Mid-infrared plasmonically induced absorption and transparency in a Si-based structure for temperature sensing and switching applications

In this paper, a novel silicon-based integrated structure is proposed for plasmon-induced transparency (PIT) and plasmon-induced absorption (PIA) in the mid-infrared (MIR) band. The device consists of a semiconductor-insulator-semiconductor (SIS) plasmonic bus waveguide coupled to three rectangular nano-cavities. The transmission properties of the structure are numerically simulated by finite-difference time-domain (FDTD) method. The wavelengths of the PIA and PIT peaks can be simply tuned by adjusting the geometrical parameters of the device. It is shown that the proposed structure can be used either as a temperature sensor with the sensitivity of 1.48 nm/∘C or as a plasmonic switch operating in the MIR range with the transmission of 83% and modulation depth (MD) of 20.74 dB. The proposed multifunctional device has potential applications for photonic switching and lab-on-a-chip applications in the MIR band.