Author Archives: cheer chen

SMF or MMF? Which Is the Right Choice for Data Center Cabling?

Selecting the right cabling plant for data center connectivity is critically important. The wrong decision could leave a data center incapable of supporting future growth, requiring an extremely costly cable plant upgrade to move to higher speeds. In the past, due to high cost of single mode fiber (SMF), multimode fiber (MMF) has been widely and successfully deployed in data center for many years. However, as technologies have evolved, the difference in price between SMF and MMF transceivers has been largely negated. With cost no longer the dominant decision criterion, operators can make architectural decisions based on performance. Under these circumstances, should we choose SMF or MMF? This article may give you some advice.

MMF Can’t Reach the High Bandwidth-Distance Needs
MMF datacenterBased on fiber construction MMF has different classifications types that are used to determine what optical signal rates are supported over what distances. Many data center operators who deployed MMF OM1/OM2 fiber a few years ago are now realizing that the older MMF does not support higher transmit rates like 40GbE and 100GbE. As a result, some MMF users have been forced to add later-generation OM3 and OM4 fiber to support standards-based 40GbE and 100GbE interfaces. However, MMF’s physical limitations mean that as data traffic grows and interconnectivity speeds increase, the distance between connections must decrease. The only alternative in an MMF world is to deploy more fibers in parallel to support more traffic. Therefore, while MMF cabling has been widely and successfully deployed for generations, its limitations now become even more serious. Operators must weigh unexpected cabling costs against a network incapable of supporting new services.

SMF Maybe a Viable Alternative
Previously, organizations were reluctant to implement SMF inside the data center due to the cost of the pluggable optics required, especially compared to MMF. However, newer silicon technologies and manufacturing innovations are driving down the cost of SMF pluggable optics. Transceiver module with Fabry-Perot edge emitting lasers (single-mode) are now comparable in price and power dissipation to VCSEL (multimode) transceivers. Besides, Where MMF cable plants introduce a capacity-reach tradeoff, SMF eliminates network bandwidth constraints. This allows operators to take advantage of higher-bit-rate interfaces and wave division multiplexing (WDM) technology to increase by three orders of magnitude the amount of traffic that the fiber plant can support over longer distances. All these factors make SMF a more viable option for high-speed deployments in data centers.

SMF datacenter

Comparison Between SMF and MMF
10GbE has become the predominant interconnectivity interface in large data centers, with 40GbE and 100GbE playing roles in some high-bandwidth applications. Put simply, the necessity for fiber cabling that supports higher bit rates over extended distances is here today. With that in mind, the most significant difference between SMF and MMF is that SMF provides a higher spectral efficiency than MMF, which means it supports more traffic over a single fiber using more channels at higher speeds. This is in stark contrast to MMF, where cabling support for higher bit rates is limited by its large core size. This effectively limits the distance higher speed signals can travel over MMF fiber. In fact, in most cases, currently deployed MMF cabling is unable to support higher speeds over the same distance as lower-speed signals.

Name Interface FP (SMF) VCSEL (MMF)
Link Budget (dB)
4 to 6 2
Reach (in meters) (Higher value is better)
10GbE 1300 300
40GbE 1300 150
100GbE 1300 <100

As operators consider their cabling options, the tradeoff between capacity and reach is important. Network operators must assess the extent to which they believe their data centers are going to grow. For environments where users, applications, and corresponding workload are all increasing, single-mode fiber offers the best future proofing for performance and scalability. And because of fundamental changes in how transceivers are manufactured, those benefits can be attained at prices comparable to SMF’s lower performing alternative.


Fusion Splicing–A Popular Option for Data Center

Fusion splicingAs fiber deployment has become mainstream, splicing has naturally crossed from the outside plant (OSP) world into the enterprise and even the data center environment. Fusion splicing involves the use of localized heat to melt together or fuse the ends of two optical fibers. The preparation process involves removing the protective coating from each fiber, precise cleaving, and inspection of the fiber end-faces. Fusion splicing has been around for several decades, and it’s a trusted method for permanently fusing together the ends of two optical fibers to realize a specific length or to repair a broken fiber link. However, due to the high costs of fusion splicers, it has not been actively used by many people. But these years some improvements in optical technology have been changing this status. Besides, the continued demand for increased bandwidth also spread the application of fusion splicing.

