highindex

High-index in optics refers to materials whose refractive index is higher than that of standard optical glasses. In practical terms, these are materials with a visible-band refractive index around 1.6 or higher. Refractive index describes how much light slows in a material compared with air, and higher indices allow greater bending of light at interfaces. High-index materials often exhibit greater dispersion, quantified by the Abbe number; many high-index glasses have lower Abbe numbers, which leads to stronger chromatic aberration unless mitigated by design and coatings.

Applications for high-index materials span several fields. In ophthalmology, high-index lenses produce thinner and lighter prescription lenses for strong prescriptions. In photography and cinematography, they enable compact, high‑power lenses with reduced weight. In telecommunications and photonics, high-index materials are used for waveguides and integrated optics because large index contrast enhances light confinement and allows smaller device footprints. Anti-reflective coatings also use combinations of high-index and low-index layers to minimize reflections across wavelengths.

Materials and examples vary. Common high-index options include certain oxide glasses from the heavy-metal-oxide family, which can reach refractive indices around 1.6–1.9, and specialty polymers such as polycarbonate, which sits near 1.58–1.60. Other families used in specific applications include chalcogenide glasses for infrared optics and titanium dioxide–rich coatings that raise local index. Manufacturing and design considerations include cost, mechanical properties, and dispersion management, as high-index materials often trade off higher bending power with greater chromatic dispersion.