Category: Fiber Transceivers

Optical transceivers, Active Optic Cables, data center switches, and cable management in data centers.

Do You Have Any Idea of Water-Resistant Fiber Optic Cable?

by http://www.fiber-mart.com

There is no doubt that fiber optic cables play an integral role in telecommunication industry. Applications like data centers, local area networks, telecommunication networks, industrial Ethernet, and wireless network are all needing fiber optics to ensure smooth connectivity. Each application requires a specific cable design based on performance requirements, environmental conditions, and installation type. The common fiber optic cables like LC to LC patch cord cannot adapt to the harsh environment (e.g. moisture environment or underground deployment), thus water-resistant fiber optic cables are highly demanded on the market due to their water proof nature. Here is what you should know about the water-resistant fiber optic cable.
Overview of Water-resistant Fiber Optic Cables
Water-resistant fiber optic cable refers to the special type of fiber optic cable that are designed and specified for installations where the cable will come in contact with water or moisture, such as aerial, direct buried, or in conduit. The cables in these applications are exposed to or can be temporarily submerged in water, so they contain either a water-resistant gel-filled or gel-free (dry gel) polymer.
Generally, fiber optic cables can be divided into three types—outside plant cable (OSP), indoor/outdoor, and indoor, which are specified based on the environment and location where they are installed. With the exception of indoor cables, all cables contain water-resistant gel-filled or gel-free material to protect them from water and moisture. Before the use of gel-filled and gel-free materials, flooded core was another water-blocking method that is rarely used today (it has been replaced with gel-filled). The following image shows the gel-filled cables.
water_tolerance
The gel is a gooey substance that must be removed when accessing and installing the cable. Gel-free cables, which are now more widely used, contain a super-absorbent polymer powder that is activated when it comes in contact with water or moisture. This blocks the water from penetrating the cable and allows for some expansion and contraction with temperature changes. Indoor cables do not contain water-resistant material since they are not typically exposed to water. Indoor (and indoor/outdoor) cables must meet additional flammability requirements dictated by local codes, such as the National Electrical Code.
Tight-Buffered & Loose Tube Cable Construction Provides Excellent Moisture Resistance
Water-resistant materials and cables are included in many industry specifications and standards. Generally, there are two basic water-resistant cable designs: Tight-buffer cables (primarily used inside buildings), Loose tube cables (used for OSP and indoor/outdoor).
It is known to all that most tight-buffered cable designs (seen in image below) are specified for indoor use, but some of them are designed with water-resistant powder and yarn, making them suitable for some indoor/outdoor applications. This tight-buffered cable utilizes an different design approach to deal with the moisture issue. Buffer materials are low-porosity plastics with excellent moisture resistance. This construction very effectively minimises the water molecule and OH-ion concentration level at the glass surface and virtually eliminates the stress corrosion phenomenon.
tight-buffered-cable
In loose tube cables (seen in image below), in order to prevent the water from reaching the 250Ľm coated fibers, the tubes surrounding the fibers must be filled with water-absorbent powder or gel that withstands high-moisture conditions, making them excellent for outside plant applications. This approach is especially made to waterproof the cable by filling the empty spaces in the cable with gel. The gel-filled tubes can also expand and contract with temperature changes, which makes loose-tube cable great for harsh, high-humidity environments where water or condensation can be a problem. However, gels can move, flow, and settle, leaves an uncertainty of the filled level of any particular point of a loose-tube gel-filled cable. Because loose-tube cable is typically 250 microns, you’ll need a fan-out kit to build up the individual fiber strands to 900 microns when making the transition at the entrance point from outdoor loose-tube to indoor to tight-buffered cable.
loose-tube-cable
The same level of protection remains in place all along the fiber, regardless of installation conditions, environment, or time. The balance of the tight-buffered, tight bound cable designs is such that it minimizes the open spaces available in the cable structure in which water can reside. Even if an outer cable jacket is cut, or water otherwise enters the cable structure, only a very small percentage of the cross-sectional area is open to water.
Conclusion
When selecting the suitable fiber optic cables, one must consider the application, the installation location, and the appropriate cable design and type according to specifications and standards. The water-resistant optic cable is specially made for moisture environment to insure the smooth connectivity. However, whether to have the loose tube fiber optic cable or tight buffered cable, it depends on the installation location. fiber-mart.COM offers a full range of fiber optic cables at very economical rates. These cables are widely used and are highly demanded on the market due to their water proof nature. In addition to this, we offer these cables in various fiber optic cable specifications, such as duplex/simplex fiber cable, single-mode/multimode fiber optic cable, LC/FC/SC/ST fiber optic cable and so on. LC to FC patch cord is absolutely high quality and low price, just as the other fiber optic cables. If you want to know more about our products, please contact us directly.

