The connectors and adapters are coded throughout to ensure the correct orientation of the plug connection. The three polarity methods A, B and C as defined in TIA-568-C, for their part, are used to guarantee the right bi-directional allocation. This chapter describes these methods briefly.

Method A

Method A uses straight-through type A backbones (pin1 to pin1) and type A (key-up to key-down) MPO adapters. On one end of the link is a straight-through patch cord (A-to-B), on the other end is a cross-over patch cord (A-to-A). A pair-wise flip is done on the patch side. Note that only one A-to-A patch cord may be used for each link. MPO components from R&M have been available for Method A since 2007. It can be implemented quite easily, because e.g. just one cassette type is needed, and it is probably the most widespread method.

 

Method B

Method B uses cross-over type B backbones (pin1 to pin12) and type B (key-up to key-up) MPO adapters. However, the type B adapters are used differently on the two ends (key-up to key-up versus key-down to key-down), which requires more planning effort and expense. A straight-through patch cord (A-to-B) is used on both ends of the link. Method B does not enjoy wide use because of the greater planning effort and expense involved and because singlemode MPO connectors cannot be used. R&M does not support this method either or does so only on request.

 

Method C

Method C uses pair-wise flipped type C backbones and type A (key-up to key-down) MPO adapters. A straight-through patch cord (A-to-B) is used on both ends of the link. In other words, the pair-wise flip of polarity occurs in the backbone, which increases the planning effort and expense for linked backbones. In even-numbered linked backbones, an A-to-A patch cord is needed. Method C is not very widespread either because of the greater planning effort and expense involved and because it does not offer a way of migrating to 40/100GbE. R&M does not support Method C or does so only on request.

 

Method R

Method R (a designation defined by R&M) has been available since 2011. It requires just one type of patch cord (A-to-B). The crossover of the fibers for duplex signal transmission (10 GBase-SR) takes place in the pre-assembled cassette. The connectivity diagram for the trunk cable and patch cord or the light guidance remains the same all the time, even for parallel transmission (Method B) for setting up 40/100 GbE installations. That means capacity can be expanded directly in an uncomplicated and inexpensive manner. In addition, the only thing that has to be done is replace the cassettes with panels.

A specific lengths pre-assembled MTP/MPO Trunk cable with 12 or 24 fibers is delivered to data center for easy installation, because an It is impossible to manually to assemble MPO/MTP plug connector with 12 or 24 fibers on site during installation.

The advantages of MPO/MTP Trunk cable with the following advantages

• Higher Quality
Higher quality is usually achieved through factory assembly and inspection of individual parts. A factory-prepared inspection certificate is also useful for longterm documentation and in turn quality assurance purposes.

• Minimum Skew
A crucial factor in achieving a successful parallel optical connection is keeping the signal offset (skew) between the four or ten parallel fibers to an absolute minimum. Only in this way can information be successfully re-synchronized and re-combined at its destination. Factory-assembled trunk cables allow skew to be measured, minimized and logged.

• Shorter Installation Times
Pre-assembled MPO cable systems provide plug-and-play advantages and can be inserted and set up immediately.
This reduces installation time enormously

• Better Protection
Because they are completely assembled at the factory, cables and plug connectors remain completely protected from
environmental influences. Optical fibers that lie open in splice trays are at a minimum exposed to ambient air and may age faster as a result.

• Smaller Cable Volumes
Smaller diameters can be realized in MPO cabling systems that are produced from loose tube cables. The results are
correspondingly smaller cable volumes, better conditions for acclimatization in the data center and a lower fire load.

• Lower Overall Costs
When splice solutions are used, a few factors that are not always foreseeable boost total costs: time-intensive,
equipment-intensive splicing, needs for specialty works, bulk cables, pigtails, splice trays, splicing protection, holders. In contrast, pre-assembled trunk cables not only bring technical advantages, but usually result in lower total costs than splicing solutions.

