How to Use Field Assembly Connector?

by Fiber-MART.COM

The expansion of FTTH application has brought prosperity to the manufacturing of field assembly connectors for fast field termination. This type of connector gains its popularity due to the applicability to cable wiring and compact bodies which are easily stored in optical fiber housings. With excellent features of stability and low loss, field assembly connector has now become a reliable and durable solution for fiber optic systems. However, do you really know the field assembly process of the connector? This article provides an easy guide to show you the way of using field assembly connector.

Introduction to Field Assembly Connector

Before getting to know the instruction process, let’s have a look at the basic knowledge about field assembly connector. Field assembly connector or fast connector is an innovative field installable optical fiber connector designed for simple and fast field termination of single fibers. Without using additional assembling tools, field assembly connector can be quickly and easily connected to the drop cable and indoor cable, which saves a lot of required termination time. It is specially designed with the patented mechanical splice body that includes a factory-mounted fiber stub and a pre-polished ceramic ferrule. Field assembly connector is usually available for 250 µm, 900 µm, 2.0 mm and 3.0 mm diameter single-mode and multimode fiber types. The whole installation process only takes about 2 minutes which greatly improves the working efficiency.

Internal Structure of Field Assembly Connector

From the following figure, we can see the specific internal structure of field assembly connector. The ferrule end face of the connector is pre-polished in a factory for later connection with the fiber. A mechanical splice is also formed at the end of the ferrule for mechanical fixation of optical fiber. The mechanical splice consists two plates, one with a V groove, another with flat surface above the V groove, and a clamp for the insertion of the two plates. When inserting the fiber, a wedge clip will keep the V groove open for easier installation. After the fiber insertion, the wedge clip can be extracted from the V groove.

Features and Applications

Key Features

Field-installable, cost-effective, user-friendly

No requirement for epoxy and polishing

Quick and easy fiber termination in the field

No need for fusion splicer, power source and tool for pressure

Visual indication of proper termination

Applications

Fiber optic telecommunication

Fiber distribution frame

FTTH outlets

Optical cable interconnection

Cable television

Field Assembly Instruction Guide

Although it is an simple way to use field assembly connector, the right operation process is also important. Here will introduce some basic steps for connector installation.

Step 1, prepare the field assembly connector parts and related tools required during the process. There is no need for special tools, but fiber cleaver and jacket stripper are still necessary.

Step 2, insert the connector boot into the fiber cable.

Step 3, cut and reserve 10mm bare fiber by fiber cleaver and then make sure the total fiber length of 30 mm.

Step 4, insert the fiber from bottom until the stopper and make fiber present micro bend.

Step 5, press the press cover to tight the bare fiber.

Step 6, lock the boot with yarn.

Step 7, cut the yarn.

Step 8, screw the boot and put on housing to complete assembly.

Precautions

Here are some precautions for you to notice during the process:

Point 1, the product is sensitive to dirt and dust. Keeping it away from any possible contamination is necessary.

Point 2, the performance will be influenced by the fiber cutting surface condition. Use a cutter with a sharp blade for the best results.

Point 3, insert the fiber into the connector slowly. If the fiber is roughly inserted, it might be damaged or broken, leading to failure of connector installation. Broken fiber could scatter in all directions.

Point 4, do not remove the dust cap until the connector has been completely assembled in order not to cause a high insertion loss.

Point 5, a proper amount of index matching gel is applied in the connector. Do not insert fiber more than once into connector.

Conclusion

Fiber assembly connector enables quick termination to improve reliable and high connector performance in FTTH wiring and LAN cabling systems. All the above solutions provided by fiber-mart.COM are available to meet your requirements. Please visit the website for more information.

How to Troubleshoot a Faulty PON With an OTDR

It is easy to trouble shoot the failure which occurs on a point-to-point FTTx network by using an optical time domain reflectometer (OTDR) test. However, troubleshooting a faulty point-to-multipoint network (i.e. PON network) differs significantly and are more complex than a point to point network. This post will introduce the potential faults which may occur in a PON, and explain how to troubleshoot them with an OTDR.

 

Brief Introduction of PON

A PON (passive optical network) is a telecommunications network that uses point-to-multipoint fiber to the premises in which unpowered optical splitters are used to enable a single optical fiber to serve multiple premises. A basic PON (see Figure 1) consists of an optical line terminal (OLT) at the service provider’s central office and a number of optical network termination (ONT) or optical network units (ONUs) near end users. Sometimes, a second splitter can be connected in cascade to the first splitter to dispatch services to buildings or residential areas (see Figure 2). The International Telecommunications Union (ITU-T) and Institute of Electrical and Electronic Engineers (IEEE) have created several standards for optical access systems based on PON architecture (G.982, G.983 or G.984 for ITU and 802.3ah or 802.3av for IEEE).

