Månadsvis arkiv: March 2016

Pluggable Optical Module Series – Technical Overview

Over the years, data centers have witnessed the enormous increase in data-carrying capacity and constant innovation in optical standard products for higher-level networking services. Greater bandwidth, higher port density, longer distance reach, as well as lower power consumption, all these have populated the deployment of fiber links for high-performance optical networks. To establish such fiber links, pluggable modules, one of the key instruments, are needed in ensuring the high-speed, accurate and secure data transmission. These pluggable optical modules provide customers with flexible options for their interfaces, serving as the convenient and cost-effective solution for a comprehensive range of applications in data centers.

There are a variety of pluggable optical modules available for different uses, including Gigabit Interface Converters (GBICs), Small Form-Factor Pluggable (SFP), SFP+, XFP, C Form-Factor Pluggable (CFP), Quad Small Form-Factor Pluggable (QSFP+), etc. This text mainly gives the technical overview on three types: SFP, XFP, and SFP+.

SFP Module

This bidirectional device, SFP module, is a compact, compatible and hot-swappable transceiver, supporting short or long distance transmission. It contains a transmitter and a receiver in the same physical package.

SFP modules are commonly available in several different categories:

  • 1000BASE-SX—It’s a fiber optic standard Gigabit Ethernet (GbE) standard for operation over multi-mode fiber (MMF) using a 770 to 860nm near infrared (NIR) light wavelength.
  • 1000BASE-LX—This standard is specified to work over a distance of up to 5km over 10µm single-mode fiber (SMF). It can also run over all common types of MMF with a maximum segment length of 550m.
  • 1000BASE-T—Also known as IEEE 802.3ab, this standard is designed for GbE over copper wiring (Cat-5, Cat-5e, Cat-6, Cat-7). 1000BASE-T uses all these four twisted-pair cabling for simultaneous transmission in both directions through the use of adaptive equalization and a five-level pulse amplitude modulation (PAM-5) technique with a maximum length of 100m. Take GLC-TE for example, this Cisco compatible 1000BASE-T SFP listed in Fiberstore is able to realize 100m link length with copper RJ-45.

GLC-TE, Cisco compatible 1000BASE-T SFP

SFP+ Module

The SFP+ module is an enhanced version of the SFP transceiver developed to support data rates up to 16 Gbit/s. The SFP+ specification was first published on May 9, 2006, and version 4.1 published on July 6, 2009. SFP+ supports 8Gbit/s Fibre Channel, 10 GbE and Optical Transport Network standard OTU2.

Just like the SFP, the SFP+ module is also a bidirectional device with a transmitter and receiver in the same physical package. The image below shows the SFP+ module block diagram.

SFP+ module block diagram

  • Transmitter: In the transmit direction, the SFP+ module receives an electrical signal from the host board Asic/SerDes and converts the data to an optical signal through the laser driver that controls the laser diode in the Transmitter Optical Sub-Assembly (TOSA).
  • Receiver: In the receive direction, the transceiver module receives an optical signal through a photodiode mounted together with a trans-impedance preamplifier(TIA), and converts it to an electrical equivalent. Depending on the SFP+ architecture, either a limiting or a linear electrical interface will be implemented on the module.

For a limiting interface, the host ASIC Receive Equalizer compensates the printed circuit board (PCB) trace impairment between the module and the ASIC.

For a linear interface, the host Electronic Dispersion Compensation (EDC) provides the adaptive signal processing that is capable of compensating for impairments due to optical fiber, connector, electro-optics and PCB trace effects.

I2C Management Interface: The third functional capability of the SFP+ module is the 2-wire serial, I2C, interface. I2C is used for serial ID, digital diagnostics and module control functions. The enhanced digital diagnostics monitoring interface allows real-time access to the device, allowing monitoring of received optical power, laser bias current, laser optical output power, etc.

XFP Module

This  module (10Gigabit SFP) is also a bidirectional device with a transmitter and receiver in the same physical package.

XFP, 10Gigabit SFP

  • Transmitter :In the transmit direction, the XFP module receives a 10-Gbps electrical data signal and converts it to an optical signal through an electrical to optical converter. The optical output power is held constant by an automatic power control circuit. The transmitter contains a Clock Data Recovery (CDR) circuit. The function of this circuit is to attenuate and reshape any jitter received on the electrical interface.<
  • Receiver: In the receive direction, the XFP module receives a 10-Gbps optical signal and converts it to an electrical equivalent. The receiver contains a CDR circuit.