Inspection should be done first before cleaning as it can decide if you need to clean. Once cleaning is required, dry cleaning which is an efficient method to remove dusts and finger grease is usually the preferred method to use due to the possibilities of residue when using alcohol based products.

However, dry cleaning method is not always sufficient to completely remove all contaminants. Thus, if the second inspection reveals that the MPO/MTP connector is still contaminated after the first dry cleaning, wet+dry cleaning method (Figure 4) is recommended to use for second cleaning. If the connector is still contaminated after second cleaning using wet+dry method, you could try to redo it once more. But in this case, permanent damage of the connector must be excluded. Once permanent damage is detected, the connector has to be replaced.

Figure 4. Wet+Dry Cleaning

Tips: Always reinspect connector after cleaning!

Cassette cleaner and one-click MPO/MTP cleaner are both available for MPO/MTP connector dry cleaning.

Cassette cleaner (Figure 5) is designed for effective cleaning of almost all fiber optic connectors with an accessible ferrule including LC, MU, SC, FC, ST, MPO/MTP, MTRJ and so on. If you only need to clean the accessible connector with a wide range of connector styles, it is an ideal choice for you. Moreover, by replacing the tape, it is more cost-effective for long-term use. But always remember that don’t reverse cleaning direction to avoid bringing back the wiped contaminants while using cassette cleaner.

Figure 5. Use Cassette Cleaner to Clean MTP Connector

The one-click MPO/MTP cleaner (Figure 6) is an easy-to-use cleaning tool for MPO/MTP accessible connector and adapter cleaning. If connector and adapter are both required to clean in your system, it is a good choice for you. Just with a simple “one-click”, the cleaning is done. A one-click MPO/MTP cleaner can be used up to 600 cleans.

Figure 6. Use One-click MPO/MTP Cleaner to Clean MTP Connector

In addition to the cleaner, other cleaning accessories such as lint-free wipe, optical grade dust remover, lint-free swab, etc. are necessary to achieve dry or wet+dry cleaning.

 

Fiber optic cleaning is a key part in whole fiber optic systems. MPO/MTP connector is more susceptible to contamination due to its larger contact area and multiple fiber design. Thus, choosing a right cleaning method and cleaning tool is very important for MPO/MTP cleaning. This post recommended cleaning methods and tools for MPO/MTP cleaning.  .

MPO/MTP connector is the most common multi-fiber connector type used in today’s high-density networks, e.g. 40/100 Gigabit Ethernet. It usually contains one or two rows of fibers (12-fiber MPO/MTP or 24-fiber MPO/MTP) in a single connector. Compared to the single-fiber connectors, a MPO or MTP connector has a larger contact area (Figure 1), and alignment of the fibers is achieved by the connection of male connector (pinned connector) which has outer pins and female connector (unpinned connector) which has alignment holes (Figure 2).

Figure 1. MPO/MTP Connector VS. Single-Fiber Connector (LC Connector)

Figure 2. Male & Female MPO/MTP Connectors

When cleaning a MPO/MTP connector, all fibers on the connector must be clean for it to function properly. Because contamination of one fiber can cause signal degradation on other fibers. Additionally, due to the presence of the alignment pins, the cleaning of the extreme sides of the MPO/MTP connector end-face is often overlooked by users (Figure 3). This is also why we cannot get the expected result in spite of repetitive cleaning. For these reasons, we should choose the right cleaning method and tools for proper cleaning.

Figure 3. Cleaning Dead Zone of MPO/MTP Male Connector

In today’s fiber optic networks, especially in data centers, MTP trunk cable and MTP-LC harness cable are two most common types used. Besides, MTP connector is pin and socket connectors, which require a male side and a female side. Therefore, in terms of MTP trunk cable, there are female-female, female-male and male-male three types. In addition, when connecting two parallel optics 40G SR4 QSFP+ transceivers, only a female to female type-B MTP cable should be used. For MTP-LC harness cable, female MTP-LC harness cable and male MTP-LC harness cable are available.