 

Figure 1. Simple PON Topology

 

Figure 2. Cascaded PON Topology

Due to its architecture, operators can easily determine which subscribers are affected, and can also identify possible fault elements such as how many customers are affected and whether the PON is cascaded by using the network monitoring system at the Network Operation Center (NOC).

Possible Scenarios & Potential Faults of a PON

 

In general, we divide the faulty case of a PON as three scenarios. One case is that only one customer is affected. And the other case is occured in the cascaded PON and all affected customers are connected to the same splitter. The last case is all customers dependant on the same OLT are affected whether the PON is cascaded or not. In the first case, there are three probable potential faults. Fault may appear in the distribution fiber between the cutsomer and the closest splitter, or in the ONT equipment, or even appear in the customer’s home wiring. See Figure 3 (a) & (b).

 

Figure 3 (a). PON Case 1—Possible Faults When Only One Subscriber is Affected

 

Figure 3 (b). PON Case 1—Possible Faults When Only One Subscriber is Affected

When all customers connected to the same splitter cannot receive service, but others connected to the same OLT can, namely the second case, the cause may be that there is a fault at the last splitter or in the fiber link between the cascaded splitters. See Figure 4.

 

Figure 4. PON Case 2—Cascaded PON with Affected Subscribers Connected to Last Splitter

To the thrid case described above, if all customers are affected, the fault may occur in the splitter closest to the OLT, or in the feeder fiber/cable of the network, or directly in the OLT equipment, as the Figure 5 shown.

 

Figure 5. PON Case 3—All Subscribers are Affected (All Connected to the First Splitter)

In addition, we should know that if connectors are available at the splitters, terminals, or drops, isolating part of the faulty network will become easier. Inspecting connectors and taking OTDR measurements using 1310/1550 nm wavelengths are often performed on network sections that are out of service.

 

Why Use The Specific In-service Portable OTDR Device?

In order to troubleshoot PON networks in service, two dedicated tools are available — PON power meter and In-service 1625 or 1650 nm OTDR. As we know, a PON power meter is normally employed to verify that the signal is transmitted correctly to and from the ONT. A PON meter measures the power levels of all the signals and can then discriminate whether the issue comes from the customer’s ONT or from the network. However, you might be very confused with that why use In-service OTDR. The use of a classical OTDR with 1310 or 1550 nm test wavelengths would interfere with the traffic signals and disturb the traffic. At the same time, the traffic signals could also disturb the receiver of the OTDR, making it difficult to interpret OTDR traces. Due to mutual disturbances, classical OTDRs cannot be used, and specific in-service OTDRs are required.

The in-service OTDR was designed specifically for testing live fiber networks. This dedicated device uses an out-of band wavelength (test wavelength far away from traffic wavelength) to enable OTDR testing without disturbing either the network transmitters or the receivers. In the case of a PON network, WDM is no longer needed, except for monitoring purposes (using a remote fiber test system). The PON network is a point-to-multipoint configuration and the troubleshooting test is performed directly from an accessible element (ONT or splitter). The operator can disconnect the element because service is already off downstream toward the customer. First, the in-service OTDR must not disturb the other customers while shooting the OTDR test wavelength upstream toward the OLT, which is most likely the case, as OLTs reject signals above 1625 nm, based on ITU-T recommendations. Second, the traffic signals that the OTDR receives will be rejected to obtain accurate OTDR traces. The specific long-pass filter used to protect the OTDR diode can be added either via a jumper between the OTDR and the network or built into the OTDR.

 

Most equipment providers enable the use of the 1625 nm wavelength for safe testing. Some countries, such as Japan, are nevertheless pushing the 1650 nm wavelength as reflected in the ITU-T L.41 recommendation, which provides maintenance wavelengths on fiber-carrying signals. The 1650 nm wavelength is preferred based on the design of the filters and also because it is further away from the traffic signals (current and future PON technologies).

Case of PON Troubleshooting with OTDR

 

In order to make the whole troubleshooting or testing work smothly, it is essential to select the right OTDR tool, the correct pulse width, and the best location to start troubleshooting. OTDR configuration should be set according to the equipment being qualified and the distance to cover.

 

In response to the possible scenarios and potential faults of a PON described above, here are some solutions with OTDR to be introduced in the following. To avoid complexity, this document only analyzes the cases where connectors are only available at the ONT/OLTs.

