Key Laboratory of THz Optoelectronics

Beijing, China

Key Laboratory of THz Optoelectronics

Beijing, China
SEARCH FILTERS
Time filter
Source Type

Li J.,Capital Normal University | Li J.,Beijing Key Laboratory of Metamaterials and Devices | Li J.,Key Laboratory of THz Optoelectronics | Xu W.-Q.,Capital Normal University | And 20 more authors.
Optik | Year: 2017

Diffractive optical elements (DOEs) are designed by the simulated annealing method for simultaneously implementing color separation and light focusing (CSLF) functions. Through changing the maximum permitted phase, the quantization level number, the input pixel number or the target focusing region width, various CSLF DOEs are optimally designed. Optical performances of the designed DOEs are calculated by the Fresnel diffraction integral method. Simulation results reveal that the designed DOEs not only successfully realize the expected CSLF functions, but also exhibit an excellent performance of high focusing efficiency or high signal to noise ratio under specific parameter circumstances. It is expected that the designed DOEs should have practical applications in solar cell systems or optical interconnection systems. © 2017 Elsevier GmbH


Wang J.,Capital Normal University | Wang J.,Key Laboratory of THz Optoelectronics | Wang J.,Beijing Advanced Innovation Center for Imaging Technology | Zhao G.,Capital Normal University | And 2 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2016

Terahertz (THz) radiation has the higher penetration to clothing, cardboard boxes, plastic packaging materials and other similar dielectrics. Its lower photon energy compared with X-rays make the detected material and the human being to be not destroyed. THz application in field of security are developed by many countries. In this research, we present a multiband of passive terahertz imaging by the thermal radiation measurement. The Noise Equivalent Temperature Difference(NETD) is obtained. The result shows that NETD of the passive imaging system is 0.8K at 94 GHz, and 1.5K at 250GHz. We found that the main source of noise is the noise from detection circuit. Finally, the improvement methods of detecting sensitivity are analyzed and discussed. © 2016 SPIE.


Fu Y.,Capital Normal University | Fu Y.,Key Laboratory of THz Optoelectronics | Fu Y.,Beijing Advanced Innovation Center for Imaging Technology | Zhao G.,Capital Normal University | And 5 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2016

A photo-excited tunable and broad band metamaterial absorber in the terahertz region is proposed. The metamaterial absorber is composed of three layers like the sandwich, the top layer is a ring metal-semiconductor square split ring and the bottom layer is a metallic ground plane, these two layers are separated by a dielectric spacer, which we choose as the polyimide. The conductivity of the silicon can be tuned actively with the incident pump power. We use the full wave simulation and the equivalent circuit parameter to analysis this absorber, and interpreted the phenomena showed when the conductivity of the silicon filled in the gap of ring is changed by the electric field. The proposed equivalent circuit parameter can save more time to design this kind of absorber in need. The proposed photo-excited tunable metamaterial absorber can also be used as terahertz modulators and switches. © 2016 SPIE.


Zhang L.-F.,Capital Normal University | Zhang L.-F.,Beijing Key Laboratory of Metamaterials and DevicesBeijing | Zhang L.-F.,Key Laboratory of THz Optoelectronics | Ye J.-S.,Capital Normal University | And 19 more authors.
Optics Communications | Year: 2015

Abstract Based on Fermat's principle, we have designed a three-dimensional long-imaging-depth (LID) lens for point light source imaging. The thickness function of the designed LID lens is given analytically. Imaging properties of the designed LID lens are simulated by the Fresnel diffraction integral method. Numerical simulations demonstrate that the designed LID lens has gained a much longer imaging depth in the axial direction, in comparison with the conventional lens. In addition, compared with the conventional lens, the transverse imaging spot size and the imaging efficiency of the designed LID lens have exhibited weaker reliance on the longitudinal position within the LID region. Finally, the wavelength tolerance and roughness tolerance properties of the designed LID lens are disclosed. © 2015 Elsevier B.V.

Loading Key Laboratory of THz Optoelectronics collaborators
Loading Key Laboratory of THz Optoelectronics collaborators