Figure 2: Type-B polarity MTP cable types

In today’s fiber optic networks, especially in data centers, MTP trunk cable and MTP-LC harness cable are two most common types used. Besides, MTP connector is pin and socket connectors, which require a male side and a female side. Therefore, in terms of MTP trunk cable, there are female-female, female-male and male-male three types. In addition, when connecting two parallel optics 40G SR4 QSFP+ transceivers, only a female to female type-B MTP cable should be used. For MTP-LC harness cable, female MTP-LC harness cable and male MTP-LC harness cable are available.

Figure 2: Type-B polarity MTP cable types

As demand grows for higher speed, large data centers being built today have begun to make preparations for 40G/100G transmission. MTP cables, with great performance and high speed, have become the main component in data centers.

In today's data centers, MTP cables, like 8-fiber or 12-fiber MTP cable, are frequently used to establish an optical path between switch tiers. Different from common fiber patch cords, one MTP cable has multiple fibers inside, which leads to more complex in the polarity management. Because the MTP connector terminates multiple fibers in a single high-density interface. And there are different fiber positions. To match these fiber position, TIA standards define three types of polarity MTP cables: type-A, type-B and type-C. Different types polarity cables may have different applications. In this tutorial, we will mainly introduce the type-B polarity MTP cables and its applications.

To bring a data center online, getting high performance network with less time and money is always what people concern about. The termination and cabling of fiber optic links in today’s data center are necessary and usually take a lot of time and labor. In traditional ways, these fiber optic links are terminated on field. In some data centers, engineers still use the traditional methods to terminate fiber optic links for data center cabling. However, risks like signal loss are increased with the traditional field fiber optic termination. To increase the working efficiency and network performance with less time and money, pre-terminated fiber cabling solutions are being widely introduced in the modern data center.

In fact, pre-terminated cables go through the same procedures as field terminated cables, but these steps are taken at the manufacturer’s facility or cable assembly house and delivered to the job site with the connectors already terminated, properly polished, and the entire cable assembly tested on either both end or one end. Which helps to eliminate the necessity for on-site field termination. Compared with field terminated cabling products, pre-terminated fiber cable assemblies are more convenient and flexible. They are most suited for network installations that are planned well in advance, taking into account both current and future requirements.

We can imagine a number of fiber conbinations that could be coupled by a device, some of which are shown in the figures below.

A 2 × 1 coupler is used to combine two light inputs into a single fiber (a). When the direction of light propagation is changed, this device will split one optical signal into two (b). In this operation, the coupler is called a fiber optic splitter in accordance with the function it performs. There are couplers that couple or split, 1 × N or N × 1 ports (c). They are called tree couplers and may have an N × M configuration. An important coupler for a WDM networks is a star coupler (d). In it the same number of ports serve as inputs and outputs. It is an N × N bidirectional (BIDI) coupler. However, a star coupler can be built as an N × M unidirectional coupler.

A coupler with a 50:50 output ratio that is, a splitter is called a 3 dB coupler. This simple device can be used as the basic building block of tree and star couplers. However, this is not the best approach to take because we need M = (N/2) log₂N 3-dB couplers to make an N × N star coupler and only 1/N portion of the power launched into each port will appear at every output. This is why modern tree and star couplers for broadcast WDM networks are fabricated directly using the FBT technique.

Uniformity is the coupler characteristic used for equal split ratios. For example, an ideal 1 × 2 coupler would split the input power equally into two output ports. In reality, however, the power at each ouput port will vary from the 50:50 ratio. The physical reason for this inequality is different losses due to insertion for different couplings originated during the fabrication process. Uniformity for a 50:50 coupler is shown as below:

Uniformity(dB) = 10 log(P₀/P₁) - 10 log(P₀/P₂)] = 10 log(P₂/P₁)

It is a measure of the inequality of the split power in different fibers.

