Fiber Patch Cords

The difference between OM3 and OM4 fibers

A fiber-optic is made of glass or plastic and transmits signals in the form of light. Optical fibers use reflection to propagate the light through a channel. A high dense glass or plastic core is surrounded by a less dense glass or plastic cladding respectively. The difference in density of the two materials must be enough to reflect the beam of moving light back into the core, instead of being refracted into cladding. This phenomena is called total internal reflection.

Optical fiber can be used as a medium for communication. It is particularly beneficial for long-distance communications, since the light propagates inside the fiber with very little attenuation as related to copper cables.

The benefits of optical fiber with deference to copper systems are:

Wider bandwidth, a single optical fiber can support many voice calls or TV channels as compared to copper wire. Electrical insulator, optical fibers are non-conductive, so optical fibers can be looped on electric poles alongside high voltage power cables. Resistance to electromagnetic interference, light transmitted through the optical fiber is not affected by nearby electromagnetic radiation, therefore the information transmitted through the optical fiber is protected from electromagnetic interference. Low attenuation loss over long distances, power loss can be as low as 0.2 dB per km in optical fiber, which allows transmission for greater distances without the need for frequent repeaters.

Based on light propagation method, optical fibers can be classified into two main types that are multimode and single mode.  Multimode can be implemented in two forms: step-index and graded-index.

Multimode is so named because multiple beams from a light source move through the core in different paths. How these beams move within the cable, depends on the structure of the core. The word index here refers to the index of refraction. In multimode step-index fiber, the density of the core remains same from the center to the edges. The term step index refers to the suddenness of this change, which contributes to the distortion of the signal as it passes through the fiber. Another type of multimode fiber, called multimode graded-index fiber. As discussed above, the index of refraction is related to density. A graded-index fiber is one with changing densities. Density is much higher at the center of the core and decreases slowly to its lowest at the edge.

Single-Mode uses step-index fiber and an extremely focused source of light that bound the beams to a small range of angles. The single mode fiber is manufactured with a far smaller diameter than that of multimode fiber, and with significantly lower density.

Multimode fibers are identified by the OM (optical mode) label. Before we discuss the difference between OM3 and OM4 fiber types, these are few thing to know which are common in both types. The connectors used for both types are same, the transceivers used in both fibers are the same, since both operate on 850nm VCSELS (Vertical-Cavity Surface-Emitting Lasers), and the fiber size is same 50/125. Also be noted that OM3 is fully compatible with OM4.

Nowadays OM3 and OM4 have been everywhere for years, even if OM4 cable has been in production for about 10 years. However, it was standardized in 2009 and is called OM4 cable since then. Previously it was identified by several names such as OM3+ or Enhanced OM3.

There is just construction difference between both fiber cables. The difference in internal construction of OM4 cable within 50/125 size allows the OM4 cable to operate on higher bandwidth. When measured at 850nm, OM3 operates at a bandwidth of 2500 megahertz, while OM4 has a bandwidth of 4700 megahertz.

An OM3 can support 10 gigabit at 300 meters, whereas an OM4 can support 10 gigabit for a distance of 550 meters. As far as 40 gigabit and 100 gigabit are concerned, OM3 will achieve 100 meters, on the other hand OM4 is capable to reach up to 150 meters.  

As stated earlier, the only variance among an OM3 and an OM4 is the actual fiber cable. The cost for OM4 is higher due to the manufacturing. The wider bandwidth available in OM4 cabling allows longer link lengths for 10 gigabit, 40 gigabit and 100 gigabit systems.

Costs vary depending on the construction type of the cable. However, OM4 cable is much expensive as of OM3 cable. There are several factors at here which are used to figure out whether OM3 or OM4 is needed. But the origin is the cost versus what distances needed. In the perfect example, if someone had abundant resources, they would just use single mode fiber. Since single mode has all the bandwidth one need, so one can go quite of distance but it is very expensive. As most of all data centers have their premises under 100 meters so it really just comes down to a costing issue right there.

What should I watch out for when buying Fiber Optic Patch Cords?

A Fiber Optic Network wouldn’t exist without optical transceivers and patch-cords. They are essential to the functioning of the Fiber Optic Network Architecture. They come in various shape and sizes and knowing which and how to choose them can literally save the entire network of unwanted issues.