New Price of Fusion Splicers
Fusion splicers costs have been one of the biggest obstacles to a broad adoption of fusion splicing. In recent years, significant decreases in splicer prices has accelerated the popularity of fusion splicing. Today’s fusion splicers range in cost from $7,000 to $40,000. The highest-priced units are designed for specialty optical fibers, such as polarization-maintaining fibers used in the production of high-end non-electrical sensors. The lower-end fusion splicers, in the $7,000 to $10,000 range, are primarily single-fiber fixed V-groove type devices. The popular core alignment splicers range between $17,000 and $19,000, well below the $30,000 price of 20 years ago. The prices have dropped dramatically due to more efficient manufacturing, and volume is up because fiber is no longer a voodoo science and more people are working in that arena. Recently, more and more fiber being deployed closer to the customer premise with higher splice-loss budgets, which results in a greater participation of customers who are purchasing lower-end splicers to accomplish their jobs.

More Cost-effective Cable Solutions
The first and primary use of splicing in the telecommunications industry is to link fibers together in underground or aerial outside-plant fiber installations. It used to be very common to do fusion splicing at the building entrance to transition from outdoor-rated to indoor-rated cable, because the NEC (National Electrical Code) specifies that outdoor-rated cable can only come 50 feet into a building due to its flame rating. The advent of plenum-rated indoor/outdoor cable has driven that transition splicing to a minimum. But that’s not to say that fusion splicing in the premise isn’t going on.

Longer distances in the outside plant could mean that sticking with standard outdoor-rated cable and fusion splicing at the building entrance could be the more economical choice. If it’s a short run between building A and B, it makes sense to use newer indoor/outdoor cable and come right into the crossconnect. However, because indoor/outdoor cables are generally more expensive, if it’s a longer run with lower fiber counts between buildings, it could ultimately be cheaper to buy outdoor-rated cable and fusion splice to transition to indoor-rated cable, even with the additional cost of splice materials and housing.

As fiber to the home (FTTH) applications continue to grow around the globe, it is another situation that may call for fusion splicing. If you want to achieve longer distance in a FTTH application, you have to either fusion splice or do an interconnect. However, an interconnect can introduce 0.75dB of loss while the fusion splice is typically less than 0.02dB. Therefore, the easiest way to minimize the amount of loss on a FTTH circuit is to bring the individual fibers from each workstation back to the closet and then splice to a higher-fiber-count cable. This approach also enables centralizing electronics for more efficient port utilization. In FTTH applications, fusion splicing is now being used to install connectors for customer drop cables using new splice-on connector technology and drop cable fusion splicer.

FTTH drop cable fusion splicer

A Popular Option for Data Centers
A significant increase in the number of applications supported by data centers has resulted in more cables and connections than ever, making available space a foremost concern. As a result, higher-density solutions like MTP/MPO connectors and multi-fiber cables that take up less pathway space than running individual duplex cables become more popular.

Since few manufacturers offer field-installable MTP/MPO connectors, many data center managers are selecting either multi-fiber trunk cables with MTP/MPOs factory-terminated on each end, or fusion splicing to pre-terminated MTP/MPO or multi-fiber LC pigtails. When you select trunk cables with connectors on each end, data center managers often specify lengths a little bit longer because they can’t always predict exact distances between equipment and they don’t want to be short. However, they then have to deal with excess slack. When there are thousands of connections, that slack can create a lot of congestion and limit proper air flow and cooling. One alternative is to purchase a multi-fiber pigtail and then splice to a multi-fiber cable.

Inside the data center and in the enterprise LAN, 12-fiber MPO connectors provide a convenient method to support higher 40G and 100G bandwidth. Instead of fusing one fiber at a time, another type of fusion splicing which is called ribbon/mass fusion splicing is used. Ribbon/mass fusion splicing can fuse up to all 12 fibers in one ribbon at once, which offers the opportunity to significantly reduce termination labor by up to 75% with only a modest increase in tooling cost. Many of today’s cables with high fiber count involve subunits of 12 fibers each that can be quickly ribbonized. Splicing those fibers individually is very time consuming, however, ribbon/mass fusion splicers splice entire ribbons simultaneously. Ribbon/mass fusion splicer technology has been around for decades and now is available in handheld models.

Ribbon/Mass Fusion Splicer

Fusion splicing provides permanent low-loss connections that are performed quickly and easily, which are definite advantages over competing technologies. In addition, current fusion splicers are designed to provide enhanced features and high-quality performance, and be very affordable at the same time. Fiberstore provides various types and uses of fusion splicers with high quality and low price. For more information, please feel free to contact us at

Original article source:

Optical Fiber Benefits the Green Data Center Building

Green DataCenterWith the amount of energy now required to power the world’s data centers, one of the greatest challenges in today’s data centers is minimizing costs associated with power consumption and cooling, which is also the requirement of building the green data center. Higher power consumption means increased energy costs and greater need for heat dissipation. This requires more cooling, which adds even more cost. Under these circumstances, high-speed optical fiber offers a big advantage over copper to reduce the network operational and cooling energy.

