Mode coupling
Encyclopedia
In the term mode coupling, as used in physics and electrical engineering, the word "mode" refers to eigenmodes of an idealized, "unperturbed", linear system
. Most often, these eigenmodes are plane wave
s. The superposition principle
says that eigenmodes of linear systems are independent of each other: it is possible to excite or to annihilate a specific mode without influencing any other mode; there is no dissipation
. In most real systems, however, there is at least some perturbation
that causes energy transfer between different modes. This perturbation, interpreted as an interaction between the modes, is what is called "mode coupling".
Important applications are:
See also nonlinear optics
and nonlinear acoustics
.
Linear system
A linear system is a mathematical model of a system based on the use of a linear operator.Linear systems typically exhibit features and properties that are much simpler than the general, nonlinear case....
. Most often, these eigenmodes are plane wave
Wave
In physics, a wave is a disturbance that travels through space and time, accompanied by the transfer of energy.Waves travel and the wave motion transfers energy from one point to another, often with no permanent displacement of the particles of the medium—that is, with little or no associated mass...
s. The superposition principle
Superposition principle
In physics and systems theory, the superposition principle , also known as superposition property, states that, for all linear systems, the net response at a given place and time caused by two or more stimuli is the sum of the responses which would have been caused by each stimulus individually...
says that eigenmodes of linear systems are independent of each other: it is possible to excite or to annihilate a specific mode without influencing any other mode; there is no dissipation
Dissipation
In physics, dissipation embodies the concept of a dynamical system where important mechanical models, such as waves or oscillations, lose energy over time, typically from friction or turbulence. The lost energy converts into heat, which raises the temperature of the system. Such systems are called...
. In most real systems, however, there is at least some perturbation
Perturbation
Perturbation or perturb may refer to any of numerous concepts in several fields:* Perturbation theory, mathematical methods that give approximate solutions to problems that cannot be solved exactly...
that causes energy transfer between different modes. This perturbation, interpreted as an interaction between the modes, is what is called "mode coupling".
Important applications are:
- In fiber optics
- In lasers (compare mode-locking)
- In condensed matter physics, critical slowing down can be described by a mode-coupling theory.
See also nonlinear optics
Nonlinear optics
Nonlinear optics is the branch of optics that describes the behavior of light in nonlinear media, that is, media in which the dielectric polarization P responds nonlinearly to the electric field E of the light...
and nonlinear acoustics
Nonlinear acoustics
Non-linear acoustics is a branch of physics dealing with sound waves being distorted as they travel.-Introduction:A sound wave propagates through a material as a localized pressure change...
.