Research On All-optical Switcher In Terahertz

Terahertz communication has huge advantages comparing with the traditional communication. But optical switcher as the foundation of terahertz communication, however, the research of the switcher has not been great progress, due to the material in nature could not directly apply to the terahertz spectrum. So it is urgent to fabricate an optical switcher which could work at the terahertz frequency to fill the gap of foundation device in terahertz communication system. This paper is fabricate two different structure of metamaterials as the samples to promote research progress of switching devices.Using Microwave simulation software CST Microwave Studio to simulate,through finite element method(FEM), the electromagnetic response of split ring resonator structure and electric split ring resonators structure in the terahertz band, and analyzed the changes of theirs electromagnetic response, after introducing photosensitive materials with the optical pump power. The simulation shows that these two structures could realize the terahertz all-optical switchers by stimulating the photogenic charge carrier of the intrinsic silicon.The change rate at the resonance frequency of these two metamaterial is 79% and61.2%, respectively. Each of these could be the switch effect.For the realization of the structures in simulation, this paper propose a method to fabricate optical tunable metamaterial which using ion implantation.Using standard silicon microelectronic technology to fabricate the sample of terahertz all-optical switcher which has the same structure as the simulation. Use the terahertz time-domain spectroscopy system and S790 semiconductor lacer to test the optical response of the sample. From the result of the test, it is found that the lacer pump could tune the transmission of the metamaterial samples.Experimental tests show that the laser pumped can tune the resonance of metamaterial samples, and the SRRs has the largest change rate of 29%.The two-dimensional material graphene will be introduced to the all-optical switcher samples, for taking the advantage of graphene’s high carrier mobility toimprove the modulation depth of the device. Firstly, by transferring the graphene to the high resistivity silicon wafer, we found that the modulation depth is change deeper in experiment, which change from 33% to 47.3%. The result shows that the device has the function of optical switcher. While transferring the graphene to the terahertz all-optical switcher sample it is found the similar phenomenon in it.