Tag Archives: Multimode Fiber

40G Deployment: The Cost Difference Between SMF and MMF

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40G network are now being extensively adopted within LANs and data centers. 100G is still predominantly in the carrier network, but could soon extend its stretch to your local network. There exists much confusion as to whether to choose single-mode fiber (SMF) or multimode fiber (MMF) for deploying 40G bandwidth, and how to get fully prepared for scaling to higher-speed 100G. If you are hesitating to make the choice, you may find this article helpful.

40G Cost: Difference Between SMF and MMF

Multimode Fiber (MMF): Cost-effective With Higher Tolerance to Dirt

Cost-effectiveness: Multimode fiber (MMF) has been evolving to handle the escalating speed: OM3 has been superseded by OM4 and OM5 is there ready to use. MMF has a wider array of short distance transceivers that are easier to get. One of the liable argument that in favor of using MMF is that multimode optics use less power than single-mode ones, but only in condition that you have tens of thousands of racks. In essence, MMF still has its position under certain circumstances, like cabling within the same rack, in Fiber Channel and for backbone cabling in some new construction buildings.

smf mmf

Tolerance to Dirt: Multimode fiber tends to have a lot more tolerance to dirty connections than single-mode fiber. It can handle very dirty couples or connectors to ensure reliable and consistent link performance. Besides, it is easy to terminate, and more accommodating bend radius. So MMF is preferred by links that change frequently or are less than permanent.

smf mmf

Single-mode Fiber (SMF): Higher Capability and Better Future-proofing

Speed capability: Capacities are really vital for network growth. SMF does so with relatively larger capability than that of MMF. The gap between SMF and MMF cabling is much wider for high-density, high-speed networks. If you want to go further with SMF, say scaling to 100G or beyond, you simply need to upgrade the optics. Unlike using MMF, in which you have to upgrade the glass (OM3 to OM4 to OM5), the labor cost concerning this cannot be underestimated. The capacity for scaling of SMF alone makes it worth the cost. You can use single-mode for almost everything, no need for media conversion. SMF offers enough bandwidth to last a long time, making it possible to upgrade 100 Gbps to Tbps with CWDM/DWDM.

smf mmf

Future proofing: Despite the fact that SM optical transceivers usually cost higher than MM optics, SMF cabling is cheaper and can support much longer distance and reliable performance. Not to mention that bandwidth on SMF keeps going up and up on the same old glass. The good news is that the cost of SMF is dropping in recent years, and it is redesigning to run with less power, thus advocators of SMF think that it is pretty much the only rational choice for infrastructure cabling and the sure winner for today and tomorrow.

SMF and MMF: A Simple Comparison of Cost

There is no doubt that SMF is a better investment in the long run, but MMF still has a long way to go in data center interconnections. In fact the price difference of SMF optics and MMF optics can be minimized if you choose the right solution. Assuming to connect two 40G devices at 70 m away, let’s see the cost of SMF and MMF in the following chart.

Module Connector Type SMF or MMF Price 2 Connections 4 Connections 6 Connections
40GBASE-SR4 MPO12 MMF, OM4 $49.00 $564.48 $1128.96 $1693.44
40GBASE-BiDi LC MMF, OM4 $300.00 $1534.24 $2734.24 $3934.24
40GBASE-LR4 LC SMF, OS2 $340.00 $1,609.84 $2,969.84 $4,329.84
80 Gbit 160 Gbit 240 Gbit

 

Conclusion

Choosing the right fiber for your network application is a critical decision. Understanding your system requirements in order to select the appropriate fiber will maximize the value and performance of your cabling system. Be sure to select the right cable on the basis of aspects including link length, performance, and of course costs. FS provides a broad range of 40G optical transceivers and fiber patch cables with superior quality and fair price. For more details, please visit www.fs.com.

Common Mistakes in Fiber Optic Network Installation

When install a fiber optic network, people may make some common mistakes, which were usually overlooked. In this article, I will list the most common ones. Hope to give you some guidance for your optical network installation.

1. Single Strand Fiber Device Must Be Used in Pairs

You will never buy two left shoes, but people often make a similar mistake when they’re working with Single Strand Fiber (SSF). Single strand fiber technology allows for the use of two independent wavelengths, such as 1310 and 1550 nm, on the same piece of cable. The most common single strand fiber device is Bi-Directional (BiDi) transceiver. Two BiDi transceiver must be matched correctly. One unit must be a 1310nm-TX/1550nm-RX transceiver (transmitting at 1310 nm, receiving at 1550 nm) and the other must be a 1550nm-TX/1310nm-RX transceiver (transmitting at 1550 nm, receiving at 1310 nm). The 1550nm-TX/1310nm-RX transceiver is more expensive than the 1310nm-TX/1550nm-RX transceiver, due to the cost of their more powerful lasers. So network engineers may hope to save money by installing a pair of 1310nm-TX/1550nm-RX transceivers. But, like mismatched shoes, it doesn’t work.

