Fiber Optic Loopback Overview

What is Fiber Optic Loopback?

Fiber optic loopback is also known as fiber optic loopback cable or fiber optic loopback module. It is designed to provide a media of return patch for a fiber optic signal, offering a generous yet manageable fiber loop virtually eliminating bend loss, and commonly used for fiber optic testing applications or network restorations. It can also utilized to diagnose the problems of optical networking equipment. Sending a loopback test to network equipment, one at a time, is a technique for isolating a problem. Fiber optic loopbacks is compliant with Fast Ethernet, Fibre Channel, ATM and Gigabit Ethernet, etc.

Types of Fiber Optic Loopbacks

Fiber optic loopbacks can be with different jacket types, cable diameters, connector terminations and cable lengths. Traditional fiber optic loopbacks, namely fiber optic loopback cables, can be regarded to be two fiber optic connectors on the same piece of simplex fiber jumpers put together, thus it forms a loop. Classified by the connector types, the most common two types of fiber optic loopback cables are SC and LC type, besides there are also FC, MTRJ, and MTP types.

In addition to the traditional fiber optic loopbacks, there are also molded fiber optic loopbacks (or fiber optic loopback plugs), i.e. fiber optic loopback modules, with compact design. Unlike the traditional fiber optic loopback cables with visible cable parts, fiber optic loopback module has its cables and fibers well protected inside the housing. It integrates every part into one single body, which help save space and make it easier to operate as well as offer better protection to the whole product. By incorporating a rigid connector shell for fiber protection with an easy to use, ergonomic package, the fiber optic loopback module is designed for durability and performance. Molded fiber optic loopbacks are also mainly available in SC and LC types, which are easy to use for fiber optic test purpose in the lab experiments or manufacturing environment.

Just like fiber optic patch cables, fiber optic loopbacks can also be classified by fiber types: single-mode and multimode. The fiber types can be 9/125µm single-mode fiber, 50/125µm multimode fiber, or 62.5/125µm multimode fiber. Typically single mode SC and LC loopbacks are blue, and typical multimode LC and SC loopbacks are beige. The color also goes with the practice of SC LC fiber patch cable.

Applications of Fiber Optic Loopback

A tipical application of fiber optic loopback is to check fiber optic transceiver by loopback test. Loopback test means a hardware or software method, a loopback test, feeds a received signal or data back to the sender. It is utilized as an aid in debugging physical connection problems.

Loopback test is the easiest way to ensure the transceiver is working faultlessly. On fiber optic transceiver manufacturing floors and in R&D labs, a fiber optic loopback is used to verify the transceiver whether it is working perfectly as designed. Basically what the loopback does is directly routing the laser signal from the transmitter port back to the receiver port. Then the transmitted pattern is compared with the received pattern to make sure they are identical and have no error.

FS.COM Fiber Optic Loopback Solution

Fiber optic loopbacks feature single-mode and multimode loopback plugs designed for equipment testing, self-testing, engineering, network diagnostics and measurement applications. They play an important role in troubleshooting in laboratories and manufacturing environments. A high optical performance is achieved due to precision ceramic ferrule. The fiber optic loopbacks are precision terminated and feature extremely low loss characteristics for transparent operation in the test environment and in form of cable and module types.

Why Choose Fiber Optic Cables in AV Systems?

As audio and video technologies continue to evolve, AV systems are continuously challenged with supporting high resolution video, audio, and control signals. The combination of light and glass presents some unique properties that give AV professionals powerful tools in common AV applications. A fiber optic cable can be used to send high resolution video, audio, and control signals on a single fiber over 30 km (18.75 miles), and avoids the risk of signal loss or degradation, ground loop hums, and electrical interference. Because transmission of content is inherently secure and immune to outside interference, fiber applications are favored in government, military, and medical environments. This article will mainly introduce four advantages of the installation of fiber optic cables in AV applications.

High Resolution Video, Audio, and Control Signals

Fiber optic cables are low-loss channels that enable transmission of high resolution video, audio, and control signals over long distance. Losses in fiber optic cables are 0.2 to 3.5 dB/km, compared to 60 dB/km for legacy RG6 coaxial cable at 100 MHz. The low-loss nature of single-mode fiber cables can enable transmission of WQXGA 2560x1600 video signals up to 30 km. Due to these advantages, fiber optic cables are widely used in campuses, sports stadiums and large office buildings, etc. Besides, installing fiber optic cables with extremely high bandwidth can ensure that future applications can be addressed with today’s fiber installations.