Fiber optic connector, or optical fiber connector, is a component to terminate the end of fiber optical cable, and enables quicker connection and disconnection than fiber splicing. It mechanically couples and aligns the fiber cores to make light pass successfully. Therefore, fiber optic connector has an important impact on the fiber optic transmission reliability and the performance of the system. Quality optical connectors lose very little light due to reflection or misalignment of the fibers.

Fiber optic connector types are as various as the applications for which they were developed. Different connector types have different characteristics, different advantages and disadvantages, and different performance parameters. But all connectors have the same three basic components: ferrule, connector body, cable, coupling device.

Figure 1: fiber optic connector structure

Ferrule: the ferrule acts as a fiber alignment mechanism and holds the glass fiber. It has a hollowed-out center that forms a tight grip on the fiber. Ferrules are typically made of metal, ceramic or quality plastic.

Connector Body: also known as the connector housing, the body holds the ferrule and attaches to the jacket and strengthens members of the fiber cable itself. It is usually constructed of metal or plastic and includes one or more assembled pieces which hold the fiber in place.

Coupling Device: coupling device is a part of the connector body that keeps the connector in place when attached to another device like as bulkhead coupler and optical transceiver.

 

                        Figure-5: Cleaning Methods for Fiber Optic Adapter

Small as it is, fiber optic adapter is still an important part of the whole optical system, which should and also deserves to be cleaned according to the appropriate cleaning procedures. There are two basic cleaning methods—dry cleaning and wet cleaning.

1. Dry Cleaning: First, insert a dry adapter cleaning stick (or fiber adapter sleeve brush) inside the adapter and pull out with twisting motion; cleaning inside surface of the alignment sleeve. After cleaning the adapter with the connector installed on one end, inspect the connector end face for contamination.

2. Wet Cleaning: Insert an adapter cleaning stick (or fiber adapter sleeve brush) moistened with fiber optic cleaning solution (or > 91% Isopropyl Alcohol) inside the adapter and pull out with twisting motion; cleaning inside surface of the alignment sleeves. Follow up with a dry swab. After cleaning the adapter with the connector installed on one end, inspect the connector end face for contamination.

Also it is pretty clear visually shown on a infographic above (at least we hope so, as a lot of work are done to create above infograph), here’s a description of what you can see above.

Optical networks require signal being splitted somewhere in design to serve for multiple customers. Splitter technology has made a huge step forward in the past few years by introducing PLC (Planar Lightwave Circuit) splitter. It has proven itself as a higher reliable type of device compared to the traditional FBT (Fused Biconical Taper) splitter. While being similar in size and outer appearance, both types of splitters provide data and video access for business and private customers. However, internally the technologies behind these types vary, thus giving  service providers a possibility to choose a more appropriate solution.

FBT splitter is made out of materials that are easily available, for example steel, fiber, hot dorm and others. All of these materials are low-price, which determines the low cost of the device itself. The technology of the device manufacturing is relatively simple, which has the impact on its price as well. In scenario where multiple splits are needed, the size of the device may become an issue. It is important to keep in mind that splitters are being deployed in the fields either in cabinets or in strand mountings, so the size of device plays a critical role. FBT splitters only support three wavelengths (850/1310/1550 nm) which makes these devices unable to operate on other wavelengths. Inability of adjusting wavelengths makes FBT splitters less customizable for different purposes. Moreover, the devices are to a high extent temperature sensitive, providing a stable working range of -5 to 75 C. In certain areas, such as Scandinavian countries this temperature restrictions may be crucial. The signal processed by FBT splitters cannot be splitted evenly due to lack of management of the signals

PLC splitter manufacturing technology is more complex. It uses semiconductor technology (lithography, etching, developer technology) production, hence it is more difficult to manufacture. Therefore, the price of the device is higher. However, there is a number of advantages the device possesses. The size of the device is compact, compared to FBT splitters, making it suitable for density applications. PLC splitter operates at wider temperature range (-40 to 85 C), allowing its deploying in the areas of extreme climate. The split ratio goes up to 64, providing a high reliability. Furthermore, the signal can be split equally due to technology implemented. A range of wavelengths (1260 – 1650 nm) is provided, so the wavelengths are adjustable. Critical points of the device that might fail are input and output, so the general risk of failure is low.

