Phys.org October 24, 2022 After experimentally studying the optical properties of dielectric reflective metalenses including their off-axis focusing performance, researchers in Saudi Arabia proposed reflective metalens based on titanium dioxide (TiO2) and silicon dioxide (SiO2), which operate at a visible wavelength of 0.633 µm. Unlike conventional reflective metalenses based on metallic mirrors, the proposed device was designed based on a modified parabolic phase profile and was integrated onto a dielectric distributed Bragg reflector periodic structure to achieve high reflectivity with five dielectric pairs. The focusing efficiency characteristics of the metalens were experimentally studied for beam angles of incidence between 0∘ […]
Tag Archives: Dielectric materials
Breaking an optical rule: Engineers find a way to manipulate light at the nanoscale
Phys.org September 12, 2022 According to Moss rule the absorption edge and the sub-bandgap refractive index of a semiconductor exhibit a rigid trade-off setting an upper limit on the refractive index of a dielectric for a given operating wavelength. According to a team of researchers in the US (Rice University, Johns Hopkins University) there are many dielectric materials that surpass the Moss rule, referred to as super-Mossian dielectrics. They discussed the general features of super-Mossian dielectrics and their physical origin to facilitate the search for high index dielectrics. They developed iron pyrite with index nearly 40% higher than the Moss […]