We present thermal control of electromagnetically induced transparency (EIT) by actively modulating the dark mode in terahertz (THz) metamaterials, including a cut wire and a split-ring resonator (SRR). By integrating indium antimonide (InSb) into the SRR and increasing the temperature, the active modulation of EIT is realized. The coupling mechanism is numerically analyzed through the coupled oscillator model, and the result of fitting the EIT intensity agrees well with the simulation results when the temperature changes from 200 to 240 K. By analyzing the electric field distribution, the physical mechanism is the change in the damping rate of the dark mode resonator due to the increase in InSb temperature. Our work has practical significance in designing tunable THz functional devices.
the purpose of this study was to describe the incidence of serious bacterial infections in febrile outpatient pediatric kidney transplant recipients and to assess the utility of using white blood cell indices to identify patients at low risk for bacteremia.a retrospective study was conducted on all kidney transplant recipients followed at a single children's hospital. All outpatient visits from January 1, 1995 to June 6, 2007 in which fever was evaluated were reviewed. Patients with history of a primary immunodeficiency, receiving concurrent chemotherapy, or a stem cell or small bowel transplant were excluded. Demographic, historical, physical examination, laboratory, and radiographic data were then recorded.in all, 101 patients had 251 individual episodes of fever evaluation. In 209 visits, a blood culture was drawn with results available. There were 21 (10.0%) true positive blood cultures and 3 (1.4%) false positives. Two-thirds of the true positive blood cultures occurred in patients with indwelling hardware. There was a positive urine culture in 52/192 (27.1%) visits. Pneumonia was diagnosed in 14/74 (18.9%) visits. In nonill-appearing children without indwelling central lines or focal bacterial infections, the incidence of bacteremia was zero. No practical decision rule based on white blood cell indices could be derived.the majority of bacteremic cases in febrile outpatient pediatric kidney transplant patients occurred in patients with indwelling hardware. We did not detect any occult cases of bacteremia in this study cohort. A larger prospective multicenter study is required to confirm the low incidence of bacteremia in this patient subset.
A novel design for complete transfer and robust three-waveguide coupler is presented in this paper, which employs shortcut to adiabaticity (STA) based on stimulated Raman adiabatic passage (STIRAP). Most recently, some remarkable papers on STA of STIRAP [Phys. Rev. A 94(6), 063411 (2016) and Nat. Comm. 7, 12479 (2016)] have been proposed in both theoretical and experimental configurations. In this paper, we propose to design a novel three-waveguide coupler by employing STA based on STIRAP, which can achieve much shorter device length and also maintain the robust performance against perturbations on device geometry parameters compared to previous devices. This finding significantly improves the performance and fabrication of integrated optical devices to build up more compactable devices.
Abstract We experimentally demonstrate an electrically triggered terahertz (THz) dual-band tunable band-pass filter based on Si 3 N 4 –VO 2 –Si 3 N 4 sandwich-structured hybrid metamaterials. The insulator–metal phase transition of VO 2 film is induced by the Joule thermal effect of the top metal layer. The finite-integration-time-domain (FITD) method and finite element method (FEM) are used for numerical simulations. The sample is fabricated using a surface micromachining process, and characterized by a THz time-domain-spectrometer (TDS). When the bias current is 0.225 A, the intensity modulation depths at two central frequencies of 0.56 THz and 0.91 THz are about 81.7% and 81.3%, respectively. This novel design can achieve dynamically electric–thermo–optic modulation in the THz region, and has potential applications in the fields of THz communications, imaging, sensing, and astronomy exploration.
In this paper, we present a full quantum description for coupling mechanism of the metamaterial. We start the derivation from quantum master equation to fit the spectrum of THz metamaterial. Therefore we can employ the quantum master equation to describe the coupling of metamaterial, such as the electromagnetically induced transparency (EIT) and bound state in the continuum (BIC). In this paper, we build up a bridge between the quantum mechanism and coupling mechanism of metamaterial, so-called quantum–classical analogies. Based on our theory, we can find the more quantum phenomenon with corresponding to the coupling phenomenon of the metamaterial.
In this paper, we utilize coupled mode theory (CMT) to model the coupling of surface plasmon polaritons (SPPs) between tri-layered corrugated thin films (CTF) structure coupler in the terahertz region. Employing the stimulated raman adiabatic passage (STIRAP) quantum control technique, we propose a novel directional coupler based on SPPs evolution in tri-layered CTF in some curved configuration. Our calculated results show that the SPPs can be completely transferred from the input to the output CTF waveguides, and even we consider SPPs propagation loss, the transfer rate is still above 70%. The performance of our coupler is also robust that it is not sensitive to the geometry of device and wavelength of SPPs. As a result, our device can tolerate defect induced by fabrication and manipulate THz wave at broadband.
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