Furukawa electric S178, User Manual

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General Information
2-3
Core Concentricity Core Non-circularity
Optical fiber is
basically classified as
either single-mode
(SM) or multi-mode
(MM). Single-mode
fiber, which includes
dispersion-shifted
fiber types, will transmit a single-mode (path) of data at
wavelengths greater than the cut-off wavelength (1170 nm). Approximately 80% of the light is
transmitted within the core, and 20% is transmitted in the surrounding cladding. Therefore, the
transmission path is more accurately referred to as the mode field and not as the core. With a
core diameter of typically 8 µm and a mode field diameter of approximately 10 µm, single-mode
fiber can transmit more data than multi-mode fiber and with less attenuation.
In multi-mode fiber, the optical signal is transmitted entirely within the core. These fibers have a
core size of 50 µm to 100 µm (50 µm or 62.5 µm, typically) and are commonly used in local area
networks (LANs), short distance links and closed circuit television (CCTV).
claddings
core1
core2
cladding
core
cladding
center
core
center