 

Brief Introduction to Network Adapter

Generally for a home network, the most important consideration is the speed you have contracted for with your Internet service provider (ISP). And network adapters as an important element in wire management, are required to connect to the Internet with or without an Ethernet cable. There are many types of network adapters, an wireless one can help people connect to the home or office network as long as the computer is in the vicinity. This article will provide some information about network adapters that may be useful to potential buyers.
Main Features of Network Adapters
The wireless network adapter is quite similar to a memory stick in appearance. The device will usually insert into a USB port and has a LED light that indicates operability and power. The devices can be portable and quite effective. Some are slightly larger and may be the size of a credit card. Because of their size, the devices are convenient and easy to install. More designers are coming to appreciate the compactness of network adapters.
network adapter
When the device is pled in, it will scan for local networks to connect to and display them for the user. Users simply have to click the name of the network they wish to join. Any credentials that need to be provided should be provided, and this is all it requires to surf the network wirelessly. Most devices only require the credentials once, and it will boot each time it’s logged in.
The Important of Network Adapter
Network adapters are necessary for those who desire network connectivity. Network adapters bring so much more functionality and flexibility when it comes to connecting to the Internet. Wireless network adapters are even more desirable. Designers are recognizing that network adapters are instrumental to the success of the device. Local technology companies can provide network adapters at an affordable price to clients who need the functionality and the scalability. Network adapters are instrumental to connecting single or multiple devices to the Internet.
Software Drivers Are Necessary
Wireless network adapters need a piece of software called a device driver. These network drivers will allow applications to communicate with the network adapter hardware. When the network drivers are communicating with the hardware, the devices operate easier. Drivers can make current and past technology more compatible. If an upgrade is necessary from a PCI card or a PCMCIA, USB devices with update driver software is the preferable choice.
Backwards and Forwards Compatibility
Laptop computers will come equipped with a built-in WiFi card. When the wireless standards change and a new card is required, network adapters are usually backwards and forwards compatible. This is desirable if you want the newer and faster standard. For instance, most network adapters will support both the 802.11g standard and the 802.11n standard to ensure that they are both backwards and forwards compatible.
However to Ensure the Performance of Your Network Adapter
The network interface is where the data hits the computer. It’s the port or WiFi adapter that receives the data from the air or cable and translates it into something the computer can understand. No matter how fast the data arrives at the interface, it will only pass through as fast as the interface can process it. Many things can slow it down.
It’s important to remember that an interface that is capable of higher speeds than your network provides will not help things go faster. Spending money on a Gigabit network card won’t give you 1000 Mbps if your ISP is only supplying 25 Mbps.
Furthermore, a Ethernet cable in a cable management systems used to achieve the connectivity will also pose threat to the internet speed. Ethernet cables are presented in different categories. The most commonly used is Cat5, Cat5e and Cat6. CAT 5, rated at 100 Mbps; CAT 5e rated at 1000 Mbps; and CAT 6 rated at 10,000 Mpbs. CAT 5 is fine for most internet access through DSL or cable, while CAT 5e works well on connections over 100Mbps, as well as Gigabit business networks and home fiber optic connections. CAT 6 is probably overkill for most home networks, but is useful for business networks over 1 Gbps.
Other than cables used in home network, there are other factors that can throttle the performance of your network. Therefore, to use an external test server tests not only your home setup, including your adapter, but everything between you and the server doing the test.