The optical transceivers can vary from interface, transmission media and distance, data rate and brand. Luckily CBO BlueOptics© manufacture transceivers of any kind, capable for maximum performance and the most important they are compatible with every vendor’s equipment on the market.

However buying the correct patch cords is a very hard job if you lack in experience and knowledge about Fiber Optics. Even if you feel you are experienced, getting a second opinion from another experienced colleague won’t be a bad idea. When buying patch cords there are many details to keep an eye on but most importantly the transmission media, the transceiver interface (connector), the data rates and distances capability.

From the transmission’s perspective there are two types of transceivers existing, fiber based and copper based transceivers. The Multi Source Agreement (MSA) has identified the most commonly used copper transceivers: 100BASE-T, 1000BASE-T and 10GBASE-T. These transceivers usually have a RJ45 connector so they require the Cat-5/6/7 RJ45 cables for connectivity.

Fiber Optic based transceivers on the other hand are more complicated because they require patch cords for connectivity. There are two types of Fiber Optic Patch Cords: Single- mode and Multi- mode patch cords. Single- mode patch cables are classified as OS1 and OS2 while Multi- mode patch cables are classified as OM1, OM2, OM3 and OM4. Knowing the various types of patch cables and their differences is essential to building a stable Networking environment.

Before digging deeper in their differences let’s see how the whole Fiber Optics concept works.
The Fiber Optic concept is based on converting electrical signals into optical light and sending them through a hair-thin glass or plastic fiber. The light is driven through the core of the fiber cable which is basically the center of the cable. This core is surrounded by an optical material which is called “cladding” which helps keep the optical light in the cable instead of breaking out of it. This is called “total internal reflection”. The CBO BlueOptics© core and the cladding are made of advanced and ultra-pure Corning glass for maximum performance. The whole cable is coated with protective covering and on top of the covering is coated with an outer coating also called “the jacket”. These layers of coating help protect the cable from the outside effects like bending, moisture and temperature.

Single- mode Fibers are fibers with a small core which allow only one string of light to pass through it. With this solution the number of light reflections inside the cable decreases and thus the cable has the capability to drive the light signal further in distance. These cables are used for long distance, high bandwidth applications. There are two types of Single- mode Fibers, OS1 and OS2. The main difference is that OS1 is used mainly for indoor Datacenter application and OS2 is used for outdoor use underground or over ground application.

Multi- mode Fibers are fibers with larger core in diameter and because of it multiple strings of optical light can be driven down the cable. Thus the number of light reflections inside the cable increases and the light bounces in the cable limiting its distance capability. These cables are mainly used in the LAN network or access layers.  There are four types of Multi- mode Fibers, OM1, OM2, OM3 and OM4 which can provide different distances:

MMF Type

1G

10GB

40GB/100GB

OM1

300 meters

36 meters

N/A

OM2

500 meters

86 meters

N/A

OM3

1 kilometer

300 meters

100 meters

OM4

1 kilometer

550 meters

150 meters

When it comes to their connectors, fiber optics connectors are unique to each other. Because the optical cable transmits light signals instead of electrical signals the connector itself must be extremely precise. Instead of metal pins aligning to each other on the both sides of the copper cables, the optical cables must align the microscopic, hair-thin fibers perfectly to each other for the connection to be successful. There are commonly two types of connector designs, simplex and duplex. Duplex consists of two connectors per end and as the name suggests, simplex consists of one connector per end. The fiber optic connector is commonly made of three components: ferrule, a thin structure that holds the glass fiber, connector body, plastic or metal structure that holds the ferrule and a coupling mechanism, a part of the connector that holds the connector in place when it’s connected to a device. BlueLAN© patch cords use a zirconia ceramic ferrule for ultra-quality transmission. The most common connectors are:

  • - Straight Tip Connector (STP) - This is one of the first fiber optics connectors to hit the market. These connectors consist of a 2.5mm ferrule inside of a plastic or metal body. These connectors have a twist on/off type of coupling mechanism.

  • - Subscriber Connector (SC) – These connector also consist of a 2.5mm ferrule for holding the glass fiber. They use a push on/pull off type of coupling mechanism. Their body is square shaped, most commonly made of plastic. This connector have been developed in Japan by one of its leading telecommunication companies NTT.