What Is Green Data Center?
The word “green” invokes natural images of deep forests, sprawling oak trees and financial images of dollar bills. The topic of green has been gaining momentum across international, commercial and industrial segments as global warming and greenhouse gas effects hit headlines. In terms of different fields, the word “green” has different definitions. Specific to the data center segment of the telecommunications industry, green data center is a repository for the storage, management, and dissemination of data in which the mechanical, lighting, electrical and computer systems are designed for maximum energy efficiency and minimum environmental impact.

green data enter

How to Build Green Data Center?
Green data center address two issues which plague the average data center. One is the power required to run the actual equipment, the other is the power required to cool the equipment. Reduced the power required will effectively lessen not only the energy consumption but also the impact on environment. Green solutions include:

  • More efficient hardware components and software systems
  • Innovative cooling systems
  • Using natural ways to cool equipment
  • Building near advantageous natural resources or environments
  • Effective server and rack management for better air-flow

How Does Optical Fiber Benefit the Green Data Center Building?
Compared to copper cable, optical fiber may offer many advantages in contribution to building green data center. Usually, optical fiber connectivity can enhance green data center installations by utilizing high-port-density electronics with very low power and cooling requirements. Additionally, an optical network provides premier pathway and space performance in racks, cabinets and trays to support high cooling efficiency when compared to copper connectivity. All these advantages can be summarized as the following three points.

Lower Operational Power Consumption
Optical transceiver requires less power to operate compared to copper transceiver. Copper requires significant analog and digital signal processing for transmission that consumes significantly higher energy when compared to optical media. A 10G BASE-T transceiver in a copper system uses about 6 watts of power. A comparable 10G BASE-SR optical transceiver uses less than 1 watt to transmit the same signal. The result is that each optical connection saves about 5 watts of power. Data centers vary in size, but if we assume 10,000 connections at 5 watts each, that’s 50 kW less power—a significant savings opportunity thanks to less power-hungry optical technology.

Less Cooling Power Consumption
Optical system requires far fewer switches and line cards for equivalent bandwidth when compared to a copper card. Fewer switches and line cards translate into less energy consumption for electronics and cooling. One optical 48-port line card equals three copper 16-port line cards (as shown in the following picture). A typical eight-line card chassis switch would have 384 optical ports compared to 128 copper ports. This translates into a 3:1 port advantage for optical. It would take three copper chassis switches to have equivalent bandwidth to one optical chassis switch. The more copper chassis switches results in more network and cooling power consumption.

Line card port density in a 10G optical system vs. copper system

More Effective Management for Better Air-flow
Usually, a 0.7-inch diameter optical cable would contain 216 fibers to support 108 10G optical circuits, while 108 copper cables would have a 5.0-inch bundle diameter. The larger CAT 6A outer diameter impacts conduit size and fill ratio as well as cable management due to the increased bend radius. Copper cable congestion in pathways increases the potential for damage to electronics due to air cooling damming effects and interferes with the ability of ventilation systems to remove dust and dirt. Optical cable offers better system density and cable management and minimizes airflow obstructions in the rack and cabinet for better cooling efficiency. See the picture below: the left is a copper cabling system and the right is an optical cabling system.

copper cabling system vs optical cabling system

Data center electrical energy consumption is projected to significantly increase in the next five years. Solutions to mitigate energy requirements, to reduce power consumption and to support environmental initiatives are being widely adopted. Optical connectivity supports the growing focus on a green data center philosophy. Optical cable fibers provide bandwidth capabilities that support legacy and future-data-rate applications. Optical fiber connectivity provides the reduction in power consumption (electronic and cooling) and optimized pathway space utilization necessary to support the movement to greener data centers.

The Latest Generation of PON – NG-PON2

To meet the large demand for high capacity transmission in optical access systems, 10G-PON (10G Passive Optical Network) has already been standardized by IEEE (Institute of Electrical and Electronics Engineers) and ITU (International Telecommunication Union). To enable the development of future optical access systems, the most recent version of PON known as NG-PON2 (Next-Generation Passive Optical Network 2) was approved recently, which provides a total throughput of 40 Gbps downstream and 10 Gbps upstream over a single fiber distributed to connected premises. The migration from GPON to 10G-PON and NG-PON2 is the maturity of technology and the need for higher bandwidth. This article will introduce the NG-PON2 technology to you.


