a narrow spectrum terahertz emitter based on graphene photoconductive antenna

Many terahertz applications such as sensing, imaging, and spectroscopy require coherent terahertz (thz) sources. a basic ti-au dipole antenna on gaas substrate is designed initially and it is enhanced into a photoconductive antenna for terahertz emission. a spectral width of 120 ghz is obtained from the emission spectrum. in order to compare the spectral characteristics, a graphene dipole antenna is designed on the same substrate. it is observed that graphene dipole yields a narrower spectral width of 70 ghz, due to its high q factor. spectral width of the graphene dipole antenna is further made narrow to 25 ghz, by incorporating a λ/4 stub on the stripline to produce a filtering operation. the antenna provides a directivity of 6.14 dbi with stub which shows an improvement of 0.3 db when compared with an antenna without stub.