ROF-OFDM system within terahertz-wave frequency range from 350GHz to 510GHz

2019 ◽  
Author(s):  
Mingming Zhao ◽  
Kaihui Wang ◽  
Jimmy Yu ◽  
Can Wang ◽  
Jiangnan Xiao ◽  
...  
Keyword(s):  
Terahertz Wave ◽  
Wave Frequency ◽  
Frequency Range ◽  
Ofdm System

Properties of Bi and BiSb Nano-Dimensional Layers in Thz Frequency Range

2020 ◽  
Vol 312 ◽  
pp. 206-212
Author(s):  
Ivan L. Tkhorzhevskiy ◽  
Anton D. Zaitsev ◽  
Petr S. Demchenko ◽  
Dmitry V. Zykov ◽  
Aleksei V. Asach ◽  
...  
Keyword(s):  
Phase Shift ◽  
Time Domain ◽  
Terahertz Wave ◽  
Film Structure ◽  
Charge Carriers ◽  
Frequency Range ◽  
Terahertz Time Domain Spectroscopy ◽  
Antimony Content ◽  
Mobility Of Charge Carriers ◽  
Substrate Film

In the present paper we demonstrate and compare different properties of Bi and Bi1-xSbx thin films placed on polyimide (PI) substrate in frequency range from 0.2 to 1.0 THz. Bi films with a thickness of 40, 105 and 150 nm have been studied as well as 150 nm Bi1-xSbx solid solutions with Sb concentration of 5, 8, 12 and 15 %. An effective refractive index and permittivity of whole substrate/film structures have been derived by using terahertz time-domain spectroscopy (THz-TDS) method. These measurements have shown the positive phase shift in PI substrate with a thickness of 42 μm and revealed that it is barely transparent in studied frequency range, but the whole substrate/film structure provides the negative phase shift of terahertz wave. It was shown that the permittivity depends on mobility of charge carriers which is driven by film thickness and antimony content.

Slowly Varying Wave Drift Forces Analyzed From Model Test Data on a Moored Ship in Shallow Water

2009 ◽  
Author(s):  
Carl Trygve Stansberg ◽  
Csaba Paˆkozdi
Keyword(s):  
Noise Reduction ◽  
Shallow Water ◽  
Model Test ◽  
Transfer Functions ◽  
Numerical Study ◽  
Wave Frequency ◽  
Irregular Waves ◽  
Spectral Peak ◽  
Frequency Range ◽  
Wave Drift

Model test estimation of quadratic transfer functions (QTFs) is investigated for slowly varying wave drift excitation on a large moored ship in shallow water. Cross-bi-spectral analysis in irregular waves is used. A numerical study is run first, with a known, synthetical QTF model characterized by a strong off-diagonal variation, combined with a very lightly damped linear slow-drift dynamical system. The purpose is to check the accuracy of the analysis. For this simple model, a good accuracy is obtained in the estimated QTF. This is because of a refined noise reduction method which works well in this case. The wave frequency range of valid estimates is where the wave spectrum S(f) is higher than 7% of the spectral peak. Without the refinement, the useful range is reduced to where S(f) is higher than 15% of the spectral peak, based on a 3-hour sea state simulation. The method is then applied on experimental surge motion records from 1:50 scaled model tests carried out in an offshore basin, simulating 15m water depth. It is found that the QTF estimation procedure works reasonably well, but the accuracy is lower than that in the numerical study because the refined noise reduction could not be used due to the particular characteristics of the QTF. Therefore a basic version without the refinement had to be used. Still, results appear to be fairly reliable in the reduced wave frequency range with S(f) > 15% of the spectral peak, i.e. from 0.07Hz to 0.10Hz in this case.

FABRICATION AND CHARACTERIZATION OF BROADBAND TERAHERTZ WIRE-GRID POLARIZER

2010 ◽  
Vol 19 (04) ◽  
pp. 827-833 ◽  
Author(s):  
Z. C. CHEN ◽  
M. H. HONG ◽  
T. C. CHONG
Keyword(s):  
Time Domain ◽  
Quartz Substrate ◽  
Terahertz Wave ◽  
Mean Value ◽  
Frequency Range ◽  
Terahertz Time Domain Spectroscopy ◽  
Free Standing ◽  
Wire Grid ◽  
The Wire ◽  
Wire Grid Polarizer

A wire-grid terahertz polarizer fabricated on quartz substrate working in broadband is demonstrated. The transmission spectra of the fabricated wire-grid polarizer are characterized by terahertz time domain spectroscopy, showing the good performance of this polarizer in the terahertz frequency range up to 3.5 THz. The transmission of the peak in the time domain is 80% when the incident terahertz wave polarization is perpendicular to the wire-grid. The transmission of the peak is lower than 10% when the incident polarization is parallel to the wire-grid. The polarization factor ranges from 0.92–0.99 with the mean value of 0.97 in the frequency range from 0.1 to 3.5 THz, which is better than that of the free-standing wire-grid polarizer.

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