Author: Fiber-MART.COM

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What is the Purpose of a Power Meter & Light Source?

A Power Meter & Light Source is a low cost way to certify optical fiber. These two pieces of test equipment are used to measure fiber optic light continuity, loss and lastly the actual strength of the optical signal.

Signal Loss

In fiber optics when a beam of light which carries a signal goes through the optical fiber the strength of that beam of light will diminish over distance. This means the signal strength becomes weaker. This loss of light power will affect the fiber optic network in a negative way. The loss of light power or attenuation of the optical fiber is caused by two issues, scattering and absorption of the light source. If the degradation is too great then performance of the network will be affected.

The following can be the cause of signal loss:

• Tight Bends in the Cable

• Dirty or Improperly Cleaned Connectors

• Too much Stress on the Cable During Installation

• Poorly Installed Connectors

• Improper Splicing Technique

• Poor Cable Quality

What Equipment is Needed to Conduct a Power Meter & Light Source Test?

What Training Does an Installer Need?

A Power Meter and Light Source are a pretty simple piece of test equipment to use. The actual connection of the fiber to the test equipment is fairly straightforward. If you are familiar with handling fiber optics the test is very easy. If you are new to fiber optics this test should not present any issues. A simple short video explaining the test should be all you need.

Why use an OTDR in Place of a Power Meter & Light Source?

The Power Meter and Light Source are more limited than an OTDR. A Power Meter can only measure the received optical power. The OTDR can not only tell you there is a break is in the fiber, it can also measure the distance between the test point and the break. In addition, it is able to give you reflectance for each connector. Even though the OTDR can reveal additional information, the Power Meter and Light Source are still an important piece of optical fiber test equipment and their importance should not be underestimated when testing an optical fiber network.

How Does A Power Meter & Light Source Work?

By attaching a reference cable to the light source, power can be measured at the opposite end of the fiber optic cable. The signal is sent from the light source down the fiber. These two pieces of test equipment are used to measure fiber optic light continuity, loss, and lastly the actual quality of the signal. In short, it measures the power of the optical signal that has passed through the fiber cable from the light source.

Steps to Using a Power Meter and Light Source

Using the Power Meter & Light Source to test a fiber optic cable is relatively easy.

• First take the reference cord end face and clean it with 99% reagent grade isopropyl alcohol and lint free fiber optic wipes.

• Next plug the reference cord into the light source and select the wavelength you are testing. When testing a multimode cord attach a mandrel wrap to strip out the higher modes of light that can interfere with the test results. A mandrel wrap is not necessary for singlemode.

• Clean the other end of the reference cord and insert that end into the Power Meter. Now zero out the reference cord by hitting the “zero” button. After zeroing out, do not unplug the reference cord from the Light Source. Take the cord to be tested and clean one end, then attach the connector adapter. Clean the other end of the patch cord.

• Remove the reference cord from the power meter and attach to the test cord adapter, insert the other end of the test cord into the power meter. The reading on the power meter will give you the loss on the connector mated to the reference cord only. To get the loss reading on the other end simply unplug the test cord from the reference cord and switch the connectors. You have now completed the one cord reference test.

• For a two cord reference test attach a connector adapter to the reference cord and insert the other end to the power meter. Zero out the power meter. You are now ready to get a loss reading for the entire cord being tested.

• Take the test cord and clean both ends with the cleaning alcohol and wipes. Connect the test cord in between the two reference cords. The power meter will show a full cord reading for total power loss. Record your loss as needed.

What to Look for when Purchasing a Power Meter and Light Source

The Power Meter and Light Source or Optical Loss Test Set are must have tools for the fiber installer. While they are fairly simple tools to operate, care should be taken in choosing the Power Meter and Light Source as there are many models to choose from.

• Is the equipment easy to use or does it require a huge manual?

• Operation of this piece of equipment should almost be intuitive.

• Appearance is important. Is it easy to hold?

• There should be a minimal amount of buttons on the unit.

• Are screens easy to read? Is it backlit?