  • - Lucent Connector (LC) – The Lucent Connector has been developed by Lucent Technologies. Their body resembles the one of the Subscriber Connectors because of its square shape. It has a ferrule of 1.25 mm and they are held together with a clip for duplex configuration.

  • - MPO/MTP Connectors – These connectors are a special type of connectors designed to end multiple fiber strands into a single ferrule. They can commonly support up to 12 optical fiber strands. They have a push on/pull off coupling mechanism. Because of the high number of strands ending into a single ferrule, this type of connector is mainly used for cross-connect and breakout applications. All CBO BlueOptics© MPO/MTP patch cables and connectors fulfill or exceed the latest requirements defined in Telecordia GR-326 and GR-1435. CBO BlueOptics© have the option of up to 72 cores in a single fiber core for even the most complex and bandwidth demanding Datacenter installations. For the installation of these cables the use of MPO/MTP cassette is a must. CBO BlueOptics© offers a wide range of cassettes available with SC and LC ports.

  • - RJ-45 Connectors – These are the standard RJ45 connectors that consist of 8 wire conductors in 8 different positions. They are widely used for Ethernet solutions. CBO manufactures type 5e, 6 and 6a RJ45 connectors. BlueLAN© RJ45 patch cords come with full copper wires and gold coating on the metal contacts to ensure maximum quality connection.

CBO BlueOptics© also develops and manufactures a mix type of cables which have LC-SC and LC-ST connectors.  All CBO BlueOptics© feature a Low Smoke Zero Halogen sheathing.

When buying optical patch cords mainly we should turn our attention to these factors:

  • - Choosing the correct transmission media for our installation
  • - Choosing the cable that will provide the best transmission data rate for that installation

  • - Choosing SMF or MMF depending on the distance of the installation

  • - Choosing the correct optical connector depending on the transceivers used

Following these steps together with the valuable experience will guarantee a hole in one.

PVC vs LSZH Cables

PVC or Poly Vinyl Chloride and LSZH or Low Smoke Zero Halogen are two types of cable sheaths that are commonly used in several types of conductor cables. Every conductor cable requires an insulation to provide protection from electric current flowing through it. Insulation materials are designed keeping in view the installation location, current flow through the cable and flexibility of the cable.

PVC Cables

PVC is the most commonly used synthetic compound used for insulation of copper cables. PVC cables are soft, flexible and light weight. The drawback with PVC cables is that if exposed to fire and flame, they produce a thick black smoke and when combined with water, results in the production of hydrochloric acid (HCl) which is a very corrosive acid and can cause physical injury and damages the other equipment as well in case of fire.

LSZH Cables

To address the above mentioned problem, research and development work was carried out to formulate a compound that is fire retardant and does not produces any harmful substances when exposed to fire. LSZH material was manufactured, LSZH cables are more stiff, corrosive and less flexible.

It is to be noted here that the gases produced by burning LSZH materials is also toxic, extra caution must be taken when exposed to burning LSZH materials. The only advantage of using LSZH cables is that the dangerous gas/acid combination is avoided.

There are two types of LSZH cable jackets:

  • Thermoset LSZH
  • Thermoplastic LSZH

Let us explore the advantages and disadvantages of the above mentioned types.

The Thermoset LSZH cables typically offer improved performance than the thermoplastic LSZH cables. Chlorinated thermoset jackets are commonly used in various applications due to their ability to pass the most rigorous flame tests. LSZH does not have the long track record of performance that chlorinated thermosets possess, and therefore, are questioned about the lifespan and performance of these cables.

Recent advancements in chemistry have allowed manufacturers to develop thermoset LSZH cables that produce the same test results as chlorinated thermosets, such as the IEEE 1202 and UL VW-1 flame tests. A past problem has been the water absorption tests required in many cable standards. LSZH material typically absorbs a greater amount of moisture than non-LSZH material. Moisture absorption affects the physical and electrical properties of the cables. New compounds and processing methods have allowed manufacturers to solve this problem as well.

LSZH cables find their usage in different areas, the most important and practical usage being in the space confined areas, areas with close proximity to human beings and areas where sensitive equipment is installed. Firstly, LSZH cable standards were adopted by military organizations as LSZH cables were a best fit for sub-marines, aircrafts and battle tanks. With the passage of time, LSZH cables are also found in modern datacenters as the modern datacenters contain large amounts of cabling, and are usually enclosed spaces.

