Single-mode (or monomode) fiber enjoys lower fiber attenuation than multimode fiber and retains better fidelity of each light pulse, as it exhibits no dispersion caused by multiple modes. Thus, information can be transmitted over longer distances. Like multimode fiber, early single-mode fiber was generally characterized as step-index fiber meaning the refractive index of the fiber core is a step above that of the cladding rather than graduated as it is in graded-index fiber. Modern single-mode fibers have evolved into more complex designs such as matched clad, depressed clad, and other exotic structures.
Core Size and Numerical Aperture
Single-mode fiber shrinks the core down so small that the light can only travel in one ray. The typical core size of a single-mode fiber is 9 microns.
Since only one mode is allowed to travel down the fiber path, the total internal reflection phenomenon does not occur and the concept of numerical aperture is reduced to its definition (the same as for multimode fibers). It measures the core and cladding refractive indices difference but has little impact on the information propagation. The NA for a single-mode fiber is usually smaller than for a multimode fiber.
Single-mode Fiber Patch Cable
Singlemode patch cords are used for telcom networks and also used for high speed metropolitan and access network. Our singlemode patch cords are manufactured using LSZH cables which conform to IEC, EIA TIA and Telecordia standards. OS1/OS2 patch cords are terminated with our standard connector which gives optimum optical performance. They are terminated with combinations of FC, SC, ST LC, and MTRJ fiber optic cable connectors and are available in simplex and duplex styles. (Related products have Singlemode fiber cable LC to LC, Singlemode ST patch cord, Singlemode SC patch cord, ect.) The main application areas include computer work station to outlet and fiber optic patch panels or optical cross connect distribution centers, optical fiber CATV, telecommunication networks, Local Area Networks (LAN) and for use with test equipment.
Now Figure 1 shows the Single-mode duplex fiber patch cable lc-sc from Fiberstore, see the following description:
The Single-mode duplex fiber patch cables lc-sc features 9/125 micron fiber for high-speed, high bandwidth data transmissions over Gigabit Ethernet and Fiber Channel networks, with support for duplex single-mode applications. This LC-SC patch cable is housed in a LSZH (Low-Smoke, Zero-Halogen) flame retardant jacket, to ensure minimal smoke, toxicity and corrosion when exposed to high sources of heat, in the event of a fire – an ideal solution for use in industrial settings, central offices and schools, as well as residential settings where building codes are a consideration. Each Duplex 9/125 (OS1) Single-Mode Fiber Patch Cable is individually tested and certified to be within acceptable optical insertion loss limits for guaranteed compatibility and 100% reliability, and is backed by our lifetime warranty.
Center Wavelength and Reach
Single-mode fibers carry optical signals in the second and third telecom windows where attenuation is minimized. The center wavelength of the laser emitting into the fiber is approximately 1310 nm and 1550 nm, respectively. CWDM and DWDM channels operate over single-mode fibers in the third window with a wavelength drifting tolerance stricter than for non-WDM channels.
Common lasers suitable for applications over single-mode fiber are Fabry-Perot and distributed feedback (DFB) lasers.
As for multimode fibers, the reach is the minimum distance guaranteed for a type of laser, over a type of fiber at a certain data rate. The reach over a single-mode fiber is generally limited by accrued chromatic and polarization-mode dispersion, which are typically of greater impact as data rates are higher. Additionally, the reach can also be limited by the degradation of optical signal over noise ratio (OSNR) in the case of amplified links. Finally Fabry-Perot lasers are used for shorter-reach applications as their spectrum width is large and more subject to dispersion. DFB lasers are typically used for longer reaches as their spectrum width is narrow and therefore relatively less subject to dispersion.
This article comes from: http://www.fiber-patch-cords.com/blog/a/75/Single-mode-Fiber-Patch-Cable-For-Data-Environments