These small pluggable optical modules extend distance reach, allowing easy replacement in case that component failures would happen. Fiberstore offers a wide range of transceiver modules, like SFP (GLC-TE), SFP+, XFP, QSFP+ (eg. JG325B). They all are fully compatible with major brands, test-assured and cost-effective. For more information about transceiver modules, you can visit Fiberstore.

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Transceiver Selection Guide for Your Networking Use

Thanks to the advances made in fiber optical technologies, fiber solutions have been deployed in ever-increasing applications where high-speed and high-performance data transmission is needed. They outweigh the copper solutions in such aspects as higher bandwidth, longer distances and Electromagnetic interference (EMI) immunity. Transceivers, one of the key components required in such fiber connections for high networking performance, have experienced the never-ceasing industrial designs, from lower port density to higher, from the standard modules to the final hot-pluggable ones, to meet the ever more flexible networking infrastructure.

There is a broad selection of hot-pluggable transceiver modules available for fiber networking use, and you may feel a little confused about how to select the correct transceivers for your networking transmission. In this article, I will illustrate different aspects of transceivers that need to be known before choosing a transceiver.

Transceiver Basics

Before giving guidance to transceiver selection, it’s necessary to know the basics of transceiver. Transceiver is a combination of a transmitter and a receiver in a single package, while they function independently for bidirectional communication. Typically, a fiber optic transceiver converts the incoming optical signal to electrical and the outgoing electrical signal to optical. More specifically, the transmitter takes an electrical input and converts it to an optical output from a laser diode or LED. The light from the transmitter is coupled into the fiber with a connector and is transmitted through the fiber optic cable plant. The light from the end of the fiber is coupled to a receiver where a detector converts the light into an electrical signal which is then conditioned properly for use by the receiving equipment.

Here go the several aspects of transceivers that are helpful in your purchasing.


Multi-source agreements (MSAs) between different equipment vendors specify guidelines for electrical and optical interfaces, mechanical dimensions and electro-magnetic specification of a transceiver. The equipment vendors follow these MSA defined values for designing their systems to ensure interoperability between interface modules. The form-factor or the MSA-type is needed so that the transceiver can mechanically and electrically fit into a given switch, router, etc. Transceiver MSAs define mechanical form factors including electric interface as well as power consumption and cable connector types. There are various MSA types: SFP (eg. MGBSX1), SFP+, XFP, CFP, CFP2, CFP4, QSFP and so on.

several MSA types

Transmission Media

Transceivers can work over single-mode fiber (SMF), multi-mode fiber (MMF), and copper. In different Ethernet applications, media can achieve different link lengths when combined with transceivers. Take Gigabit Ethernet (GbE) applications for example, single-mode transceivers can have a transmission distance of 5km to 120km, while multi-mode transceivers are defined to have the maximum reach of 55om, with copper solution establishing even fewer link length at 25m. Take MGBLX1 for example, this Cisco compatible 1000BASE-LX SFP works through SMF for 10km reach.

Power Budget

The transceiver power budget is the difference between transmitter launch power and receiver sensitivity and has to be 2-3dB larger (Margin) than the measured link loss. If the link loss cannot be measured, it has to be calculated. Therefore transmission distance [km], the number of ODFs, patches and passive optical components (Muxes) have to be known. Common values for power budget are <10, 14, 20, 24, 28, >30dB.

power budget

If you’re seeking high-speed data carrier, transceivers can help accomplish goals. By transmitting data at 10Gbit/s, 40Gbit/s, 100Gbit/s or 12940Gbit/s, they can ensure that data arrives quickly. Transceiver modules that are capable of handling fast speeds can help with downloads and high and low bandwidth video transmission.


Transceivers are instrumental in ensuring that the data is transmitted securely, expeditiously, and accurately across the media. Choosing the right type of transceiver for your network is not always easy, but knowing above discussed parameters beforehand helps you narrow it down to a few transceivers. Fiberstore offers a sea of transceiver modules which are fully compatible with major brands, like the above mentioned MGBSX1 and MGBLX1, the Cisco compatible transceiver modules. For more information about transceiver modules, you can visit Fiberstore.