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.Generally,Mode Conditioning patch cords are required for link distances greater than 984 feet(300 meters).

 

Detailed Picture(Offset)

If your gigabit LX switch is equipped with SC or LC connectors,please be sure to connect the yellow leg(Singlemode)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.(see diagram below)

 

 

Common fiber optic cable is fragile, which needs to be protected, especially when in harsh applications where cables could be compromised by rodents, constant wear and tear or weather damage. Armored fiber patch cable retains all the features of standard fiber cable but is much stronger due to its extra layers of armor. With the protection of flexible and durable steel tube, armored fiber patch cable will ensure the excellent operation of your network.

Ideal for harsh installation conditions that require exceptional durability. It is used as interconnection or cross connection in data center. It is also used in ceiling, corridor and other harsh environment.

 

Electrodes are the most essential consumable of fusion splicing machine. In general, after a period of use, it needs to be replaced. This is the basic maintenance of fusion splicing machine. Thus, users of fusion splicing machines should have the ability to judge when to replace electrodes and master the maintenance knowledge of replacing electrodes. This post will guide you how to judge when to replace the electrodes and explain the replacing steps by taking example of the latest Fujikura fusion splicing machine FSM-80S.

When to Replace Electrodes of Your Fusion Splicing Machine
What’s the best time to replace the electrodes of your fusion splicing machine, and how do you know when to replace it? Different users have different methods according to their working experiences. But the most basic method to judge when to replace the electrodes will be introduced here. Generally, there are two basic ways to judge whether the fusion splicing machine needs to be replaced its electrodes.

There is a function of a fusion splicing machine called arc discharge count. Electrodes should be replaced after reaching the manufactures recommended arc discharges. In general, the fusion splicing machine will alarm to remind users to replace the electrodes in that case. You should replace the electrodes of your fusion splicing machine when you see this alarm. Otherwise, splicing loss and quality will be effected.

Users can confirm whether the electrodes need to be replaced through some abnormal conditions during using. For example, if you find that your fusion splicing machine often prompt discharge not stable during the splicing, or discharge correction can not pass normally, or even the tip of the electrodes are oxidate severely and bald, you should replace the electrodes in those cases.

How to Replace Electrodes of Fusion Splicing Machine
Electrodes Replacing Steps
We can see the electrodes replacing steps in the following picture. It shows us the electrodes replacing steps of the Fujikura latest FSM-80S fusion splicing machine.

 

 

After replacing the electrodes, it’s necessary to stabilize the electrode and conduct discharge correction in order to make sure that the new electrodes perform well. These can usually be done through instructions of the fusion splicing machine. In addition, we should use the discharge correction feature to get the best discharge power of the machine in daily use.

 

5G is the “fifth generation” of wireless networks. It will cover a wide range of devices, including both mobile and fixed network infrastructure, i.e. both mobile smartphones, wearables and settled machines will be wireless. So does that mean in future we will need no fiber cables running around?

At first glance, people may think 5G wireless will work via radio signals and no fiber will be used. On the contrary, the success of future 5G significantly depends on fiber.

Beneath the surface of the world’s wireless infrastructure lies a big net interwoven by the fiber optic cables. And at present 90% of all internet traffic travels over wireline fiber, even if it finally terminates in a wireless device.



5G is targeted at a connection speed of 1-10 Gbps, which is ten to hundred times higher than 4G. The overwhelming traffic to data centers will demand a transport media that is capable of high bandwidth and long distance, and fiber is the best future-proof choice among all mediums. For some big companies who know the role of fiber have invested more on it in preparing for 5G deployment, such as Verizon.


