Photonics Dictionary

In optics and photonics, "phase" refers to a property of electromagnetic waves, such as light, that describes the position of a wave at a given point in time within its oscillation cycle. More...

1. The angle between two vectors that represent two simple periodic quantities that vary sinusoidally and that have the same frequency. 2. See phase.

A term for the ring-shaped stop in a phase contrast microscope. The phase annulus limits the amount of light that reaches the phase plate from the direction of the specimen and retards the light by a...

The use of a reflective device, which can be fashioned from a variety of materials including gases, solids, dyes, aerosols, semiconductor crystals and plasmas, to replicate a laser beam by reversing...

With respect to a traveling plane wave at a known frequency, the space rate of decrease of phase of a field component in the direction of propagation, measured in radians per unit length.

Phase contrast microscopy is an optical microscopy technique that enhances the contrast of transparent and colorless specimens, making it possible to visualize fine details and internal structures...

Phase distortion refers to a change in the phase relationships between different frequency components of a signal. In the context of signal processing, it occurs when the phase response of a system...

A hologram that is formed on a recording medium by changing the phase of the illuminating wave in correspondence with the recording exposure. It may be formed by contact printing onto a resist...

In optics and photolithography, a phase mask refers to a device that modifies the phase of light waves passing through it. The phase mask is used to control the spatial distribution of the light's...

Phase matching is a crucial concept in the field of optics, particularly in nonlinear optics and the generation of coherent light. It refers to the condition where the phases of two or more waves,...

A phase screen, in the context of optics and wave optics, refers to a surface or medium that introduces a phase delay to an incident wavefront passing through it. This concept is often used in the...

A technique used to generate a phase shift between reference and sample light beams. The phase shift can be performed through the use of a mirror that is moved along the optic axis by a piezoelectric...

The determination of the relative phase shift of an image as a function of frequency. A phase change of 180° with respect to the object results in an image with the black and white areas...

The propagation or hindrance of waves reaching each aperture of the interferometer because of atmospheric turbulence.

For a particular mode in a waveguide, the ratio of the angular frequency to constant phase.

An erasable data recording and storage medium that uses a laser to heat the crystalline surface of the disc to a certain temperature, at which it becomes amorphous and records a bit of information;...

Microscopy technique to convert the phase structure of the wave transmitted or reflected by the specimen into a corresponding intensity structure in the image plane.

A microscope that has an annular stop in the lower focal plane of the condenser, and a quarter-wave retarding and absorbing ring in the upper focal plane of the objective that just fills the image of...

A circuit that uses feedback to synchronize the phase of a voltage-controlled oscillator with the phase of an incoming or reference signal.

A phase-modulated sensor is a type of sensor that uses modulation of the phase of a signal to measure changes in a physical quantity. In such sensors, variations in the phase of the signal are...

A type of matched filter that responds only to the phase of incoming light; the output has a much greater intensity than that of a classical matched filter, which responds to phase and amplitude. The...

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 vapor-phase oxidation process for fabricating graded-index optical fibers. It differs from outside vapor phase deposition in that the preform is developed radially rather than longitudinally. An...

The state of a liquid crystal in which the molecules are arranged in layers with their long axes in the plane of each layer. The alignment in each layer is parallel and the alignment in adjacent...

A type of phase-shift keying using a one-bit delay line.

Phase shift in electromagnetic signals caused by daily variations in the ionosphere, often during sunrise or sunset.

A technique used to create an achromatic phase shift based on the principle of geometric phase. The phase shift is experienced by a light beam as a result of a cyclic change in its state of...

That state determining that two waves of like frequency will travel through their maximum and minimum values of the same polarity simultaneously.

A method that produces low-loss optical fibers. A glass tube rotates while reactants pass through the tube and heat is externally applied by a burner that traverses the tube. The oxidizable vapors in...

A method of reducing dark current in charge-coupled devices by holding all the clocks at negative voltage during the integration period.

A form of liquid crystal with an appearance of moving, threadlike structures, particularly visible when observed in thick specimens with polarized light. During this phase, the molecules of the...

The coupling of laser or light beams via nonlinear optical techniques such as four-wave mixing to achieve spatial variation of the electrical field of the target beam. This technique is also referred...

Optical phase distortion refers to a phenomenon where the phase of an optical wavefront is altered as it propagates through a medium. This distortion can result from variations in the refractive...

A process for the production of optical fibers. A glass bait is rotated in a traversing flame of a reaction burner. Reactants passed through the flame react with oxygen at the high temperatures to...

Conceptual formulas that characterize both the transmittance functions of lenses and propagation in the Fresnel zone.

Quantitative phase imaging (QPI) is an advanced imaging technique used in microscopy to measure and analyze the optical phase information of transparent specimens. Unlike traditional brightfield...

Self-phase modulation (SPM) is a nonlinear optical phenomenon that occurs when an intense laser beam passes through a medium, causing a change in the phase of the light due to its interaction with...

An aperture consisting of a semitransparent central region whose amplitude transmittance only is varied, and the relative phase difference between the central and annular region is fixed as p -...

A form of liquid crystal in which flow does not take place in the usual manner. When examined with polarized light, the substance often forms drops that display a series of fine lines. X-ray...

The change in position of the image of a sine wave object from its ideal position. Usually measured in degrees with 360° designating a full cycle of the image.

A form of liquid crystal in which the 90° twist of the twisted nematic phase has been increased to 180° or more, resulting in higher contrast and a wider viewer angle in the display.

A type of recording material, usually a photodielectric polymer, offering in situ development mechanisms because of its density storage capabilities, high diffraction efficiencies and excellent noise...

A form of liquid crystal widely used in displays, achieved by sandwiching a liquid crystal material between two substrates whose inside surfaces have been prepared with a special coating that aligns...