Thursday, June 4, 2015

Abstract-Branchlike nano-electrodes for enhanced terahertz emission in photomixers

Qing Yang Steve Wu1, Hendrix Tanoto1, Lu Ding1, Chan Choy Chum1, Bing Wang2, Ah Bian Chew1, Agnieszka Banas3, Krzysztof Banas3, Soo Jin Chua4,5 and Jinghua Teng1,5
1 Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A*STAR), Singapore 117602, Singapore
2 School of Physics, Huazhong University of Science and Technology, Wuhan, People's Republic of China
3 Singapore Synchrotron Light Source, National University of Singapore, Singapore 117576, Singapore
4 Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576, Singapore
5 Authors to whom any correspondence should be addressed. 

Branchlike nano-electrode structures were found to improve the THz emission intensity of a photomixer by approximately one order of magnitude higher than that of a photomixer with one row of nano-electrodes separated by the same 100 nm gap. The enhancement is attributed to a more efficient collection of generated carriers, which is in turn due to a more intense electric field under the branchlike nano-electrodes' structures. This is coupled with an increased number of effective areas where strong tip-to-tip THz field enhancements were observed. The optical-to-THz conversion efficiency of the photomixers with the new branchlike nano-electrodes was found to be 10 times higher. The more efficient THz photomixer will greatly benefit the development of continuous-wave THz imaging and spectroscopy systems.

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