Approaching Subwavelength Terahertz Imaging Using Photo-Induced Coded Apertures on Mesa-Array Structures

We report a novel approach for potentially achieving subwavelength terahertz (THz) imaging using photo-induced coded apertures on mesa-array structures. The proposed structure consists of a two-dimensional array of semiconductor mesas, which results in free carriers being confined inside each mesa, and consequently much refined photopatterns being generated for achieving subwavelength imaging resolution. A Si mesa-array structure was fabricated and tested. A modulation depth of ~22 dB was obtained in the frequency range of 740–750 GHz under a light intensity of ~9 W/cm2. Initial imaging experiments were performed and the results indicate a great potential of achieving subwavelength resolution. The advanced PI-CAI technique utilizing mesa-array structures provides a novel solution for approaching subwavelength-resolution THz imaging.