TUNABLE ELECTRO-OPTICAL SWITCH IN INFRARED COMMUNICATION BAND THROUGH COUPLING SURFACE PLASMON POLARITONS AND MAGNETIC POLARITONS

Optical switch is an essential component in optical communication, which essentially modulates the transmittance in the radiation characteristics of objects. Micro-nano optical switches have the advantage of shorter switching time compared to traditional mechanical optical switches, but their extinction ratio (ER) is lower than that of mechanical optical switches, which seriously restricts the development of micro-nano optical switch. In this article, we achieved an ER of up to 42.6 dB in the infrared communication band (6000cm^-1-8000cm^-1) based on the electrochromic material lithium titanate (LTO) using the coupling of surface plasmon polariton (SPP) and magnetic polaritons (MP). When the optical switch is in “on” mode, the transmittance can reach 0.967 at wavenumber 6400cm^-1, however the transmittance is suppressed to 5.27×10^-5 at wavenumber 6400cm^-1 when the optical switch is in “off” mode. The oblique incidence calculation shows that our optical switch can still maintain good performance under high angle incidence. Our research may contribute to the development of infrared optical communication.