Brief Introduction of PM Fiber Patch Cords

Polarization maintaining (PM) fiber optic patch cord is a kind of special fiber patch cord. It can be used in many areas. Here’s what you need to know about PM fiber patch cords if your designs require them.

What is a PM Fiber Patch Cord?

A PM optical fiber is a single mode optical fiber in which linearly polarized light, if properly launched into the fiber, maintains a linear polarization during propagation, exiting the fiber in a specific linear polarization state. PM fiber patch cord is a fiber optic cable made with PM fiber and terminated on both ends with high-quality ceramic fiber connectors. PM fiber patch cord is a base device of optical passive component.

Characteristics of PM Fiber Patch Cords

If the polarization of the input light is not aligned with the stress direction in the fiber, the output light will vary between linear and circular polarization (and generally will be elliptically polarized). And the exact polarization will also be sensitive to variations in temperature and stress in the fiber. The light shall be coupled at the fiber entrance parallel to the slow axis or to the fast axis, then the maintaining of the polarization is therefore possible. It is important to make sure that the polarization of the input light is maintained. PM fiber patch cords maintain the existing polarization of linearly-polarized light that is launched into the fiber with the correct orientation. PM fiber patch cords also feature low insertion loss, high extinction ratio, high return loss, excellent changeability over a wide wavelength range and excellent environmental stability and reliability.

Types of PM Fiber Patch Cords

There are a wide variety of PM fiber patch cords available that support different data rates and suit various connector types. According to different criteria, PM fiber patch cords can be categorized into various types. The following is some detailed information about types of PM fiber patch cords based on 4 different criteria:

Classification by connector type―PM fiber patch cords are capped at both ends with fiber connectors. FC, SC, LC and ST are the commonly used connector types for PM fiber termination. According to the connectors on the both ends, there are many different kinds of PM fiber patch cords, such as LC-FC, SC-FC, or FC-FC PM fiber patch cords.

Classification by fiber type―PM fiber patch cords are built with polarization maintaining fiber. To ensure the polarization of both the input and output light in a PM fiber, several different shapes of rod are used, and the resulting fiber is sold under brand names such as “Panda” and “Bow-tie”. With different PM fiber, there are corresponding PM fiber patch cords, such as Panda PM fiber patch cords and Bow-tie PM fiber patch cords.

Classification by cable type―PM fiber patch cords can also be categorized according to the cable types. There are mainly three kinds of cable types, 250um bare fiber, 900um loose tube jacket and 3mm loose tube jacket. So based on the cable types, there are 3 kinds of PM fiber patch cords.

Classification by fiber length―The standard length is 1 meter. It can vary for special requirements. The length of PM fiber patch cords can be custom made.

Applications of PM Fiber Patch Cords

PM fiber patch cords are often used in polarization sensitive fiber optical systems for transmission of light that requires the PM state to be maintained. PM optical patch cord is a special optical component using the properties of optical fibers specially manufactured so that its transmission parameters can support a particular application. They have a large number of uses, including high-data-rate communications systems, polarization sensitive components, and interferometric sensors. They are also widely used in PM fiber amplifiers, fiber lasers, high speed communication systems, testing equipment and instrumentation applications. Area of use of PM fiber patch cords is very broad and includes equipment such as instrumentation, spectroscopy, aerospace, medical diagnostics and many other industrial applications.

What Is Fiber Optic Pigtail and How to Splice It?

In fiber optic cable installation, how cables are attached to the system is vital to the success of network. If done properly, optical signals would pass through the link with low attenuation and little return loss. Fiber optic pigtail offers an optimal way to joint optical fiber, which is used in 99% of single-mode applications. This post contains some basic knowledge of fiber optic pigtail, including pigtail connector types, fiber pigtail classifications, and fiber pigtail splicing methods.

Fiber Pigtail Specification

Fiber optic pigtail is a fiber optic cable terminated with a factory-installed connector on one end, leaving the other end terminated. Hence the connector side can be linked to equipment and the other side melted with optical fiber cables. Fiber optic pigtail are utilized to terminate fiber optic cables via fusion or mechanical splicing. High-quality pigtail cables, coupled with correct fusion splicing practices offer the best performance possible for fiber optic cable terminations. Fiber optic pigtails are usually found in fiber optic management equipment like ODF, fiber terminal box and distribution box.

