Things to Know About Bend Insensitive Multimode Fiber

by http://www.fiber-mart.com

Bend insensitive multimode fiber (BIMMF) has become a very active area within the telecommunication industry once it was introduced and popularized. It typically signifies technical advancements in the production of multimode optical fiber for easier installation, and cable management for multimode fiber cables through improvements in bend insensitivity. This article will focus on some useful information about BIMMF from the perspective of its working principle, performance in networking and unique advantages as well.
What Is Bend Insensitivity?
An optical fiber consists of a core and a cladding. Although both of these regions are made from glass in telecommunications grade fibers, they are significantly different from each other. Each region is designed to capture light within the core and transmit it to the opposite end of the fiber. During this process, the light may follow many paths, depending on the angle at which the light hits the boundary, it is either reflected back into the core, or it gets lost into the cladding. Therefore, the light losses during transmission cause a weaker optical signal at the other end.
Optical fiber is sensitive to stress, particularly bending. When conventional fibers are bent tightly, some of the signal will leak out of the fiber at the site of the bend due to macrobend loss, which will results in system failure and unplanned downtime. Various attributes in the fiber determine when this occurs. The relative ease with which this happens is known as bend sensitivity. On the contrary, bend insensitivity is a positive feature that can provide for additional robustness and simplify installation of multimode fiber.
Introduction to Bend Insensitive Multimode Fiber (BIMMF)
Bend-insensitive multimode fiber (BIMMF) has an innovative core design that enables it to significantly reduce macrobend loss even in the most challenging bend scenarios. It is hence natural that bend insensitive multimode fiber can withstand tough treatment. The difference between traditional multimode fiber and BIMMF mainly lies in the fact that the BIMMF design can include an optical trench. This trench effectively improves the fiber’s macrobend performance by retaining more of the light that would have escaped the core of a traditional multimode fiber. So when compared with standard multimode fibers, BIMMF is proved to be a good candidate for loss and bend critical applications because of their higher immunity to bending losses, without loosing performances or compatibility to other standard high bandwidth multimode fibers.
Compatibility With Conventional Fibers
There is a lot of buzz around the issue of bend insensitive fiber— is it compatible with regular fibers? Can they be spliced or connected to other conventional fibers without problems? Modeling and testing on BIMMF has shown that an optimized BIMMF is backward compatible and can be mixed with non-BIMMF without inducing excess loss. Hence, BIMMF and MMF could easily be mixed in an optical channel without complicating the estimation of losses. Moreover, BIMMF may lead to higher tolerance to possible misalignments when two connectors are mated. This is an additional positive feature for 40 and 100 Gigabit applications.
In summary, a well-designed BIMMF complies with all relevant industry standards and adheres to the following:
BIMMF OM2, OM3 and OM4 multimode fibers are fully compliant and fully backward-compatible with all relevant industry standards.
BIMMF is fully backward-compatible and may be used with the existing installed base of 50/125um multimode grades including OM2, OM3 and OM4.
BIMMF may be spliced or connectorized to conventional 50/125um fiber types with commercially available equipment and established practices and methods, no special tools or procedures are required.
BIMMF not only meets all relevant macrobend standards, but sets a new level of bend performance.
Advantages of BIMMF
Bend insensitive multimode fiber is available in all laser optimized grades, OM2, OM3 and OM4, and exhibits 10 times less signal loss in tight bend scenarios and therefore protects enterprise and data center systems from unplanned downtime due to signal loss and associated significant revenue loss.
This fiber type offers extremely low bending loss at both the 850 and 1300 nm operating windows, while maintaining excellent long term fiber strength and reliability. The fiber can be installed in loops as small as 7.5 mm radius with less than 0.2 dB bending loss at 850 nm and 0.5 dB at 1300 nm.
In addition, bend insensitive multimode fibers enable new possibilities for cable and patch panel design to further improve the benefits of using fiber. Optical cable manufacturers can now design thinner, more flexible trunk cables, making for easier cable installation and further improving airflow in conduits, patch panels and racks. Due to the ability of the fib cable to be bent tightly with significantly less signal loss, connector modules can be made smaller which in turn leads to an increased density within racks and smaller racks.

