Optical fiber in theory, its bandwidth is infinitely high, the transmission capacity is infinitely large, the transmission distance is infinity. The lighter weight is almost perfectly signal transmission medium can simultaneously transmit N-way telephone, an N-channel TV signal …… However, current applications, fiber optic cable is farther with the theoretical difference. Fragile physical properties of silica aside aside, its transmission capacity is only open several windows.
In May 2002, ITU-T tissue optical band of the optical fiber communication system is divided into O, E, S, C, L, U6 a band. Known as the first window, single-mode optical fiber O with 2 window multimode fiber 850nm C with said window 3 L with 4 windows, E with 5 window. Multimode fiber and single-mode fiber communication band summary can be listed in the following table
|Frequency band||Window||Wavelength range (nm)||Frequency range (THz)|
|Short wavelength band||1460-1530||205.3-195.9|
|Longer wavelength band||4||1565-1625||191.6-184.5|
|Ultralength wavelength band||1625-1675||184.5-179.0|
Due to the lower prices of the LED light source, 850nm, 1300nm wavelength with multi-mode fiber optic cable to set up a small network of choice for laser light source 1310nm wavelength 1550 nm single-mode fiber optic cable can constitute the basis of a large network, if the single-mode fiber optic cable available window morewords, wavelength division multiplexing (MDM) will be a core fiber multi-wavelength optical signals transmit at the same time to achieve ultra-high speed transmission effect, so you can maximize the potential of the single-mode fiber optic cable. 2 core telephone line telephony and network use at the same time, by ADSL “cat” because voice and data use different frequency, wavelength division multiplexing (MDM) technology principle similar to ADSL technology, this technology is generally used in the bandwidth requirements of a higher position backbone.
Intelligent building applications, fiber optic cable is often close to support multi-mode-based, such as multi-mode fiber optic cable with the emission wavelength of 850nm or 1300nm LED light source, or 850nm VCSEL laser wavelength. Single-mode used in long distance system buildings, single-mode fiber optic cable with emission wavelength 1310nm or 1550nm FP or DFB laser, means that most of the fiber optic cable is only open a window.
The fiber optic cable can transfer window open, open a few, which are subject to dispersion, loss, DMD, PMD and other factors, but also with light sources and other fiber optic network equipment. From a long-term perspective, the more support window cable in practicality, compatibility, scalability is higher.