single-strand-fiber

2. Don’t Use Single-Mode Fiber over Multimode Fiber

Some people may want to make use of legacy cabling or equipment from an older fiber installation to save cost. But keep in mind that single-mode and multimode fiber are usually incompatible. Multimode fiber uses cable with a relatively large core size, typically 62.5 microns (om2, om3 and om4), and 50 microns (om1) still used in some installations. The larger core size simplifies connections and allows for the use of less powerful, less expensive light sources.  But the light therefore tends to bounce around inside the core, which increases the modal dispersion. That limits multimode’s useful range to about 2 km. Single-mode fiber combines powerful lasers and cabling with a narrow core size of 9/125 microns to keep the light focused.  It has a range of up to 120 km, but it is also more expensive. If you tried to use single-mode fiber over a multimode fiber run.  The core size of the fiber cable would be far too large.  You’d get dropped packets and CRC errors.

single-mode-multimode-fiber

3. Understand All kinds of Fiber connectors First

Fiber optic transceivers use a variety of connectors, so make clear their differences before you begin ordering products for a fiber installation is necessary. SC (stick and click) is a square connector. ST (stick and twist) is a round, bayonet-type. LC, or the “Lucent Connector”, was developed by Lucent Technologies to address complaints that ST and SC were too bulky and too easy to dislodge. LC connectors look like a compact version of the SC connector. SFP (small form‐factor pluggable) transceivers usually use LC connector.  Less common connectors include MT-RJ and E2000.

st-lc-sc

4.Connector Links and Splice Times Also Affect 

Although single-mode fiber suffers from less signal loss per km than multimode, all fiber performance is affected by connectors and splices. The signal loss at a single connector or splice may seem insignificant. But as connectors and splices become more numerous signal loss will steadily increase. Typical loss factors would include 0.75 dB per connector, 1 dB per splice, 0.4 dB attenuation per km for single-mode fiber and 3.5 dB attenuation per km for multimode fiber.  Add a 3 dB margin for safety. The more splices and connectors you have in a segment, the greater the loss on the line.

5. Don’t Use APC connector with UPC Connector

Fiber connections may use Angle Polished Connectors (APC) or Ultra Polished Connectors (UPC), and they are not interchangeable. There are physical differences in the ferules at the end of the terminated fiber within the cable (shown in the figure below).  An APC ferrule end-face is polished at an 8° angle, while the UPC is polished at a 0° angle. If the angles are different, some of the light will fail to propagate, becoming connector or splice loss. UPC connectors are common in Ethernet network equipment like media converters, serial devices and fiber‐based switches. APC connectors are typical for FTTX and PON connections.  ISPs are increasingly using APC.

apc-upc-connector

6. Don’t Connect SFP to SFP+ Transceivers

Small Form Pluggable (SFP) transceivers are more expensive than fixed transceivers.  But they are hot swappable and their small form factor gives them additional flexibility. They’ll work with cages designed for any fiber type and their prices are steadily dropping.  So they have become very popular. Standard SFPs typically support speeds of 100 Mbps or 1 Gbps. XFP and SFP+ support 10 Gbps connections. SFP+ is smaller than XFP and allows for greater port density.  Though the size of SFP and SFP+ is the same, you can’t connect SFP+ to a device (SFP) that only supports 1 Gbps.

SMF or MMF? Which Is the Right Choice for Data Center Cabling?

Selecting the right cabling plant for data center connectivity is critically important. The wrong decision could leave a data center incapable of supporting future growth, requiring an extremely costly cable plant upgrade to move to higher speeds. In the past, due to high cost of single-mode fiber (SMF), multimode fiber (MMF) has been widely and successfully deployed in data center for many years. However, as technologies have evolved, the difference in price between SMF and MMF transceivers has been largely negated. With cost no longer the dominant decision criterion, operators can make architectural decisions based on performance. Under these circumstances, should we choose SMF or MMF? This article may give you some advice.

MMF Can’t Reach the High Bandwidth-Distance Needs
MMF datacenterBased on fiber construction MMF has different classifications types that are used to determine what optical signal rates are supported over what distances. Many data center operators who deployed MMF OM1/OM2 fiber a few years ago are now realizing that the older MMF does not support higher transmit rates like 40GbE and 100GbE. As a result, some MMF users have been forced to add later-generation OM3 and OM4 fiber to support standards-based 40GbE and 100GbE interfaces. However, MMF’s physical limitations mean that as data traffic grows and interconnectivity speeds increase, the distance between connections must decrease. The only alternative in an MMF world is to deploy more fibers in parallel to support more traffic. Therefore, while MMF cabling has been widely and successfully deployed for generations, its limitations now become even more serious. Operators must weigh unexpected cabling costs against a network incapable of supporting new services.