 

Choosing the Right Fiber Optic Cable

There are so many fiber optic cable options available that one might wonder where to start. This article will set you on the right path in the decision process. Let’s begin by focusing on the broad categories of fiber optic cable. Below you can make “either/or” decisions. A handy reference chart that summarizes key cable features can be found below.
Multimode or Single Mode?
Multimode Cable – Applications: Multimode fiber is used to transport high volumes of data over relatively short distances (compared to single mode fiber). Common applications include Data Centers and other Local Area Network (LAN) applications. Note that multimode distance capabilities have increased over the years. Multimode fiber cable now offers an economical alternative to single mode cable for certain applications. Design: Multimode cable has a relatively large core (either 50 or 62.5µm) that enables multiple streams of data to be transported simultaneously.
Single Mode Cable – Applications: Telcos and CATV companies use single mode cable to transport signals over long distances. Business campuses and other institutions also use single mode cable for longer cable runs, such as links between buildings. Design: The core diameter of single mode fiber is so small (9µm) that it permits only one mode of light to pass through it at any given time. This characteristic reduces attenuation and enables light to be transmitted over great distances. While the purchase price of single mode cable is less than multimode cable in general, single mode transceivers and network interfaces are generally more expensive than those used for multimode systems.
Simplex or Duplex?
Applications: Simplex and Duplex cables are typically used for fiber optic patch cables and desktop installations that don’t require a high fiber count. Design: Simplex cables contain a single 900µm coated fiber or a combination of a 900µm coated fiber surrounded by an aramid yarn strength member with an outer jacket diameter varying between 3, 2, 1.8 and 1.6mm. Duplex cables contain two 900µm coated fibers surrounded by an aramid yarn strength member with an outer jacket diameter varying from 3, 2, 1.6 and 1.2mm.
Loose Tube or Tight Buffer?
Loose Tube Cable: Applications: Loose tube cable is ideal for use in long distance outside plant applications that require a high fiber count. The cable is designed to withstand harsh outdoor environments; the cable’s unjacketed fibers are free to expand and contract with temperature changes. Design: Fibers within loose tube cables are surrounded by a water blocking component (either gel or a dry water-blocking material). Although loose tube cables are engineered to withstand damp outdoor environments, they are not designed to be submerged in water, but can come in contact with water. Terminating Loose Tube Fibers – The fibers within the gel-filled tubes of the cable have a very thin acrylate coating which is 250µm in diameter. Before terminating, the fibers must be put into small plastic tubes (called a breakout kit or box). The tubes protect the thin fibers and make them easier to handle when terminating and connecting to network equipment.
Tight Buffer Cable: Applications: Tight buffer cable is typically used indoors. A tight buffer (cable jacket) encapsulates each fiber. The 900 micron buffer enables the fibers to be directly terminated without requiring a breakout kit, which saves substantial time. These cables do not typically provide protection from water migration and do not isolate fibers well from the expansion and contraction of other materials due to temperature extremes. Tight-buffered cables, often called premise or distribution cables, are ideally suited for indoor-cable runs. Design: Tight buffer cables have two protective coatings; a 900 micron PVC jacket and 250 micron acrylate coating, all encased in an outer PVC jacket.
Distribution or Breakout?
Distribution Cable: Applications: Distribution cable is ideal for networks that terminate multiple fibers at a common location, such as a patch panel or communications closet. Fibers within a distribution cable have their own 900 micron individual cable jackets. This space-saving feature enables up to 144 fibers to be bundled within the cable. Fibers in a “Micro Distribution” cable do not have the 900 micron tight buffered PVC jacket, instead they contain color coded 250 micron acrylate coated fibers. Because of the decreased diameter of the individual fibers in the cable, a micro distribution cable may contain up to 432 or more fibers. A disadvantage of micro distribution cable is that the unjacketed fibers require the use of a breakout kit for termination. Design – Distribution cable contains a number of 250µm – 900µm fibers that are color-coded for easy identification. The cable includes an aramid yarn strength member and a thick outer jacket that provides protection and strength during cable installation. If required, the cables can be purchased with interlocking armor.
Breakout Cable: Applications: Breakout cable is ideal for applications where fibers are connected directly to equipment, including local hubs. Also, the robust design of breakout cable makes it well suited for use as drop cables. Design – Breakout cable differs from distribution cable in that each of the fibers in a breakout cable is 900 micron tight buffered and surrounded by aramid yarn all encased in a 2mm or 3mm PVC jacket. Then all of these 2 or 3mm jacketed fibers are encased in an outer jacket. This additional jacketing can save substantial time and installation cost, especially if the fibers are being terminated with connectors. One disadvantage of breakout cable is that the fiber jackets take up room within the cable, so breakout cable cannot contain as many fibers as distribution cable. Fiber counts for breakout cable are typically 2-24 fibers (maximum is 48 fibers).

