利用循环移频环路产生的倍频因子可调谐太赫兹信号
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摘要
太赫兹(THz)波在电磁波频谱中占有很重要的地位,THz技术是国际科技界公认的一个非常重要的交叉前沿领域。因此,提出了一种以循环移频环路(RFSL)为基础产生THz信号的微波光子学系统。输入光信号经由RFSL多次移频后在高速光电探测器中拍频产生THz信号。在RFSL中,基于射频(RF)控制的单边带(SSB)调制器是光信号移频的主要器件,每经过一次SSB调制器,光信号将产生一个与RF信号频率相等的移频间隔。THz信号的倍频因子由光在环路中循环的圈数控制。THz信号的频率随着倍频因子的增加而增加,频率大小为倍频因子与移频间隔的乘积。实验上实现了THz信号的倍频因子从1～25可调谐,测量了拍频获得的5～20 GHz微波信号光谱和电谱,测量了20 GHz信号功率以及中心频率的稳定性,并最终实验获得了0.25 THz的信号。
Terahertz(THz) waves occupy a very important position in the electromagnetic spectrum. THz technology is recognized as a major cross-cutting frontier in the international scientific and technology community. Photonic generation of THz signal using a recirculating frequency-shifting loop(RFSL) was proposed and experimentally demonstrated. The frequency of optical source was shifted by the RFSL and beats with each other in a high-speed photodetector to generate a THz signal. In the RFSL, the single sideband(SSB) modulator driven by a radio frequency(RF) signal was a key component for frequency-shifting. The frequency multiplication factor(FMF) of the THz signal was controlled by the lap number circulating in the loop. The frequency of the THz signal increased with the improvement of FMF and equals to the frequency multiplication factor multiplied by the frequency of RF signal. Experimentally,tunable signals from 5 GHz to 20 GHz were generated and the FMF was successfully tuned from 1 to 25.The stability of the power and center frequency was detected when the frequency of the signal was20 GHz. 0.25 THz signal was finally generated by this system.
Terahertz(THz) waves occupy a very important position in the electromagnetic spectrum. THz technology is recognized as a major cross-cutting frontier in the international scientific and technology community. Photonic generation of THz signal using a recirculating frequency-shifting loop(RFSL) was proposed and experimentally demonstrated. The frequency of optical source was shifted by the RFSL and beats with each other in a high-speed photodetector to generate a THz signal. In the RFSL, the single sideband(SSB) modulator driven by a radio frequency(RF) signal was a key component for frequency-shifting. The frequency multiplication factor(FMF) of the THz signal was controlled by the lap number circulating in the loop. The frequency of the THz signal increased with the improvement of FMF and equals to the frequency multiplication factor multiplied by the frequency of RF signal. Experimentally,tunable signals from 5 GHz to 20 GHz were generated and the FMF was successfully tuned from 1 to 25.The stability of the power and center frequency was detected when the frequency of the signal was20 GHz. 0.25 THz signal was finally generated by this system.
引文
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[4]Hu Weidong,Ji Jinjia,Liu Ruiting,et al.Terahertz atmosphere remote sensing[J].Chinese Optics,2017,10(5):656-665.(in Chinese)胡伟东,季金佳,刘瑞婷,等.太赫兹大气遥感技术[J].中国光学,2017,10(5):656-665.
[5]Guo Lihan,Wang Xinke,Zhang Yan.Terahertz digital holographic imaging of biological tissres[J].Optics and Precision Engineering,2017,25(3):611-615.(in Chinese)郭力菡,王新柯,张岩.生物组织的太赫兹数字全息成像[J].光学精密工程,2017,25(3):611-615.
[6]Ren Jiaojiao,Li Lijuan,Zhang Dandan,et al.Terahertz time domain spectral reflective tomography technology[J].Infrared and Laser Engineering,2018,47(2):0225002.(in Chinese)任姣姣,李丽娟,张丹丹,等.太赫兹时域光谱反射式层析成像技术[J].红外与激光工程,2018,47(2):0225002.
[7]Li Ting,Guo Xiaoyang,Meng Qinglong,et al.Analysis of impact factors of output characteristics for optically pumped THz lasers[J].Infrared and Laser Engineering,2015,44(7):1980-1985.(in Chinese)李婷,郭晓阳,孟庆龙,等.光泵THz激光器输出特性的影响因素分析[J].红外与激光工程,2015,44(7):1980-1985.
[8]Yang Dabao,Wang Junlong,Zhang Lisen,et al.Development of 0.1 THz finline fundamental single-balanced mixer circuit[J].Infrared and Laser Engineering,2017,46(4):0420004.(in Chinese)杨大宝,王俊龙,张立森,等.0.1 THz鳍线单平衡式基波混频电路研究[J].红外与激光工程,2017,46(4):0420004.
[9]Wang Junlong,Yang Dabao,Xing Dong,et al.Research of0.22 THz wide-hand mixing circuit[J].Infrared and Laser Engineering,2017,46(11):1125003.(in Chinese)王俊龙,杨大宝,邢东,等.0.22 THz宽带混频电路研究[J].红外与激光工程,2017,46(11):1125003.
[10]Yao J.Microwave photonics[J].Journal of Lightwave Technology,2009,27(3):314-335.
[11]Zhang H,Cai L,Xie S,et al.A novel radio-over-fiber system based on carrier suppressed frequency eightfold millimeter wave generation[J].IEEE Photonics Journal,2017,9(5):2731620.
[12]Liang Dong,Tan Qinggui,Jiang Wei,et al.Efficient THz generation via optical frequency 24-tupling without optical filter[C]//Proceedings of IEEE International Conference on Infrared,Millimeter,and Terahertz Waves,2015.
[13]Li W,Yao J.Microwave and terahertz generation based on photonically assisted microwave frequency twelvetupling with large tunability[J].IEEE Photonics Journal,2010,2(6):954-959.
[14]Takesue H,Horiguchi T,Kobayashi T.Numerical simulation of a lightwave synthesized frequency sweeper incorporating an optical SSB modulator composed of four optical phase modulators[J].Journal of Lightwave Technology,2002,20(11):1908-1917.