Numerical and experimental study of terahertz solid immersion focusing system

In our work, we developed a method of THz solid immersion microscopy for continuous-wave reflection-mode imaging of soft biological tissues with a sub-wavelength spatial resolution. We have analyzed the performance of the developed THz solid immersion lens and demonstrated a 0.15λ-resolution of the proposed imaging modality at λ = 500 μm. We have applied the developed method for the THz imaging of various soft biological tissues and reconstructed refractive index distribution of the objects. The observed results justify capabilities of the proposed THz imaging modality in biophotonics.