Will Wideband Multimode Fiber be a new option for future data centers?

Multimode fiber has evolved from OM1, OM2, OM3 to OM4 since entering the market in the 1980s. Among them, OM3 is for vertical cavity surface emitting laser (VCSEL) light source optimized multimode fiber, the effective mode bandwidth (EMB) reaches 2000MHZ. Km, which can support transmit distance up to 300 meters or 100 meters for 10GBASE-SR transceiver 100GBASE-SR10 transceiver respectively. OM4’s effective mode bandwidth (EMB) compared to OM3 is increased by more than 1 times to 4700MHZ.Km, but support 100GBase-SR10 transceiver is only 150 meters effective transmission distance, that is relative to the OM3 fiber, 100G Ethernet Network transmission distance increased by only 50%, obviously can not meet the needs of the future high-speed network.
As one of the options for future data centers, Wideband Multimode Fiber (WBMMF) is far superior to traditional OM4 multimode fiber in efficient mode bandwidth (EMB), so it can provide enough margin space for high-speed Ethernet in future. Before understanding it, we need to carefully understand the development of single mode and multimode fiber.
Single mode Fiber and Multimode Fiber, the Difference and Selection
Single mode fiber is mainly used in multi-frequency data transmission applications, the transmission mode is usually used wavelength division multiplexing (WDM) transmission mode, after the multiplexing of optical signals only need to use a single mode fiber to achieve data transmission. The 100GBASE-LR4 released in 2010, using 2-core Single mode Fiber (1 transmit +1 receive) 1, can be in one core fiber simultaneously multiplexing 4 wavelengths, each wavelength transmits at 25Gbps.
The transmission rate of single mode fiber is higher than that of multimode, and the transmission distance is 50 times higher than that of multimode, so its price is higher than MMF. Compared with MMF, the core diameter of single mode fiber is much smaller, and the characteristics of small core diameter and single mode transmission make the optical signal transmitted in SMF not distorted by the overlapping of light pulses. In all fiber types, the signal attenuation rate of single mode fiber is the lowest and the transmission speed is the most.
However, single mode fiber needs to use a high-cost laser (LD) Light transmitter transceiver, single mode laser transceiver Price is at least more than 3 times than the multimode transceiver, the power consumption of at least twice times.
Conventional multimode fiber generally uses serial transmission mode, in this mode, increasing the transmission rate of Ethernet must increase the transmission rate of each core fiber/channel. At present, the Ethernet maximum serial transmission rate is 10Gbps/channel, and IEEE is developing 25Gbps/Channel, 50Gbps/Channel Network standard. Take 400G Ethernet as an example, there will be 3 different versions like 25Gbps, 50Gbps, and 100Gbps, the fiber core number needs 32 cores/16 cores/8 cores respectively. 400G Ethernet uses NRZ, PAM4, DMT, and higher-level coding means more complex circuits and power consumption, and thus higher costs.
In the past practical applications, the most common determinant of selecting multimode or single mode is distance. If only child miles are preferred multimode because the LED transmitter/receiver is much cheaper than a single mode laser. If the distance is greater than 5 miles, the single mode fiber is best. Another issue to consider is bandwidth; if future applications may include the transmission of large-bandwidth data signals, the single mode will be the best choice.
In the 2010 years, with 100g-NG, 200G/400G Ethernet, and even 1T Ethernet, the traditional multimode fiber has become the bottleneck of the future Ethernet network, and the emergence of the WBMMF breaks the bottleneck of traditional multimode fiber. It draws on the wavelength division multiplexing (WDM) technology of single mode fiber, extends the range of available wavelengths in network transmission, and can support 4 wavelengths on one-core MMF, and reduces the number of fiber cores needed to 1/4.
Shortwave Wavelength Division Multiplexing technology utilizes a high cost-effective vertical cavity surface emitting laser (VCSEL) light source, the optimized wideband multimode fiber (WBMMF) can support 4 wavelengths on one-core multimode fiber, reduce the number of fiber cores required to 1/4, and increase the effective mode bandwidth (EMB), so the 40 / 100G transmission distance extended to 300 meters.
Conclusion
At present, 96% of the world’s data centers, the backbone of the network core (Spine) switch to the Server cabinet Branch (Leaf) switch within 300 meters, therefore, shortwave wavelength division multiplexing (SWDM) and wideband multimode fiber (WBMMF) will continue to be the tradition of multimode fiber as the mainstream transmission medium of data center 40G/100G/400G Ethernet. In the future, the combination of shortwave wavelength division multiplexing (SWDM) and parallel transmission technology requires only 8-core wideband multimode fiber (WBMMF) to support more high-speed applications such as 200G/400G Ethernet.

