Application-specific custom fibers
Application-specific custom fibers
Application-specific custom fibers-Many communications fibers are optimized for specific applications, for example fiber to the home (FTTH), internal transmission in data centers and submarine cables across the sea.
The world of fiber optic communications continues to evolve and many of you know that the price of single-mode fiber for communications is declining. One size does not fit all optical communications needs.
Progressive refractive index single-mode fibers conforming to the International Telecommunications Union specification G.652, sometimes called “standard single-mode,” have been widely used for decades, while other single-mode fibers have been developed and used for new applications, such as multimode fibers, which have found new niches and new types of fibers have emerged. Here is a list of some important fibers for optical communications.
Multimode refractive index gradient optical fiber
Multiplexing of conventional fibers
Standards for single-mode fibers
Fibers insensitive to loss of curvature (link: How do fibers resist curvature?)
Small diameter fibers
Low peak water fibers
Microstructured hollow core fibers (link: Lumenisity launches hollow core cable for 10 Gbit DWDM transmission (10km)
Fiber structures for reducing curvature loss and improving light conduction
Fibers tailored to specific applications have certain advantages. Flex-resistant fibers are necessary for interior applications where flexing is common. Shrinking the fiber jacket can increase the number of fibers in a cable. Low-water fibers enable coarse wavelength division multiplexing (WDM) in 20 nm steps between 1270 and 1610 nm.
Ultra-low loss fibers allow for increased amplifier spacing. Multimode gradient index fibers enable high data rates to be transmitted over short distances, reducing the cost of transmitters and receivers.
Progressive index multimode fibers
First developed in the late 1960s to increase the bandwidth of large core fibers, multimode gradient index fibers are today primarily used for short data links. In the past, LED light sources were used, but today most data links use VCSELs to emit light at wavelengths between 800 and 960 nm. Most graded refractive index fibers are 50 μm in diameter, with some still using 62,5 μm core diameter fibers.
In practice, multimode data links use only about 550 m, while single-mode fibers use longer distances. Although multimode fibers have lower losses in the 1310 nm band than at shorter wavelengths, inexpensive mass-produced VCSELs are only in the short wavelength band. The OM5 standard makes it possible to achieve transmission rates of several gigabits per second.
The OM5 standard offers short-wavelength division multiplexing (SWDM) at 25 Gbps over two or four wavelengths in a 100 Gbps bandwidth from 850 to 953 nm. In January 2020, an IEEE working group approved the IEEE P802.3cm 400 Gbps multimode fiber standard, which distributes 400 Gbps signals over four or four wavelengths in a width 100 Gbit/s bandwidth. The main applications are hyperscale data centers, hosting centers and large data centers. The main applications are in large data centers and on short high-speed links in 5G networks.
