Microphotonics is a branch of

technology Technology is the application of knowledge to reach practical goals in a specifiable and reproducible way. The word ''technology'' may also mean the product of such an endeavor. The use of technology is widely prevalent in medicine, science, ...

that deals with directing light on a microscopic scale and is used in

optical networking Optical networking is a means of communication that uses signals encoded in light to transmit information in various types of telecommunications networks. These include limited range local-area networks (LAN) or wide-area networks (WAN), which cr ...

. Particularly, it refers to the branch of technology that deals with wafer-level integrated devices and systems that emit, transmit, detect, and process light along with other forms of

radiant energy Radiant may refer to: Computers, software, and video games * Radiant (software), a content management system * GtkRadiant, a level editor created by id Software for their games * Radiant AI, a technology developed by Bethesda Softworks for ''The ...

with

photon A photon () is an elementary particle that is a quantum of the electromagnetic field, including electromagnetic radiation such as light and radio waves, and the force carrier for the electromagnetic force. Photons are massless, so they always ...

as the

quantum In physics, a quantum (plural quanta) is the minimum amount of any physical entity (physical property) involved in an interaction. The fundamental notion that a physical property can be "quantized" is referred to as "the hypothesis of quantizati ...

unit. Microphotonics employs at least two different materials with a large differential

index of refraction In optics, the refractive index (or refraction index) of an optical medium is a dimensionless number that gives the indication of the light bending ability of that medium. The refractive index determines how much the path of light is bent, or ...

to squeeze the light down to a small size. Generally speaking, virtually all of microphotonics relies on

Fresnel reflection The Fresnel equations (or Fresnel coefficients) describe the reflection and transmission of light (or electromagnetic radiation in general) when incident on an interface between different optical media. They were deduced by Augustin-Jean Fres ...

to guide the light. If the photons reside mainly in the higher index material, the confinement is due to

total internal reflection Total internal reflection (TIR) is the optical phenomenon in which waves arriving at the interface (boundary) from one medium to another (e.g., from water to air) are not refracted into the second ("external") medium, but completely reflected b ...

. If the confinement is due many distributed

s, the device is termed a

photonic crystal A photonic crystal is an optical nanostructure in which the refractive index changes periodically. This affects the propagation of light in the same way that the structure of Crystal structure, natural crystals gives rise to X-ray crystallograp ...

. There are many different types of geometries used in microphotonics including

optical waveguides An optical waveguide is a physical structure that guides electromagnetic waves in the optical spectrum. Common types of optical waveguides include optical fiber waveguides, transparent dielectric waveguides made of plastic and glass, liquid light ...

, optical microcavities, and

Arrayed waveguide grating {{Unreferenced, date=April 2019 Arrayed waveguide gratings (AWG) are commonly used as Optical add-drop multiplexer, optical (de)multiplexers in wavelength division multiplexing, wavelength division multiplexed (WDM) systems. These devices are capa ...

Photonic crystals

Photonic crystal A photonic crystal is an optical nanostructure in which the refractive index changes periodically. This affects the propagation of light in the same way that the structure of Crystal structure, natural crystals gives rise to X-ray crystallograp ...

s are non-conducting materials that reflect various wavelengths of light almost perfectly. Such a crystal can be referred to as a perfect mirror. Other devices employed in microphotonics include micromirrors and photonic wire waveguides. These tools are used to "mold the flow of light", a famous phrase for describing the goal of microphotonics. The crystals serve as structures that allow the manipulation, confinement, and control of light in one, two, or three dimensions of space.

Microdisks, microtoroids, and microspheres

An optical microdisk, optical microtoroid, or optical microsphere uses internal reflection in a circular geometry to hold on to the

photons A photon () is an elementary particle that is a quantum of the electromagnetic field, including electromagnetic radiation such as light and radio waves, and the force carrier for the electromagnetic force. Photons are massless, so they alway ...

. This type of circularly symmetric optical resonance is called a

Whispering gallery mode Whispering-gallery waves, or whispering-gallery modes, are a type of wave that can travel around a concave surface. Originally discovered for sound waves in the whispering gallery of St Paul's Cathedral, they can exist for light and for other wave ...

, after

Lord Rayleigh John William Strutt, 3rd Baron Rayleigh, (; 12 November 1842 – 30 June 1919) was an English mathematician and physicist who made extensive contributions to science. He spent all of his academic career at the University of Cambridge. Amo ...

coined the term.

Application

Microphotonics has biological applications and these can be demonstrated in the case of the "biophotonic chips", which are developed to increase efficiency in terms of "photonic yield" or the collected luminescent signal emitted by fluorescent markers used in biological chips. Currently, microphotonics technology is also being developed to replace electronics devices and bio-compatible intracellular devices. For instance, the long-standing goal of an all-optical router would eliminate electronic bottlenecks, speeding up the network. Perfect mirrors are being developed for use in

fiber optic cable A fiber-optic cable, also known as an optical-fiber cable, is an assembly similar to an electrical cable, but containing one or more optical fibers that are used to carry light. The optical fiber elements are typically individually coated with ...

References

Microtechnology Photonics {{tech-stub

Photonic crystals

Microdisks, microtoroids, and microspheres

Application

See also

References