Fiber Pigtail vs Fiber Patch Cord: What Is the Difference?

Fiber optic pigtail has fiber connector installed at only one end, and the other end is left empty. While both ends of a fiber patch cord are terminated with fiber optic connectors. Patch cord fibers are usually jacketed, whereas fiber pigtail cables are usually unjacketed for they are usually spliced and protected in a fiber splice tray. Moreover, patch cord fiber can be cut into two pieces to make two pigtails. Some installers prefer to do this to avoid the problem of testing a pigtail cables in the field—just test the performance of a fiber patch cord, then cutting it into halves as two fiber pigtails.

Fiber Optic Pigtail Types

Fiber optic pigtails are available in various types: Grouped by pigtail connector type, there are LC fiber optic pigtails, SC fiber pigtails and ST fiber pigtails, etc. By fiber type, there are single-mode fiber optic pigtail and multimode fiber optic pigtail. And by fiber count, 6 fibers, 12 fibers optic pigtails can be found in the market.

By Fiber Type

Fiber optic pigtails can be divided into single-mode (colored yellow) and multimode (colored orange) fiber. Multimode fiber optic pigtails use 62.5/125 micron or 50/125 micron bulk multimode fiber cables and terminated them with multimode fiber optic connectors at one end. 10G multimode fiber cables (OM3 or OM4) are also available in fiber optic pigtails. The jacket color of 10G OM3 and OM4 fiber optic pigtail is usually aqua. Single-mode fiber pigtail cables use 9/125 micron single-mode fiber cable and terminated with single-mode fiber connectors at one end.

By Connector Type

According to different types of pigtail cable connector terminated at the end, there are LC fiber pigtail, SC fiber pigtail, ST fiber pigtail, FC fiber pigtail, MT-RJ fiber pigtail, E2000 fiber pigtail and so on. With different structures and appearance, each of them has their own advantages in different applications and systems. Let’s go through some widely used ones.

SC Fiber Optic Pigtail: SC pigtail cable connector is a non-optical disconnect connector with a 2.5mm pre-radiused zirconia or stainless alloy ferrule. SC fiber pigtail is economical for use in applications such as CATV, LAN, WAN, test and measurement.

FC Fiber Optic Pigtail: FC fiber pigtail takes the advantage of the metallic body of FC optical connectors, featuring the screw type structure and high precision ceramic ferrules. FC fiber optic pigtails and its related products are widely applied for the general applications.

ST Fiber Optic Pigtail: ST pigtail connector is the most popular connector for multimode fiber optic LAN applications. It has a long 2.5mm diameter ferrule made of ceramic (zirconia), stainless alloy or plastic. Hence SC fiber pigtails are commonly seen in telecommunications, industry, medical and sensor fields.

Like fiber optic patch cords, fiber optic pigtails can be divided into UPC and APC versions. Most commonly used types are SC/APC pigtail, FC/APC pigtail and MU/UPC pigtail.

By Application Environment

Some pigtail cables are specially installed to withstand the harsh or extreme environments, so here comes armored fiber pigtail and waterproof fiber pigtail.

Armored Pigtail: enclosed with stainless steel tube or other strong steel inside the outer jacket, armored fiber optic pigtails provide extra protection for the fiber inside and added reliability for the network, while reduce the unnecessary damage caused by rodents, construction work, weight of other cables.

Waterproof Pigtail: designed with a stainless steel strengthened waterproof unit and armored outdoor PE (Poly Ethylene) jacket, waterproof fiber pigtail is a great fit in harsh environments, like communication towers, CATV and military. Waterproof pigtail cable boosts good toughness, tensile and reliable performance, facilitating the use in outdoor connections.

By Fiber Count

Fiber optic pigtails could have 1, 2, 4, 6, 8, 12, 24 and 48 strand fiber counts. Simplex fiber optic pigtail has one fiber and a connector on one end. Duplex fiber optic pigtail has two fibers and two connectors on one end. Each fiber is marked “A” or “B” or different colored connector boots are used to mark polarity. Similarly, 4, 6, 8, 12, 24, 48 and more than 48 fibers fiber optic pigtails have their corresponding feature.

