Natural Hyperbolic Dispersion with Anisotropic Epsilon‐Near‐Zero and Epsilon‐Near‐Pole in Squaraine Molecular Film

Epsilon-near-zero (ENZ) optical material has been employed in a number of novel linear and nonlinear applications, owing to the vanishing polarization upon an incident wave. In uniaxial medium possessing hyperbolic energy–momentum dispersion wave, ENZ can take place at ordinary extraordinary permittivities. Organic thin films presenting lamellar structure have reported exhibit transverse negative with permittivity. Here, organic film permittivity is demonstrated. Newly synthesized polymethine dye (i.e., squaraine indolenine triethyleneglycol molecule) self-organizes form layered pristine film, both positive dispersions are observed visible wavelengths. Analysis tens-nanometer-thick shows that epsilon-near-pole (ENP) occur longitudinal as well component dielectric Optical characterization presented, importance such monolithic discussed.