Abstract-Properties of BIBO crystal in the terahertz regime

Nazar Nikolaev,  Zhiming Huang,  Jingguo Huang,  Yang Li,  Yury Andreev, Grigory Lanskii

https://www.spiedigitallibrary.org/conference-proceedings-of-spie/11348/1134818/Properties-of-BIBO-crystal-in-the-terahertz-regime-Conference-Presentation/10.1117/12.2555663.full?SSO=1

In recent years, the terahertz sources have attracted much attention for its special use compared with so for UV-visible range. Crystal with high quality and special properties is their indispensable part. Optical properties such as the absorption coefficient and refractive index at three basic crystal orientations (x, y, and z-direction) of the BIBO crystal have been studied by the Terahertz Time-Domain Spectroscopy at room temperature. A large birefringence was observed. The measured refractive index components were approximated in the form of Sellmeier equations. Phase-matching curves for collinear down-conversion of IR laser frequencies into the THz domain were preliminarily estimated. A prospect of BIBO crystals as THz generators are discussed, and comparison with popular crystals is given.

Abstract-Terahertz monolithic integrated waveguide transmission lines based on wide bandgap semiconductor materials

Journal of Applied Physics

Yang Li, Xiao-Hua Ma, Lin-An Yang, Jin-Ping Ao, Yue Hao,

Geometry of the TMIW-TL and the TMIW-GCPW transitions based on the SiC substrate: (a) ideal model and (b) actual model.

https://aip.scitation.org/doi/10.1063/1.5083097

In this paper, terahertz monolithic integrated waveguide (TMIW) transmission lines (TLs) are analyzed and fabricated based on wide bandgap semiconductor materials. The ignored parameters of TLs at low frequencies, such as the via-hole shape, the titanium/gold thickness and roughness, and the micropipe effect of material, are especially investigated based on the semiconductor fabrication technique and the terahertz-wave theory. Subsequently, the fine optimized TMIW-TL and the transition to grounded coplanar waveguide are fabricated. The measurement shows that the attenuation constant of a TL is as low as 0.19 dB/λg at 220 GHz. The proposed TMIW can provide electrical performance similar to the conventional air-filled waveguide, while it has only 10% of the volume, which indicates a great potential for future terahertz integrated systems.

Abstract-High efficient terahertz generation from cryogenic gallium phosphide based on collinear difference frequency

Jingguo Huang, Yang Li, Yanqing Gao, Gaofang Li, Zhiming Huang, Junhao Chu, Yury Andreev

https://www.spiedigitallibrary.org/conference-proceedings-of-spie/11046/1104631/High-efficient-terahertz-generation-from-cryogenic-gallium-phosphide-based-on/10.1117/12.2524100.short?SSO=1

In this paper, a high efficient terahertz source based on n-type gallium phosphide crystal via cryogenic process is investigated through collinear difference frequency generation pumper by 1064 nm Nd:YAG laser and its OPO system. Absorption coefficient of this crystal at THz range shows a dramatic decrease from ~ 50 cm^-1 to 0.5 cm-^-1 as the temperature decreases from 300 k to 80 k. Four times enhancement of the terahertz emission power and much more broad spectra range (~ 0.2- 3.8 THz) has been achieved in this kind of 0.5 mm length gallium phosphide crystal during the whole varied temperature difference frequency generation from 300 k to 80 k. These results indicate that cooling down the crystal temperature is an effective way to improve the terahertz source property, such as terahertz output power and frequency range.

© (2019) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only

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-Trapped spoof surface plasmons with structured defects in textured closed surfaces

Hong-Wei Wu, Hua-Jun Chen, Hui-Ying Fan, Yang Li, and Xian-Wen Fang

https://www.osapublishing.org/ol/abstract.cfm?uri=ol-42-4-791&origin=search

We demonstrate that a defect unit in periodic textured closed surfaces is able to trap spoof surface plasmons (SPs) into a deep subwavelength scale. The resonant frequency of a trapped spoof SP can be tuned freely by properly tailoring the dimension of the defect unit. By introducing multiple defect units with different dimensions at different positions of the textured closed surfaces, the spoof SPs with different frequencies trapped effectively at desired places are also demonstrated. In addition, we further design a graded defect structure with continuously variable dimensions to trap the spoof SPs over an ultrawide spectral band. The interval between the trapped waves on the closed surfaces can be tuned conveniently by changing the grade of the defect dimensions. The designer structures may indicate potential applications in the optical switch and storage in the microwave and terahertz frequencies.

© 2017 Optical Society of America

Abstract-Design of 3D filtering antenna for the application of terahertz

•  Yang Li ¹ ; Lin-an Yang ¹ ; Shao-bo Wang ¹ ; Lin Du ¹ ; Yue Hao ¹
• 
  
http://digital-library.theiet.org/content/journals/10.1049/el.2016.3808

• 
  
• Affiliations: 1: The State Key Discipline Laboratory of Wide Band Gap Semiconductor Technology, School of Microelectronics, Xidian University, Xi'an 710071, People's Republic of China 

A new terahertz (THz) filtering antenna realised by 3D substrate integrated circular waveguide (3D-SICW) is presented. The filtering antenna is designed on a low-temperature co-fired ceramic substrate. Different from traditional planar structure, the direction of power in 3D-SICW is along Z-axis and this will significantly enhance the performance of the devices at THz frequency. The filtering antenna is constructed by two 3D-SICW cavities and a standard substrate integrated waveguide (SIW) cavity, where one SICW cavity and the standard SIW cavity form the bandpass filter by using electric coupling and the other SICW cavity is used as antenna. The results indicate that the passband of filtering antenna range from 170.4 to 177.8 GHz and the gain of antenna is about 5.7 dB. Finally, the filtering antenna is fabricated and measured to verify the simulation prediction. The measured and simulated results are in good agreement at such high frequency