SMF Maybe a Viable Alternative
Previously, organizations were reluctant to implement SMF inside the data center due to the cost of the pluggable optics required, especially compared to MMF. However, newer silicon technologies and manufacturing innovations are driving down the cost of SMF pluggable optics. Transceivers with Fabry-Perot edge emitting lasers (single-mode) are now comparable in price and power dissipation to VCSEL (multimode) transceivers. Besides, Where MMF cable plants introduce a capacity-reach tradeoff, SMF eliminates network bandwidth constraints. This allows operators to take advantage of higher-bit-rate interfaces and wave division multiplexing (WDM) technology to increase by three orders of magnitude the amount of traffic that the fiber plant can support over longer distances. All these factors make SMF a more viable option for high-speed deployments in data centers.

SMF datacenter

Comparison Between SMF and MMF
10GbE has become the predominant interconnectivity interface in large data centers, with 40GbE and 100GbE playing roles in some high-bandwidth applications. Put simply, the necessity for fiber cabling that supports higher bit rates over extended distances is here today. With that in mind, the most significant difference between SMF and MMF is that SMF provides a higher spectral efficiency than MMF, which means it supports more traffic over a single fiber using more channels at higher speeds. This is in stark contrast to MMF, where cabling support for higher bit rates is limited by its large core size. This effectively limits the distance higher speed signals can travel over MMF fiber. In fact, in most cases, currently deployed MMF cabling is unable to support higher speeds over the same distance as lower-speed signals.

Name Interface FP (SMF) VCSEL (MMF)
Link Budget (dB)
4 to 6 2
Reach (in meters) (Higher value is better)
10GbE 1300 300
40GbE 1300 150
100GbE 1300 <100

Conclusion
As operators consider their cabling options, the tradeoff between capacity and reach is important. Network operators must assess the extent to which they believe their data centers are going to grow. For environments where users, applications, and corresponding workload are all increasing, single-mode fiber offers the best future proofing for performance and scalability. And because of fundamental changes in how transceivers are manufactured, those benefits can be attained at prices comparable to SMF’s lower performing alternative.

Source:http://www.fs.com/blog/smf-or-mmf-which-is-the-right-choice-for-data-center-cabling.html

WBMMF – Next Generation Duplex Multimode Fiber in the Data Center

Enterprise data center and cloud operators use multimode fiber for most of their deployments because it offers the lowest cost means of transporting high data rates for distances aligned with the needs of these environments. The connections typically run at 10G over a duplex multimode fiber pair—one transmit (Tx) fiber and one receive (Rx) fiber. Upgrading to 40G and 100G using MMF has traditionally required the use of parallel ribbons of fiber. While parallel transmission is simple and effective, continuation of this trend drives higher cost into the cabling system. However, a new generation of multimode fiber called WBMMF (wideband multimode fiber) is on the way, which can enable transmission of 40G or 100G over a single pair of fibers rather than the four or ten pairs used today. Now, let’s get close to WBMMF.

What Is Wideband Multimode Fiber?
WBMMF is a new multimode fiber type under development that will extend the ability of conventional OM4 multimode fiber to support multiple wavelengths. Unlike traditional multimode fiber, which supports transmission at the single wavelength of 850 nm, WBMMF will support traffic over a range of wavelengths from 850 to 950 nm. This capability will enable multiple lanes of traffic over the same strand of fiber to transmit 40G and 100G over a single pair of fibers and to drastically increase the capacity of parallel-fiber infrastructure, opening the door to 4-pair 400GE and terabit applications. Multimode fiber continues to provide the most cost-effective platform for high bandwidth connectivity in the data center, and with the launch of the WBMMF solution, that platform has been extended to support higher speeds with fewer fibers and at greater distances.

Wideband Multimode Fiber

What Is the Technology Behind WBMMF?
WBMMF uses short wavelength division multiplexing (SWDM) to significantly increase its transmission capacity by four times. WDM technology is well known for its use in single-mode transmission, but has only recently been adapted for use with vertical cavity surface-emitting lasers (VCSELs), which have been proven in high-speed optical communications and are widely deployed in 10G interconnection applications. SWDM multiplexes different wavelengths onto duplex MMF utilizing WDM VCSEL technology. By simultaneously transmitting four VCSELs, each operating at a slightly different wavelength, a single pair WBMMF can reliably transfer 40G (4x10G) or 100G (4x25G). The use of SWDM then enables WBMMF to maintain the cost advantage of multimode fiber systems over single-mode fiber in short links and greatly increases the total link capacity in a multimode fiber link.