Difference between singlemode and multimode fiber

Optic fiber bases its velocity on the speed at which these beams of light travel from one point to another. There are two types of fiber cables that are commonly used it, singlemode and multimode. Both have a conduit in the center called its core through which the light travels in a straight line or by bouncing off the walls made of cladding, an optical material that helps bounce the light.
Speed is the premise of optical fiber and it has revolutionized the market and changed the way that we connect because of it. Reaching up to 100 Gbps, data transmission is near instantaneous thanks to the beams of light that travel throughout the fiber.
Singlemode patch cords: It has the peculiarity that inside of its core, data travels without bouncing off of its walls which allows and maintains higher transfer speeds. The data transfers linearly which means that not too many beams of light can travel at once through the tiny proportions of this conduit. This type of fiber is used to cover great distances and it’s constructed with cores that can measure 9 microns with a cladding of 125 microns.
There are two types of singlemode cables:
OS1 Singlemode cable can be use in indoors situations, where the distance it can be deploy is maximum 2,000 meters. This allows up to 1 to 10 gibabit in Ethernet.
OS2 Singlemode are designed for all uses, making it more than suitable to outdoor purposes. The distance it can be deploy variate between 5,000 metres to 10,000 metres. This allows up to 1 to 10 gibabit in Ethernet. OS1 and OS2 are large distance cables due it the poor capacity to bend.
Singlemode is very useful to transmit data over long distances, thus making it perfect for college campus and cable television networks, singlemode fiber is a vital part for broadband networks
Multimode patch cords: This is the “domestic” fiber and in contrast with singlemode fiber, it allows the beams of light to bounce off of the cladding walls resulting in a greater quantity of light beams traveling at once through the core. In contrast with the singlemode, the multimode’s core measures 50 to 62.5 microns, granting more space for data to travel through. The cladding of 125 microns grants the light to bounce and travel through the fiber. Multimode fiber is used for local-area network, build-to-build data centers and to be used it FTTH. Multimode also may reach up to 100Gbps Ethernet.
Checking which cable is most suitable for your projects or needs is very important, and may even signify a better investment. When you are building your network backbone you need to be prepare for a variety of situations, considering factors such as attenuation. For any FTTx structure you will probably need singlemode and multimode, but the selections of the exact type will make the job a “plug-and-play” situation.

Everything you need to know about OM1 vs OM2 vs OM3 vs OM4 vs OM5

There are four commonly used OM (multimode) fibers: OM1, OM2, OM3 and OM4. Each type of them has different characteristics. The article will compare these four kinds of fibers from history,the side of core size, bandwidth, data rate, distance, color and optical source in details.

Fiber optic cable can be divided into several types. Usually we see single-mode and multimode fiber types available on the market. Multimode fibers are described by their core and cladding diameters. The diameter of the multi-mode fiber is either 50/125 µm or 62.5/125 µm. At present, there are four commonly used OM (multimode) fibers: OM1, OM2, OM3 and OM4. Each type of them has different characteristics. The article will compare these four kinds of fibers from history,the side of core size, bandwidth, data rate, distance, color and optical source in details.

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The picture above shows the development of OM multimode fibers. The Lime Green OM5 fibers are newly released and sure to be the mainstream transmission media in the near future.

specification of OM1, OM2, OM3 and OM4

Core Size

Multimode fiber is provided with the core diameter from 50 µm to 100 µm. Apart from OM1 with a core size of 62.5 µm, other three types are all using the 50 µm. The thick core size makes them able to carry different light waves along numerous paths without modal dispersion limitation. Nevertheless, in the long cable distance, multiple paths of light can cause signal distortion at the receiving end, resulting in an unclear and incomplete data transmission. And this is why all the types of multimode fiber can only be used for short distance.

