Optically controlled reconfigurable terahertz waveguide filters based on photo-induced electromagnetic band gap structures using mesa arrays

Abstract

In this work, we present a novel approach to the implementation of optically controlled reconfigurable terahertz (THz) waveguide filters based on photo-induced electromagnetic band gap (PI-EBG) structures using semiconductor mesa arrays. In this approach, EBG structures are dynamically generated through spatially-resolved photogeneration of free carriers in semiconductor mesa structures; the use of mesa arrays improves the spatial resolution, leading to more refined PI-EBG patterns and improved circuit operation at THz frequencies. A band-stop filter prototype in the WR-5.1 band (140-220 GHz) was designed, simulated, and analyzed in detail. Simulations show that the stop-band rejection and bandwidth of the proposed device can be adjusted by changing the filling factor of the photo-patterns illuminated onto the mesa array. The center frequency of the stop-band can also be tuned from 166 to 200 GHz by changing the period of the PI-EBG patterns. The proposed reconfigurable THz waveguide filters based on PI-EBG are promising for a wide range of applications in advanced THz sensing, imaging, and communications.