Tamm Cavity in the Terahertz Spectral Range
Simon Messelot, C. Symonds, J. Bellessa, J. Tignon, S. Dhillon, Jean‐Blaise Brubach, P. Roy, J. Mangeney
Abstract
Electromagnetic resonators, which are based on optical cavities or electronic circuits, are key elements to enhance and control light-matter interaction. In the terahertz range, current optical cavities exhibit very high-quality factors with (λ/2)3 mode volumes limited by diffraction, whereas resonant electronic circuits show low quality factor but provide strong subwavelength effective volume (10–6λ3). To overcome the limitations of each type of resonator, great efforts are being devoted to improving the performances of current methods or to the emergence of original approaches. Here, we report on an optical resonator based on Tamm modes newly applied to the terahertz range, comprising a metallic layer on a distributed Bragg reflector and demonstrating a high-quality factor of 230 at ∼1 THz. We further experimentally and theoretically show a fine-tuning of the Tamm mode frequency (over a 250 GHz range) and polarization sensitivity by subwavelength structuration of the metallic layer. Electromagnetic simulations also reveal that teraherz Tamm modes are confined over a λ/2 length within the distributed Bragg reflector and can be ideally coupled to both bulk materials and 2D materials. These terahertz Tamm cavities are therefore attractive as basic building blocks of lasers, for the development of advanced terahertz optoelectronic devices such as sensitive detectors, high-contrast modulators, narrow filters, and polarizers, as well as for terahertz cavity quantum electrodynamics in nanostructures.