Terahertz far-field subwavelength imaging by frequency scanning

We theoretical and simulated demonstrate frequency scanning can be an effective approach to realize terahertz far-field subwavelength imaging. The imaging device composed of metallic gratings and coupler has the ability of coupling evanescent wave and transforming them to corresponding propagating waves so that the subwavelength details will be conserved in the imaging process. By carrying out frequency scanning simulation and a simple data processing from 0.1 THz to 0.24 THz, the operating spatial spectrum is dramatically extended to 5k0 (k is the wavenumber of 0.24 THz) in the far-field, which is well verified our method. Better spatial spectrum range can be expected by decreasing period of grating and increasing scanning frequency points. We are confident this method will find useful applications in terahertz imaging area.