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A voltage-controllable VO2 based metamaterial perfect absorber (MPA) is proposed for CO2 gas sensing application.

A design of electric split-ring metamaterial (eSRM) with tunable terahertz (THz) free spectra range (FSR) characteristic is presented. The proposed eSRM is composed of double semicircle-shaped ring resonators with two connected metallic bars. By changing the radius of the semicircle-shaped ring resonators, the tuning ranges of FSR are 0.187 THz and 0.024 THz in transverse electric (TE) and transverse magnetic (TM) modes, respectively, which indicates eSRM could operate stably in TE and TM modes. Furthermore, eSRM exhibits switching and polarization-dependent characteristics by exploiting comb driver to control the distances between ring resonators along ${x}$ -and ${y}$ -axis directions. The electromagnetic responses could be tuned and switched between dual- and quad-resonance in both TE and TM modes. eSRM shows polarization angle-sensitive characteristic and the corresponding FSR could be tuned from 919 GHz to 336 GHz by changing the polarization angle of incident THz wave. In view of the above optical characteristics of eSRM, it is used for the sensing application exposed on different surrounding refraction index. The sensitivity, quality factor (Q-factor), and figure of merit (FOM) are calculated. The sensitivity is 0.457 THz/RIU and the average Q-factor and FOM are 40.65 and 35.47, respectively. These results indicate the proposed eSRM could be used in widespread applications, such as dual-/quad-resonance switches, polarization switches, and high-efficient environmental sensors. [2021-0006]

We propose and demonstrate a metamaterial design by integrating a microelectromechanical system (MEMS) electrothermal actuator (ETA) platform and a cross-shaped metamaterial (CSM) to perform opto-logic function characteristics. Reconfigurable and stretchable mechanisms of CSM are achieved by driving different DC bias voltages on ETA to improve the limitations induced by the conventional use of the flexible substrate. The optical responses of CSM are tunable by the electrical signals inputs. By driving a DC bias voltage of 0.20 V, a tuning range of CSM is 0.54 THz is obtained and it and provides perfect zero-transmission characteristics. In addition, the "XNOR" logic gate function of CSM is realized at 1.20 THz, which plays a key role in the all opto-logic network communication system. The proposed MEMS-based CSM exhibits potential applications in logical operation, signal modulation, optical switching, THz imaging, and so on.

We present four designs of actively tunable micro-electro-mechanical system-based racetrack-shaped metamaterials (RSMs), which are denoted as RSM_1, RSM_2, RSM_3, and RSM_4, respectively. RSM_1 is composed of asymmetrically single RSM, while RSM_2, RSM_3, and RSM_4 are all composed of asymmetrically double RSM layers with different rotation angles of 0°, 90°, and 180°, respectively. RSM_1 exhibits single-resonance in the transverse electric mode and dual-resonance in the transverse magnetic mode to perform the polarization-dependent characteristic. RSM_2, RSM_3, and RSM_4 exhibit tunable multi-resonance characteristics. By changing the height of the suspended layer, RSM_2, RSM_3, and RSM_4 exhibit optical switching characteristics. These switching resonances can be equivalent to binary bits, i.e., “0” and “1,” which can be programmed for opto-logic applications. These four designs of RSM devices possess the programmable multidigit switching characteristic by changing the incident polarization light. This study provides the possibility of a terahertz metamaterial to be used in the switch, programmable device, radar, and optical wireless communication applications.

We propose two tunable metareflectors (MRs) composed of a suspending nanodisk and an annular hole on silicon (Si) substrate with aluminum (Al) mirrors atop. They are denoted as MR-1 and MR-2 for the former and latter, respectively. The proposed MRs exhibit high-efficient cyan-magenta-yellow (CMY) color filtering, and ultrabroad tuning range characteristics. The electromagnetic energy of the resonant wavelength is confined within the suspending nanostructure and bottom Al mirror and then performed a perfect absorption. By changing the height between suspending nanostructure and the bottom Al mirror, MRs exhibit active tuning and single-/dual-resonance switching characteristics spanning the entire visible spectra range. Furthermore, the resonant wavelengths of MRs are sensitive to the surrounding ambient media, which are red-shifted and modulated from single- to dual-resonance by changing the environmental refraction index. The corresponding sensitivities are 500 nm/RIU and 360 nm/RIU for MR-1, 289 nm/RIU and 270 nm/RIU for MR-2, respectively. These results provide an effective strategy for use in high-resolution displays, high-sensitive sensors, optical switches, optical communications, and flexible virtual reality (VR)/augmented reality (AR) applications.

