Generation of Terahertz, Microwave, Radio Waves from a Laser-excited Wire Antenna
We report a laser-excited wire antenna(LEWA)generating radiation covering a spectrum from radio to THz frequencies.When the wire was irradiated by a mode-locked Ti:sapphire laser with a 160-fs pulse width,focused to 280GW/cm2 intensity on the wire,we detected the THz radiation with a 3-THz bandwidth,reaching the detection limit of our electro-optic sampling system.The amplitude of the detected THz signal was comparable to that generated from a ZnTe emitter under the same experimental condition.The microwave LEWA was driven by a Nd:YAG laser amplifier producing 40-mJ pulse energy in a 460-ps pulse width.We installed the LEWA in front of an S-band metal waveguide,which functions as a spectral filter to pass and reject the radiation above and below the cutoff frequency of 2.08GHz for the dominant TE10 waveguide mode.By using a ring antenna,we measured 1.7 and 2.6GHz microwave signal before and after the waveguide,respectively.In a separate experiment,the radio wave was further produced from a LEWA with its laser-excited tip biased at an anode voltage +500V.When irradiated by a laser pulse with 42mJ energy in a 7ns pulse width,the LEWA generated radiation power 3-4 orders of magnitude higher than that from a direct laser-excited antenna without the biased voltage.The radiation power scales with the square of the laser induced photocurrent between the antenna tip and the anode(800A in our case).With a higher biased anode field and shorter-wavelength excitation laser,this antenna has a potential to reach MW-GW radiation power in the microwave or even in the millimeter-wave spectrum.
Kuan-Yan Huang Chia-Hsiang Chen Ming-Hsiung Wu Yen-Chieh Huang
HOPE Laboratory,Institute of Photonics Technologies National Tsinghua University,Hsinchu 30013,Taiwan
国际会议
Progress in Electromagnetics Research Symposium 2013(2013年电磁学研究新进展学术研讨会)
台北
英文
519-524
2013-03-01（万方平台首次上网日期，不代表论文的发表时间）