SWDM WBMMF

Why Does WBMMF Make Sense?
In order to increase transmission speeds up to 10G or 25G, transceiver vendors simply increased the speed of their devices. When 40G and 100G standards were developed, transmission schemes that used parallel fibers were introduced. This increase in fiber count provided a simple solution to limitations of the technology available at the time. It was accepted in the industry and allowed multimode links to maintain a low cost advantage. However, the fiber count increase was not without issues. At some point, simply increasing the number of fibers for each new speed became unreasonable, in part because the cable management of parallel fiber solutions, combined with the increasing number of links in a data center, becomes very challenging. Please see the picture below. Usually, 40G is implemented using eight of the twelve fibers in an MPO connector. Four of these eight fibers are used to transmit while the other four are used to receive. Each Tx/Rx pair is operating at 10G. But if we use WDMMF, two fibers are enough. Each Tx/Rx pair can transmit 40G by simultaneously transmitting four different wavelengths. This enables at least a four-fold reduction in the number of fibers for a given data rate, which provides a cost-effective cabling solution for data center.

Parallel fibers vs WBMMF

Conclusion
WBMMF is born at the right moment to meet the challenges associated with escalating data rates and the ongoing need to build cost-effective infrastructure. Besides, WBMMF will support existing OM4 applications to the same link distance. Optimized to support wavelengths in the 850 nm to 950 nm range to take advantage of SWDM, WBMMF ensures not only more efficient support for future applications to useful distances, but also complete compatibility with legacy applications, making it an ideal universal medium that supports not only the applications of the present, but also those of the future.

Original article source: http://www.fs.com/blog/wbmmf-next-generation-duplex-multimode-fiber-in-the-data-center.html

Understanding Wavelengths in Fiber Optics

The light we are most familiar with is surely the light we can see. Our eyes are sensitive to light whose wavelength is in the range of about 400 nm to 700 nm, from the violet to the red. But for fiber optics with glass fibers, we use light in the infrared region which has wavelengths longer than visible light. Because the attenuation of the fiber is less at longer wavelengths. This text may mainly tell you what the common wavelengths used in fiber optics are and why they are used.

wavelength-nm

Wavelengths Definition

In fact, light is defined by its wavelength. It is a member of the frequency spectrum, and each frequency (sometimes also called color) of light has a wavelength associated with it. Wavelength and frequency are related. Generally, the radiation of shorter wavelengths are identified by their wavelengths, while the longer wavelengths are identified by their frequency.

Common Wavelengths in Fiber Optics

Wavelengths typically range from 800 nm to 1600 nm, but by far the most common wavelengths actually used in fiber optics are 850 nm, 1300 nm, and 1550 nm. Multimode fiber is designed to operate at 850 nm and 1300 nm, while single-mode fiber is optimized for 1310 nm and 1550 nm. The difference between 1300 nm and 1310 nm is simply a matter of convention. Both lasers and LEDs are used to transmit light through optical fiber. Lasers are usually used for 1310nm or 1550nm single-mode applications. LEDs are used for 850nm or 1300nm multimode applications.

wavelength-nm

Why Those Common Wavelengths?

As mentioned above, the most common wavelengths used in fiber optics are 850 nm, 1300 nm and 1550 nm. But why do we use these three wavelengths? Because the attenuation of the fiber is much less at those wavelengths. Therefore, they best match the transmission properties of available light sources with the transmission qualities of optical fiber. The attenuation of glass optical fiber is caused by two factors: absorption and scattering. Absorption occurs in several specific wavelengths called water bands due to the absorption by minute amounts of water vapor in the glass. Scattering is caused by light bouncing off atoms or molecules in the glass.

It is strongly a function of wavelength, with longer wavelengths having much lower scattering. From the chart below, we can obviously see that there are three low-lying areas of absorption, and an ever-decreasing amount of scattering as wavelengths increase. As you can see, all three popular wavelengths have almost zero absorption.

wavelength-nm

Conclusion

After reading this passage, you may know some basic knowledge of wavelengths in fiber optics. Since the attenuation of the wavelengths at 850 nm, 1300 nm, and 1550 nm are relatively less, they are the most three common wavelengths used in fiber optic communication. Fiberstore offer all kinds multimode and single-mode fiber optic transceivers which operate on 850 nm and 1310 nm respectively very well. For more information, please visit fs.com.

Related Article: From O to L: the Evolution of Optical Wavelength Bands

Do You Know About Mode Conditioning Patch Cord?

The great demand for increased bandwidth has prompted the release of the 802.3z standard (IEEE) for Gigabit Ethernet over optical fiber. As we all know, 1000BASE-LX transceiver modules can only operate on single-mode fibers. However, this may pose a problem if an existing fiber network utilizes multimode fibers. When a single-mode fiber is launched into a multimode fiber, a phenomenon known as Differential Mode Delay (DMD) will appear. This effect can cause multiple signals to be generated which may confuse the receiver and produce errors. To solve this problem, a mode conditioning patch cord is needed. In this article, some knowledge of mode conditioning patch cords will be introduced.

What Is a Mode Conditioning Patch Cord?

