Abstract-Double-Layer Frequency Selective Surface for Terahertz Bandpass Filter

Xiong Ri-Hui, Li Jiu-Sheng

https://link.springer.com/article/10.1007/s10762-018-0527-x

A thin, low-cost, double-layer frequency-selective surface (FSS) bandpass filter has been designed, fabricated, and measured for operation in the terahertz band. The present FSS structure is composed of double-layer tin foil with a hexagonal lattice array of circular holes. A flat passband is observed with a 3-dB bandwidth of 0.20 THz from 0.81 to 1.01 THz, which is about 22% relative to the center frequency. This bandpass filter based on double-layer FSS structures achieved average insertion loss of 0.7-dB and 106.31-dB/THz band-edge steepness. We have found good agreement between theoretical calculations and experimental results.

Abstract-A Low-Loss Design of Bandpass Filter at the Terahertz Band

 Naibo Zhang, Ruiliang Song, Mingjun Hu,  Guangcun Shan,  Chunting Wang, Jun Yang

https://ieeexplore.ieee.org/document/8370693/

This letter demonstrates a terahertz (THz) bandpass filter with a center frequency of ~340 GHz, low insertion loss of ~ −0.6 dB, and bandwidth of ~5.3%. The diaphragm thickness is quantitatively analyzed to obtain accurate filter parameters based on equivalent circuit and diaphragm coupling in THz band for the first time, and the simulation results based on calculated filter parameters show that diaphragm thickness has great influence on the filter performance. The test results show a good agreement with the theoretical analysis and simulation results. Meanwhile, the relationship between fabrication error and insertion loss was discussed and a quantitative mathematical model is given. The filter also shows an excellent performance when compared with the performance of other filters from the current literature reports.

Abstract-Analysis of a Novel Singlet and Its Application in THz Bandpass Filter Design

Yu Xiao, Peizhe Shan, Kaiqiang Zhu, Houjun Sun, Fan Yang

https://ieeexplore.ieee.org/document/8347148/

In this paper, a novel singlet based on TE301 mode resonant cavity is first introduced and analyzed. By using the mode cancelling between the dominant resonance and the spurious resonance, a transmission zero (TZ) is then produced. Furthermore, the position of TZ can be controlled properly by changing the dimensions of the resonant cavity. Based on the novel singlet, a fifth-order filter centered at 140 GHz with two TZs at 131 and 151 GHz has been presented and fabricated by conventional computer numerical control-metal-milling technology. The measured results are in excellent agreement with the simulated ones with a low insertion loss of 0.52 dB and a 3-dB bandwidth of 13 GHz. A high selectivity with a 40 dB outband rejection at 132 and 149 GHz is achieved.

Abstract- Terahertz Bandpass Filter Based on Frequency Selective Surface

Jiu-Sheng Li,  Yang Li,   Le Zhang,

http://ieeexplore.ieee.org/document/8194866/


We designed a terahertz bandpass filter based on double-layer frequency selective surface. Details of the proposed terahertz wave filter design and of the related parametric analysis are presented and discussed. The proposed terahertz filter was fabricated by laser technology. The transmission spectrum was characterized by terahertz time-domain spectroscopy. The results show that the center frequency of the terahertz filter is about 1 THz with 3-dB bandwidth of 400 GHz.

Abstract-Intensity modulation of a terahertz bandpass filter: utilizing image currents induced on MEMS reconfigurable metamaterials

Fangrong Hu, Yixing Fan, Xiaowen Zhang, Wenying Jiang, Yuanzhi Chen, Peng Li, Xianhua Yin, and Wentao Zhang

https://www.osapublishing.org/ol/abstract.cfm?uri=ol-43-1-17&origin=search

We experimentally demonstrated a tunable terahertz bandpass filter based on microelectromechanical systems (MEMS) reconfigurable metamaterials. The unit cell of the filter consists of two split-ring resonators (SRRs) and a movable bar. Initially, the movable bar situates at the center of the unit cell, and the filter has two passbands whose central frequencies locate at 0.65 and 0.96 THz. The intensity of the two passbands can be actively modulated by the movable bar, and a maximum modulation depth of 96% is achieved at 0.96 THz. The mechanism of tunability is investigated using the finite-integration time-domain method. The result shows that the image currents induced on the movable bar are opposite the resonance currents induced on the SRRs and, thus, weaken the oscillating intensity of the resonance currents. This scheme paves the way to dynamically control and switch the terahertz wave at some constant frequencies utilizing induced image currents.

