Installation Manual
Quidway S3526 Ethernet Switch
Appendix A Knowledge of Optical Fiber
A-1
Appendix A Knowledge of Optical Fiber
The center of optical fiber is a light transmission glass core, clad by a glass packet with
lower refractive index so to keep the optical fiber within the core. Outside, there is a thin
plastic shield to protect the packet.
Usually, optical fibers are packed into bundles and
are protected by a casing.
The application field of optical fibers is increasingly wide due
to the extremely high reliability, transmitting quality and the constant adoption of new
technologies in optical fiber design and manufacturing.
A.1 Multi-mode Optical Fiber and Single Mode Optical Fiber
The optical fiber system can be divided into two categories, Multi-mode fiber and Single
mode fiber, according to the light transmitting modes.
Cores of Single mode optical fibers are very small. As a result, only a Single mode can
be used to transmit in a specified wavelength. The transmitting frequency bandwidth is
wide and the transmitting capacity is enormous.
Multi-mode optical fibers are fibers for Multi-mode transmissions in a specified
wavelength.
In Multi-mode transmission, different speeds of the lights in different
modes can cause phase errors that will lead to the transmission distortion. Therefore,
their transmission frequency is limited.
There are two Multi-optical fiber systems, i.e.
62.5µm (fiber measurement) and 50µm. Both systems are approved transmission
medium in ISO/IEC 11801 standards.
A.2 Optical Fiber Connector
ITU recommends to define it as "Used to connect passive components of two or several
optical fibers steadily but not permanently" (pass by the VI research team of CCITT in
March, 1992 in Geneva).
Optical fiber connectors are indispensable passive components in optical fiber
communication system. Their application enables the removable connection between
light path.
There are various optical fiber connectors. Here, only MT-RJ, SC, and LC will be
introduced.
z
MT-RJ: This type of connectors converge two channels of optical sources into
single optical fiber, and hence reduces the number of ports for connectors.