 

In order to meet the 5G promised performance goals (see the chart below), there needs to be more fiber deployed worldwide. Because the final target is not only about higher speed, but the sub-millisecond latency, network diversity, availability and coverage that all require a solid foundation of fiber.

1. 1-10Gbps connections to end points in the field (i.e. not theoretical maximum)

2. 1 millisecond end-to-end round trip delay (latency)

3. 1000x bandwidth per unit area

4. 10-100x number of connected devices

5. (Perception of) 99.999% availability

6. (Perception of) 100% coverage

7. 90% reduction in network energy usage

8. Up to 10 year battery life for low power, machine-type devices

 

The goals of 5G network diversity, availability and coverage can be obtained by wider deployment of small cell sites/distributed antenna systems (DAS) interconnected by fiber. Small cell sites/DAS (100-200 m/less than 30 m) are closer to users in location (on light or utility poles) compared with macro cell site (3-6 km), and can support a variety of technologies and frequencies.



By deploying more small cell sites/DAS, there can be fewer terminal users covered by each site and thus enabling higher per-user capacities. If the small cell sites/DAS need to work well in future 5G, the backhaul must be fiber since copper or air cannot support the immense amount of traffic that will be generated by 5G centralized radio access network (C-RAN).


 

In addition to ability, also considering the cost-effectiveness and TCO (total cost of ownership), fiber to the cell sites or tower is deemed the superior option. And of course more connections from these sites to data centers mean more fiber will be installed.

5G wireless will not abandon fiber. Instead its deployment will greatly rely on the availability of fiber infrastructure. Also the fiber will largely boost the capacity and lower latency in future generations of wireless networks.

 

 

Visual fault locator, also called VFL for short, is an essential tool that quickly and easily locates problem areas in fiber cables. It is regarded as a part of OTDR and it is cheap. By pinpointing the exact location of the fiber damage, such as breakpoint, bending or cracking, technicians can diagnose, troubleshoot, and fix the problem effciently.

This device is based on laser diode visible light source, when the light injected into the fiber, if fiber fracture, connector failure, bending over, poor weld quality failure by launching the light of the fiber to fiber fault visualization positioning.Visual Fault Locator launched a continuous wave (CW) or pulsed mode. The typical frequency of 1Hz or 2Hz, but can also work in the kHz range. Usually the output power of 0dBm (1mW) or less, the working distance of 2 to 5km, and to support all the common connector.

Visual fault locators generally include the pen type, handheld type and portable visual fiber fault locator. In addition, designed with a FC, SC, ST adapter, VFL is used without any other type of additional adapters, it can locates fault up to 10km in fiber cable, with compact in size, light in weight, red laser output.

The visual fault locator is commonly used for fiber identification and fault location of single-mode or multi-mode fiber as well as for wavelength loss testing. It is also an ideal tool for the examination of all types of patch cords and ribbon or bunched pigtails. It is an excellent tool for the maintenance of fiber optic networks, optical systems including LAN, FDDI and ATM, telecommunications and CATV networks. It is intended for the identification,fault location of fiber optics on single mode or multimode fiber and wavelength loss testing. It can also locate the fault of OTDR dead zone and make fiber identification from one end to the other end.

While both types perform the functions above, the difference between the two categories of cleavers is the percentage yield of good cleaves. An experienced fiber optic technician will achieve approximately 90% good cleaves with a scribe cleaver, while the precision cleaver will produce 99% good cleaves. The difference doesn’t seem like much so you may hardly to make a specific decision. My suggestion is to buy precision cleavers if you plan to use a lot of mechanical splices or pre-polished splice/connectors. It will pay for itself in no time. If you decide to use the inexpensive scribe cleavers, you must learn how to use it properly. Follow directions, but also do what comes naturally to you when using the device, as they are sensitive to individual technique. Inspect the fibers you cleave to see how good they are and keep practicing until you can make consistently good cleaves.