A mode conditioning patch cord is a duplex multimode cord that has a small length of single-mode fiber at the start of the transmission length. The basic principle behind the cord is that you launch your laser into the small section of single-mode fiber, then the other end of the single-mode fiber is coupled to multimode section of the cable with the core offset from the center of the multimode fiber (see diagram below).

mode conditioning patch cord

This offset point creates a launch that is similar to typical multimode LED launches. By using an offset between the single-mode fiber and the multimode fiber, mode conditioning patch cords eliminate DMD and the resulting multiple signals allowing use of 1000BASE-LX over existing multimode fiber cable systems. Therefore, these mode conditioning patch cords allow customers an upgrade of their hardware technology without the costly upgrade of their fiber plant.

Some Tips When Using Mode Conditioning Patch Cord

After learning about some knowledge of mode conditioning patch cords, but do you know how to use it? Then some tips when using mode conditioning cables will be presented.

    • Mode conditioning patch cords are usually used in pairs. Which means that you will need a mode conditioning patch cord at each end to connect the equipment to the cable plant. So these patch cords are usually ordered in numbers. You may see someone only order one patch cord, then it is usually because they keep it as a spare.
    • If your 1000BASE-LX transceiver module is equipped with SC or LC connectors, please be sure to connect the yellow leg (single-mode) of the cable to the transmit side, and the orange leg (multimode) to the receive side of the equipment. The swap of transmit and receive can only be done at the cable plant side. See diagram below.

mode conditioning patch cord

  • Mode conditioning patch cords can only convert single-mode to multimode. If you want to convert multimode to single-mode, then a media converter will be required.
  • Besides, mode conditioning patch cables are used in the 1300nm or 1310nm optical wavelength window, and should not be used for 850nm short wavelength window such as 1000Base-SX.

Conclusion

From the text, we know that mode conditioning patch cords really significantly improve the data signal quality and increase the transmission distance. But when using it, there are also some tips must be kept in mind. Fiberstore offer mode conditioning patch cords in all varieties and combinations of SC, ST, MT-RJ and LC fiber optic connectors. All of the Fiberstore’s mode conditioning patch cords are at high quality and low price. For more information, please visit fs.com.

What are OM1, OM2, OM3 and OM4?

There are different types of fiber optic cable. Some types are single-mode, and some types are multi-mode. Multi-mode fibers are described by their core and cladding diameters. Usually the diameter of the multi-mode fiber is either 50/125 µm or 62.5/125 µm. At present, there are four kinds of multi-mode fibers: OM1, OM2, OM3 and OM4. The letters “OM” stand for optical multi-mode. Each type of them has different characteristics.

Standard

Each “OM” has a minimum Modal Bandwidth (MBW) requirement. OM1, OM2, and OM3 are determined by the ISO 11801 standard, which is based on the modal bandwidth of the multi-mode fiber. In August of 2009, TIA/EIA approved and released 492AAAD, which defines the performance criteria for OM4. While they developed the original “OM” designations, IEC has not yet released an approved equivalent standard that will eventually be documented as fiber type A1a.3 in IEC 60793-2-10.

Specifications

  • OM1 cable typically comes with an orange jacket and has a core size of 62.5 micrometers (µm). It can support 10 Gigabit Ethernet at lengths up 33 meters. It is most commonly used for 100 Megabit Ethernet applications.
  • OM2 also has a suggested jacket color of orange. Its core size is 50µm instead of 62.5µm. It supports 10 Gigabit Ethernet at lengths up to 82 meters but is more commonly used for 1 Gigabit Ethernet applications.
  • OM3 has a suggested jacket color of aqua. Like OM2, its core size is 50µm. OM3 supports 10 Gigabit Ethernet at lengths up to 300 meters. Besides OM3 is able to support 40 Gigabit and 100 Gigabit Ethernet up to 100 meters. 10 Gigabit Ethernet is its most common use.
  • OM4 also has a suggested jacket color of aqua. It is a further improvement to OM3. It also uses a 50µm core but it supports 10 Gigabit Ethernet at lengths up 550 meters and it supports 100 Gigabit Ethernet at lengths up to 150 meters.

OM1, OM2, OM3 and OM4 multi-mode fiber

Differences

There are several differences between four kinds of multi-mode fiber, and we can see them clearly from the table below:
OM1, OM2, OM3 and OM4 multi-mode fiber

  • Diameter: The core diameter of OM1 is 62.5 µm , however, core diameter of the OM2, OM3 and OM4 is 50 µm.
  • Jacket Color: OM1 and OM2 MMF are generally defined by an orange jacket. OM3 and OM4 are usually defined with an aqua jacket.
  • Optical Source: OM1 and OM2 commonly use LED light source. However, OM3 and OM4 usually use 850 nm VCSELs.
  • Bandwidth: At 850 nm the minimal modal bandwidth of OM1 is 200MHz*km, of OM2 is 500MHz*km, of OM3 is 2000MHz*km, of OM4 is 4700MHz*km.

