TYPES OF OPTICAL FIBERS

Single Mode Fiber Optic Cable Multimode Fiber Optic Cable Step Index Multimode Graded Index MultimodePlastic Optical Fiber (POF) .

A single mode fiber is a single strand of glass fiber (most applications use 2 fibers) with a diameter of 8.3 to 10 microns that has 1 mode of transmission. Due to the relatively narrow diameter, only the one mode will propagate typically 1310 or 1550nm. Single-mode optical fiber is an optical fiber in which only the lowest order bound mode can propagate at the wavelength of interest typically 1300 to 1320nm. It is made up of 3 parts:

The Fiber Optic Core: The inner light-carrying member with a high index of refraction.

The Cladding: The middle layer, which serves to confine the light to the core. It has a lower index of refraction.

The Buffer: This is the outer layer, which serves as a “shock absorber” to protect the core and cladding from damage. This coating is usually comprised of one or more coats of plastic material to protect the fiber from the physical environment. Sometimes metallic sheaths (armor) are added to the coating for further physical protection.

The single mode fiber optic cable was made specifically for the purpose of transmitting a single mode or light wave down the path of the fiber. The single mode fiber has a higher bandwidth than multimode fiber, higher transmission rate and up to 50 times more distance than multimode. However, the cost is higher than for multimode and requires a light source with a narrow spectral width.

The single-mode fiber gives you a higher transmission rate and up to 50 times more distance than multimode, but it also costs more. Single-mode fiber has a much smaller core than multimode. The small core and single light-wave virtually eliminate any distortion that could result from overlapping light pulses, providing the least signal attenuation and the highest transmission speeds of any fiber cable type. Single mode fiber is used in many applications where data is sent at multiple frequencies (using wave-division multiplexing) so only one cable would be needed.

Synonyms for single mode fiber are: mono-mode optical fiber, single-mode fiber, single-mode optical waveguide, uni-mode fiber.

October 21, 2011

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