Definitions

A method of coding information in a communications system where the shift in the phase of an electromagnetic wave represents a particular bit or character.

A phonon is a quantum of vibrational energy associated with the periodic motion of atoms or molecules in a crystalline lattice. In simpler terms, phonons are quanta of lattice vibrations in a solid...

Photoconductive antenna (PCA) is a semiconductor element that generates or detects high-frequency electromagnetic signals. Compact PCAs based on gallium arsenide (GaAs) or indium gallium arsenide...

A quantum of electromagnetic energy of a single mode; i.e., a single wavelength, direction and polarization. As a unit of energy, each photon equals hn, h being Planck's constant and n, the frequency...

A photonic engine refers to a device or system that utilizes photonics, or the science and technology of generating, controlling, and detecting photons (particles of light), to perform various...

A photonic cavity, also known as an optical cavity, is a structure that confines electromagnetic radiation within a certain region or volume. It is typically composed of materials with different...

A substance that increases a material's sensitivity to electromagnetic irradiation. In photodynamic therapy, a drug used to render a target tissue sensitive to laser light.

Photosynthetically active radiation (PAR) is the 400- to 700-nm region (visible light) of the electromagnetic spectrum that is absorbed and used by the plant for photosynthesis. Also referred to as...

A crystal consisting of a substance that has the ability to become electrically polarized and has strong piezoelectric properties. It is cut so as to emphasize the coupling to some distinct...

A fundamental law of quantum theory which states that the discrete quanta of energy transfers associated with electromagnetic radiation are proportional to the frequency of the radiation.

Plasmonics is a field of science and technology that focuses on the interaction between electromagnetic radiation and free electrons in a metal or semiconductor at the nanoscale. Specifically,...

Polarization refers to the orientation of oscillations in a transverse wave, such as light waves, radio waves, or other electromagnetic waves. In simpler terms, it describes the direction in which...

For an electromagnetic field mode varying sinusoidally with time at a given frequency, the logarithmic rate of change, with respect to distance in a given direction, of the complex amplitude of any...

The instrument used to analyze a pulsed electromagnetic wave to determine its time, amplitude, duration and shape, and to display this information in some appropriate form, either visually or...

A quantum cascade laser (QCL) is a type of semiconductor laser that operates based on the principles of quantum mechanics. It is a versatile and powerful device used for emitting coherent light in...

A spectrograph used to detect radiation in the range of the ultraviolet in the electromagnetic spectrum. It is made up of quartz because that material, unlike regular glass, is not opaque to the...

Rabi oscillations are a fundamental phenomenon in quantum mechanics that describe the periodic and reversible exchange of energy between two quantum states when subjected to an oscillating external...

Pertaining to electromagnetic radiation, with the contributions at all wavelengths of interest weighted equally.

The energy passed on as electromagnetic radiation; e.g., radio, heat or light waves.

Any of the many devices used to detect the presence of radiation from a specific region of the electromagnetic spectrum.

The detection and analysis of naturally formed extraterrestrial electromagnetic radiation within the radio frequency range of the spectrum.

An instrument designed to collect naturally formed extraterrestrial electromagnetic radiation within the radio frequency range of the spectrum in amounts sufficient to be measured.

Reflectance spectroscopy is a technique used to analyze the reflective properties of materials across various wavelengths of the electromagnetic spectrum. By measuring the reflectance of light from a...

Remote inspection refers to the process of inspecting, evaluating, or monitoring assets, equipment, infrastructure, or systems from a distance, typically using remote sensing technologies and...

Remote sensing is a method of data collection and observation where information about objects, areas, or phenomena on Earth's surface is gathered from a distance, typically using sensors onboard...

A resonator is a device or system that exhibits resonance, which is a phenomenon that occurs when an external force or stimulus is applied at a specific frequency, causing the system to oscillate...

A retroreflector is an optical device or structure that reflects incident light or electromagnetic waves back to their source, regardless of the direction from which the light approaches. Unlike...

Sapphire optical fiber is a type of optical fiber made from single-crystal sapphire, which is a form of aluminum oxide (Al2O3) that is highly transparent in the infrared region of the electromagnetic...

A sapphire window refers to a transparent optical component made from sapphire crystal. Sapphire is a single-crystal form of aluminum oxide (Al2O3) that is highly prized for its exceptional optical...

Scalar diffraction theory is a simplified approach used to describe the propagation of electromagnetic waves, particularly light, as they encounter obstacles or apertures. It is termed "scalar"...

Scanning electron microscopy (SEM) is an advanced imaging technique used in microscopy to obtain high-resolution, three-dimensional images of the surfaces of solid specimens. SEM achieves this by...

Short wavelength infrared (SWIR) refers to the portion of the infrared spectrum that encompasses wavelengths roughly between 1,000 and 3,000 nanometers (nm). In the electromagnetic spectrum, infrared...

A silicon photodiode is a semiconductor device that converts light into an electrical current. It is a type of photodetector specifically designed for detecting and measuring light intensity. Silicon...

In micropositioning, a remote positioning device in which an electric current drives a movable armature mounted on an electromagnetic coil.

Spectral repeatability refers to the consistency and reproducibility of spectral measurements across multiple trials or instances. It is a measure of how well a measurement instrument or system can...

A spectral signature, in the context of remote sensing and spectroscopy, refers to the unique pattern or characteristic spectral response of a material or object across different wavelengths of the...

A spectrophotometer is a scientific instrument used to measure the intensity of light at various wavelengths in the electromagnetic spectrum, typically in the visible and ultraviolet regions. It is...

A spectroradiometer is a device used to measure the intensity of light at different wavelengths across the electromagnetic spectrum. It provides a detailed spectral distribution of light, breaking...

Spectroscopy is a technique used in the study of interactions between matter and electromagnetic radiation. It involves measuring and analyzing how different materials absorb, emit, or scatter light,...

Supercontinuum refers to a broad spectrum of light that spans a wide range of wavelengths, typically from the visible to the near-infrared or even mid-infrared regions of the electromagnetic...

A wave that is guided by the interface between two different media or by a refractive index gradient in the medium. The field components of the wave may exist (in principle) throughout space, even to...

Surface-enhanced Raman scattering (SERS) is a powerful analytical technique that enhances the Raman scattering signal of molecules adsorbed on or near certain nanostructured surfaces. Raman...