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Considering Three Aspects Before Migrating to 40G

The dramatic growth of bandwidth requirements in data centers has led to the worldwide use of higher-performance optical products for network scalability, management, flexibility and reliability. Currently, 10GbE (Gigabit Ethernet) can’t meet the increasing needs of high speed transmission well for such applications as Big Data, cloud and Internet of Things being introduced in many industries. As such, network migration to 40/100G has already been the industry consensus.

But as the cost for 100G is far beyond what most enterprises can afford and the technology for 100G is still not mature enough, 40G has been a better solution for its lower cost and maturer technologies compared to 100G. Nowadays, some manufacturers are battling for the 40G market, which drives down the 40G deployment price, leading to the even wider deployment of 40G infrastructure. When migrating from 10G to 40G, three aspects should be considered: fiber optic transceiver, transmission media, and pre-terminated MPO assemblies.

Fiber Optic Transceiver

For any telecommunication network, fiber optic interconnection is of great importance. Photoelectric conversion is a necessary part in fiber optic network. The function of fiber optic transceiver is photoelectric conversion, which makes it one of the most commonly used components in the data center.

As for 40G transceivers, two different package forms are available: QSFP+ (Quad Small Form-factor Pluggable Plus) and CFP (C Form-factor Pluggable), with the former more widely-used than the latter. A single 40G fiber optic transceiver may not be expensive. But what a medium-sized data center needs is thousands of optical transceivers, meaning a large sum of money to be spent. In such a case, third party transceivers that are compatible with a variety types of switches come into point. They have the same performances that the original brand transceivers have, but cost less money. When selecting 40G compatible transceivers, cost and quality are very important. Choosing the compatible 40G transceivers from Fiberstore can ensure 100% compatibility and interoperability. The picture below shows the testing of Cisco compatible QSFP-40G-SR4 transceivers on a Cisco switch to ensure its compatibility and interoperability.

QSFP-40G-SR4, under test

Transmission Media

Allowing for several situations that may exist, the IEEE 802.3ba specified the different transmission media for 40G links, including the following listed media:

  • 40GBASE-CR4: 40Gb/s Ethernet over copper cable in short transmission distance.
  • 40GBASE-SR4 (eg. QFX-QSFP-40G-SR4): 40Gb/s Ethernet over four short-range multi-mode fiber (MMF) optic cables.
  • 40GBASE-LR4: 40Gb/s Ethernet over four wavelengths carried by a signal long-distance single-mode fiber (SMF) optic cable.

There also exists hybrid cabling solutions for 40G applications, like QSFP to 4SFP+ breakout cabling assembly. Take QSFP-4SFP10G-CU5M for example, this product listed in Fiberstore is the QSFP+ to 4 10GBASE-CU SFP+ passive direct-attach copper transceiver assembly with 5-meter reach.

QSFP to 4SFP+ breakout cabling assembly, for short reach, 5m

Question occurs: fiber optic cable or copper cable, which should be used in 40G migration? Copper is cheaper. But it can only support 40G transmission limited to several meters. SMF supports the longest 40G transmission distance up to 40 km. As for MMF, OM3 and OM4 are suggested to support short distance transmission. The longest distance that OM3 can support for 40G transmission is 100 m. OM4 can support a longest 40G transmission distance of 150 m. The selection of transmission media should depend on the specific applications.

MPO Assemblies for 40G

The IEEE 802.3ba standard also specifies multi-fiber push-on (MPO) connectors for standard-length MMF connectivity. Most of the 40G multi-mode Ethernet transceivers are based on the MPO technology. It is wise to increase fiber optic density by using MPO technology, but a new problem arises. As the fiber number increased, the cabling and splicing difficulty in data center increased. Unlike traditional two-strand fiber connections, MPO connectors cannot be field terminated easily. Thus, most of the data centers choose the pre-terminated MPO assemblies in 40G deployment, which is more reliable and can save more human labor. Before cabling, determine the cabling lengths and customized pre-terminated MPO assemblies with manufacturers would save a lot of time and money.


