Frequency adjustable THz microstructured photoconductive antennas

There are increased application requirements of Terahertz wave low frequency radiometers in Earth atmosphere and molecular detection. Based on the equivalent circuit model and their resonant characteristics' simulation design of the microwave electrical split ring resonators (eSRR), novel microstructured photoconductive antennas (PCAs) were proposed by combining the microwave resonant structure with the traditional stripline dipole PCA. The new PCAs were with high frequency adjustment sensitivity and obvious resonance characteristics. The novel PCAs with different dimensions were fabricated and experimentally compared with a conventional stripline dipole PCA. The terahertz radiation spectrum of the two types PCAs are significantly different: the novel PCAs have dual resonant peaks and narrowband resonating characteristics owing to the dual -frequency resonant characteristics of the microstructured eSSRs, and the 3 dB relative bandwidth is about 50%; while the conventional PCA has only a single peak with broad spectrum radiations, whose the 3 dB relative bandwidth is 93.07%. The simulation and test results of the new PCAs agree well. It is demonstrated that adjusting the resonant ring's arm length of the new PCAs can obtain a relatively larger peak frequency shift. Thus the theoretical model and the simulation results are all verified. © 2018, Editorial Board of Journal of Infrared and Laser Engineering. All right reserved.