• Is the Power Meter and Light source calibrated?

• Does the manufacturer calibrate?

• Can they provide a calibration certificate traceable to NIST standards?

• Does the unit come with a protective carry case?

• What about battery life?

• Are adapter caps included?

• Does the kit include a dual wavelength multimode or single mode light source?

• Does it come with interchangeable adapters allow flexibility with reference cords? As with any fiber optic test equipment, know the manufacturer. Find a reputable company that will stand behind their equipment. If you have questions about your choice, call or email the company and talk with a technical person that can help you decide which piece of test equipment best suits your needs. Remember, there are many manufacturers out there in the marketplace. Consider only those with reputable firms that have a good track record. One that can service and maintain your equipment if needed.

The Different Types of Fiber Optic Fusion Splicers?

You’ve probably heard the term fusion splicer before, but in case you haven’t – an optical fiber fusion splicer is used to “splice” or fuse two separate pieces of glass optical fibers together – whether the optical fiber type is single mode fiber or multimode fiber. The goal is to join the two pieces of bare fiber seamlessly. They are connected to each other by an electric arc. You may need to fusion splice for a variety of reasons – the fiber may have been broken or damaged, or you could be performing a termination of the fiber using a pigtail or a splice on connector (SOC), or you may need to extend the length of a fiber optic cable run to reach an end point in your long haul network. Fusion splicing ensures that the light will pass from one end of the fiber to the other without interruption, making sure there is the least amount of back reflection from the splice. Fusion splicing can be used instead of mechanical splices, and it is actually usually preferred because of its benefits, which we will talk about in the passages below.

Fusion splicing ensures optimal performance, the lowest loss, and the lowest amount of reflectance when compared to a mechanical splice. The price of fusion splicers varies depending on the type you choose, core alignment and ribbon or mass fusion splicers are more expensive than cladding alignment fusion splicers. Most standard fusion splicer features include a large color screen, built-in splice sleeve ovens, and many come with high precision cleavers when purchased as a kit. As technology progresses we are seeing Bluetooth options, fully automated processes, and Wi-Fi capabilities being developed.

Typical applications where fusion splicers are used include fiber to the home applications, applications where splice on connectors are being used, maintenance in data center locations, and in research and development facilities. When you have a fusion splicer you can do repairs on the fly, whether it is a broken fiber or a bad connector, a fusion splicer can be used to make the repair and get your system back up and running in no time. There are many manufacturers of fusion splicers in the marketplace, and each has its own perks, features, and benefits, but there are two main types of splicers that you could potentially purchase.

Core Alignment Splicer

In core alignment units, the cores of the fiber are aligned prior to the splice being performed, not the cladding of the fiber that you are trying to splice. These units work using a system of magnifiers, cameras, and motorized movable fiber holders or clamps to see the fiber. These parts will move the fiber in any way necessary to achieve the proper alignment of the cores of the fiber. After the alignment is achieved according to the parameters set in the software, it will then perform the splice. The operator of the splicer does not have to worry about manually moving the fiber to get the proper alignment.

These splices are performed in mere seconds after alignment is achieved. In the case of core alignment units, specific splice recipes or parameters can be set to achieve the specific results for your application. These attributes contribute to making core alignment splicers more expensive than cladding alignment units, but they are also what make core alignment units so easy to use.

Something to consider if you are working on or doing maintenance in older, established networks is that when you are splicing legacy fibers, core alignment splicers are preferred because the concentricity of the core within the fiber was not as consistent as it is in new fibers, and in this case, you will want to be sure the fiber cores are aligned, not just the claddings.

Ribbon Splicers

A ribbon splicer or mass fusion splicer is exactly what it sounds like; it is a splicer that is made to splice ribbon fiber together. In this case, instead of splicing a single fiber in a splicing cycle, the machine splices up to 12 fibers together, all at the same time. These units are typically more expensive than their single fiber counterparts. They use a cladding alignment system to line up the fibers prior to performing the splice. Almost all ribbon splicers can accommodate up to 12 fiber ribbons in their holders, but many can accommodate as few as 2 fibers. Specific ribbon fiber holders are used to splice fiber ribbons of various fiber counts. Ribbon splicers can splice single fibers with the proper holders, but it would not be cost effective to purchase a ribbon splicer if ribbon fiber is not something that you work with on a regular basis.