LSZH cable technology has advanced significantly. It is very well suited to some of the applications and environments and less suited to some environments due to their specific features. With the on-going research and development work on LSZH cables, it is possible that in the near future, LSZH will become the cabling standard and replace the PVC cabling altogether.

Which Fiber Patch Cord should be used for different Transeiver Types?

Fiber Optic Networks have many features, ready to fulfill every customer’s needs for bandwidth, stability, reliability and most important cost-effective network architecture. There are many manufacturers that are offering their products on the market. Fortunately, most of their products are compatible between them, meaning we can mix and match different products from different manufacturers. However choosing the correct equipment for a specific network design is not a simple task. We must be really good prepared and we must know the properties of every single component of the fiber optic network in order to achieve a stable network architecture with possibility for future upgrades.

One of the key aspects to focus on when designing and deploying a fiber optic network is the connection between the main transmission components, the optical transceiver and the optical fiber cable. The fiber optic transceiver is a type of self-contained, hot swappable component that has the capability to convert electrical input into optical signal and vice versa, and with the help of lasers transmit these optical signals (optical light) down the optical cable. They are a key component for the fiber optic network and its performance. They are inserted in devices like servers, storages, switches and routers in a dedicated port on the device itself. There are many Form-Factors of transceivers with various properties, however the most commonly used are SFP+, QSFP and QSFP28 transceivers. The SFP+ transceivers are Small Form-Factor transceivers capable for speeds up to 16 GB/s and up to 80 kilometers, depending on the fiber type. The QSFP and QSFP28 transceivers are Quad Small Form-Factor transceivers capable for speeds up to 40 GB/s and 100 GB/s. QSFP has a range of up to 40 kilometers and QSFP28 has a range of up to 10 kilometers on Single-mode fibers.

When it comes to fiber optic cables, or fiber optic patch cords, they are composed of a fiber optic cable with a fiber optic connector ending on each end. According to the application they would be used for, they can be divided in several categories:

  • Multi-mode or Single-mode
  • Simplex or Duplex
  • According their connectors

 

When buying an optical cable we must know the distance they would be used for because this is the deciding factor when choosing Multi-mode of Single-mode fibers. Multi-mode fibers can come in four different modes, OM1, OM2, OM3 and OM4 and each of these four modes have different reach capabilities. However Multi-mode fibers are used for short reach because of their bigger core which transmits wider wavelength. Single-mode fibers are used for long reach distances because they transmit a narrower optical light via their smaller, around 9 micrometers, core. Simplex and duplex option explains the number of fiber cores consisted in a fiber optic cable. As the name suggests, simplex consists of one fiber core, while duplex consists of two fiber optic cores. According to their connectors there are many different types of cables. The most common used are cables with duplex LC connectors and the MPO/MTP trunk and breakout fiber optic cable solution. There are also cables with SC, ST, FC, E2000 and other connectors.

When choosing the correct patch cords it’s important to know the compatibility with the transceivers. Their compatibility could be found in their datasheets. When choosing cables with appropriate connectors we should keep in mind that the MPO/MTP connector solutions are the future of optical networking because they can support speeds up to 100 GB/s and they provide a solid ground for future network upgrades. Today for 40 GB/s a 12-fiber MPO/MTP connector is used because only 8 fibers are needed for successful connection, four used for transmitting, four used for receiving and four are left unused. For 100 GB/s solutions the use of 24-fiber MPO/MTP connectors is a must. These MPO/MTP connectors provide a seamless upgrade to 40 GB/s and 100 GB/s solutions. The MPO/MTP connectors are generally used with various QSFP type of transceivers, especially with QSFP28 because QSFP28 transceivers support bandwidth bigger than 40 GB/s, up to 100 GB/s.

The LC connector stands for Lucent Connector because it was firstly designed by Lucent Technologies. This connector has a body build similar to RJ jack style. These connectors are generally used in telecom rooms and network closets of a given organization. They are most commonly used for reach up to 10 kilometers on Single-mode fibers and with SFP+ transceivers.

Today many leading IT managers are searching for a cost-effective solutions while not thinking about the future. Even though it’s more expensive to purchase, the MPO/MTP solution provides a seamless upgrade to new technologies and greater money savings on a long run. Also because of the way they are functioning they consume less space and make the whole maintenance process less complex.