OM3&OM4 are Superior to OM1&OM2

10G OM3Both OM1 and OM2 work with LED based equipment that can send hundreds of modes of light down the cable, while OM3 and OM4 are optimized for laser (eg. VCSEL) based equipment that uses fewer modes of light. LEDs can not be turned on/off fast enough to support higher bandwidth applications, while VCSELs are capable of modulation over 10 Gbit/s and are used in many high speed networks. For this reason, OM3 and OM4 are the only multi-mode fibers included in the 40G and 100G Ethernet standard. Now OM1 and OM2 are usually used for 1G which are not suitable for today’s higher-speed networks. OM3 and OM4 are used for 10G mostly at present. But in the future, since OM3 and OM4 can support the 40G and 100G, which may make them the tendency.

Related article: Singl-mode vs. Multimode Fiber Cable

Optical Mode Conditioners We Need to Know

Networking applications such as ATM have traditionally used different adapter cards to support multimode and single-mode fiber. Gigabit Ethernet standard (IEEE 802.3z) is the first industry standard to propose the use of both fiber types with the same adapter card.

Parallel Sysplex links were originally offered as either 50 Mbyte/s data rates over multimode fiber or 100 Mbyte/s data rates over single-mode fiber. With the announcement of more recent servers, support for multimode fiber has been withdrawn as a standard feature and is now available only on special request. There is a need to support 100Mbyte/s adapter cards over installed multimode fiber to facilitate migration of those customers who have been using the 50 Mbyte/s option.

In order to address these concerns, special fiber optic adapter cable have been developed, known as Mode Conditioning Patch Cable (MCP), This cable contains both single-mode and multimode fibers, and should be inserted on both ends of a link to interface between a single-mode adapters card and a multimode cable plant. The MCPs for parallel sysplex link, Gigabit Ethernet, Fiber Channel, and many other applications are available today.

mode conditioning fiber

Next, let us describe the technical issues associated with this approach. The bandwidth of fiber optic cables are typically measured using over-filled launch condition, which result in equal optical power being launched into all fiber modes. This is also known as a mode scramble launch, and is approximately equivalent to the conditions achieved when using Lambertian source such as an LED. By contrast, laser source being more highly collimated tend to produce an under-filled launch condition; this can result in either larger or smaller effective bandwidth relative to an overfilled launch, and is sensitive to small changes in the fiber’s refractive index profile. As discover in recent gigabit link tests, bandwidth measured using over-filled launch conditions is not always a good indication of link performance for laser applications over multimode fiber.

singlemode fiber

Because of the bandwidth limitations of multimode optical fiber, future multi-gigabit fiber optic interconnects will be based on single mode fiber cable. For this reasons, most new fiber installations include at least some single mode fiber in the cable infrastructure. However, many applications continue to use multimode fiber optic extensively; a recent survey of building premise cable installers reported that most LAN infrastructures currently installed are composed of about 90% multimode fiber. As the fiber cable plant is upgraded to support higher data rates on single-mode fiber, we must also provide a migration path that continues to reuse the installed multimode cable plant for as long as single mode fiber optic cable affects many important datacom applications:

I/O applications currently using multimode fiber for ESCON will need to migrate the cable plant to single-mode fiber in order to take full advantage of the higher bandwidth of FICON links. Future FICON enhancements that extend this protocol to multi-gigabit data rates will also require single-mode fiber.

Networking applications such as ATM have traditionally used different adapter cards to support multimode and single-mode fiber. Gigabit Ethernet standard (IEEE 802.3z) is the first industry standard to propose the use of both fiber types with the same adapter card.

Parallel Sysplex links were originally offered as either 50 Mbyte/s data rates over multimode fiber or 100 Mbyte/s data rates over single-mode fiber. With the announcement of more recent servers, support for multimode fiber has been withdrawn as a standard feature and is now available only on special request. There is a need to support 100Mbyte/s adapter cards over installed multimode fiber to facilitate migration of those customers who have been using the 50 Mbyte/s option.

In order to address these concerns, special fiber optic adapter cable have been developed, known as mode conditioning patch cable (MCP), This cable contains both single-mode and multimode fibers, and should be inserted on both ends of a link to interface between a single-mode adapters card and a multimode cable plant. The MCPs for parallel sysplex link, Gigabit Ethernet, Fiber Channel, and many other applications are available today.

The bandwidth of Fiber Patch Cables are typically measured using over-filled launch condition, which result in equal optical power being launched into all fiber modes. This is also known as a mode scramble launch, and is approximately equivalent to the conditions achieved when using Lambertian source such as an LED. By contrast, laser source being more highly collimated tend to produce an under-filled launch condition; this can result in either larger or smaller effective bandwidth relative to an overfilled launch, and is sensitive to small changes in the fiber’s refractive index profile. As discover in recent gigabit link tests, bandwidth measured using over-filled launch conditions is not always a good indication of link performance for laser applications over multimode fiber. when a fast rise time laser pulse is applied to multimode fiber, significant pulse broadening occurs due to the difference in propagation times of different modes within the fiber. This pulse broadening is known as differential mode delay and mode-specific attenuation in the fiber, and the launch conditions of the test. DWD is made worse by the excitation of relatively few modes groups and a high percentage of modal power concentrated in lower order modes. The impact of DWD increase with link length. There is, unfortunately, not a simple relationship between the industry specified over-fill launch measured bandwidths of the fiber and the effective bandwidth due to DWD.