Cladding Alignment Splicers

Cladding alignment units are different than a core alignment fusion splicer as they only use a fixed V-Groove to align the fibers based on the claddings of the fibers being spliced. These types of splicers are more basic units and they lack some of the bells and whistles that are commonly seen on the core alignment units. In cladding alignment splicers, the alignment of the fibers being spliced is not as perfect as a core alignment, because this type of splicer only matches up the outer cladding of the fiber, and they move only a single axis. After the splice has been performed, the core of the fiber may be slightly offset if the core concentricity of the fibers is not on dead center. These types of splicers are preferred when cost is an issue because they are more affordable, and when higher loss rates are acceptable. These units are usually handheld and normally much smaller than the core alignment units, so if space is an issue, such as in the case of being up in a bucket truck or a tight telecom closet or handhole it may be beneficial to use a smaller cladding alignment splicer.

After each splice is performed on either a cladding or core alignment unit, the splicer will give an estimated loss reading for the splice and, it will also perform a ‘proof test’ to make sure that the tensile strength the splice is stable and that it will not break apart with any minuscule mishandling. Both of these units will splice your fiber, and get the job done. So, in conclusion, whether you are looking for the premium fusion splicer or something a little more affordable, there are many options that are on the market. It all depends on the options you are looking for and the features you need to complete your job. There are super simple units, and then there are fancy high tech units, but each fiber optic technician has his or her own set of preferences and needs.

Detail introduction for MTP and MPO Fiber Optic Connector?

MTP stands for Multifiber Termination Push-on/Pull-off. You can use the term MTP connector or MPO connector, they both indicate the same multi fiber connector style – MTP is just the trademark registered name that USConec uses for their MPO connectors. You typically see these types of connectors in the data center world, as they are commonly utilized for high density, high speed, and space saving applications. Take into consideration that you are housing multiple fibers within one single connector instead of using twelve connectors for twelve fibers. These connectors enable the fastest connection speeds and provide reliability to the user. Most MTP/MPO patch cords are manufactured in a cable assembly house and polished for optimal performance, making this an easy plug and play solution for consumers.

These connectors come standard in 8, 12, 16, 24, or 32 fiber offerings, with both Singlemode and Multimode fiber options available. Multimode MTP/MPO ferrules are typically ultra-polished and singlemode ferrules are angle polished. MTP/MPO connectors must comply with quality standards laid out in the IEC (International Electrotechnical Commission) and TIA (Telecommunications Industry Association), this means that all the connector brands must have standard features so different manufacturers’ connectors and adapters can be utilized interchangeably. These standard features include the size and dimensions of the connector, the pinholes, and other physical features, as well as color coding of the connector housings to simplify fiber type identification.

These connectors allow for the ability to utilize fast connection speeds, and superior reliability in applications that need multiple fiber connections and have limited installation space.

MTP/MPO connectors are composed of a ferrule and a connector housing. Housing kits come in a variety of colors which aid in the identification of the mode of the fiber and the quality of the ferrule, in the case of multimode connectors you will see beige, black, aqua, magenta or lime green housings and single mode housings are typically green or yellow.

MTP/MPO’s come in both single mode and multimode styles; there are differences in multimode and single mode MTP/MPO’s. For a single mode MTP/MPO, it is always an APC (angled physical contact) polish while in multimode applications it is generally an ultra physical polish (UPC).

