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In the study of modern optics, the work of terahertz metamaterial absorbers is mostly multi-band perfect absorbers and ultra-wideband perfect absorbers. In contrast, in practical applications, metamaterial absorbers with adjustable resonance frequency or amplitude play an essential role in many forms. Here, we firstly designed an ultra-wideband terahertz metamaterial perfect absorber, achieving over 99% perfect absorption in the 6.6-8.9 THz range. Secondly, based on the absorber, phase change material VO2 was added to improve the structure, and three tunable terahertz metamaterial absorbers based on VO2 were designed, respectively realizing broadband movement and conversion between broadband and multi-band. Also, the terahertz absorber with dynamic tuning characteristics can flexibly control the absorption performance, providing an excellent platform for the realization of terahertz filtering, modulation, and so on.

Metamaterial absorbers have attracted more and more attention because they can achieve perfect absorption in some specific structures. At present, although most absorbers can achieve perfect absorption in one or more frequencies of the visible or near infrared regions, its cannot achieve ultra-narrow band absorption. Ultra-narrow band absorption means that devices have the opportunity to improve the effectiveness and accuracy of detection in many applications. Here, a novel design of narrowband perfect absorber based on a dielectric-dielectric-metal structure is studied, which comprises of an Al2O3 nanodisk arrays, a SiO2 dielectric layer, an Au film, and a substrate layer. The simulated results reveal that the optimized nanoabsorber can excite resonances with a narrow absorption bandwidth (FWHM) of 0.45 nm and a high-quality (Q) factor up to 1499 in the visible regime. Moreover, when it as a refractive index (RI) sensor, the maximum sensitivity(S) of 108.32 nm/RIU and figure of merit (FOM) reaching 240.7 are obtained. The device exhibits angle and polarization independence, which will eliminate the polarization and angle requirement of the equipment. As a consequence, we believe our narrowband absorber could be used in many potential applications such as the detection of photodetectors, biological, chemical and so on.

A ZnO seed layer was formed on the fluorine-doped tin oxide substrate by magnetron sputtering, and then a ZnO nanorod was grown on the ZnO seed layer by a hydrothermal method. Next, we prepared a single-crystal Ag seed layer by magnetron sputtering to form a ZnO@Ag composite heterostructure. Finally, Ag3PO4 crystals were grown on the Ag seed layer by a stepwise deposition method to obtain a ZnO@Ag@Ag3PO4 ternary heterojunction. The composite heterostructure of the material has super strong hydrophilicity and can be combined with water-soluble pollutants very well. Besides, it has excellent anti-reflection performance, which can absorb light from all angles. When Ag exists in the heterojunction, it can effectively improve the separation of photo-generated electrons and holes, and improve the photoelectric conversion performance. Based on the above characteristics, this nano-heterostructure can be used in the fields of solar cells, sensors, light-emitting devices, and photocatalysis.

A ZnO seed layer was formed on the fluorine-doped tin oxide substrate by magnetron sputtering, and then a ZnO nanorod was grown on the ZnO seed layer by a hydrothermal method. Next, we prepared a single-crystal Ag seed layer by magnetron sputtering to form a ZnO@Ag composite heterostructure. Finally, Ag3PO4 crystals were grown on the Ag seed layer by a stepwise deposition method to obtain a ZnO@Ag@Ag3PO4 ternary heterojunction. The composite heterostructure of the material has super strong hydrophilicity and can be combined with water-soluble pollutants very well. Besides, it has excellent anti-reflection performance, which can absorb light from all angles. When Ag exists in the heterojunction, it can effectively improve the separation of photo-generated electrons and holes, and improve the photoelectric conversion performance. Based on the above characteristics, this nano-heterostructure can be used in the fields of solar cells, sensors, light-emitting devices, and photocatalysis.

In this paper, ZnO@MoS2 core-shell heterojunction arrays were successfully prepared by the two-step hydrothermal method, and the growth mechanism was systematically studied. We found that the growth process of molybdenum disulfide (MoS2) was sensitively dependent on the reaction temperature and time. Through an X-ray diffractometry (XRD) component test, we determined that we prepared a 2H phase MoS2 with a direct bandgap semiconductor of 1.2 eV. Then, the photoelectric properties of the samples were studied on the electrochemical workstation. The results show that the ZnO@MoS2 heterojunction acts as a photoanode, and the photocurrent reaches 2.566 mA under the conditions of 1000 W/m2 sunshine and 0.6 V bias. The i-t curve also illustrates the perfect cycle stability. Under the condition of illumination and external bias, the electrons flow to the conduction band of MoS2 and flow out through the external electrode of MoS2. The holes migrate from the MoS2 to the zinc oxide (ZnO) valence band. It is transferred to the external circuit through the glass with fluorine-doped tin oxide (FTO) together with the holes on the ZnO valence band. The ZnO@MoS2 nanocomposite heterostructure provides a reference for the development of ultra-high-speed photoelectric switching devices, photodetector(PD) devices, and photoelectrocatalytic technologies.