Fiber Optic Pigtail Splicing: Easy and Fast Fiber Termination

The quality of fiber pigtail is typically high because the connectorized end is attached in the factory, making it more accurately than a field-terminated cables. It can be attached to optical fibers by fusion or mechanical splicing. Given the access to a fusion splicer, you can splice the pigtail right onto the cable in a minute or less, which greatly speeds the splicing and saves significant time and cost spent on field termination. While for mechanical fiber optic pigtail splicing, it precisely holds a fiber optic pigtail and fiber patch cord together, the joint could be temporary or permanent, enabling light to pass from one fiber to the other. Always ordering fiber pigtail assembly a few feet more than you’ll need. The extra slack allows for splicing errors to be corrected. Besides, selecting fiber pigtail assembly with reliable quality would made the splicing process way easier.

What You Need to Know About Fiber Polishing Machine?

Network cables are maximum absolutely wanted in conversation. They are used to hold indicators from one point to some other. However, many humans have show extra than just any everyday pleasure with the use fiber optic community cable. However, you have to know which you are about to get excited too once you may understand that these fiber optics to your network cable are not simply your common cable that deliver the sign to facilitate verbal exchange.

This fiber optics can do greater in your network cabling efforts. They are so not like your common network cable that contains confined velocity and also have obvious flaws that make more room for development. You should realize more of the things that you will reap from these cables. For one, fiber optics already use light waves as the alerts on your community cable. Thus, you could do away with faltering signal. You can handiest assume outstanding sign with speedy velocity, as rapid as light. There are many blessings in using fiber optic community cable.

Clear sign with outside interference

Fiber Optic Curing Ovens can bring more than one alerts in a single channel, in contrast to regular cable that cannot appear to be confused with extra alerts due to the lack of bandwidth. Moreover, fiber optics can nonetheless defend its signals from any outside interference from different indicators. Optical cable can come up with clear excellent sign because of its balance in opposition to different indicators.

Tight protection in carrying message packets

This is feasible due to the fact breaking light alerts in optical cables is simply difficult. Thus, the message carried thru fiber optics could not be hacked. Ordinary co-axial cables can effortlessly be intercepted with the message in the indicators at once received. If you want a secure communication over the Internet and a stable reference to your TV network, this new fiber optic network cabling can without a doubt help you.

Speedy connection because of light-based totally signals

In fiber optics, the cables would deliver mild rays as alerts. Thus, you can assume that your message will tour as speedy as light. Thus, messages can help maintain up with actual time updates and exchanges. This sort of cable might assist you hook up with the Internet and cable with top speed. When you chat with your different pals over the Internet, you could get hold of their messages fast too.

Stable message regardless of climate

The sign of your cable will not be determined by using the climate situation in your place if you’ll transfer to using fiber optics. By the usage of mild indicators, fiber optics network cables can protect the speed and overall performance of the sign from any modifications in the temperature and different climate changes. Thus, you’ll still get your rapid Internet connection regardless of what’s happening exterior.

How to Use and Maintain Fiber Patch Cables

Fiber patch cables are common assemblies seen in optical communications to link devices and network components. To ensure normal optical transmission and fiber durability, it is necessary to get familiar with the user instructions and precautions. This post will introduce the precaution for taking care of fiber patch cables from the perspectives of connecting, disconnecting, and routine maintaining, which is recommended for you to prevent a series of possible harmful consequences.

Connecting and Disconnecting Fiber Patch Cables

Fiber patch cables can be used with many network devices, such as optical transceiver modules, fiber adapter panels, fiber cassettes, media converters, and other products having fiber optic interfaces. The following part will introduce the general steps for connecting and disconnecting fiber patch cords, taking connecting a fiber patch cable to a transceiver installed in a network switch as an example.

Connecting Fiber Patch Cables

Remove the rubber safety caps covered on the fiber optic connectors at both ends of fiber patch cables and remember to keep these caps well.