The radial overfill launch method was developed as a way to establish consistent and repeatable modal bandwidth measurement of a given fiber couple with a given source. A radial over-fill launch is obtained when a laser spot is projected onto the core of the multimode fiber, symmetric about the core center with the optic axis of the source and fiber aligned; the laser spot must be larger than the fiber core, and the laser divergence angle must be less than the fiber’s numerical aperture. When these conditions are satisfied, the worst case modal bandwidth of the link is taken to be the worse case of the over-fill and radial over-fill launch bandwidth and the DWD limited bandwidth of a fiber; thus, high speed laser links implemented over multimode fiber optic cable will likely experience bandwidth values closer to the radial over-fill launch method rather than the more commonly specified over-fill launch method.

Now I work in a fiber optic shop, if you need the fiber optic cable related products, you can directly online search the website. http://www.fs.com.

The Specific Instructions of Optical Fiber Patch Cord

Optical fiber communication refers to modulate voice, video and data signals to the optical fiber as a communication transmission medium. Optical fiber can be divide into multimode fiber and single mode fiber.

The central glass core of single-mode fiber is fine (core diameter is usually 9 or 10μm), it only can transfer one mode light. The mode dispersion is small, and it is for remote communication, but it plays a major role in the chromatic dispersion, so that the spectral width of the single mode fiber has a higher light stability and the requirement that the spectral width is narrower and better stability. 1000 Mb/s fiber optic transmission distance is 550m-100km. As we all know, we commonly see 9/125μm single mode fiber patch cable in the market. And Single-mode 9/125um Fiber Optic Patch Cables are recommended for Fast, Gigabit, 10G Ethernet or SONET OC3-OC192 rate optical connections. Low prices make the 9/125um fiber attractive for in-building projects too, because of the reliability and choice of using a single-strand of fiber for same communications (simplex cords are used on Bi-Directional data links).

The central glass core of Multimode fiber is coarse (50 or 62.5μm), multiple modes of light can pass. However, its mode dispersion is among large, which limits the frequency of the transmitted digital signal, and with the increase in distance will be more severe. Multi-mode fiber transmission distance is relatively recent, generally only a few kilometers. 1000 Mb/s fiber optic transmission distance is 220m-550m. In general, we can find 62.5/125um Multi-mode fiber optic cable in the market. 62.5/125um Multimode Fiber Cables are recommended for Fast Ethernet and up to OC3/STM1 rate optical connections. They can also be used for Gigabit Ethernet multi-mode connections on distances less than 275 meters. 62.5/125um fiber is most used inside buildings.

In the network wiring, the more applications optic fiber has three types, there are 62.5μm/125μm multimode fiber, 50μm/125μm multimode fiber, and 9μm/125μm singlemode fiber. According to the rate and transmission distance, we can distinguish and choose single/multimode optic fiber. Tied the fiber bundle, outside has the protective housing, which is called fiber cable. According to different application environments, the cable can be divided into indoor and outdoor fiber optic cable.

Fiber refers that the fiber jumper with a desktop computer or device connected directly to facilitate the connection and manage the device. Fiber jumpers are also divided into two multimode and single-mode, which are connected with single mode and multimode fiber. Jumper for an active connection cable between the two devices without connectors (as distinguished: patch (patch cord) is one or both ends with connectors; jumper is at both ends of the cable has a fiber optic connectors, the device can be directly connected, but only one end of the fiber pigtail connector and the other end to the fiber splicing).

Fiber patch cord connector shape can be divided according to: FC, SC, ST, LC, etc. According TO ferrule grinding mode, it can be divided into: PC (plane), UPC (spherical surface), APC (8 degrees inclined plane ) and other (cable optical transceiver general requirements FC / APC connector). According to type of optical fiber, it can be divided into single-mode optical fiber, 50/125 multimode, 62.5/125 multimode and Gigabit, etc. According to the optical fiber connetor, we commonly see LC, SC fiber patch cord in the market,  the following products are LC-SC Fiber in our online store, if you have interest, you can go to our store to have a see.

LC SC Fiber

Fiber patch cord products are widely applied, it applies in communications room, fiber to the home, local area networks, fiber optic sensors, fiber optic communication systems, fiber optic transmission equipment connected, defense readiness and so on. Apply to cable television, telecommunications networks, computer networks and optical fiber test equipment. Broken down mainly used in several ways.

The Progress of Multimode Fiber

In 1976, Corning developed 50/125μm by the graded-index multimode fiber and 1983 by Lucent Bell Labs developed 62.5/125μm graded-index multimode fiber, they are two larger amount of Multimode Fiber. The cladding diameter and mechanical properties of these two fibers are same, but different transmission characteristics. They can provide such as Ethernet, Token Ring and FDDI protocols specified in the standard distance required bandwidth, and it can be upgraded to Gb/s rate.