Introduction to 40G QSFP+ Cabling Assemblies

Today’s high-performance computing environments featuring by switching and routing, cloud computing and virtualization require higher network speeds, greater scalability, and higher levels of performance and reliability in data centers. Some bandwidth-hungry applications, like video streaming applications, also drive data rates to higher points. These all boost the need for a migration to 40G and 100G interfaces as 1 and 10G can’t meet the bandwidth needs well. 40G interface is QSFP (Quad Small Form-factor Plable) which has several standards requiring different connectors to fit cabling infrastructure, so as to achieve network connectivity. Do you know what cabling infrastructure is needed to support 40G applications? MPO/MTP cable, direct attach cable (DAC), or LC fiber patch cable? Have any ideas? Follow this article and find the answer.
MTP/MPO Cable
MTP is a registered trademark of US Conec used to describe the connector, and MPO stands for multi-fiber push-on or also multi-path push-on. Actually, the former product is 100% compatible with the latter. Thus, only MTP is written for simplicity in the following paragraphs. In 2010, the IEEE 802.3ba standard specifies MTP connectors for standard-length multi-mode fiber (MMF) connectivity. Its small, high-density form factor makes MTP cable ideal for higher-speed 40G networks in data centers.
To support 40G applications, a 12-fiber MPO connector is needed. The typical implementations of MTP plug-and-play systems split a 12-fiber trunk into six channels that run up to 10 Gigabit Ethernet (depending on the length of the cable). 40G system uses 12-fiber trunk to create a Tx/Rx link, dedicating 4 fibers for 10G each of upstream transmit, and 4 fibers for 10G each of downstream receive, leaving the middle 4 fibers unused. The upgrade path for this type of system entails simply replacing the cassette with an MTP-to-MTP adapter module.
Direct Attach Cable
Besides MTP cable, many data centers also like to choose DACs for 40G cabling infrastructure. DAC, a kind of optical transceiver assembly, is a form of high speed cable with “transceivers” on either end used to connect switches to routers or servers. The “transceivers” on both ends of DACs are not real optics and their components are without optical lasers, thus DACs are much cheaper, preferable for 40G data center applications. As such, the fiber connectivity cost is significantly reduced by using either direct attach copper cables or active optical cables (AOCs) instead of costly fiber transceivers and optical cables.
Direct Attach Copper Cable
Direct attach copper cables are designed in either active or passive versions for short-reaches in data center. Compared with active optical cables, these copper cables are less expensive. Nowadays, there are many twinaxial cables available to support 40G (10G x four channels), in QSFP+ to QSFP+ (ie. EX-QSFP-40GE-DAC-50CM) version or in QSFP to 4 SFP+ cable assembly (eg. QSFP-4SFP10G-CU5M).
The issue is that copper cable is stiff and bulky, thus consuming precious rack space and blocking critical airflow. But with the advancing technology, manufactures produce a thinner, uniquely shielded ribbon-style twinaxial cable that can support speeds of 10G per channel while addressing many of the concerns associated with round, bundled cable. And the ribbon-style twinaxial cable is significantly slimmer than its round counterparts. Even better, the cable can be folded multiple times and still maintain signal integrity, allowing for higher density racks and space savings.
Active Optical Cable
Being a form of DAC, AOC integrates single-mode fiber (SMF) or MMF cable terminated with a connector and embedded with transceivers. It uses electrical-to-optical conversion on the cable ends to improve speed and distance performance of the cable. AOCs can reach a longer distance copper cables, and use the same interfaces as copper cables, typically used in data center. Similar to direct attach copper cables, AOCs are also available in QSFP+ to QSFP+ (eg. QSFP-4X10G-AOC20M) and QSFP+ to 4 SFP+ cabling (ie. QSFP-4X10G-AOC10M) versions.
Since 40G AOC connectors are factory pre-terminated, 40G AOC is easier for installation and thus less affected by the repeating plug during daily use than MTP cable. In case there was a fault in the interconnection, for AOC, you can just replace it with another AOC.
LC Fiber Cable
Certainly, LC fiber cable can also be the cabling solution for the long-reach 40G QSFP+ modules (40GBASE-LR4). That is, 40GBASE-LR4 QSFP+ uses a duplex LC connector as the optical interface, able to support transmission distance up to 10km over single-mode fiber (SMF).