Remove the cap from the optical transceiver.

Insert the cable connector into the optical transceiver.

Fix and fasten the fiber patch cables by placing fixing elements on a loop to help cables maintain their shape.

Disconnecting Fiber Patch Cables

Disable the interface in which the optical transceiver is installed by running a command.

Carefully unplug the cable connector from the transceiver.

Cover the transceiver with a rubber safety cap.

Cover the cable connector with a rubber safety cap.

There are some points that should be noted during the connecting and disconnecting process:

The installation personnel needs to be skilled enough with an understanding of the network layout so as to ensure the quality and safety of the installation.

Always wear safety glasses and protective glasses to avoid electric shock or touching fiber shards. Anti static wrist strap band is necessary to reduce static electricity when operating with active devices.

Pay attention to the bending radius of the fiber patch cords. Excessive pulling or squeezing will possibly cause damage to fiber jumpers.

Do not let the jumpers hang free from optical transceivers or run free on the floor randomly. It is very likely to stress the cables at the fastening point or break the cables once pulling the cables accidentally

Never look directly into the end of fiber cables when there is a laser coupled to it for the safety of your eyes.

Avoid frequently inserting or removing fiber patch cables from devices or the fiber end face will produce wear.

Thoroughly clean the working area after the completion of installation.

Maintaining Fiber Patch Cables

The daily maintenance for fiber patch cables matters a lot in the fiber optic system. There are two main aspects to which you should pay attention during routine maintenance.

Keep Fiber Patch Cables Clean

It is often heard that special attention should be given to the fiber optic patch cable cleaning, but are you clear why it is so important? In brief, for reliable and robust fiber optic networks. According to an industry survey by a major telecom company, contamination is the number-one reason for troubleshooting optical networks. Fibers are so fragile that once they are covered by dust or other contaminations, the optical signal can be degraded. What’s more, the metallic particles worn by the bodies and fiber housings of the fiber optic connectors will block a fiber, which will cause signal loss, thus eventually reducing the network performance and causing a great loss for businesses that rely on fiber-optic networks.

Generally, fiber optic cleaning refers to cleaning fiber connectors. How to ensure you clean fiber connectors using correct ways? There are two main cleaning methods: dry cleaning and wet cleaning, each performing different functions. Reel-type fiber cleaners, pen cleaners, fiber cleaning wipes, and foam swabs are the common fiber connector cleaning solutions. More information about these solutions and cleaning steps is available in How Much Do You Know About Fiber Connector Cleaning?

Store Fiber Patch Cables Properly

No matter a fiber cable is in use or out of use, there is one significant point to be considered: Do not bend or stretch your fiber cable too much. It is often the case when working with fiber optic cables, people stretch or bend them. For this reason, the worst case is the fiber may get damaged. Some breakage caused by bending can be visible, but some loss may not, such as microscopic fiber deformations caused by very low temperature, displacement of a few millimeters caused by buffer or jacket imperfections, poor installation practice or other factors. Since such loss can not be seen by the human eyes directly, it will be overlooked and things can get even worse over time. In case of a huge loss when the fiber patch cords must be replaced, the following essential elements need attention:

Design your fiber cable pathway using proper tools or components to protect fibers, such as horizontal cable managers.

Do not bend fiber patch cables beyond their minimum bend radius, especially in those tight spaces of high-density fiber patching areas.

Make sure not to hit the fiber connector against anything! On the one hand, those ends may get abraded or broken. On the other side, broken glass at the fiber end can cut someone’s skin. It is suggested to use protective caps when storing or pulling fibers.

OTDR and optical fiber microscopes are recommended if you need equipment for measuring and identifying any faults such as breaks within the fiber cable or overall attenuation.

Leads to buy the best quality Singlemode Fiber Optic Patch cables?

Many people would answer yes to this question, as from first glance they all look physically similar. However, upon closer inspection and by measuring performance, it is quite obvious that the quality can vary greatly.

For many people in the IT and telecoms industry, a fibre optic patch lead (also known as an optic fibre patch cord) is now considered a commodity item.