Easy to Install

Fibers consume very little space in conduit and cable trays, and are easy to pull. For example, duplex fiber optic cable can transmit high resolution video signals but is only a fraction of the size of a coaxial cable. Because of fiber optic cables’ small size, the installation is much easier especially in medical applications where there is often insufficient space for thicker cables. Besides, today’s field termination kits make fiber easier to terminate than other types of cabling. Simply striping, cleaving, and inserting fibers into fiber optic connectors, you can get a high quality, reliable splice in minutes. And you can also choose pre-terminated fiber cables, such as LC patch cable or SC LC fiber patch cable (as shown below). The connectors you specify are pre-terminated for you, and the fiber cables you specify are cut to the proper length that you need. When the installation is over, you can just plug and play fiber optic system.

Safe for Sensitive and Hazardous Environments

Unlike copper cables, fiber optic cables are largely comprised of glass, which does not carry electrical current, radiate energy, or produce heat or sparks. So they can be safely installed in hazardous environments, such as oil refineries, mining operations, or chemical plants, without the danger of generating an electrical spark. Applications using sensitive electronics, such as medical environments, also benefit from the lack of electrical emissions with fiber optic systems. Fiber optic applications have helped the medical field advance tremendously over the past decade. They not only allow the physician to see inside specific areas of the body and perform surgery on hard-to-reach areas, but also provide a quicker and more accurate analysis of blood work.

Low Total Cost

Fiber optic systems may provide a lower total cost of ownership over the life of the system when compared to a coaxial or twisted pair solution. In copper systems, old cables need to be removed and new cables to be pulled for each system upgrade. While fiber optic cables with high bandwidth can be reused through multiple system upgrades. In addition, fiber optic cables typically consume less power and produce less heat than copper wires, thus reducing both electrical and cooling costs. Moreover, fiber optic systems can be monitored and serviced from the main equipment room without disrupting activities in work areas.

Conclusion

Fiber optic cables provide unique advantages in an AV system, particularly in secure and long distance applications. Choosing the proper cable depends upon the number of fibers required, installation location, topology, and the overall design of the system. Cable constructions are available for both indoor and outdoor applications to provide a solution for virtually any AV system.

Learn to Identify Various Fiber Patch Cables

Fiber patch cable, also called fiber patch cord is the most fundamental component in today’s fiber optic network. It is the core of fiber optic connectivity in communication systems. However, many people are only familiar with the most common standard fiber patch cable. In fact, various kinds of fiber patch cables with unique and special functionality are already available in the market. This article will introduce several types of these fiber patch cables and tells you how to identify them.

How to Select Standard Fiber Patch Cable?

When selecting the standard fiber patch cables, the followings are the most frequently asked questions.

• What’s the fiber type of the patch cable? The available selection are Multimode (OM1, OM2, OM3, OM4) and single-mode (OS1 and OS2).
• What’s the connector type and connector polishing type on the two ends of fiber patch cable? Currently the most commonly used fiber patch cables are usually terminated with LC, SC and MPO connectors. For example, an SC LC fiber patch cable is terminated with one SC connector on one end and one LC connector on the other end, while the LC LC cable is with two LC connectors on each end.
• What’s the fiber count of the patch cable? Simplex (one fiber) and duplex (2 fibers) fiber patch cable are very common. For fiber patch cables terminated with MTP/MPO connector or breakout fiber patch cables. Their fiber count would be larger, sometime up to 24 fibers or more.
• What’s the material of the fiber patch cable jacket? PVC, LSZH, Armored, and OFNP are the choice of most situations.

Not All Fiber Patch Cable Are Created Equal

With the wide deployment of fiber patch cables in fiber optic communication, the requests for fiber patch cables are gradually being refined. Fiber patch cables are expected to provide more functions to satisfy various application environments. Actually, many specially made fiber patch cables have been created to meet these requirements. Here are some unique but useful fiber patch cables for your references.

Bend Insensitive Fiber Patch Cable for Lower Signal Loss

Bend loss issues are always a headache problem for most fiber optic network designers and installers. Why? Cause signal loss caused by bend loss issues are really hard to handle. In addition the bend loss issues are difficult to locate. That’s why bend insensitive fiber patch cables are created. Literally, it tells us that this type of fiber patch cable is not as sensitive as other fiber patch cables. The secrets is lays on the fibers which is made of bend insensitive glass. More and more data centers and FTTH systems are tend to use these bend insensitive fiber patch cables, because they do not provide lower signal loss, but also provide a much more durable and easy to maintain networking environment. Fiber optic installer is able to save installation cost with faster installation due to easier fiber optic cable handling.

