Author: Fiber-MART.COM

In FTTx and PON architectures, optical splitter plays an increasingly significant role to create a variety of point-to-multipoint fiber optic networks. But do you know what is a fiber optic splitter? In fact, a fiber optic splitter is a passive optical device that can split or separate an incident light beam into two or more light beams. Basically, there are two types of fiber splitter classified by their working principle: fused biconical taper splitter (FBT splitter) and planar lightwave circuit splitter (PLC splitter). You may have one question: what’s the difference between them and shall we use FBT or PLC splitter?

What Is FBT Splitter?

FBT splitter is based on a traditional technology to weld several fiber together from side of the fiber. Fibers are aligned by heating for a specific location and length. Because the fused fibers are very fragile, they are protected by a glass tube made of epoxy and silica powder. And then a stainless steel tube covers the inner glass tube and is sealed by silicon. As the technology continues developing, the quality of FBT splitter is very good and it can be applied in a cost-effective way.

What Is PLC Splitter?

PLC splitter is based on planar lightwave circuit technology. It composes of three layers: a substrate, a waveguide, and a lid. The waveguide plays a key role in the splittering process which allows for passing specific percentages of light. So the signal can be split equally. In addition, PLC splitters are available in a variety of split ratios, including 1:4, 1:8, 1:16, 1:32, 1:64, etc. They also have several types, such as bare PLC splitter, blockless PLC splitter, fanout PLC splitter, mini plug-in type PLC splitter, etc. Therefore, if high split counts are needed, small package size and low insertion loss are also required, you are suggested to choose PLC splitter rather than FBT splitter. For more information about PLC splitter, please refer to How Much Do You Know About PLC Splitter?

FBT vs. PLC Splitter

(1) Operating Wavelength

FBT splitter can only support three wavelengths: 850nm, 1310nm and 1550nm, which makes its inability to works on other wavelengths. While PLC splitter can support wavelength from 1260 to 1650nm. The adjustable rang of wavelength makes PLC splitter suitable for more applications.

(2) Splitting Ratio

Splitting ratio is decided by the inputs and outputs of an optical cable splitter. The maximum split ratio of FBT splitter is up to 1:32, which means one or two inputs can be splitted into an output maximum of 32 fibers at a time. However, the split ratio of PLC splitter is up to 1:64 – one or two inputs with an output maximum of 64 fibers. Besides, FBT splitter is customisable, and the special types are 1:3, 1:7, 1:11, etc. But PLC splitter is non-customisable, and it has only standard version like 1:2, 1:4, 1:8, 1:16, 1:32 and so on.

(3) Assymetric Attenuation Per Branch

The signal processed by FBT splitters cannot be splitted evenly due to lack of management of the signals, so its transmission distance can be affected. However, PLC splitter can support equal splitter ratios for all branches, so it is more stable.

(4) Failure Rate

FBT splitter is typically used for networks requiring the splitter configuration of less than 4 splits. The larger the split, the larger failure rate. When its splitting ratio is larger than 1:8, more errors will occur and cause higher failure rate. Thus, FBT splitter is more restricted to the number of splits in one coupling. But the failure rate of PLC splitter is much smaller.

(5) Temperature Dependent Loss

In certain areas, temperature can be a crucial factor that affects the insertion loss of optical components. FBT splitter can work stable under the temperature of -5 to 75℃. PLC splitter can work at a wider temperature range of -40 to 85 ℃, providing relatively good performance in the areas of extreme climate.

(6) Price

Owing to the complicated manufacturing technology of PLC splitter, its cost is generally higher than the FBT splitter. If your application is simple and short of funds, FBT splitter is definitely a cost-effective solution.

Conclusion

Although the outer appearance and size of FBT and PLC fiber splitter seem rather similar, their internal technologies and specifications differ in various ways. Over the past few years, splitter technology has made a huge step forward in the past few years by introducing PLC splitter. It has proven itself as a higher reliable type of device compared to the traditional FBT splitter.

Field assembly connectors are quicker and easier to assemble and terminate, but many in the industry raise concern over their long-term reliability. Technical and scientific community should not fall prey to the stereotypes, but unfortunately, many of the industry experts are yet to be convinced on the power of field assembly connectors.