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Bandwidth

Bandwidth is the bit-rate of available or consumed information capacity expressed typically in metric multiples of bits per second. The higher bandwidth is, the faster transmission speed can be. According to overfilled launch (OFL) and effective modal bandwidth (EMB) measurements, OM1 and OM2 fibers can only support OFL, but OM3 and OM4 are able to support both measurements. At the wavelengths of 850/1300 nm under OFL, the respective bandwidth of OM1, OM2, OM3, OM4 is 200/500 MHz*km, 500/500 MHz*km, 1500/500 MHz*km and 3500/500 MHz*km. And at the wavelength of 850 nm under EMB, the bandwidth of OM3 is 2000 MHz*km and OM4 even reaches 4700 MHz*km.

Data Rate

Data rate is a technical term that describes how quickly information can be exchanged between electronic devices. With a higher data rate, the transmission can be more effective. OM1 and OM2 support the Ethernet standards from 100BASE to 10GBASE with a minimum data rate of 100 Mbps and a maximum data rate of 10 Gbps. Compare with OM1 and OM2, OM3 fibers and OM4 fibers are enhanced to support much higher data rates of 40 Gbps and 100Gbps in 40G and 100G Ethernet.

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Distance

Multimode fiber is typically used for short distance transmission. But the maximum reaches are varied in different multimode fiber types. Also, on account of different data rates, the transmitting distances are different. However, the common feature is that OM1 always supports the shortest distance yet OM4 supports the longest. For instance, based on the same data rate of 10 Gbps, the maximum reach of OM1 is 33 m, OM2 is 82 m, OM3 is 300 m and OM4 is 550 m. Thus, if a medium-sized transmission is required, OM3 and OM4 fibers are the best choices.

Color & Optical Source

The outer jacket can also be a method to distinguish OM1, OM2 from OM3, OM4. The common jacket color of OM1 and OM2 is orange, and OM3, OM4 are in aqua. In addition, OM1 and OM2 are using a light-emitting diodes (LEDs) optical source but OM3 and OM4 adopt the vertical-cavity surface-emitting laser (VCSELs) optical source.

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color and optical source of OM1, OM2, OM3 and OM4

Application

OM1 fibers and OM2 fibers are widely employed for short-haul networks, local area networks (LANs) and private networks. OM3 is applied to a larger private networks. Different from the previous multimode types, OM4 is more advanced to be used for high-speed networks in data centers, financial centers and corporate campuses.

Conclusion

It is very important to choose the right fiber type for your application. Future-proofing network design is crucial for network planning, but there is often a cost for that speed. With a higher performance, OM3 fibers and OM4 fibers are definitely more expensive than OM1 and OM2 fibers . So plan well and spend wisely.

Singlemode fiber and multimode fiber different and selection method(1)

1.What is singlemode and multimode fiber? What is the difference between them?

The concept of single-mode and multi-mode is to classify fibers according to the propagation mode—the concept of multi-mode fiber and single-mode fiber propagation mode. We know that light is an extremely high-frequency (3×1014Hz) electromagnetic wave. When it propagates in an optical fiber, it is found from theories of wave optics, electromagnetic fields, and Maxwell equations.

When the fiber core has a geometric dimension much larger than the wavelength of the light, the light will propagate in the fiber in dozens or even hundreds of propagation modes, such as TMmn mode, TEmn mode, HEmn mode, etc. (where m, n=0, 1, 2, 3, …).

Among them, the HE11 mode is called the basic mode, and the rest are all called high-order modes.

Multimode fiber

When the fiber’s geometric size (mainly the core diameter d1) is far greater than the wavelength of light (about 1μm), there will be dozens or even hundreds of propagation modes in the fiber. Different propagation modes have different propagation speeds and phases, resulting in delays and widening light pulses after long-distance transmission. This phenomenon is called the modal dispersion of the fiber (also called inter-modal dispersion).

Mode dispersion can narrow the bandwidth of multimode fiber and reduce its transmission capacity. Therefore, multimode fiber is only suitable for smaller-capacity fiber communication.

The refractive index distribution of a multimode fiber is mostly a parabolic distribution, ie, a graded index profile. Its core diameter is about 50μm.