Using compatible third party transceivers of high quality for 40G links saves a lot of money. Taking specific applications and characteristics of 40G transmission media into consideration can also help you to save cost. Pre-terminated MPO assemblies are necessary for flexible and manageable cabling in 40G deployment. With these information in mind, cost-effective 40G migration is at the corner.

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Two Main Questions About Direct Attach Cables

The increasing bandwidth demands in data centers call for new cost-effective network solutions that are able to provide great bandwidth and improved power efficiency. As such, direct attach cables (DACs) are designed to replace expensive fiber optic cables in some Ethernet applications, like choosing SFP+ DACs and QSFP+ DACs accordingly as 10 Gigabit Ethernet (GbE) and 40GbE cabling solutions to achieve high performance. How much do you know about this kind of cable? Do you know its such basic information as classifications? If not, then you can follow this article to understand DAC in depth based on the two main questions.

Question 1: What Is DAC?

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. Often referred to as twin-ax, this direct attach twin-axial cable is very similar to coaxial cable, except for one additional copper conductor core. DACs are much cheaper than the regular optics, since the “transceivers” on both ends of DACs are not real optics and their components are without optical lasers. In some 10GbE and 40GbE infrastructures, DACs have been selected to replace fiber optic patch cord when the required link length is relatively short. And in storage area network, data center, and high-performance computing connectivity, DACs are preferable choice because of their low cost, low power consumption and high performances.

Question 2: How DAC Is Classified?

When it comes to DAC’s classifications, there exist two primary standards: Ethernet transmission rate, material of cables.

Based on Ethernet transmission rate and construction standard, 10G SFP+ DACs, 40G QSFP+ DACs, and 120G CXP+ DACs are all available, meaning that DAC can be used as transmission medium for 10GbE, 40GbE, and 120GbE applications when combined as transceivers. Typical DAC assemblies have one connector on each end of the cable. Take SFP-10G-AOC1M for example, this Cisco compatible SFP+ to SFP+ Direct-Attach Active Optical Cable assembly has one SFP+ connector on each end of the cable, designed for relatively short reach that is 1m.

SFP-10G-AOC1M, one SFP+ connector at each end

According to material of cables used, DACs are available in direct attach copper cables and active optical cables (AOCs).

Direct Attach Copper Cable

Direct attach copper cables are designed in either active or passive versions, providing flexibility with a choice of 1-, 3-, 5-, 7-, and 10-meter lengths. The former provides signal processing electronics to avoid signal issue, thus to improve signal quality. What’s more, the former can transmit data over a longer distance than the latter which offers a direct electrical connection between corresponding cable ends. Both direct attach passive copper cables and direct attach active copper cables have gained popularity in data centers. For instance, EX-QSFP-40GE-DAC-50CM, the Juniper 40G cabling product, hot-removable and hot-insertable, is the QSFP+ to  QSFP+ direct attach passive copper cable assembly, really suitable for short distances of up to 0.5m(1.6ft), appropriate for highly cost-effective networking connectivity within a rack and between adjacent racks.

EX-QSFP-40GE-DAC-50CM, for short reach

Active Optical Cable

AOC is also one form of DAC. It uses electrical-to-optical conversion on the cable ends to improve speed and distance performance of the cable while mating with electrical interface standard. Compared with direct attach copper cable, its smaller size, electromagnetic interference immunity, lower interconnection loss and longer transmission distance make it popular among consumers.

DACs offer great flexibility in cabling length choices, simplify server connectivity in top-of-rack deployments, and reduce the power needed to transmit data. More importantly, DACs ensure high system reliability after going through rigorous qualification and certification testing, helping network designers to achieve new levels of infrastructure consolidation while expanding application and service capabilities.


DACs are able to provide an end-to-end solution that is easy to maintain, thus helping improve the availability of networks that support mission-critical applications. Fiberstore offers a broad selection of DACs with high quality for state-of art performance, 10G SFP+ DACs, 40G QSFP+ DACs, and 120G CXP+ DACs all included. For more information about DACs, you can visit Fiberstore.

Originally published at http://www.fiber-optic-components.com/two-main-questions-about-direct-attach-cables.html

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Overview of 40/100GbE Terminations

Today’s data centers growth is placing increasing demands on the networking infrastructure. For some enterprises, existing 1GbE connections can’t support the growing business requirements well very, not to say 100Mbps connections. In order to accommodate these demands, it’s imperative to upgrade the data center network architecture to 40 or 100 Gigabit Ethernet (GbE) connections. This 40/100GbE network design helps to support not only the current growth, but also the increasing demands in the future.