Learning Five Ways to Test Fiber Optic Cables

In this technological world filled by fiber optic systems everywhere, one won’t fail to enjoy the benefits brought by fiber optics in daily life. In a whole fiber optic system, the most essential part should be the fiber optic cable. This cable is made up of incredibly thin strands of glass or plastic capped with the same (eg. ST ST fiber cable) or different connector types (LC ST patch cable) on the ends, used as the medium to carry information from one point to another with light-based technology. Just like electricity that can power many types of machines, beams of light can carry many types of information, so fiber optics do great to people in many ways, like broadcasting, transportation, medicine, etc..Along with the heavy use of fiber optic cables, testing the installed cables also gains importance in practical use. Since there are many standards available for testing, some people may get confused. But don’t worry. This text is written with an attempt to clear off this confusion.
Testing Principles
Generally speaking, five ways are listed in various international standards from the EIA/TIA and ISO/IEC to test installed cable plants. First three of them use test sources and power meters to make the measurement, while the last two use an optical time domain reflectometer (OTDR). Let’s first see the different results from these methods, and then delve into each one.
The use of source and power meter method, also known as “insertion loss”, simulates the way the actual network uses the cable plant. The test source mimics the transmitter, and the power meter the receiver. But insertion loss testing requires reference cables attached to the source and meter to connect to the cable under test. This insertion loss test can use 1, 2 or 3 reference cables to set the “zero dB loss” reference for testing. Each way of setting the reference gives a different loss. While OTDR is an indirect method, using backscattered light to imply the loss in the cable plant, which can have large deviations from insertion loss tests. OTDRs are more often used to verify splice loss or find damage to cables.
Source/Power Meter Method
In source and power meter method, all the three tests share the same setup (shown below), but the reference power can be set with one, two or three cables as explained next. In general, the 1 reference cable loss method is preferred, but it requires that the test equipment uses the same fiber optic connector types as the cables under test. If the cable (ST ST fiber cable) has different connectors from the test equipment (SC-SC on the tester), it may be necessary to use a 2 or 3 cable reference, which will give a lower loss since connector loss is included in the reference and will be subtracted from the total loss measurement.
Reference per TIA OFSTP-14 (1 Cable Reference)
This method, formerly called method B, uses only one reference cable. The meter, which has a large area detector that measures all the light coming out of the fiber, effectively has no loss, and therefore measures the total light coming out of the launch reference cable. When the cable is tested as below, the measured loss will include the loss of the reference cable connection to the cable plant under test, the loss of the fiber and all the connections and splices in the cable plant and the loss of the connection to the reference cable attached to the meter.
Reference per TIA OFSTP-14 (2 Cable Reference)
This one, formerly called method A, uses two reference cables with one launch cable attached to the source, and the other receive one attached to the meter. (The two cables are mated to set the reference.) Setting the reference this way includes one connection loss (the mating of the two reference cables) in the reference value. When one separates the reference cables and attaches them to the cable under test, the dB loss measured will be less by the connection loss included in the reference setting step. This method gives a loss that’s less than the 1 cable reference.
Reference per TIA OFSTP-14 (3 Cable Reference)
Reference cables are often patch cords with plugs, while the cable under test has jacks on either end. The only way to get a valid reference is to use a short and good cable as a “stand-in” for the cable to be tested to set the reference. To test a cable, replace the reference cable with the cable to test and make a relative measurement. Obviously this method includes two connection losses in setting the reference, so the measured loss will be less by the two connection losses and have greater uncertainty. Finally, here goes the picture showing the testing case with one, two, three reference cables.
OTDR Testing
With only one lunch cable, the OTDR can measure the length of the cable under test and the loss of the connection to the cable under test plus the loss of the fiber in the cable under test, and any other connections or splices in the cable under test. However, this method doesn’t test the connector on the far end of the cable under test, because it isn’t connected to another connector, and connection to a reference connector is necessary to make a connection loss measurement.
If a receive cable is used on the far end of the cable under test, the OTDR can measure the loss of both connectors on the cable under test as well as the fiber in the cable, and any other connections or splices in the cable under test. The placement of the B marker after the connection to the receive cable means some of the fiber in the receive cable will be included in the loss measured.

