Mid-infrared to terahertz spectrum, ranging from 5 μm to 5 mm in wavelength, is the focus of basic research in solid-state physics, chemistry, materials science, as well as applications in next-generation communications, homeland security, biosensing, and medical imaging. This frequency range is at the intersection between photonics and electronics, presenting tremendous opportunities to probe and harness fundamental light-matter interactions. The emerging fields of plasmonics and metamaterials have shown new possibilities to boost such light-matter interactions using engineered nanostructures. To overcome the dimension mismatch between the long-wavelength radiations and the nanostructures, new lithography techniques that fabricate an array of metal gaps of nanometer-to-Ångstrom scale have been recently developed. These next-generation nanostructures will have a great impact on the advancement of field enhancement and confinement toward the next level of applications as the following:

THz/Mid-IR absorption spectroscopy for sensing.
- Ultra-sensitive detection and fingerprinting of biomolecules in aqueous solutions
- THz/Mid-IR imaging and spectroscopy for virus sensing
- Detection of ultra-small quantity of explosive materials with functional nanostructures

Ultrafast optical spectroscopy for 2D materials, magneto-optical photonic crystals, and superconductors in a broadband spectrum range.
- Enhanced critical temperature of superconductors combined with nanogap structures.
- Magneto-Plasmonics based on magneto-optical photonic crystals
- Ultra-sensitive Infrared detector at room temperature