Optical fiber

An optical fiber is a transparent thin fiber, usually made of glass or plastic, for transmitting light. Fiber optics is the branch of science and engineering concerned with such optical fibers.

Refracted rays

In an optical fiber, a refracted ray is one that is refracted from the core into the cladding. Specifically a ray having direction such that where r is the radial distance from the fiber axis, φ(r ) is the azimuthal angle of projection of the ray at r on the transverse plane, θ(r ) is the angle the ray makes with the fiber axis, n (r ) is the refractive index at r, n (a ) is the refractive index at the core radius, a . Refracted rays correspond to radiation modes in the terminology of mode descriptors.

Related Topics:
Core - Cladding - Fiber axis - Refractive index - Radiation

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For the fiber to guide the optical signal, the refractive index of the core must be slightly higher than that of the cladding. In different types of fibers, the core and core-cladding boundary function slightly differently in guiding the signal. Especially in single-mode fibers, a significant fraction of the energy in the bound mode travels in the cladding.

Related Topics:
Refractive index - Cladding - Bound mode

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Source: from Federal Standard 1037C

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Following are the two major types of fiber-optic cable:

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• Single-mode: uses a specific light wavelength. The cable's core diameter is 8 to 10 micrometres. Single-mode fiber is often used for intercity telephone trunks and video applications.
• Multi-mode: uses a large number of frequencies (or modes). The cable's core is larger than that of single-mode fiber. Multimode fiber is the type usually specified for LANs and WANs.