 

Solution 1: Troubleshooting of the Distribution Fiber

Simple PON—Only one subscriber affected. Consider that no connectors are available at the splitter.(see Figure 6)

Case Test Location OTDR Direction What must be Seen Comment Pulse Width to be use Specific OTDR

Case 1 one customer down Customer’s home Disconnect the ONT Upstream Distribution fiber up to the closest splitter Testing through the splitter is not required, as the issue is only on the disrtibution fiber side. Short pluse 3 to 30 ns In-service OTDR

 

Figure 6. OTDR is Shot Upstream and Trace only Matters up to the Splitter

Solution 2: Troubleshooting of the Distribution Fiber and the Fiber between the Two Splitters in case of a Cascaded Network

All customers linked to the second splitter are down. Let’s consider the case where no connectors are available at the splitter.(See Figure 7.)

Case Test Location OTDR Direction What must be Seen Comment Pulse Width to be use Specific OTDR

Case 2 all the customers are down after the second splitter Customer’s home Disconnect the ONT Upstream Distribution fiber up to the two splitters Testing through the closest splitter is required. Medium pluse 100 to 300 ns In-service OTDR – short dead zone

This case requires viewing the signal after the splitter. The OTDR used must be optimized for this application and have the shortest possible dead zone as the splitter typically provides 7 to 10 dB loss.

 

Figure 7. OTDR is Shot Upstream and Trace should Display the Traffic through the Last Splitter up to the First One

Solution 3: Troubleshooting of the Feeder

Information received at the NOC shows that all customers are down. As the problem likely comes from the feeder side, the most common way to test the faulty network is to shoot an OTDR downstream from the OLT.(See Figure 8.)

Case Test Location OTDR Direction What must be Seen Comment Pulse Width to be use Specific OTDR

Case 3 all customers are down OLT Downstream Feeder Testing through the splitter is unnecessary. Short pluse 3 to 30 ns Unnecessary

 

Figure 8. OTDR is Shot Downstream and Trace should Display the Traffic Down to the First Splitter

Note: OTDR testing directly from the OLT is certainly the preferred choice when a faulty feeder is suspected (Solution 3), but this method is not recommended in the other cases.

Understand 100G Transceivers Transmission Principles

Changes to transmission speeds and expansion in data center capacities have driven the 100 Gigabit Ethernet. IHS Infonetics reports that by 2019, 100G Ethernet will make up more than 50 percent of data center optical transceiver transmissions. For 100G transceivers, there are 100GBASE-SR4, SR10 and PSM4 for short-distance transmission and 100GBASE-CWDM4, LR4 and ER4 for long-distance transmission.

 

100G Transceivers Transmission Principles

100GBASE-SR4 QSFP28 transceiver uses a 12-fiber MMF strand MTP/MPO cable for 100m connectivity (4 Tx and 4 Rx, each lane providing 25 Gbps of throughput over 850nm wavelength).

100GBASE-SR10 CFP optics use a 2×12-fiber or 24-fiber MMF strand MPO/MTP cable for 150m connectivity (10 Tx and 10 Rx, each lane providing 10 Gbps of throughput over 850nm wavelength).

 

100GBASE-PSM4 QSFP28 transceiver uses a 12-fiber SMF strand MTP/MPO cable for 500m connectivity (4 Tx and 4 Rx, each lane providing 25 Gbps of throughput over 1310nm wavelength).

 

100GBASE-CWDM4 QSFP28 transceiver provides aggregated 100G data rate over 2 km on SMF. The four optical signals from the four wavelengths are multiplexed and coupled to SMF through an industry-standard LC connector, and on the receive side, the demultiplexer splits the four wavelengths apart.

 

100GBASE-LR4 transceivers provide 100G data rate over 10 km on SMF. The four optical signals from the four wavelengths are multiplexed and coupled to SMF through an industry-standard LC connector, and on the receive side, the demultiplexer splits the four wavelengths apart.

 

Note: fiber-mart also provides Juniper compatible CFP LR4 modules with duplex SC interface.

 

100GBASE-ER4 transceivers provide 100G data rate over 40 km on SMF. The four optical signals from the four wavelengths are multiplexed and coupled to SMF through an industry-standard LC connector, and on the receive side, the demultiplexer splits the four wavelengths apart.

100G Transceivers Custom Information

For 100G transceivers, FS also provides custom service. The form factor, interface, type, label and compatible brand can be customized by your special requirements.

 

For more details about our 100G QSFP28 and CFP/CFP2/CFP4 transceiver modules, please visit our site www.fiber-mart.com.