IEEE 802.3ba 40G and 100G Standard

The Institute of Electrical and Electronics Engineers (IEEE) 802.3 working group is concerned with the maintenance and extension of the Ethernet data communications standard. And 802.3ba is the designation given to the higher speed Ethernet task force to modify the 802.3 standard to support higher speeds than 10Gbit/s, that is 40/100G in 2010. This 802.3ba 40/100G standard encompasses a number of different Ethernet physical layer (PHY) specifications which are supported by means of pluggable modules, like Quad Small-Form-Factor Pluggable (QSFP) and C Form-Factor Pluggable (CFP). As for transmission medium, the transport speeds at 40/100Gbit/s use two methods: parallel optics and copper cables, with the fiber optics solutions allowing more flexibility and greater distance reach.

40GbE Terminations

In most cases, 40GbE connections use a QSFP+ transceiver terminated to receive the multi-fiber push-on/multiplex pass-through (MPO/MPT) trunk. That is, the short-range QSFP+ transceivers (eg. QFX-QSFP-40G-SR4) use multi-mode MPO trunks to establish 40G links. During this link establishment, polarity becomes a consideration when implementing 40GbE switch-to-switch interconnects over multi-strand multi-mode fiber (MMF). Method B polarity is recommended for the functional link.

QSFP+ transceivers are also able to run on single-mode fiber (SMF) for long reach. These links are Little Connector (LC) terminated and can run up to 40km, mainly used for 40GbE interbuilding connections. Take QSFP-40G-ER4 for example, this 40GBASE-ER4 transceiver supports link lengths up to 40km over SMF with duplex LC connectors.

The QSFP+ transceiver can also be used for 40GbE to 4x10GbE partitioned applications, that is QSFP+ to 4SFP+ fan-out cabling assemblies. One end of the connection is terminated using a MPO/MPT configuration with four individual pairs terminated with LC connectors at the other end. The image below just shows the QSFP+ to 4SFP+ Active Optic Cable (AOC) assembly.

QSFP+ to 4SFP+ AOC, 40GbE to 4x10GbE partitioned application

100GbE Terminations

100GbE connections use a CFP transceiver. Two CFP options are dominant in the industry: CFP2 and CFP4. The primary differences between the two are physical density and transmit/receive lane configurations. More specifically, CFP2 supports 100GBASE-SR10, 100BASE-LR4, and 100GBASE-ER4 optical interfaces, while CFP4 doubles the port density on the line card and supports 100GBASE-SR4, 100GBASE-LR4, and 100GBASE-ER4 optical interfaces.

CFP options, for 100G transmission

40/100GbE Termination Benefits

The 40/100GbE network infrastructure provides the following benefits:

  • Reduced data center complexity: As virtualization increases, the use of fewer physical servers and switches has been made possible by 40/100GbE network infrastructure.
  • Reduced total cost: Since 40/100GbE network system simplifies the local area network (LAN) and cable infrastructures, the potential cost reduction in virtualization environment is also accessible. Besides, the 40/100GbE network infrastructure requires fewer data center space, power, and cooling resources.
  • Increased Productivity: Faster connections and reduced network latency provide network designers with faster workload completion times and improved productivity.
  • Upgrading network architecture to support speeds greater than 10GbE, that is 40/100GbE, is essential in optimizing data center infrastructure, giving a hand in moving quickly in respond to business needs. At the same time, the services and value brought by information technology itself can also be enhanced.

The high-performance 40/100GbE network architecture simplifies the cabling infrastructure and reduces per-server total cost of ownership, capable of allowing high speeds at 40/100Gbit/s. Fiberstore offers a large selection of 40/100G optical modules, as well as 40/100G fiber optic-based cables and copper cables. For more information about 40/100GbE solutions, you can visit Fiberstore.

Originally published at www.fiber-optic-cable-sale.com/overview-of-40100gbe-terminations.html

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Single Fiber – Why Choose it for Gigabit Optical Communications?