The new multimode fiber standard grades issued by ISO / IEC 11801, Multimode fiber is divided into four categories, OM1, OM2, OM3, OM4. OM1 and OM2 refer to traditional 62.5/125μm and 50/125μm multimode fiber. OM3 and OM4 refer to the new Gigabit 50/125μm multimode fiber.

62.5/125μm Graded-index Multimode fiber(OM1,OM2)

Common 62.5/125μm graded-index multimode fiber is the IEC-60793-2 fiber optic products specification Alb type. As the core diameter and a numerical aperture of 62.5/125μm fiber is greater, which has a strong anti-concentrating ability and bending characteristics, especially in the 20th century, before the mid-1990s, the lower the rate of the LAN, less demanding on the fiber bandwidth, thus making this fiber to obtain the most widely used, becomes 20 years between the mid-1980s to the mid-1990s mainstream products in most countries data communications fiber market. Belong OM1 and OM2 fiber types of Alb full power injection (OFL) bandwidth respectively 200/500MHz.km (850/1300nm) 500/500MHz.km (850/1300nm).

Now you can see the follow products about 62.5 Multimode Fiber

Duplex OM1 62.5/125 Dia2.5mm Fiber Patch Cable

SMA905- SMA905 Duplex OM1 62.5/125 Dia2.5mm Fiber Patch Cable from Fiberstore

50/125μm graded-index multimode fiber(OM1,OM2)

Common 50/125μm OM2 Fiber graded-index multimode fiber is the IEC-60793-2 fiber optic products specification Ala.1 type. Historically, in order to reduce as much as possible the cost of the LAN system, widely used inexpensive LED as the light source, rather than expensive LD. Since the LED output power is low, the divergence angle is much larger than LD, while the core diameter and a numerical aperture of 50/125μm multimode fiber are relatively small, is not conducive to efficient coupling with the LED, as large core diameter and numerical aperture of 62.5/125μm (Alb class) fiber enables more light power coupled into the fiber link to, therefore, 50/125μm graded-index multimode fiber in the mid-90s as good as 62.5/125μm (Alb class) that is widely used fiber.

Since the 20th century, a local area network developed up to lGb / s rate, it didn’t meet the requirement 62.5/125μm OM1 Fiber bandwidth with LED light source. Compared with 62.5/125μm multimode fiber, 50/125μm multimode fiber core diameter and a numerical aperture smaller, 50/125μm gradient in the number of multi-mode fiber conduction mode refractive index of about 62.5/125μm multimode fiber conduction mode 1/2.5, thus effectively reducing the modal dispersion of a multimode optical fiber, such that the bandwidth is significantly increased production costs .50/125μm multimode optical fiber is reduced to about 1/3. So make it again been widely used. IEEE802.3z Gigabit Ethernet standard provides 50/125μm multimode and 62.5/125μm multimode fiber can be used as a transmission medium using Gigabit Ethernet. But for the new network is generally preferred 50/125μm multimode fiber. Belong OM1 and OM2 fiber types are Ala. 1 full power injection (OFL) bandwidth respectively 200/500MHz.km (850/1300nm) and 500/500MHz.km (850/1300nm)

OM3 Optical Fiber

Traditional OM1 and OM2 multimode fiber from the standard mode and design are based LED, as the operating wavelength of 850 nm, a low price VCSEL (Vertical Cavity Surface Emitting Laser) and the emergence of wide application, 850nm importance window increased. VCSEL can be lower than the price of long-wavelength lasers to improve network speed to the user. 50/125μm multimode fiber has a higher bandwidth 850nm window, low price VCSEL can support longer transmission distances for Gigabit Ethernet protocol, and the high rate support longer distances. With the improvement of network speed and size, modulation rates up to 10Gb/s short-wavelength VCSEL laser light sources become one of the high-speed network. Since the difference between the two light-emitting devices, optical fibers must transform itself to adapt to changes in light. In order to meet the needs of 10 Gb / s transfer rate, the International Organization for Standardization / International Electrotechnical Commission (ISO/IEC) and the Telecommunications Industry Alliance (TIA) joint drafting of a new generation of 50 μm core multimode fiber standard. ISO/IEC in the new multi-mode fiber grade they will develop a new generation of multi-mode fiber is zoned 0M3 category (IEC standard A1a.2)

OM4 Optical Fiber

OM4 optical fiber is optimized for the 50μm core multimode fiber, currently, the OM4 (IEC standard A1a.3) criteria is actually an upgraded version of an OM3 multimode fiber. Compared with standard OM3 OM4 fiber, fiber bandwidth indicators just do upgrade. That OM4 standards are made to improve the 850nm wavelength effective modal bandwidth (EMB) and the full bandwidth of the injection (OFL) compared to OM3 fiber.