- 标题
- 摘要
- 关键词
- 实验方案
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Design and analysis of a Zeonex based diamond-shaped core kagome lattice photonic crystal fiber for T-ray wave transmission
摘要： A new kind of Zeonex based single mode photonic crystal fiber (PCF) has been designed and analysed for low loss terahertz wave transmission. The novel twist is introduced in a kagome lattice PCF by placing a diamond shaped core. Various geometrical parameters including core diameter, pitch distance, porosity, strut length and strut width are adjusted to optimize the PCF. Using Finite Element Method (FEM) simulation results show a low effective material loss (EML) of 0.04 cm?1 that is 80% lower than bulk material absorption loss of Zeonex, low confinement loss of 0.0001 cm?1 at 1 THz frequency and near zero flattened dispersion variation of 0.98 ± 0.09 ps/THz/cm with 1 THz transmission bandwidth. Owing to the above remarkable properties, the proposed waveguide can be a suitable candidate for improved transmission of terahertz waves.
关键词： Waveguide,Photonic crystal fiber,Dispersion,Terahertz,Effective material loss
更新于2025-09-09 09:28:46
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Modulation Mode Detection & Classification for in-Vivo Nano-Scale Communication Systems Operating in Terahertz Band
摘要： This work initiates the efforts to design an intelligent/cognitive nano receiver operating in Terahertz (THz) band. Specifically, we investigate two essential ingredients of an intelligent nano receiver—modulation mode detection (to differentiate between pulse based modulation and carrier based modulation), and modulation classification (to identify the exact modulation scheme in use). To implement modulation mode detection, we construct a binary hypothesis test in nano-receiver’s passband, and provide closed-form expressions for the two error probabilities. As for modulation classification, we aim to represent the received signal of interest by a Gaussian mixture model (GMM). This necessitates the explicit estimation of the THz channel impulse response, and its subsequent compensation (via deconvolution). We then learn the GMM parameters via Expectation-Maximization algorithm. We then do Gaussian approximation of each mixture density to compute symmetric Kullback-Leibler divergence in order to differentiate between various modulation schemes (i.e., M -ary phase shift keying, M -ary quadrature amplitude modulation). The simulation results on mode detection indicate that there exists a unique Pareto-optimal point (for both SNR and the decision threshold) where both error probabilities are minimized. The main takeaway message by the simulation results on modulation classification is that for a pre-specified probability of correct classification, higher SNR is required to correctly identify a higher order modulation scheme. On a broader note, this work should trigger the interest of the community in the design of intelligent/cognitive nano receivers (capable of performing various intelligent tasks, e.g., modulation prediction etc.).
关键词： nano-scale communication,Expectation-Maximization algorithm,Kullback-Leibler divergence,Gaussian mixture model (GMM),modulation classification,Terahertz (THz) band,modulation mode detection
更新于2025-09-09 09:28:46
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Fast-Tunable Terahertz Metamaterial Absorber Based on Polymer Network Liquid Crystal
摘要： This paper introduces a tunable metamaterial absorber (MA) based on polymer network liquid crystal (PNLC) in the terahertz (THz) frequency band. Under the optimal polymerization condition, through electrical control of the orientation of the PNLC embedded in the frequency selective surface, the resonant frequency of the absorber can be tuned from 416.5 to 405.0 GHz, corresponding to fractional frequency bandwidth of 2.8%. The experimental results show that the proposed MA based on the PNLC offers an adjustment time of 10 ms and recovery time of 85 ms, which is significantly faster than the tunable metamaterial devices based on conventional nematic liquid crystal (LC).
关键词： liquid crystal,response time,absorber,terahertz,polymer network
更新于2025-09-09 09:28:46
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Broadband Terahertz Spectroscopy of Phonon-Polariton Dispersion in Ferroelectrics
摘要： Electromagnetic waves at frequencies below the X-ray region strongly couple to the optical vibrational modes in a solid. These coupled excitations have been called phonon polaritons. The relationship of the polariton frequency versus the polariton wavevector shows a remarkable dispersion, especially in the vicinity of the transverse and longitudinal optical mode frequencies. The signi?cant frequency dependence enables valuable applications such as a tunable terahertz radiation source. The polariton dispersion relations of technologically important dielectric and ferroelectric crystals were reviewed in the broad terahertz range using terahertz time-domain spectroscopy, far-infrared spectroscopy, and Raman scattering spectroscopy.
关键词： terahertz,phonon polariton,ferroelectrics,spectroscopy
更新于2025-09-09 09:28:46
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Design and Characterization of an Ultra Low Loss, Dispersion-Flattened Slotted Photonic Crystal Fiber for Terahertz Application
摘要： A novel photonic crystal fiber (PCF) based on TOPAS, consisting only rectangular slots is presented and analyzed in this paper. The PCF promises not only an extremely low effective material loss (EML) but also a flattened dispersion over a broad frequency range. The modal characteristics of the proposed fiber have been thoroughly investigated using finite element method. The fiber confirms a low EML of 0.009 to 0.01 cm?1 in the frequency range of 0.77–1.05 THz and a flattened dispersion of 0.22 ± 0.01 ps/THz/cm. Besides, some other significant characteristics like birefringence, single mode operation and confinement loss have also been inspected. The simplicity of the fiber makes it easily realizable using the existing fabrication technologies. Thus it is anticipated that the new fiber has the potential to ensure polarization preserving transmission of terahertz signals and to serve as an efficient medium in the terahertz frequency range.