MTP/MPO connectors are gaining popularity in the fiber world because they allow for the ability to utilize fast connection speeds, and superior reliability in applications that need multiple fiber connections and have limited installation space. Cable Options for the MTP/MPO Connectors

Ribbon Cable

Most commonly MTP/MPO connectors are terminated on 12 or 24 fiber ribbon fiber optic cable because ribbon cable already comes in a multi-fiber array. Ribbonized fiber is most commonly constructed of 12 color coded bare fibers held together in a flat form by glue or adhesive called a matrix. MTP/MPO connectors are the ideal choice for this cable construction. Ribbon cable also assures the fiber lengths are equal, delivering high speed data requirements with minimum error rates. The MTP/MPO connector can be terminated easily on this cable style, and ribbon is usually compact in size compared to other fiber cable constructions, making this a space saving solution.

Micro Distribution

Micro Distribution Cable is also an option for building MTP/MPO cables as they are a small, compact cable solution that can house high fiber counts. This cable, like ribbon cable, allows for runs in small ducts, panels, and other tight spaces.

Polarity Types

There are three main polarity types when referring to MTP/MPO’s there is Polarity A, Polarity B, and Polarity C, and also an 8 fiber option. If you are building a custom MTP patch cable you may have the option for custom configured polarities but in reality, the most common types of polarity are the 3 options listed above. Polarity refers to the configuration of the fibers within the connectors, each of these fibers corresponds to a transmit and receive fiber connecting your equipment, and if these fiber links do not match, your connection will not work properly.

Polarity is one of the most important factors when deploying an MTP patch cord; you must know what configuration is being utilized in the system in order to properly mate to the equipment. The adapters for the MTP’s will also need to correspond to the polarity of the MTP that will be mating with the adapter, all the polarities must be the same within a system.

Polarity A

Polarity A is also referred to as key up – key down polarity or Straight Through Polarity, this means that the fibers are configured with Fiber 1-Fiber 1, Fiber 2-Fiber 2, Fiber 3-Fiber 3, and Fiber 4-Fiber 4 and so on. Each 1 fiber must match the other 1 fiber in the configuration.

Polarity B

Polarity B is key up to key up configuration. In this polarity Fiber 1 is matched to Fiber 12, and Fiber 2 is matched to Fiber 11 and so on. This is also referred to as Reversed Polarity.

Polarity C

Polarity Type C is also key up to key down, but instead of the fibers going Fiber 1-Fiber 1 such as in Type A polarity, instead Fiber 1 will be matched with Fiber 2, and Fiber 3 will be matched with Fiber 4, and Fiber 5 will be matched with Fiber 6 and so on down the configuration. This polarity is also called Flipped Pairs Polarity.

12 Fiber MTP/MPO 40 Gig SR4 Pinout

An 8 fiber pinout is used for 40 Gig applications, in this configuration, only 8 of the fibers are lit up, 10G per lane (fiber) bi-directional multiplied by 8 fibers equals 40G bi-directionally, with 4 remaining unused within the connector. Commonly this configuration is Fiber 1-Fiber 12, Fiber 2-Fiber 11, Fiber 3-Fiber 10, and Fiber 4-Fiber 9 with Fibers 5, 6, 7 and 8 being dark.

MTP/MPO Adapters/Mating Sleeves

MTP/MPO adapters or mating sleeves must also be selected according to the polarity method of the system they are being installed in. So for Polarity A and C, you will need a key up to key down adapter or mating sleeve and for Polarity B you will need a key up to key up mating sleeve. It should also be known that you cannot mate two connectors of the same gender, so you cannot mate two male MPO connectors or two female connectors. Connectors are aligned within the mating sleeve by the guide pins of the male connector. You will choose the correct mating sleeve according to the system’s polarity.

MTP/MPO Gender

MTP’s come in two different genders – Male and Female. The female MTP connector does not have any pins and the male connectors have two stainless steel guide pins within the connector housing. Each connector will align with a specific adapter depending on if the connector has pins or no pins and whether or not the polarity is a key up to key up type or key up to key down type.

Recently we have seen gender and polarity changeable MTP connectors. With a small tool, you can open the housing and remove the pins if necessary based on the needs of the installation. These types of connectors are especially valuable in the field because you do not need to send the connectors or the patch cord back to the manufacturer to have the gender changed.