However, when choosing to buy the best quality singlemode fibre optic patch leads, the following should be considered:

What is Fibre Optic Patch Lead Connector Grade (Performance)?

IEC standards dictate the connector performance requirement for each grade of fibre optic patch lead connector. These standards guide end users and manufacturers in ensuring compliance with best practices in optical fibre technology.

Generally, Grade A, B or C options are available, with Grade A providing the best performance.

According to IEC 61753 and IEC 61300-3-34 Attenuation Random Testing Method, ‘Grade C’ connectors have the following performance characteristics: Attenuation: 0.25dB mean, >0.50dB max, for >97% of samples. Return Loss: >35dB.

‘Grade B’ connectors have the following performance characteristics: Attenuation: 0.12dB mean, >0.25dB max, for >97% of samples. Return Loss: >45dB.

‘Grade A’ connector performance (which is still yet to be officially ratified by IEC) has the following performance characteristics: Attenuation: 0.07dB mean, >0.15dB max, for >97% of samples. While the Return Loss using IEC 61300-3-6 Random Mated Method is >55dB (unmated – only angled connectors) and >60dB (mated), this performance level is generally available for LC, A/SC, SC and E2000 interfaces.

What Singlemode Optic Fibre Types are available?

For singlemode fibre optic patch leads, two fibre types are generally available, G652D or G657A2.

G652D and G657A2 specifications refer to the glass and cable construction of optical fibre and are generally the fibres of choice in optical fibre patch leads for singlemode systems.

657A2 optical fibre in patch leads, provide an improved bend radius and flexibility, which may allow for better cable management and routing in congested areas. The improved bend radius may also allow for increased density in high-density patching fields. G657A2 optical fibre is becoming very popular in Data Centre and Enterprise network deployments.

What are Optical Fibre Connector types?

For singlemode optical fibre patch leads, the following connector types are available, LC, SC, SC/A, ST, FC, E2000.

The most common types of connectors used in modern transmission systems are SC, SC/A and LC (either simplex or duplex connectors).

Selecting the correct patch lead connector type is usually dictated by the transmission equipment or patch panel that the patch lead needs to connect with.

Why the Optical Fibre Cable Diameter is important

In high-density patching areas, the selected patch lead cable diameter can either increase or decrease congestion. It is generally recommended that simplex fibre optic patch leads have a diameter of approximately 2mm.

When selecting duplex singlemode fibre optic patch leads, there are a couple of options. Firstly, a figure 8 (2 x 2mm cords) patch cord is available, with each connector being physically separated (simplex connector). Secondly, the more common option for duplex fibre patch leads is a round 3mm duplex cable. This option requires the use of a uniboot duplex fibre optic connector, however, the smaller cable diameter helps reduce congestion in patching fields.

100G QSFP28 Optical Transceiver Comparison

Nowadays, the trend for 100G Ethernet network is bullish and inevitable. Thus, the demands for 100G modules are becoming greater and greater that account for a relatively high proportion of network construction costs. Among various 100G optical transceivers that are capable of connecting 100G traffic, the 100G QSFP28 optical transceiver is the most preferred module for smaller size and lower power consumption. What are 100G QSFP28 optical transceivers? What are the differences between them? How do we choose 100G QSFP28 optics? Today, we will make a comprehensive comparison of 100G QSFP28 optical modules for you.

What Is 100G QSFP28 Optical Transceiver?

The 100G QSFP28 optical transceiver is designed for 100 Gigabit Ethernet, EDR InfiniBand, or 32G Fibre Channel. It generally has the exact same footprint and faceplate density as 40G QSFP+. Just as the 40G QSFP+ is implemented using four 10Gbps lanes, the 100G QSFP28 module is implemented with four channels of high-speed differential signals with data rates ranging from 25Gbps up to potentially 40Gbps. With an upgrade electrical interface, the QSFP28 100G transceiver is capable of supporting signals up to 28Gbps. QSFP 100G SR4, QSFP 100G LR4, QSFP 100G PSM4, QSFP 100G CWDM4, and QSFP 100G ER4 are the five common types of 100G QSFP28 modules designed to meet the different transmission distance requirements. Compared with 100G CFP/CFP2/CFP4 transceivers, the 100G QSFP28 module surpasses them with the strong ability to increase density, decrease power consumption, and decrease the price per bit.