Keyed LC Fiber Patch Cable for Data Security

Keyed LC fiber patch cable, is also called secured LC fiber patch cable. Because fiber optic connectors on the two ends of fiber patch cables are specially designed as LC connectors, which can ensure the data security at the mechanic level. Keyed LC fiber patch cable is identified by the connector color. Keyed LC fiber patch cable is just a part of the Keyed LC connectivity product family. It should be used with the same colored fiber adapters or fiber adapter panels. Each color of a set of keyed LC connectivity products represents a unique keying pattern that only allows matched color mating. This is how keyed LC fiber patch cable can provide data security for fiber optic network.

Uniboot LC Fiber Patch Cable for Easier Cable Management

Uniboot LC fiber patch cable is a fiber patch cable with two fibers wrapped in the same strand of cable. A duplex LC fiber optic connector which can provide easy polarity reversal is terminated on each end of the uniboot LC fiber patch cable. The following picture show the polarity reversal of a typical uniboot LC fiber patch cable. With less cabling space are require, better cooling is available. With easier polarity reversal, no additional tools are required. And easier cable management can be enjoyed.

HD TAB Fiber Patch Cable for Space Saving

HD (high density) TAB fiber patch cable is a fiber patch cable with its connectors attached with a push pull tab, which can provide easier finger access and cable locating. Today’s fiber optic network is increasing depended on high density which results in difficult finger access and difficult cable management. With a push-pull tab attached on the connector, problem are solved easily. The connecting and disconnection of fiber patch cables will be easier without affecting other surrounding links. Currently most HD TAB fiber patch cables available the market are terminated with LC and MTP/MPO connectors.

HD Uniboot LC Fiber Patch Cable—Space Saving to the Extreme

HD uniboot LC fiber patch cable combine the advantages of uniboot LC fiber patch cable and HD TAB fiber patch cable. Combining two optical fibers in a single cable strand and attaching a push-pull tab on the connectors, HD uniboot LC fiber patch cable can minimize the required cabling spaces to extreme. It is an ideal solution for high density cabling environment.

6 Steps Help You Choose Fiber Optic Patch Cables

Fiber optic patch cable, also known as fiber optic patch cord or fiber patch cord, is one of the most fundamental components in optical communication. Fiber optic patch cables are available in OM1, OM2, OM3, OM4 multimode and OS1, OS2 single-mode types. And each end of the cable is terminated with a high performance hybrid or single type connector comprising of a SC, ST, FC, LC, MTRJ, E2000 connector in simplex and duplex. Usually the fiber optic patch cables are classified by the fiber optic connector types, such as SC fiber patch cord, ST fiber optic patch cord, LC fiber optic patch cord, FC fiber optic patch cord, etc. With so many types of fiber optic patch cables, how to choose the right one for your network? Just follow these 6 steps.

Step 1: Choose the Right Connector Type (LC/SC/ST/FC/MPO/MTP)

On both ends of the fiber optic patch cable are terminated with a fiber optic connector (LC/SC/ST/FC/MPO/MTP). Different connector is used to plug into different device. If ports in the both ends devices are the same, we can use such as SC to SC patch cable, LC to LC patch cable. If you want to connect different ports type devices, LC-SC/LC-ST/LC-FC patch cables may suit you.

Step 2: Choose Single-mode or Multimode Cable Type?

Single-mode fiber patch cord uses 9/125um glass fiber, while multimode fiber patch cord uses 50/125um or 62.5/125um glass fiber. Single-mode fiber optic patch cable is used in long distance data transmission. multimode fiber optic patch cable is use in short distance transmission. Typical single-mode fiber optic patch cable used yellow fiber cable and multi mode fiber optic patch cable used orange or aqua fiber cable.

Step 3: Choose Simplex or Duplex Cable Type?

Simplex means this fiber optic patch cable is with one cord, at each end is only one fiber connector, which is used for bidirectional (BIDI) fiber optic transceivers. Duplex can be regarded as two fiber optic patch cable put side by side, which is used for common transceivers.

Step 4: Choose the Right Cable Length (0.5m/1m/5m/10m/20m/30m/50m)

Fiber optic patch cables are made in different lengths, usually from 0.5m to 50m. You should choose an appropriate cable length according to the distance between the devices you want to connect.

Step 5: Choose the Right Connector Polish Type (UPC/APC)

Since the loss of the APC connector is lower than UPC connectors, usually, the optical performance of APC connectors is better than UPC connectors. In the current market, the APC connectors are widely used in applications such as FTTx, passive optical network (PON) and wavelength-division multiplexing (WDM) that are more sensitive to return loss. But APC connector is usually expensive than UPC connector, so you should weigh the pros and cons. With those applications that call for high precision optical fiber signaling, APC should be the first consideration, but less sensitive digital systems will perform equally well using UPC. Usually, connector color of APC patch cable is green, and of UPC patch cable is blue.