It is a fact that fusion connection is a physical union of two glass threads that provides lowest possible loss due to connection loss, typically in the range of less than 0.05dB. A quick check on the technical data sheets of industry leading suppliers of Field Assembly connectors reveals that the typical loss from mechanical connection falls around less than 0.1dB.

What is the impact of 0.05dB over an FTTH network of 20 kilometers? Let us have a look before we jump in to conclusion.

An FTTH network typically spans around 20 kilometers. Considering an optical loss of 0.25dB/km maximum for the fiber at 1550nm, the attenuation contributes 5 dB loss. Loss due to connectors at the equipment side and splices in between contributes around 2.5dB to make a subtotal of 7.5dB. Splitters are common in PON network and usually it is two-stage splitting such as 1×4 and 1×8. Loss due to 1×4 splitting is around 8 dB and that due to 1×8 splitting is around 11 dB. Subtotal loss due to splitters is 19dB. Thus we get a total loss of 26.5 dB irrespective of the type of last mile connection.

In case of Field Assembly connector, typical loss is 0.2 dB. If we use two Field assembly connectors at the last mile, the subtotal loss would be 0.4 dB and the Total network loss would be 26.9 dB

In case of splicing, the typical loss is 0.05 dB and thus the subtotal loss would be 0.1 dB. Thus we get a total network loss of 26.6 dB.

For networks using field Assembly connectors, average loss would be 1.345 dB/km and for networks using splicing method, the average loss would be 1.33 dB/km. Per kilometer loss is higher by 0.015 dB for Field Assembly connectors, which is very negligible considering the loss budget of 28 dB for FTTH networks.

The author does not have any business interest to promote field assembly connectors, but just presenting the factors that may help you to take right decisions. Most of the concerns on field assembly connectors arise from their long-term performance and reliability as they utilize the index-matching gel/gum. Globally leading manufacturers utilize high precision manufacturing technologies and high quality material to assure the long-term performance. Cheaper products will have their own risk. We should not compromise on quality to save 20 or 30 cents.

Conclusion: Field Assembly Connectors are recommended for FTTH Networks. You need to buy from good and reputed suppliers. Never ever compromise on quality. Compromising on quality has high risk on the service quality and also your own reputation as a reliable person in the industry.

It is estimated that more than 5 billion optical fiber kilometers are installed on the earth including all kind of installations such as Submarine, Aerial, underground and premise. This number can be roughly converted to 138 million cable kilometers if we consider an average fiber count of 36 fibers per cable. With the progress of fiber to the home projects, this average will further go down since the premise cables are of smaller fiber counts. Higher count cables are mostly deployed in backbone/metro core networks. Extremely high count cables are utilized for data centers, but the lengths are limited. Recent reports from Prysmian shows development of 6912F cable for datacenter application.

Submarine cables have smaller fiber counts typically in the range of 6 to 12. Submarine cable system utilizes latest transmission technologies to achieve highest possible data transmission speeds and capacity over a single fiber. Long distance communication lines are made of typically from 24 to 48 fiber count cables. Metro-core/backbone networks utilize high fiber count cables typically in the range of 144 to 576 fibers per cable. In extremely high density population areas this number goes up to 1000 to 2000 fibers per cable.

As the number of fibers in a cable goes up, the chances of fiber break also goes up. Recent studies conducted to analyze fiber breaks throw light to this direction. It is estimated that more than at every 1 (one) minute 1 (one) fiber break occurs per 1000 kilometers of installed cable daily worldwide. Higher the number of fibers in a cable, higher will be the probability of fiber breaks. This not only indicates the higher probability of fiber breaks on high fiber count cables, but also indicates to the higher construction/digging activities in the metro area.

Number of fiber breaks in one day worldwide is estimated to be around 1566 on a rough calculation based on studies conducted by FCC in 2002 and the total fiber cable kilometers installed so far. Survey findings have revealed that on an average it takes around 4 hours to rectify/repair and bring back the network to its original condition. For submarine cables, it may take days or even weeks, depending on the damage. Almost 70% of the recovery time is spent to identify the nature and location of the fault. 30% of the recovery time is spent to do the actual repairing work.