MTP connectors are becoming more popular as bandwidth and space are at a premium in data center solutions and other applications, and the notion of why we would use twelve connectors when you can use one single connector. MTP/MPO cords are an easy plug and play solution for any fiber technician to use.

Different Types of Fiber Optic Cleavers

If you have ever spliced optical fiber then you know what a fiber optic cleaver is. If you are new to fiber, then the mention of a cleaver may be a new concept. In simple terms, a cleaver is used to cut your fiber so you have two ends that will line up and can be welded together using a fusion splicer or they can be brought together in a mechanical splice. Fiber optic cleavers are essential tools when splicing and putting connectors on in the field. There are different brands of cleavers and they all have different looks but they all perform the same job. If you are used to a certain manufacturer and you like them, then you should stay with them. When you buy a splicer kit it usually will include a precision Fiber Optic cleaver.  When we talk about cleavers, there are several features and different types for you to consider. We will discuss these in the article below.

Different Types of Cleavers

The two main types of cleavers are field cleavers and precision cleavers. Field cleavers are also known as beaver cleavers. These cleavers are used primarily for Multimode fiber applications and they are sometimes used with quick term connectors. When using this kind of cleaver you will press the blade down on the fiber to score the glass and then bend the “tail” to break the glass fiber.

On the other hand, there are precision cleavers. These cleavers are used for fusion splicing and when terminating single mode fiber with quick term connectors. A precision cleaver makes a perfect flat cut, leaving a 90 degree cleave angle on the end of the fiber. It prepares the fiber so that it is ready to splice two pieces together. There are several different manufacturers and with that also some different features and slightly different looks. In the end, they all have the same goal of getting a fiber ready to splice or put a quick term connector on.

Steps to Follow When Cleaving

When you are using either style cleaver, field or precision, there are common steps that will need to be performed before you cleave. The first step is to remove the outer most jacket of the cable you are working on. To do this you will use a tool called strippers. Once you have removed the jacket(s) from the fiber, then you have to get the acrylate coating off of the fiber. This is a coating layer that is put on the glass which allows the fiber to be handled and put on a spool without breaking. As the acrylate coating peels off, you will see it almost curl like when scooping ice cream. This step is critical. Make sure all of this acrylate fiber coating is removed. If any of this coating is left on the fiber, when you go to cleave it, it will make it seem like the cleaver is not working properly. I have had a number of tech calls that start out with “My cleaver is not working properly; I need a new one.” The first question I ask is “Did you go back over your fiber with the 250um slot in your strippers?” Normally you hear silence at the end of the line, then they say thank you and they will call if something else is wrong. You usually do not hear back from that person. So make sure that you remove all of the acrylate coating. Once this is done then you use your alcohol or other fiber optic cleaning solution and wipes to clean off the fiber. If it is cleaned properly, you will hear it squeak while you run the wipe with alcohol over the bare fiber. Always clean the fiber before you cleave. Never clean the fiber after you cleave it because it is very likely that you will damage the end of the fiber.

Types of Precision Cleavers

Precision cleavers work in a variety of ways. There are three step cleavers that require technicians to go through three steps in order to cleave the fiber. These steps usually include closing the lid, pushing the cleaver blade to cut your fiber, and then opening the lid to remove the cleaved fiber. There are one step cleavers where all you do is push the lid down and the cleaver will do everything else, including sliding the cleaver blade and moving the piece of glass into your scrap bin. These kinds of cleavers have helped to speed up the process, and make it easier to prep your fiber for splicing.

When using a cleaver there are a couple of things that you need to pay attention to in order to maintain the cleaver. One of these maintenance tasks is the rotating of the cleaver blade. A cleaver blade has up to 16 different positions that are used and each position has a limit on how many cleaves it can perform well. Each position is good for roughly one thousand cleaves. So every thousand cleaves the blade should be rotated to a new position.