We propose a design of tunable double split-ring metamaterial (DSRM) in the terahertz (THz) frequency range. It is composed of a H-shaped resonator sandwiched by two face-to-face split-ring resonators (SRRs) on silicon on insulator (SOI) substrate. The electromagnetic responses of DSRM can be manipulated between single-resonance and dual-resonance by changing the incident polarization light, which shows polarization sensitive characteristic. DSRM exhibits a tunable function in the frequency range of 0.16 THz to 0.21 THz through enlarging the gap within two SRRs at TE mode. DSRM also shows stable characteristic by changing the distance between two face-to-face SRRs at TE and TM modes. Furthermore, to enhance the flexibility and applicability of DSRM, it is exposed on the surrounding environments with different refraction indexes. The correction coefficients are 0.997 for DSRM at TE and TM modes. These results show that DSRM exhibit the linear red-shifting of resonances by increasing the environmental refraction index. This work paves a way to the possibility of metamaterial devices with great tunability and polarization-dependence characteristics in the sensing applications.

We propose a novel infrared (IR) meta-absorber by using chalcogenide glass (ChG) material. The merits of ChG are zero extinction coefficient, excellent IR transparency, high third-order nonlinearity, adjustable refraction index, dispersion, and energy bandgap in IR wavelength range. Therefore, it is very suitable for the meta-absorber design. This ChG -based meta-absorber is composed of ring-disk nanostructures. The resonant wavelength and intensity of reflection spectra could be tuned by changing the outer ring of ring-disk nanostructures in horizontal and vertical displacements. The maximum quality factor (Q-factor) is 625. These unique characteristics of IR meta-absorber with ring-disk nanostructures can be used as a tunable IR filter and multi-resonance switch. Furthermore, the proposed device exhibits superior electromagnetic behaviors to be used as a high-efficiency environmental sensor.

The integration of micro-electro-mechanical system (MEMS) with metamaterial has provided a novel route to achieve programmability via its reconfigurable capabilities. Here, we propose and demonstrate a MEMS-based metadevice by using switchable winding-shaped cantilever metamaterial (WCM) for active logical modulation. WCM can be actuated by external driving voltage, and the logical modulation bit is performed by releasing MEMS cantilevers to represent “on” and “off” states. While the underneath substrate surface of a MEMS-based metadevice is rough after releasing the cantilevers, the metadevice is allowed to operate on the reconfigurable switching state and avoid the snapping down of the device when the system is overloaded. Such a reconfigurable and programmable MEMS-based metadevice exhibits multifunctional characteristics to simultaneously perform the logic operations of “OR” and “AND” gates. By exploiting the tuning mechanism of the MEMS-based metadevice, the arbitrary metamaterial configuration can be implanted into WCM. This opens a wide avenue to further enlarge the operating frequency range and applications in optoelectronic fields. These unique results provide various possibilities in multifunctional switching, active logical modulating, and optical computing applications.

Haemaphysalis longicornis is distributed worldwide and transmits a variety of pathogens, causing human and animal disease. Use of chemical acaricides, as a primary tick control method, has several disadvantages, including acaricide resistance, environmental damage and residue accumulation in livestock. Development of a livestock vaccination aimed at a tick protective antigen could be an effective, labor-saving and environmentally-friendly method of reducing tick infestation and transmission of tick-borne pathogens. Lipocalins are low molecular weight proteins that play important roles in blood feeding, immune response and reproduction in ticks. In our study, the open reading frame (ORF) of a lipocalin homologue from H. longicornis (HlLIP) was successfully cloned, which consisted of 387 bp encoding a protein of 128 amino acids. The HlLIP protein sequence showed a close sequence homology with Ixodes persulcatus lipocalin. The HlLIP gene was constitutively detected in all developmental stages and in all tissues of the unfed female tick. The ORF of the HlLIP gene was sub-cloned into pET-32a (+) to obtain the recombinant protein (rHlLIP) and its immunogenicity was comfirmed by western blot. A vaccination trial on rabbits against H. longicornis infestation demonstrated that the rHlLIP protein could significantly prolong the period of tick blood feeding, and reduce tick engorged weight, oviposition and egg hatching rate. The vaccination efficacy of the rHlLIP protein was 60.17 % based on engorged weight, oviposition and egg hatching rate of ticks. The results obtained in this study demonstrate that rHlLIP protein is a promising antigen that could potentially be developed as a vaccine against H. longicornis infestation.