps.

We present the emergence of nanobridge networks through a nanofabrication technique based on image-reversal electron beam lithography and demonstrate plasmonic structures with high aspect ratio sub-20 nm gaps capable of strong intensity enhancement in the mid-infrared range. The proposed technique, which employs the engineering of natural formations of nanobridges in predefined templates, could serve as an alternative path for realizing mid-infrared plasmonic resonators with potential applications in surface plasmon polariton-based integrated optics, and enhancement of light-matter interaction for high efficiency photodetection and nanoscale light emitters.

Electrically controlled enhancement in plasmonic mid-infrared photodiode.

Surface plasmon polaritons (SPPs) have been attracting tremendous attention in application of enhanced optoelectronic devices owing to their capability of localizing electromagnetic waves in deep subwavelength scale. We propose a plasmonic mid-infrared InAsSb-based n-i-p photodiode with electrically-controlled photocurrent enhancement achieved by controlling the overlap between SPP depth and the absorption layer, from which maximum electrically controlled enhancement factors of ~5x and ~6x have been achieved for room temperature (293 K) and 77 K operation, respectively, corresponding to electrical tuning factors of 11.9 and 26.

Single Plasmonic Structure Enhanced Dual-band Room Temperature Infrared Photodetection.

Dual-band photodetection in mid- and near-wave infrared spectral bands is of scientific interest and technological importance. Most of the state-of-the-art mid-infrared photodetectors normally operate at low temperature and/or suffer from toxicity and high cost due to limitations of material properties and device structures. The capability of surface plasmons in confining electromagnetic waves into extremely small volume provides an opportunity for improving the performance for room temperature operation.

Surface plasmon induced direct detection of long wavelength photons.

Millimeter and terahertz wave photodetectors have long been of great interest due to a wide range of applications, but they still face challenges in detection performance. Here, we propose a new strategy for the direct detection of millimeter and terahertz wave photons based on localized surface-plasmon-polariton (SPP)-induced non-equilibrium electrons in antenna-assisted subwavelength ohmic metal-semiconductor-metal (OMSM) structures. The subwavelength OMSM structure is used to convert the absorbed photons into localized SPPs, which then induce non-equilibrium electrons in the structure, while the antenna increases the number of photons coupled into the OMSM structure.

Extreme Sensitivity of Room-Temperature Photoelectric Effect for Terahertz Detection.

Extreme sensitivity of room-temperature photoelectric effect for terahertz (THz) detection is demonstrated by generating extra carriers in an electromagnetic induced well located at the semiconductor, using a wrapped metal-semiconductor-metal configuration. The excellent performance achieved with THz detectors shows great potential to open avenues for THz detection.

Aluminum based structures for manipulating short visible wavelength in-plane surface plasmon polariton propagation.

We report aluminum based structures for manipulation of surface plasmon polariton (SPP) propagation at short wavelength range. Our simulation shows that aluminum is a good metal to excite and propagate SPPs with blue light and that the SPP wavelength can be reduced from about 465 nm to about 265 nm by monitoring the thickness of a coated Si(3)N(4) layer above the aluminum film. It is also shown that the damping becomes more significant with the increase of the thickness of the Si(3)N(4) layer.

Room-temperature photoconductivity far below the semiconductor bandgap.

A concept to stimulate photoconductivity in a semiconductor well below its bandgap in a metal-semiconductor-metal structure with sub-wavelength spacing is proposed. A potential well is induced in the semiconductor by external electromagnetic radiation to trap carriers from the metals. This opens an avenue to generate carriers by photons without adequate excitation energy and is expected to have great significance in modern materials.