 

Four Aspects About Multi-mode Fibers

Data centers are never ceased their steps to bring greater speed and efficiency to telecommunication and datacoms industries. An enormous amount of data is transmitted, gathered and analyzed everyday, all which requires a vast number of high-bandwidth interconnections between data centers, and people. During these interconnections, fiber optic cables see their heaviest use.
Fiber optic cables can deliver more bandwidth for voice, video and data applications, and carry thousands of times more information than copper wire. With fiber optic cables, reliable and secure data transmission is ensured. Fiber optic cables are available in single-mode and multi-mode versions based on transmission mode standard. This article puts its focus on the latter version: multi-mode fiber (MMF), discussing MMF from its core size attenuation, bandwidth and manufacturing ways.
MMF: Larger Core Size
It’s known that MMF has a much larger core size and cladding diameter, whose different types are distinguished by jacket color: for 62.5/125 µm (OM1) and 50/125 µm (OM2), orange jackets are recommended, while aqua is recommended for 50/125 µm “laser optimized” OM3 and OM4. MMF’s larger core endows it greater light gathering capacity, allowing multiple modes of light to propagate through the fiber simultaneously. Thus, MMF is more suitable for relatively shorter-reach application, usually less than 600m. When it’s deployed in GbE applications, the maximum reach is 550m in combination of 1000BASE-SX SFP (ie. 1783-SFP1GSX).
MMF: Attenuation/Signal Loss
Attenuation refers to the reduction of signal loss when light travels through the fiber optic cable, which is measured in decibels per kilometer (db/km). Insertion loss is the total attenuation from all sources plus any reflection losses over a specific fiber length. Such attenuation is often caused by absorption of optical energy by tiny impurities in the fiber such as iron, copper, or cobalt. Sometimes, the scattering of the light beam as it hits microscopic imperfections, called Rayleigh scattering can also lead to signal loss phenomenon. Attenuation problem is a commonplace in MMFs.
MMF: More Bandwidth
Bandwidth quantifies the complicated data-carrying capacity of MMF, given in units of megahertz-kilometer (MHz·km). Bandwidth behavior of MMF arises from multi-modal dispersion (multi-path signal spreading) which happens as the result of light traveling along different modes in the core of fibers. The bandwidth specification of performance of a MMF is verified through optical measurements during fiber manufacture. Actual system performance and data-rate handling rely heavily on bandwidth, affected by transceiver technology and device characteristics.
MMF: Manufacturing Ways
MMF can be manufactured in two ways: step-index or graded index.
Step-index fiber has an abrupt change or step between the index of refraction of the core and the index of refraction of the cladding. Multi-mode step-index fibers have lower bandwidth than other fiber designs.
Graded index fiber is designed to reduce modal dispersion inherent in step index fiber. This design maximizes bandwidth while maintaining a larger core diameter for simplified system assembly, connectivity and lower network costs. Graded index fiber is made up of multiple layers with the highest index of refraction at the core. Each succeeding layer has a gradually decreasing index of refraction as the layers move away from the center. High order modes enter the outer layers of the cladding and are reflected back towards the core. Multi-mode graded index fibers have less attenuation (loss) of the output pulse and have higher bandwidth than multi-mode step-index fibers.
MMF related transceivers: Multi-mode Transceivers
A fiber optic transceiver is a package, usually a plable module, comprising of a receiver on one end of the fiber and a transmitter on the other end. Over the years, multi-mode bandwidth specifications and measurement methods have evolved along with the transceiver technology, so as to keep up with delivery of higher transmission speeds. The combination of transceiver and fiber optic cable plays an important role in fiber’s practical link length. As for multi-mode transceivers which have larger core, they are often used in short-reach applications with 850mn wavelength. Listed below are several commonly-used multi-mode transceiver ports: 1000BASE-SX, 10GBASE-SR, 10GBASE-LRM, among which 10GBASE-SR port type enjoys widely deployment in 10GbE applications when the required distance is not so long. Take F5-UPG-SFP+-R for example, this F5 compatible 10GBASE-SR SFP+ transceiver listed in Fiberstore takes OM3 MMF as its transmission medium for 300m reach.
Besides what have been discussed above, there is also another MMF feature that comes into your mind: that is the affordability. MMF is less expensive than its counterpart single-mode fiber (SMF). Because of this, more people prefer MMF to SMF when the required distance is not so long. Thus, this big saving can be re-invented in other projects.