Differences between the 100G QSFP28 Transceiver

In this section, we will describe the differences between these 100G QSFP28 optics from the perspectives of standards, laser types, transmission media and transmission distances.

100G QSFP28 Optical Module Standards

The 100G QSFP28 optical module standards are mainly defined by two key organizations, namely IEEE and Multi Source Agreement (MSA). The QSFP28 SR4, QSFP28 LR4, QSFP28 ER4 are defined by the IEEE. How to clarify these three items from their names? The ‘QSFP’ means the form factor; ‘28’ represents that each lane has a maximum transmission rate of 28Gbps; ‘SR’ means short reach (100m), ‘LR’ is long reach (10km) and ‘ER’ is extended reach (40km). ‘4’ represents that the module has 4 lanes. For example, the QSFP28 LR4 means that it is a long reach 100G module which can transmit 100G signals over four wavelengths with a transmission distance of 10km.

100GBASE-SR4 and 100GBASE-LR4 are the most commonly used 100G interface specifications defined by the IEEE. However, the transmission distance of QSFP28 SR4 is too short to meet all interconnection requirements and the cost of QSFP28 LR4 is too high for large data centers. Therefore, MSA brought a solution for mid-range connectivity to the market and defined the standards of QSFP28 PSM4 and CWDM4. Although the capability of QSFP 100G LR4 completely covers QSFP28 CWDM4, but the QSFP 100G CWDM4 solution is much cheaper and more competitive than QSFP28 LR4 in the scenario of 2km transmission.

The VCSEL laser features with small size, low power consumption, easy integration, low price and high coupling efficiency with multimode fibers, which is often used for QSFP28 SR4 modules. The QSFP28 LR4 and QSFP28 ER4 optics are used for long-distance transmission (10km or 40km), which need lasers with advantages of large eye volume, small dispersion, large extinction and long distance. The EML is designed to meet all those requirements for QSFP 100G LR4 and QSFP 100G ER4 transceivers. The DML can realize the signal modulation through the way of modulating the injection current of the laser. Since the magnitude of the injection current changes the refractive index of the active region of the laser, causing wavelength drift to generate dispersion. Thus, it is difficult to achieve high-speed signal modulation and it can not transmit for a very long distance. Thus, the DML laser is suitable for QSFP28 PSM4 and QSFP28 CWDM4 modules with a transmission distance of 500m or 2km.

QSFP 100G Transmission Media & Transmission Distance

The 100G QSFP28 optical transceivers are equipped with LC duplex or MTP/MPO-12 connectors, which transmission distances vary from 70m to 40km. The transmission distances of the QSFP28 optics decide the application scenarios of them. All the QSFP28 100G transceivers can be applied to direct connection, interconnection in enterprises and data center networks. The following diagram shows the specific differences of the QSFP 100G optics.

How to Select the 100G QSFP28 Optical Transceiver?

After introducing the differences of the various kinds of 100G QSFP28 optical transceiver, you may have a basic understanding of them. How to choose your QSFP28 100G modules in the practical application? Here is a selection guide for you.

For transmission distance between 5m and 100m, you can choose the QSFP28 SR4 optical transceiver module, it can transmits 70m using OM3 fibers or 100m using OM4 fibers.

For transmission distance between 100m to 2km, you can choose QSFP 100G PSM4 or QSFP28 CWDM4 modules. The cost of QSFP28 CWDM4 is much higher than the QSFP28 PSM4. However, the QSFP28 CWDM4 requires only two single mode fibers in two-way transmission which is much less than the eight single mode fibers of QSFP28 PSM4, the total cost of the QSFP 100G PSM4 raises very quickly. In practical applications, it is necessary to decide whether to use QSFP28 PSM4 or QSFP28 CWDM4 depending on the interconnection distance.

For transmission distance between 10km to 40km, you can choose QSFP 100G LR4 which has a maximum transmission distance of up to 10 km or QSFP28 ER4 transceivers which transmission distance can reach up to 40km.