Auto Rotating Blades

Most recently there have been upgrades to cleaver technology that assist to extend the life of a blade, as well as making it easier on a tech to maintain. One of these features is an auto rotating blade. This assists in making sure that the blade is used evenly and it will help to extend the life of the blade. How it works is that every time you make a cleave on a piece of fiber the blade automatically rotates to the next position on the blade. This will help extend the life of a blade.

There are times when you will cleave on a set position and it will get worn quickly or produce bad cleaves and force you to rotate the blade before you get the thousand cleaves in the one position. By auto rotating it helps to eliminate one position getting worn down too quickly.

Another feature that has been added to some of the newer cleavers is the Wi-Fi/Bluetooth feature which allows the cleaver to “talk” to the splicer. The splicer keeps track of the cleave count. This will tell you when a blade should be changed. If a particular position is throwing bad cleaves, it keeps track to not use a certain position on the blade itself.

In conclusion, cleavers are a very important tool when working with fiber. Make sure to maintain them, and to prep your fiber correctly, and you will have a very successful job and you will save money and time.

Why Do You Need a PON Power Meter?

The requirements for testing fiber optic networks will vary depending on the specific type of network as well as the network designer’s overall test requirements. Regardless of type, there are two basic or generic pieces of Optical Test Equipment that will be used; an Optical Time Domain Reflectomer or OTDR, and a pair of optical test equipment pieces that are referred to as a Power Meter & Light Source. These tests are typically measured in “dB”. The term dB is the expression of attenuation or power loss over an optical fiber as it travels from a termination end to a point along the fiber’s path. Once an optical fiber is connected to a piece of active equipment then all tests are in dBm. The active equipment will be transmitting an actual or real optical power at a specific wavelength and referenced at 1mW.

A PON power meter is essential for field technicians installing or maintaining any type of PON network. PON Power Meters are able to simultaneously test upstream and downstream through optical fibers, at 1490nm, 1550nm, and 1310nm wavelengths, as well as estimate signals of the voice, data, and video streams.

The term PON stands for “passive optical network”. A PON is a fiber optic telecommunications network that delivers broadband to transmit data over fiber optic cables to the customer premises. Its architecture implements a point-to-point or a point-to-multipoint arrangement of nodes in a communications network. A Point-to-Multipoint network uses a single fiber to serve multiple endpoints by using unpowered or passive fiber optic splitters. A splitter is used to divide the fiber bandwidth among multiple access points. Passive optical networks are often referred to as the “last mile” between an internet service provider (ISP) and its customers.

Point-To-Point or P-T-P type optical network

A P-T-P network is a network that has two termination points and nothing in-between. As with all fiber optic networks, when it is being constructed the fibers must be terminated to allow for any tests to be performed. So one end of the network is terminated and an OTDR test is performed on each fiber to ensure that the termination and length of fiber beyond does not have any issues. That test result will be stored for future needs and noted in “dB”. If the network requires splicing then after the fibers are spliced, the OTDR again is used to ensure that the splice and added fiber length again meets requirements. The testing with the OTDR continues and is completed after the end of each fiber is terminated. At this point, another set of tests is required which is commonly referred to as an End-To-End test. This test requires the use of a light source and a power meter and again all test results are stored. The optical power meter will be set to “dB” and referenced to a light source which is typically called “Zeroing”. The units are then moved to opposing ends and the field technicians will send and receive wavelengths specified by the designer. Again this is a measurement that will be used against the designer’s overall Link Loss Budget. The P-T-P network will have its termination ends referred to as “A” and “B” and at least two unique wavelengths will be sent and received over each fiber. This is typically required to ensure that any wavelength used by a transmitter can be used between the two that are specified. The network designer will define these wavelengths as well as provide a label for these ends. The technician that is performing the tests will reference these labels in any reporting back to the designer.