 

Three Useful Fiber Patch Cords and Their Use

With the rapid advancement of fiber optic technology and trend towards optical communications, fiber optic patch cord has realized its great use in high speed data transmission networks, found in routers, fiber patch panels, media converters and even in hubs and switches. Compared to its previous counterpart, fiber optic jumper causes lower signal loss, delivers more bandwidth and carries more information, becoming more and more popular in cabling installation or upgrading between or inside buildings. Just like the transceiver modules which fall in many types based on different standards, fiber optic patch cables are also available in several kinds, including single-mode/multi-mode, simplex/duplex, MPO/MTP cable, armored patch cord, and so on. This article aims to introduce the last three useful fiber patch cords and their use.
Simplex/Duplex Patch Cables
Simplex cable, also known as single strand cables, has one fiber, tight-buffered (coated with a 900micron buffer over the primary buffer coating) with Kevlar (aramid fiber) strength members and jacketed for indoor use. The jacket is usually 3mm (1/8 in.) diameter, but some 2mm cable is sometimes used with small form factor connectors. Duplex (zipcord) cable has two fibers joined with a thin web.
Since simplex patch cord consists of only one fiber link, it’s used in such applications that only require one-way data transfer. But when the equipment can transmit and receive on two different wavelengths, simplex cable can also be considered. For example, transmit could be at 1310nm and receive could be at 1550nm. This application is found more with single-mode simplex patch cable.
Duplex patch cable is suitable for applications that require simultaneous, bidirectional data transfer. Typical applications include workstations, fiber switches and servers, Ethernet switches, backbone ports, and similar hardware.
MPO/MTP Cable
MPO/MTP cable uses multi-fiber MPO/MTP connectors for setting up high-performance data networks in data centers, so as to achieve greater bandwidth and handle network traffic requirements. Specifically, in MPO/MTP cable component, each one of the connector are used with ribbon type fiber optic cables which contain multi-fiber in one single jacket, so that MPO/MTP patch cord greatly saves space, very convenient to use. Based on single ferrule MT technology, the MPO/MTP cable assemblies are able to provide up to 72 fiber connections in a single point, reducing the physical space and labor requirement, while providing the same bandwidth capacity of a multi-fiber cable with individual fiber connector terminations per cable. MTP cables can be divided into trunk and harness versions (image below).
MPO/MTP patch cables have great use in Gigabit applications, especially in 40GbE. Often, MPO/MTP connectors terminate OM3 or MO4 to form structured cabling, serving as the transmission medium for 40GBASE optics (ie. QFX-QSFP-40G-SR4).
Armored Patch Cord
Armored patch cord enjoys all the features of standard fiber patch cord, available in single-mode and multi-mode version (shown below), except its much stronger characteristic. It won’t get damaged even it is stepped by an adult. What’s more, this kind of patch cord is anti-rodents, and when it’s utilized, people do not need to worry that the rodent animals like the rats may bite the cables and make them broken. Although armored fiber cables are strong, they are actually as flexible as standard fiber jumper cords, and they can be bent randomly without being broken.
Armored patch cable can be made with the similar outer diameter to the standard patch cable, which makes it a space-saving design. In addition, armored fiber cables can be with different jacket colors and jacket types, like OFNR. Light in weight, armored fiber patch cords can be with SC, ST, FC, LC, MU, SC/APC, ST/APC, FC/APC, LC/APC types of terminations.
The armored fiber optic patch cords are more robust designed, suitable to be deployed in FTTH projects inside the buildings. They use stainless steel armor inside the jacket to be resistant of high tension and pressure, able to resist the weight of an adult person.