Advanced applications, including voice and data convergence, as well as storage area networking, are putting burdens on today’s fiber optic networking infrastructure, especially on the fiber cabling. With speeds in data centers now increasing from 10Gbps to 40Gbps, to 100Gbps, and 120Gbps, etc., different fiber technologies are required for Gigabit optical communications, like single strand fiber (simplex fiber cable) and duplex fiber cable. This text mainly introduces the single strand fiber, a relatively simple solution chosen for fiber optimization, and its benefits that drive the need to deploy single strand fiber for Gigabit optical communications.

Single Fiber Technologies

Single strand fiber, just as its name shows, uses one strand of glass instead of two dedicated strands with one for receiving and the other for transmitting. It doubles the capacity of the installed fiber plant, which in turn doubles the per fiber return on investment (ROI) with no need for more physical fiber.

Early single fiber solutions were based on single wavelength directional coupler technologies. With these solutions, the same wavelength (1310nm for up to 50km or 1550nm for longer distances) travels in each direction (transmit & receive). At the edges, the two signals are coupled into a single fiber strand with a directional coupler (splitter-combiner). This coupler identifies the direction of the two signals (ingress or egress) and separates or combines them. This kind of solution is normally very reliable and cost effective, as long as special installation and connector type (APC -angle polished connector) requirements are observed. Otherwise, this solution is prone to reflections when traversing patch panels and in the cases of fiber cuts or dirty connectors.

single fiber 1310nm TX/1510nm Rx

In recent years, a new single strand fiber technology has emerged based on two wavelengths traveling in opposite directions. External WDM couplers (multiplexers) combine or separate the two wavelengths at the edges. As technology progressed, the external passive WDM coupler became integrated into a standard interface fixed optic transceiver.

Single Fiber SFP (Small Form Pluggable)

The growing demand of single fiber solutions driven by the Ethernet bandwidth has led to the development of a wide range of single fiber pluggable SFP transceivers. These hot-pluggable optic transceivers are designed in small-form factor for high-density solutions, covering many industrial protocols and allowing flexibility in distance choices. Besides, they provide advanced optical performance, Digital Diagnostics Monitoring (DDM). Commonly-used single SFPs include 1000BASE-LX SFPs (eg.EX-SFP-1GE-LX shown below), 1000BASE-ZX SFPs, etc.

EX-SFP-1GE-LX,single fiber SFP

Single Fiber Benefits

The benefits of the single strand versus the dual strand fiber implementation can be considerable.

  • Operational and Capital Expense Savings

Single fiber solutions, like any other fiber optimization methods, affect both the capital expenses (CAPEX) and the operational expenses (OPEX). For fiber users like carriers and enterprises that lease dark fiber from their provider rather than owning the fiber plant, the OPEX savings is extremely significant by avoiding avoid the need to install additional fiber strands to accommodate growth without imposing limitations due to engineering capabilities.

  • Fiber Run — Engineering Cost

The design and engineering of a fiber run is a complex process. It may require crossing roads or freeways, which leads to possible thorough design, and inflexible work scheduling. The deployment cost might include trenching or other expenses. In many cases, the price of labor, services, and licenses required to install new cabling can far exceed the cost of the media and supporting electronics.

  • Fiber Termination and Accessories Cost

New fiber runs require terminating and connecting any fiber strand. This process requires qualified labor that will polish, connectorize, and test every fiber strand. Reducing the number of terminated fiber strands by half results in a significant cost reduction.

  • Network Reliability and Maintenance Cost

Reliability and availability are key in any communications system. Use of single fiber pluggable-based transceivers in an existing dual fiber link opens the possibility of creating redundant link solutions. In fiber assembly, a larger number of fiber strands increase the chance of fiber failure. The larger the fiber strands are, the higher the failure chances are, thus the maintenance cost increase accordingly. This can be reduced through the simplicity of single fiber technology.


Single fibers are considered as the simple way for fiber optimization, for they not only double the capacity of the installed fiber plant, but also help to achieve overall savings in Gigabit optical communications. Fiberstore offers single fibers available in both single-mode and multi-mode versions, which are all quality assured. In addition, single fiber optical transceivers can also be found in Fiberstore, such as 1000BASE-LX SFP (EX-SFP-1GE-LX mentioned above), 10GBASE-ZR SFP+ (SFP-10G-ZR). For more information about single fibers, you can visit Fiberstore.