Point-To-Multipoint PON type network

Now when a Point-To-Multipoint network is constructed such as a Passive Optical Network or PON many of the tests and test equipment remain the same but will require a few special features. The OTDR testing during construction remains the same, with tests performed each time a fiber is terminated or spliced. Again, this continues to the far ends of the fibers after they are terminated. Once all fibers are terminated, again they will be tested using a power meter and light source. The need for special equipment is required for the activation phase of a PON network and that’s where the similarity between a P-T-P and a P-T-Multipoint ends.

The PON network activation phase begins by connecting a power meter up to an active piece of equipment called an Optical Line Terminal or OLT and set to the appropriate wavelength and the unit is set to “dBm” and this becomes the referenced power.

NOTE: There are several generations of PON network OLTs which use different wavelengths so the optical power meter must have the capability to be set to those wavelengths. GPON is 1490nm, XGPON is 1577nm and NGPON has multiple wavelengths ranging from 1596nm to 1602nm.

As the links are connected out to the far end, the technician repeats the test and ensures that there are no issues. This testing continues out to the far end, which in a PON network there is a piece of active equipment called an Optical Network Terminal or ONT or at times called an Optical Network Unit or ONU. Regardless, that piece of equipment receives light from the OLT transmitter and communicates back to the OLT with its own transmitter. The ONT cannot communicate back to an OLT without first receiving the OLT’s transmitter’s wavelength. At this time, there is an absolute need to use a specialized optical power meter which can measure the OLT’s power and allow that power to pass through and provide the signal to the ONT/ONU so it can send back a signal.

The PON meter has two test ports; one is named DROP and the other ONT or ONU. The technician connects the drop, which is connected via a fiber all the way back to the OLT into the port named DROP and then connects the ONT/ONU connectorized fiber pigtail into the ONT/ONU port. Now the PON meter is in-line between the OLT and ONT/ONU and allows for the OLT to communicate with the ONT/ONU. The technician again will be observing the incoming OLT power level, as well as the outgoing ONT/ONU power level. If all is well, the drop is connected to the ONT/ONU and service activation tasks can continue.

I hope you have found this article informative and that you learned a bit about FTTx networks.

What is a Mode Conditioning Patch Cord?

This special fiber patch cord is a duplex multimode patch cable that has a small length of single mode fiber at the start of the transmission length. It is designed to solve the technical issue involved in using single mode equipment on the existing multimode cable plant. Mode conditioning fiber patch cord aims to drive the distance of installed fiber plant beyond its original intended applications, as well as to improve data signal quality.

Optical Mode Conditioners provide a convenient and reliable method of connecting multimode fiber plants with 1000Base- LX based transmission equipment compliant with IEEE 802.3 standards. Mode conditioners provide a method of offsetting a single-mode fiber core with a corresponding multimode fiber. This calibrated offset reduces a phenomena called differential mode dispersion, or DMD, which can cause the transmitting laser pulse to spread out and merge into neighboring pulses creating bit errors in the transmission signal.

Mode conditioners are built in the form of a simple duplex patch cable, so they can easily be installed in a system without the need for additional components or hardware. Their length can range from one meter and up to support virtually any network topography.

The need for this patch cord is due to the single-mode launch nature of the -LX (1300nm) transceiver modules used for Gigabit Ethernet. These modules have to operate for both single-mode and multimode fibers. Launching a single-mode laser into the center of a multimode fiber can cause multiple signals to be generated that confuse the receiver at the other end of the fiber. These multiple signals, caused by Differential Mode Delay (DMD) effects, severely limit the cable distance lengths for operating Gigabit Ethernet. A mode conditioning patch cord eliminates these multiple signals by allowing the single-mode launch to be offset away from the center of a multimode fiber. This offset point creates a launch that is similar to typical multimode LED launches.

Things to know when using mode conditioning cables to patch an existing multimode cable plant to your Gigabit LX equipment.

Usually used in pairs, mode conditioning cables usually require a MC cable at each end to connect the equipment to the cable plant. The only reason to order an odd number of mode conditioning cables is to have a spare on hand.

If your Gigabit LX switch 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. It is imperative that this configuration be maintained on both ends. The swap of transmit and receive can only be done at the cable plant side.