| Optical switch is widely used in optical communication,optical network,optical interconnection and space light,and it is one of the most widely used optical devices.However,most of the current researches on optical switches are based on volatile optical switches,which is not conducive to the integration of the system and the reduction of energy consumption.Since the floating-gate nonvolatile optical switch can maintain the working state for a long time without applying voltage,the power consumption and heat dissipation requirements of the system are greatly reduced.Therefore,study of the floating-gate optical switch needs to be furthered.In the field of electronics,graphene has been widely used in non-volatile devices due to its ultra-thin thickness and excellent properties.In the field of optics,the superior modulation of graphene on terahertz band makes the design of floating gate structure non-volatile terahertz optical switch possible.In this paper,the resonance enhancement of metal electrode and terahertz wave incident light,the application of floating gate structure in optical switching devices,and the modulation effect of graphene on terahertz wave are studied theoretically and experimentally.The main work includes the following three aspects:(1)The structures of three metal electrodes were designed and optimized.The structure and parameters of metal electrode were designed based on the theory and CST(Computer Simulation Technology)simulation software.The transmission effect of optical switch in the range of 0.1-0.4THz was prepared and tested,which preliminarily verified that the transmission rate of the designed metal electrode structure was significantly higher than that of the flat metal electrode.(2)Theoretical simulation of non-volatile terahertz optical switch.The floating gate structure and graphene material were introduced into the terahertz optical switch.CST software was used to establish the floating gate structure non-volatile optical switch model,Matlab software was used to calculate the photoelectric characteristics of graphene,and a CST material database was established.By simulating the transmission of incident light with different chemical potentials of graphene,the modulation effect of graphene on terahertz wave is preliminarily verified.(3)Nonvolatile terahertz optical switches were fabricated and tested.Through a large number of experiments,the high-quality transfer of graphene was achieved,the insulation of the oxide layer was greatly improved,and the optical switch with a withstand voltage of about 7V was successfully prepared.The results of electrical C-V(Capacitance-Voltage)test show that the optical switching has a hysteresis loop storage window of about 1.3 V.The optical test results preliminarily confirmed that the optical switch is indeed non-volatile.And the applied voltage changes the transmission effect of graphene on the incident light,which can modulate the intensity of the terahertz wave. |
