Terahertz micro-resonators investigated in the near- and far-field

Terahertz (THz) frequencies are ascribed to the part of the spectrum with frequencies of 0.1 to 10 THz with free space wavelengths of 0.3 to 3 mm. Research at THz frequencies has gained a lot of momentum over the last few decades due to certain interesting attributes of this spectral range mainly in the fields of spectroscopy and communication. Resonant structures, due to their ability to microscopically manipulate electromagnetic field distribution around matter and cause macroscopic effects in the far-field and/or subwavelength confinement of electromagnetic fields, have been studied extensively in the optics followed closely by the research at THz frequencies. At these frequencies, they can be used as devices for sub-wavelength spectroscopy as well as components in communication systems. However, the efficiency of these devices depend critically on the accurate characterization of the electromagnetic field distribution around it. In this talk, we will explore how the electric near-field distribution in the vicinity these resonant structures can be fully characterized beyond the diffraction limit using a near-field micro-spectroscopic technique. We will further investigate how conventional far-field spectroscopic technique becomes insufficient for accurate spectral characterization of these structures. We will also investigate how coupling between resonant structures (both radiative and non-radiative) can be harnessed to achieve photonic analogue of interesting physical effects, such as, electromagnetically induced transparencies, relevant for photonics devices.