Plasmonic wideband GST-based switch in the near-infrared region

Abstract

In this paper, we present a GST-based wideband plasmonic switch. With the excitation of localised surface plasmons and concentration of electric field in the structure, a near-perfect and wideband absorption is achieved. The switch consists of a GST layer, which acts as a Fabry–Perot cavity. Increasing the temperature and changing the state of GST lead to a high difference between the absorption spectra in amorphous and crystalline states in a wide range of wavelength. Therefore, the switch has a high extinction ratio of 13.71 dB at the wavelength of 1343 nm. Also, the response time of the switch is obtained as 46 fs. The structure has near-perfect absorption up to the incident angle of about 20°. Moreover, due to the symmetry of structure, the absorption spectrum is independent of polarisation. To show the validity of simulation results, the analytical method of equivalent circuit model is presented. The proposed polarisation-insensitive switch with high extinction ratio, fast response time and wide bandwidth can be used in photodetectors, plasmonic modulators and logic gates.