Originally published at www.fiber-optic-cable-sale.com/single-fiber-why-choose-it-for-gigabit-optical-communications.html

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FAQs About Laser-Optimized Fiber

Fiber optical networks have dominated for long-haul communications for years, increasingly used in short distance applications, such as local area networks (LANs). And the Ethernet data-rate needed for these high-performance fiber optic networks increases from 1Gbps to 10Gbps, to 40Gbps, to 100Gbps, or even higher. Together with this speed increase, a term, laser-optimized fiber, has crept into the telecommunication market. What is laser-optimized fiber? How much do you know about it? Knowing answers to these frequently asked questions (FAQs) about laser-optimized fiber will help you prepare for the latest wave in optical communication networks.

FAQ 1: What Is Laser-Optimized Fiber?

Laser-optimized multi-mode fiber (LOMMF: OM3 & OM4) differs from standard MMF (OM1 & OM2), because the former has graded refractive index profile fiber optic cable in each assembly. This means that the refractive index of the core glass decreases toward the outer cladding, so the paths of light towards the outer edge of the fiber travel quicker than the other paths. This increase in speed equalizes the travel time for both short and long light paths, ensuring accurate information transmission and receipt over much greater distances up to 300 meters (OM3) and 400 meters (OM4) at 10Gbps, while OM1 and OM2 can only realize 26 meters and 33 meters link length respectively at the same data rate. And when 1000BASE-SX SFP transceivers transmit and receive signals over LOMMF and standard MMF at 1Gbps, the possible link lengths achieved are also different, with OM1 275-meter reach, OM2, OM3, and OM4 up to 550-meter reach. Take MGBSX1 for example, this compatible Cisco 1000BASE-SX SFP listed in Fiberstore supports up to 550-meter link length over OM2.

MGBSX1, 550m link length over MMF

FAQ 2: Why Have MMF Been “Optimized” for Use with Lasers?

As the demand for bandwidth and higher throughput increased, especially in building and campus backbones, LEDs, short for Light Emitting Diodes, that are used as light sources in fiber optic systems could not keep pace. With a maximum modulation rate of 622Mb/s, LEDs would not support the 1 Gb/s and greater transmission rates required. The use of traditional lasers (Fabry-Perot, Distributed Feedback) typically used over single-mode fiber (SMF) could accommodate this problem. However, it’s very expensive due to the higher performance characteristics required for long-distance transmission on SMF. As such, a high-speed laser light source, a Vertical Cavity Surface Emitting Laser (VCSEL) was developed. These VCSELs are inexpensive, suited for low-cost 850nm multi-mode transmission systems, allowing for data rates up to 100Gbps in the enterprise. With the emergence of these VCSELs, MMFs have been “optimized” for operation with lasers.

FAQ 3: Why Are LOMMFs the Best Choice for Use with VCSELs?

After VCSELs appears, to fully capitalize on the benefits that VCSELs offer, LOMMFs have been specifically designed, fabricated, and tested for efficient and reliable use with VCSELs.

LOMMF,specifically designed, fabricated, and tested

LOMMFs have a well-designed and carefully controlled refractive index profile to ensure optimum light transmission with a VCSEL. Precise control of the refractive index profile minimizes the modal dispersion, also known as Differential Mode Delay (DMD). This ensures that all modes, or light paths in the fiber arrive at the receiver at about the same time, minimizing pulse spreading and, therefore, maximizing bandwidth.

LOMMF is completely compatible with LEDs and other fiber optic applications. LOMMFs can be installed at slower data rates or higher data rate. When there occurs the data rate migration from 10Gbps to 40Gbps, there is no need to pull new cable. You only need to upgrade the optics modules to VCSEL-based transceivers, avoiding infrastructure redesign.


LOMMFs are the suitable medium for short-wave 10G optical transmission. Their great bandwidth- and information-carrying capacity make them more popular among consumers than standard MMFs especially in 10GbE systems. Fiberstore supplies countless OM3 and OM4, as well as OM1 and OM2 for your network projects. Besides, other kinds of fiber optic cables, like MTP cable and SMF, are also available in Fiberstore. For more information about fiber optic cables, please visit Fiberstore.

Originally published at www.fiber-optic-cable-sale.com/faqs-about-laser-optimized-fiber.html

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