A tunable terahertz (THz) narrowband absorber in view of bulk Dirac semimetal (BDS) is designed in this paper. The tunable terahertz absorber's basic unit comprises BDS, intermediate medium, and metal substrate. The BDS has good surface conductivity and the Fermi energy of that is flexible tunable, and the good surface conductivity might make controlled by Fermi energy. The absorption characteristics of the designed absorber are simulated by the finite integral time domain technique. The calculation results show that the designed absorber achieves ideal absorption in 139.97 μm, 163.52 μm, 247.76 μm bands, and the absorption rate is more than 0.96, which realizes ideal narrowband absorption and dynamic tuning. We find that the absorption peaks are flexible and adjustable by changing the Fermi energy of BDS, and the frequency adjustability of the absorber is analyzed. In addition, the effects of different structural parameters on the absorption efficiency and the absorption performance at different incident angles are studied. These results show that, compared with traditional metamaterials, Dirac semimetallic absorbing materials can tune the resonant frequency more effectively, even without reconstructing the structure, which has great application value in many fields, and provide a new reference for future research.

In this paper, an all-optical 4-to-1 digital multiplexer is proposed based on photonic crystals. A digital multiplexer is a combinational logic device allowing control of which one of four input ports can be connected to the output port. For performing this functionality, in addition to the input and output ports, the multiplexer also has two control ports. Nonlinear ring resonators are used to design the proposed structure. The maximum rise and fall times of the proposed structure are about 1.5 and 1 ps, respectively.

In this paper, a multi-band multi-tunable graphene absorber structure is proposed. The absorber is made by “+” intersecting double-ellipse graphene, L-shaped graphene layer, medium layer, the metal layer, and Si substrate. By using this structure, we investigated the possibility of graphene surface plasmon resonance in the incident far-infrared wave and THz wave range. For this structure, we use the FDTD Solution of finite time domain difference software to conduct theoretical research on it. The results show that the absorbing device in the range of the infrared in λ1 = 10.78 μm, λ2 = 12.20 μm and λ3 = 21.74 μm show perfect absorption peak of absorption rate is as high as 99.97%、99.81% and 99.91%, respectively. By controlling the Fermi level or the geometric parameters of the graphene layer can dynamically adjust the resonant wavelength of absorbing device, and polarization insensitivity characteristics. And in TE or TM mode, it can maintain good absorption performance in a wide range of 0° ~ 60°. We believe that our research results will open new doors for the use of metamaterial absorbers with multi-band, multi-tunable, polarization-independent and insensitive to large-angle oblique incidence. In the future, it can be used in photoelectric detection, photovoltaic cells, photoelectric sensors, photoelectric thermal radiation and other fields.

Using optical beam interference inside photonic-crystal-based waveguides is a promising method for designing and realizing all-optical logic gates and other digital devices. In this paper we design and propose an all-optical 1-bit comparator using optical beam interference. In the proposed structure, the logic states of input ports are determined based on their initial phases. The 180 deg and 0 deg phases are used as logic 0 and 1. However, the logic states of the output ports are determined based on the amplitude of the optical signal at the output ports. For the proposed structure, the maximum rise and fall times are about 0.6 ps and 0.3 ps, respectively.

Because of lack of high throughput screening devices for mechanobiological study, genome wide screening for mechanoresponsive genes has not been conducted. To overcome this situation, we developed a stretching device on a 96-well plate elastic chamber to be applicable to existing high throughput screening devices. We evaluated that this system allowed cells to be exposed to almost constant level of stretching within each well.

Polydimethylsiloxane (PDMS) is a commonly used silicone elastomer with broad applications. Particularly for bioengineering use, PDMS is treated with oxygen plasma with which its surface is oxidized to allow positive interaction with water and live cells. In exchange for the acquisition of hydrophilicity, the oxidized PDMS becomes mechanically brittle so that resulting formation of cracks affects the system in various ways. However, tensile strength (TS), which is an inherent capacity of a material to withstand tensile loads before breaking and is thus a key parameter limiting the use of the material, remains unclear regarding oxidized PDMS. Here we determine the TS of oxide layers created on the surface of PDMS based on micro-stretch experiments using a custom-made device. We show that the surface layer displays cracks upon tensile loading of small strains of within 10% to have a TS of ~10–100 kPa, which is approximately two orders of magnitude lower than that of unmodified PDMS. We further show that the TS sharply decreases with oxidation duration to become highly brittle, while the thickness of the resulting oxide layer finally reaches a plateau even with prolonged plasma treatment. Consequently, we suggest that gradual surface modification of PDMS takes place only within a finite region even with prolonged plasma treatment, as distinct from previously held assumptions. These quantitative data provide critical design information for the oxide layer of plasma-hydrophilized PDMS.