关键词： dispersion,micro-structured fibers,terahertz,photonic crystal fibers,effective material loss
更新于2025-09-09 09:28:46
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Effective Medium Model of Periodic Nanolayered Transparent Shields
摘要： An innovative effective medium model based on the transfer matrix method is proposed for the simulation of 1D-periodic subwavelength metal–dielectric laminated structures excited by TM- or TE-polarized plane wave with oblique incidence angles. The homogeneous medium of each period is characterized by TM or TE complex effective permeability and conductivity. The resulting effective single layer (ESL), having the same total thickness of the multilayer laminate, is represented by a transfer matrix given by the product of the transmission matrices of the periods composing the structure. Notice that this model allows the homogenization of n-layer periods, while the effective medium approximation method is formulated for only two-layer periods. The ESL is used to compute the transmission and reflection coefficients and the shielding effectiveness of 1D-periodic nanolayered transparent coatings made by alternating layers of silver, zinc oxide, or titanium dioxide films, in the frequency range from 100 MHz up to 10 THz. The propagating wave performances of the ESL are compared with the ones given by the rigorous multilayer model. Finally, two different screens made of transparent coatings over glass are proposed and analyzed.
关键词： 1D-periodic multilayer (ML) coating,Effective homogeneous model,terahertz (THz) shielding effectiveness
更新于2025-09-09 09:28:46
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Encyclopedia of Wireless Networks || Energy Modeling for Nanoscale Terahertz Communication
摘要： Energy modeling for nanoscale terahertz communication is required to investigate the relationship between energy harvesting and consumption in nanoscale terahertz communication and analyze the trade-off between them by jointly considering the constraints of nanonetworks and the peculiarities of terahertz communications, in order to achieve perpetual nanonetworks.
关键词： Energy consumption,Nanoscale communication,Terahertz,Energy harvesting
更新于2025-09-09 09:28:46
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Peculiarities of band structure of one-dimensional photonic crystals
摘要： In this paper, the peculiarities of the band structure of one-dimensional photonic crystals are studied, when the periodic (quasiperiodic) medium is inhomogeneous in relation to both the dielectric and magnetic properties. It is shown that the photonic band gap does not appear at small angles of incidence, in the case when the modulation depths of the dielectric permittivity and magnetic permeability coincide. The possibilities of obtaining photonic bandgaps in the terahertz radiation region are considered. The features of the band structure of photonic crystal with different spatial periods of the dielectric permittivity and magnetic permeability are investigated. It is shown that in this case, four PBGs appear in each diffraction reflection order.
关键词： Dielectric permittivity,Band structure,Magnetic permeability,Photonic crystals,Terahertz radiation
更新于2025-09-09 09:28:46
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[IEEE 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz2018) - Nagoya, Japan (2018.9.9-2018.9.14)] 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Terahertz (THz) Direct Detectors based on Superconducting HEBs with Thermal, Microwave and THz Biasing
摘要： Terahertz (THz) direct detectors based on superconducting niobium nitride (NbN) hot electron bolometers (HEBs) with thermal, microwave (MW) and THz biasing have been studied at 0.65 THz and 4.2 K in detail. The current responsivity and noise equivalent power (NEP) have been measured and compared respectively. The detectors with the MW and THz biasing have about one order higher current responsivity than that of the thermal one. With the MW biasing, an NEP at the order of pW/√Hz is obtained by choosing the MW frequency and power appropriately.
关键词： Terahertz,direct detectors,microwave biasing,niobium nitride,current responsivity,hot electron bolometers,superconducting,THz biasing,thermal biasing,noise equivalent power
更新于2025-09-09 09:28:46
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[IEEE 2018 14th IEEE International Conference on Solid-State and Integrated Circuit Technology (ICSICT) - Qingdao, China (2018.10.31-2018.11.3)] 2018 14th IEEE International Conference on Solid-State and Integrated Circuit Technology (ICSICT) - Emerging Terahertz Technologies for Security, Quality Control, Vision and Medical Applications
摘要： The spectrum of electromagnetic radiation covers a broad range of frequencies, spanning from micro-, millimeter- and radiowaves from one side to visible, ultraviolet and X-ray bands on the other. Nowadays, both these spectral ends are effectively explored in a multitude of devices and applications. In contrast, the intermediate zone, grouping electromagnetic waves of frequencies from 100 GHz to 10 THz, remains largely unexplored, lending itself a name of 'THz gap'. A very useful property of THz radiation is that it easily penetrates through most of non-metallic materials, at the same time providing spectroscopic information for matter classification. It allows to investigate internal structure or content of objects. Also, unlike UV or X-ray, THz waves are non-ionizing and hence harmless to humans and animals, eliminating the need for safety measures.
关键词： Terahertz,non-ionizing,THz gap,electromagnetic spectrum,spectroscopy
更新于2025-09-09 09:28:46