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Single Mode Fiber

When the fiber’s geometry (mainly the core diameter) can be similar to the wavelength of light, if the core diameter d1 is in the range of 5~10μm, the fiber only allows one mode (base mode HE11) to propagate in it, and all other high-order modes are all cut off. This kind of fiber is called single-mode fiber.
Since it only has one mode to propagate and avoids the problem of mode dispersion, single-mode fiber has a very wide bandwidth and is particularly suitable for large-capacity optical fiber communications. Therefore, in order to achieve single-mode transmission, the parameters of the fiber must satisfy certain conditions. Through formulae calculations, for a fiber with NA=0.12, single-mode transmission above λ=1.3 μm, the radius of the fiber core should be ≤ 4.2 μm, ie its core diameter d1 ≤ 8.4 μm.
Because the core diameter of a singlemode fiber is very small, more stringent requirements are imposed on its manufacturing process.

2.What are the advantages of using optical fiber?

1) The passband of the fiber is very wide and the theory can reach 30T.
2) The length of non-relay support is up to tens to hundreds of kilometers, and the copper wire is only a few hundred meters.
3) Not affected by electromagnetic fields and electromagnetic radiation.
4) Light weight and small size.
5) Optical fiber communication is not powered, and the use of safety can be used in flammable, volatile and other places.
6) The use of a wide range of ambient temperatures.
7) Long service life.

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3.how to choose the optical cable?

In addition to selecting the number of optical fiber cores and optical fibers, the optical cable must be selected according to the use environment of the optical cable to select the structure of the optical cable and the outer sheath.

1) Optical cable for outdoor use When loosely buried, it is better to use loose-sheathed cable. When overhead, a loose PE cable with a black PE sheath with two or more ribs can be used.
2) Optical fiber cables used in buildings should use tight-fitting optical cables and pay attention to their fire-retardant, toxic and smoke characteristics. The type of flame-retardant but smoke (Plenum) or flammable and non-toxic type (LSZH) can be used in the pipeline or in forced ventilation. The type of flame-retardant, non-toxic and non-smoking (Riser) should be used in the exposed environment.
3) When vertical or horizontal cabling is installed in a building, it can be used when using tight-fit optical cable, distribution optical cable or branch optical cable that are common in the building.
4) Select single-mode and multi-mode optical cables based on network applications and optical cable application parameters. Usually, indoor and short-distance applications use multimode optical cables, while outdoor and long-distance applications use single-mode optical cables.

4.In the connection of optical fibers, how to choose different applications of fixed connection and active connection?

The active connection of the fiber is achieved through a fiber optic connector. An active connection point in the optical link is a clear split interface. In the choice of active connection and fixed connection, the advantages of fixed connection are reflected in lower cost, light loss, but less flexibility, and the active connection is the opposite. When designing the network, it is necessary to flexibly select the use of activities and fixed connections according to the entire link situation to ensure flexibility and stability, so as to give full play to their respective advantages. The active connection interface is an important test, maintenance, and change interface. The active connection is relatively easy to find the fault point in the link than the fixed connection, which increases the convenience of replacement of the faulty device, thereby improving system maintenance and reducing maintenance costs.

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5.Fibers are getting closer to user terminals. What do you need to pay attention to when it comes to the meaning of “fiber to the desktop” and system design?

“Fiber-to-the-desktop” in the application of the horizontal subsystem, and the relationship between copper and copper cable is complementary and indispensable. Optical fiber has its unique advantages, such as long transmission distance, stable transmission, free from electromagnetic interference, high support bandwidth, and no electromagnetic leakage. These characteristics make the optical fiber play an irreplaceable role in some specific environments:
1) If the information point transmission distance is greater than 100m, if you choose to use copper cable. Replicators must be added or network equipment and weak rooms must be added to increase costs and hidden troubles. Using fiber can easily solve this problem.
2) There are a large number of sources of electromagnetic interference in specific work environments (such as factories, hospitals, air-conditioning rooms, power equipment rooms, etc.), and optical fibers can be operated stably without electromagnetic interference in these environments.
3) There is no electromagnetic leakage in the fiber. It is very difficult to detect the signal transmitted in the fiber. It is a good choice for places where the security level is relatively high (such as military, R&D, auditing, government, etc.).
4) The environment with high demand for bandwidth has reached more than 1G. Optical fiber is a good choice.

There are many differences between single-mode fiber and multi-mode fiber, and the selection method is not the same. Let’s talk about it today. For more details, please keep an eye on Singlemode fiber and multimode fiber different and selection method(2).