Step 6: Choose the Right Cable Jacket (PVC/LSZH/OFNP/Armored)

Usually, there are three cable jacket types: Polyvinyl Chloride (PVC), Low Smoke Zero Halogen (LSZH) and Optical Fiber Nonconductive Plenum (OFNP). You can see their features in figure below and choose the right one for your network.

Apart from those three types of cables mentioned above, there is another common cable—Armored Cable. The double tubing and steel sleeve construction make these patch cables completely light tight, even when bent. These cables can withstand high crushing pressures, making them suitable for running along floors and other areas where they may be stepped on. The tubing also provides excellent cutting resistance, abrasion resistance, and high tensile strength.

As a global leading designer, manufacturer of high quality components and systems for the photonics industry at competitive prices, FS.COM provides various type of fiber optic cables and fiber patch cords including common single-mode 9/125, OM1 62.5/125, 10GOM3/OM4 patch cables, armored patch cables, fiber optic pigtails, multi core patch cables, MPO/MTP patch cables and other special patch cables, with SC, ST, FC, LC, MU, MTRJ, E2000, APC/UPC terminations including LC to SC patch cable, SC SC patch cords, etc.

Simplex and Duplex Fiber Optic Patch Cable Overview

When talking about fiber optic patch cable, related products that initially come into our mind are single mode and multimode fiber patch cable. However, there are still many other relevant terminologies such as multimode duplex LC LC cable, LC to LC duplex single mode patch cable and single mode simplex cable. For those who are new in this field, there is still much confusion about them. This paper will introduce simplex fiber patch cable and duplex fiber patch cable. In order to have a better understanding of simplex and duplex fiber optic patch cable, the definition of simplex and duplex will be explained in the first part.

What Do Simplex and Duplex Mean?

According to the ITU-T definition, a simplex circuit is one where signals can flow in only one direction at a time. One end is the transmitter, while the other is the receiver and that is not reversible. For example, in TV, audio or visual information flows from transmitter to numerous receivers.

However, at other times, communications can flow in the reverse direction. That is half-duplex. Half-duplex system means a communication channel that operates in one direction at a time and may be reversible. A good analogy for half-duplex system will be two roads with a traffic controller at each end, in order to ensure smooth flow of traffic, the traffic controller only allows one direction at a time. But if one party transmits at the same time, a collision occurs, resulting in lost messages.

“Duplex” comes from “duo” that means “two”, and “plex” refers to “weave” or “fold”. A duplex system has two clearly defined paths with each path providing information in only one direction, that is A to B over one path, B to A over the other. Compared with half-duplex, a full-duplex system, or sometimes called double-duplex allows communication in both directions and allowing this to happen simultaneously. Just like the cellphone, both parties can speak and be heard at the same time.

Simplex vs Duplex Fiber Optic Cables

Simplex fiber optic patch cable consists of a single strand of glass fiber, and is used for applications that only require one-way data transfer. It is commonly used where only one single transmit and receive line is desired. Simplex fiber optic patch cable is available in single mode and multimode. For instance, a single mode simplex fiber patch cable is a great option for data travelling in one direction over long distance.

Duplex fiber optic patch cable consists of two strand fibers of glass structured in a zipcord arrangement where each fiber strand has independent coatings that are linked together by a thin layer of coating material. Duplex fiber patch cable is most used where separate transmit and receive signals are required, that is, one strand transmits in one direction while the other strand transmits in the opposite direction. It is available in single mode and multimode. Multimode duplex fiber optic patch cable or single mode duplex fiber optic patch cable is usually used for applications that require simultaneous and bi-directional data transfer. For example, 10 gigabit multimode duplex cables can support 10 Gb/s bandwidth in both directions within a short distance. LC to LC duplex single mode fiber patch cable can make simultaneous data transfer with LC-LC connectors over long distance.

Conclusion

Through the above analysis, do you have a clearer understanding of simplex fiber patch cable and duplex fiber patch cable? When choosing one over the other, the key factor is that the equipment requires one-way or bi-directional data transfer. FS.COM supplies numerous types of simplex and duplex fiber optic patch cables (or fiber jumpers), such as single mode simplex fiber patch cable, LC to LC duplex single mode patch cable, 10 gigabit multimode duplex cables, LC ST duplex patch cord and so on. I believe you can always find a suitable fiber optic patch cable for your devices here.