August 29, 2011
Tight buffer or tight tube cable designs are typically used for ISP applications. Each fiber is coated with a buffer coating, usually with an outside diameter of 900 m. Tight buffer cables have the following cable ratings:
August 29, 2011
An important consideration in fiber-optic cable installation is the cable's minimum bend radius. Bending the cable farther than its minimum bend radius might result in increased attenuation or even broken fibers. Cable manufacturers specify the minimum bend radius for cables under tension and long-term installation. The ANSI TIA/EIA-568B.3 standard specifies a bend radius of 1.0 inch under no pull load and 2.0 inches when subject to tensile loading up to the rated limit.
August 29, 2011
Shallow-water systems are similar to their armored loose-buffered terrestrial counterparts, whereas deep-water submarine cables use a special hermetically sealed copper tube to protect the fiber from the effects of deep-water environments. Deep-water and submarine cables also have dual armor and an asphalt compound that is used to fill interstitial spaces and add negative buoyancy. In addition to the significant external physical forces that might be encountered in a submarine environment, the other major concern is the effect of hydrogen on the performance of the optical fiber in cables used in such applications.
August 28, 2011
Nonlinear characteristics include self-phase modulation (SPM), cross-phase modulation (XPM), four-wave mixing (FWM), stimulated Raman scattering (SRS), and stimulated Brillouin scattering (SBS).
August 28, 2011
FWM can be compared to the intermodulation distortion in standard electrical systems. When three wavelengths (λ1, λ 2, and λ 3) interact in a nonlinear medium, they give rise to a fourth wavelength (λ 4), which is formed by the scattering of the three incident photons, producing the fourth photon. This effect is known as four-wave mixing (FWM) and is a fiber-optic characteristic that affects WDM systems.
August 28, 2011
When light propagates through a medium, the photons interact with silica molecules during propagation. The photons also interact with themselves and cause scattering effects, such as stimulated Raman scattering (SRS), in the forward and reverse directions of propagation along the fiber. This results in a sporadic distribution of energy in a random direction.