Metro/backbone networks suffer mostly due to mistakes in construction work. Location of Installed cables are either unknown or wrongly informed to the construction workers. If the installed cable locations are not properly marked, inadvertent mistakes may happen from the installation crew. Premise area is more sensitive to fiber breaks since the fiber enters home and is in the middle of daily life and movements. ITU-T recommendations categorize bend insensitive fibers for premise application. Apart from lower attenuation increase with smaller bends, bend-insensitive fibers, that are categorized as ITU-T G.657A fibers, have higher resistance to the bending and therefore lower chance for break compared to the conventional fibers (G.652D).

As an access to providing high-speed Internet speed, Fiber to the home (FTTH) has been highly favored in recent years. It can achieve high-speed and long distance transmission, from a central point directly to individual buildings such as residences, apartment buildings and businesses through installation and use of optical fiber. FTTH drop cable plays a prominent role during this process. So what is FTTH drop cable? And how to install? This article would provide a satisfied answer for you.

About FTTH Drop Cable

FTTH drop cable contains 1 to 4 colored singlemode optical fibers with 250 µm individually, which provides a good solution for fiber to the home last mile solution. The cable contains two Fibre Reinforced Plastic (FRP) strength members and Low Smoke Zero Halogen (LSZH) jacket with nominal dimension 2 x 3 mm. They are fully meet the RoHS standards. With its small diameter, light weight and special structure, it is easy to use, to handle and to pull the fibers out from the cables. It is an ideal option for direct installation into the houses.

Features&Benefits

—Choice of fibre types

—Individually coloured optical fibres

—Notched 2 x 3 mm construction for easy stripping

—Singlemode optical fibre meeting ITU-T G.657A1 or ITU-T G.657A2 standard

How to Choose Right LSZH Jacket?

You can choose white LSZH jacket for indoor use and black LSZH jacket for outdoor use within short distance. For the white cables that are installed where they may be in direct sunlight for extended periods of time will need to be replaced more often. So we need to pick black LSZH jacket for they are UV-resistant.

Indoor And Outdoor Applications

There are mainly three applications of FTTH drop cables: internal FTTH applications horizontal and riser, clipping to surfaces including skirting boards, and short distance external use with black LSZH jacket. Due to time and space limiting, this article would mainly introduce the internal horizontal and riser cabling for FTTH applications, which attach great importance to FTTH cabling.

Horizontal Cabling

Drop cable all dielectric for Fibre To The Home (FTTH or FTTx) application, this means we need intrabuilding conduit. Conduit can be made of metallic tubing or rigid polyvinyl-chloride plastic. Conduit runs should be limited to 100 feet, with no more than two 90-degree bends between pull points or boxes. It runs can be in ceilings or walls or under floors.

To apply the FTTH fiber drop cable, we need pull boxes. They are installed for fishing the run and looping the cable for the next length of conduit. Pull boxes are not used for splicing cable. Fish tapes or pull cords should always be placed in the conduit to ease installation. Inner duct is an excellent tool for protecting cable and easing future installations.

Riser Cabling

Drop optical fiber cables intended for vertical applications have a calculated maximum vertical rise value assigned to them. The vertical rise is the distance the cable may be pulled vertically before being supported. It is determined by the weight of the cable and its ability to resist buckling or kinking.

You can use split wire mesh grips to pull cable vertically. The device works like basket or finger grips, supporting the cable without crushing the core. Cables should be supported by cable ties, straps or clamps in wiring closets. Whenever possible, begin the installation from the top, allowing the weight of the cable to help the pull rather than adding more load.

Conclusion

FTTH dramatically and unprecedentedly increases the connection speeds available to computer users. FTTH drop optical cable is a special cable that provide a perfect solution for FTTH transmission. The article mainly discussed its definition, benefits and applications. If you need this kind of fiber cable, you can take fiber-mart a try. We offer FTTH fiber drop cable with high quality but low cost. For more details, please visit www.fiber-mart.com.