Metamaterials in the context of Optical filter

⭐ Core Definition: Metamaterials

A metamaterial (from the Greek word μετά meta, meaning 'beyond' or 'after', and the Latin word materia, meaning 'matter' or 'material') is an engineered material whose properties arise not from the chemical composition of its base substances, but from their deliberately designed internal structure. These properties are often rare or absent in naturally occurring materials. Metamaterials are typically fashioned from multiple materials, such as metals and plastics, and arranged in repeating patterns at scales that are smaller than the wavelengths of the phenomena they influence. Their shape, geometry, size, orientation, and arrangement give them their properties of manipulating electromagnetic, acoustic, or seismic waves: by blocking, absorbing, enhancing, or bending waves, to achieve benefits that go beyond what is possible with conventional materials. Those that exhibit a negative index of refraction for particular wavelengths have been the focus of a substantial amount of research.

Potential applications of metamaterials are diverse and include sports equipment, optical filters, medical devices, remote aerospace applications, sensor detection and infrastructure monitoring, smart solar power management, lasers, crowd control, radomes, high-frequency battlefield communication and lenses for high-gain antennas, improving ultrasonic sensors, and even shielding structures from earthquakes. Metamaterials offer the potential to create super-lenses. A form of 'invisibility' was demonstrated using gradient-index materials. Acoustic and seismic metamaterials are also research areas.

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Metamaterials in the context of Snell's law

Snell's law (also known as the Snell–Descartes law, and the law of refraction) is a formula used to describe the relationship between the angles of incidence and refraction, when referring to light or other waves passing through a boundary between two different isotropic media, such as water, glass, or air.In optics, the law is used in ray tracing to compute the angles of transmission or refraction, and in experimental optics to find the refractive index of a material. The law is also satisfied in meta-materials, which allow light to be bent "backward" at a negative angle of refraction with a negative refractive index. (When light travels from a denser to a rarer medium, the formula is reciprocated (sin r divided by sin i) to find out refractive index)

The law states that, for a given pair of media, the ratio of the sines of angle of incidence $\left(\theta _{1}\right)$ and angle of refraction $\left(\theta _{2}\right)$ is equal to the refractive index of the second medium with regard to the first ( $n_{2,1}$ ) which is equal to the ratio of the refractive indices $\left({\tfrac {n_{2}}{n_{1}}}\right)$ of the two media, or equivalently, to the ratio of the phase velocities $\left({\tfrac {v_{1}}{v_{2}}}\right)$ in the two media.