Photo-Induced Coded-Aperture Imaging at 740 GHz using Mesa Arrays for Achieving Subwavelength Resolution

We report a novel approach for achieving subwavelength terahertz (THz) imaging using photo-induced coded apertures on mesa array structures. The structure facilitates the generation of high-resolution photopatterns by confining photo-induced free carriers inside isolated mesas. Such mesa-array structures were successfully fabricated on Si substrates. Measurement shows that an average modulation depth of ~20 dB over the frequency range of 500-750 GHz has been achieved using the mesa-array under a light intensity of ~11.7 W/cm2, which agrees well with theoretical analysis and full-wave simulation. For a prototype imaging demonstration, a set of objects were successfully imaged at 740 GHz over different areas, and the initial results indicate that a ~438 μm imaging resolution has been achieved. The coded-aperture imaging using mesa-arrays is promising for extension to subwavelength imaging for applications in high-performance THz sensing and imaging systems.