© 2017 Optical Society of America

Abstract-Free-standing double-layer terahertz band-pass filters fabricated by femtosecond laser micro-machining

Yanzhang Lin, Haizi Yao, Xuewei Ju, Ying Chen, Shuncong Zhong, and Xiangfeng Wang

https://www.osapublishing.org/oe/abstract.cfm?uri=oe-25-21-25125

We report on the fabrication and transmission properties of free-standing single-layer and double-layer THz bandpass filters. These filters are fabricated on aluminum foils using femtosecond laser micro-machining. The aluminum foils are periodically patterned with cross apertures with a total area of 1.75×1.75 cm2, also known as frequency-selective surfaces. Their terahertz transmission properties were simulated using the FDTD method and measured using a time-domain terahertz spectroscopy system. The simulation results agree with the measurements results very well. The performance of single-layer bandpass filters is as good as the commercial equivalents on the market. The double-layer filters show extraordinary transmission peaks with changing spacing between the two layers. We show the contour map of the electric field distribution across the apertures, and ascribe the new transmission peaks to the interference and coupling of surface plasmon polaritons between the two layers.

© 2017 Optical Society of America

Abstract-GaN-based metamaterial terahertz bandpass filter design: tunability and ultra-broad passband attainment

Khodaee M, Banakermani M, Baghban H.

http://www.ncbi.nlm.nih.gov/pubmed/26479795

Engineering metamaterial-based devices such as terahertz bandpass filters (BPFs) play a definitive role in advancement of terahertz technology. In this article, we propose a design procedure to obtain a considerably broadband terahertz BPF at a normal incidence; it shows promising filtering characteristics, including a wide passband of ∼1.34  THz at a central frequency of 1.17 THz, a flat top in a broad band, and high transmission, compared to previous reports. Then, exploiting the voltage-dependent carrier density control in an AlGaN/GaN heterostructure with a Schottky gate configuration, we investigate the tuning of the transmission properties in a narrow-band terahertz filter. A combination of the ultra-wide, flat-top BPF in series with the tunable, narrow band filter designed in the current study offers the ability to tune the desired resonance frequency along with high out-of-band rejection and the suppression of unwanted resonances in a large spectral range. The proposed structure exhibits a frequency tunability of 103 GHz for a voltage change between -8 and 2 V, and a transmission amplitude change of ∼0.51. This scheme may open up a route for the improved design of terahertz filters and modulators.

Abstract-Ultrabroad terahertz bandpass filter by hyperbolic metamaterial waveguide

Ultrabroad terahertz bandpass filter by hyperbolic metamaterial waveguide Xuetong Zhou, Xiang Yin, Tian Zhang, Lin Chen, and Xun Li  »View Author Affiliations

Optics Express, Vol. 23, Issue 9, pp. 11657-11664 (2015)
http://dx.doi.org/10.1364/OE.23.011657

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http://www.opticsinfobase.org/oe/abstract.cfm?uri=oe-23-9-11657

We propose and demonstrate an ultrabroad terahertz (THz) bandpass filter (BPF) by integrating two different-sized tapered hyperbolic metamaterial (HMM) waveguides, each of which has wide but different absorption and transmission bands, into a unit cell. With proper structural design of each HMM waveguide to control the absorption and transmission bands, we numerically demonstrate the designed BPF is capable of operating with a broad passband in the THz domain. A typical TM-polarized HMM BPF has a peak transmission of 37% at 3.3 THz with the passband bandwidth of 2.2 THz ranging from 2.97 to 5.17 THz. The co-designed three-dimensional HMM BPF also shows the capability of operating with independence to the polarization of incident light because of the structural symmetry and has sharp bandedge transitions of 22.6 and 17.6 dB/THz to the stop bands, respectively. The presented results here hold great promise for developing practical THz BPF with various applications in THz field.

© 2015 Optical Society of America