- Industry: Telecommunications
- Number of terms: 29235
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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 field component. Note: The propagation constant, , is a complex quantity given by = +i, where , the real part, is the attenuation constant and , the imaginary part, is the phase constant. 2. In a physical transmission medium, e.g., a coaxial cable or optical fiber, the velocity of an electrical or electromagnetic signal expressed as a decimal fraction of the speed of light in vacuuo.
Industry:Telecommunications
For an electromagnetic wave, the time over which a propagating wave may be considered coherent. Note 1: In long-distance transmission systems, the coherence time may be reduced by propagation factors such as dispersion, scattering, and diffraction. Note 2: In optical communications, coherence time, , is calculated by dividing the coherence length by the phase velocity of light in a medium; approximately given by = 2/ (c) where is the central wavelength of the source, is the spectral width of the source, and c is the velocity of light in vacuum. Note 3: "Coherence time" is usually applied to the optical regime.
Industry:Telecommunications
For an electromagnetic wave, the time over which a propagating wave may be considered coherent. Note 1: In long-distance transmission systems, the coherence time may be reduced by propagation factors such as dispersion, scattering, and diffraction. Note 2: In optical communications, coherence time, , is calculated by dividing the coherence length by the phase velocity of light in a medium; approximately given by = 2/ (c) where is the central wavelength of the source, is the spectral width of the source, and c is the velocity of light in vacuum. Note 3: "Coherence time" is usually applied to the optical regime.
Industry:Telecommunications
For an optical fiber, a device or optical system used to create an approximation of the equilibrium mode distribution.
Industry:Telecommunications
For an optical fiber, a refractive index profile characterized by a uniform refractive index within the core and a sharp decrease in refractive index at the core-cladding interface. Note 1: The step-index profile corresponds to a power-law index profile with the profile parameter approaching infinity. Note 2: The step-index profile is used in most single-mode fibers and some multimode fibers.
Industry:Telecommunications
For an optical fiber, an unbound mode. Note: In an optical fiber, a radiation mode is one having fields that are transversely oscillatory everywhere external to the waveguide, and which exists even at the limit of zero wavelength. Specifically, a radiation mode is one for which where is the imaginary part (phase term) of the axial propagation constant, integer is the azimuthal index of the mode, n (a) is the refractive index, where a is the core radius, and k is the free-space wave number, k = 2/, where is the wavelength. Radiation modes correspond to refracted rays in the terminology of geometric optics. Synonym unbound mode.
Industry:Telecommunications
For an optical fiber, an unbound mode. Note: In an optical fiber, a radiation mode is one having fields that are transversely oscillatory everywhere external to the waveguide, and which exists even at the limit of zero wavelength. Specifically, a radiation mode is one for which where is the imaginary part (phase term) of the axial propagation constant, integer is the azimuthal index of the mode, n (a) is the refractive index, where a is the core radius, and k is the free-space wave number, k = 2/, where is the wavelength. Radiation modes correspond to refracted rays in the terminology of geometric optics. Synonym unbound mode.
Industry:Telecommunications
For an optical fiber, that portion of a joint loss that is not intrinsic to the fibers, e.g., loss caused by end separation, angular misalignment, or lateral misalignment.
Industry:Telecommunications
For an optical fiber, the optical quality of the surface at the end of the fiber.
Industry:Telecommunications
For an optical fiber, the square of the product of the diameter of the near-field pattern and the sine of the radiation angle of the far-field pattern. The diameter of the near-field radiation pattern is defined here as the full width at half maximum and the radiation angle at half maximum intensity. Note: Effective mode volume is proportional to the breadth of the relative distribution of power amongst the modes in a multimode fiber. It is not truly a spatial volume but rather an "optical volume" equal to the product of area and solid angle.
Industry:Telecommunications