What Is NG-PON2?
NG-PON2 is a 2015 telecommunications network standard for PON which was developed by ITU. NG-PON2 offers a fiber capacity of 40 Gbps by exploiting multiple wavelengths at dense wavelength division multiplexing (DWDM) channel spacing and tunable transceiver technology in the subscriber terminals (ONUs). Wavelength allocations include 1524 nm to 1544 nm in the upstream direction and 1596 nm to 1602 nm in the downstream direction. NG-PON2 was designed to coexist with previous architectures to ease deployment into existing optical distribution networks. Wavelengths were specifically chosen to avoid interference with GPON, 10G-PON, RF Video, and OTDR measurements, and thus NG-PON2 provides spectral flexibility to occupy reserved wavelengths in deployments devoid of legacy architectures.

How Does NG-PON2 Work?
If 24 premises are connected to a PON and the available throughput is equally shared then for GPON each connection receives 100 Mbps downstream and 40 Mbps upstream over a maximum of 20 km of fiber. For 10G-PON, which was the second PON revision, each of the 24 connections would receive about 400 Mbps downstream and 100 Mbps upstream. The recently approved NG-PON2 will provide a total throughput of 40 Gbps downstream and 10 Gbps upstream over a maximum of 40 km of fiber so each of the 24 connections would receive about 1.6 Gbps downstream and 410 Mbps upstream. NG-PON2 provides a greater range of connection speed options including 10/2.5 Gbps, 10/10 Gbps and 2.5/2.5 Gbps. NG-PON2 also includes backwards compatibility with GPON and 10G-PON to ensure that customers can upgrade when they’re ready.

NG-PON2 Work Principle

NG-PON2 Advantages
The NG-PON2 technology is expected to be about 60 to 80 percent cheaper to operate than a copper based access network and provides a clear undeniable performance, capacity and price advantage over any of the copper based access networks such as Fiber to the Node (FTTN) or Hybrid Fiber Coax (HFC). At present, three clear benefits of NG-PON2 have been proved. They are a 30 to 40 percent reduction in equipment and operating costs, improved connection speeds and symmetrical upstream and downstream capacity.

Reduced Costs
NG-PON2 can coexist with existing GPON and 10G-PON systems and is able to use existing PON-capable outside plant. Since the cost of PON FTTH (Fiber to the Home) roll out is 70 percent accounted for by the optical distribution network (ODN), this is significant. Operators have a clear upgrade path from where they are now, until well into the future.

Improved Connection Speeds
Initially NG-PON2 will provide a minimum of 40 Gbps downstream capacity, produced by four 10 Gbps signals on different wavelengths in the O-band multiplexed together in the central office with a 10 Gbps total upstream capacity. This capability can be doubled to provide 80 Gbps downstream and 20 Gbps upstream in the “extended” NG-PON2.

Symmetrical Upstream and Downstream Capacity
Both the basic and extended implementations are designed to appeal to domestic consumers where gigabit downstream speeds may be needed but more modest upstream needs prevail. For business users with data mirroring and similar requirements, a symmetric implementation will be provided giving 40/40 and 80/80 Gbps capacity respectively.

With the introduction of NG-PON2, there is now an obvious difference between optical access network and copper access network capabilities. Investment in NG-PON2 provides a far cheaper network to operate, significantly faster downstream and upstream speeds and a future-proof upgrade path all of which copper access networks do not provide, thus making them obsolete technologies. Telephone companies around the world have been carrying out trials of NG-PON2 and key telecommunication vendors have rushed NG-PON2 products to market.

Original article source:


Understanding Wavelengths in Fiber Optics

The light we are most familiar with is surely the light we can see. Our eyes are sensitive to light whose wavelength is in the range of about 400 nm to 700 nm, from the violet to the red. But for fiber optics with glass fibers, we use light in the infrared region which has wavelengths longer than visible light. Because the attenuation of the fiber is less at longer wavelengths. This text may mainly tell you what the common wavelengths used in fiber optics are and why they are used.


Wavelengths Definition

In fact, light is defined by its wavelength. It is a member of the frequency spectrum, and each frequency (sometimes also called color) of light has a wavelength associated with it. Wavelength and frequency are related. Generally, the radiation of shorter wavelengths are identified by their wavelengths, while the longer wavelengths are identified by their frequency.

Common Wavelengths in Fiber Optics

Wavelengths typically range from 800 nm to 1600 nm, but by far the most common wavelengths actually used in fiber optics are 850 nm, 1300 nm, and 1550 nm. Multimode fiber is designed to operate at 850 nm and 1300 nm, while single-mode fiber is optimized for 1310 nm and 1550 nm. The difference between 1300 nm and 1310 nm is simply a matter of convention. Both lasers and LEDs are used to transmit light through optical fiber. Lasers are usually used for 1310nm or 1550nm single-mode applications. LEDs are used for 850nm or 1300nm multimode applications.


Why Those Common Wavelengths?

As mentioned above, the most common wavelengths used in fiber optics are 850 nm, 1300 nm and 1550 nm. But why do we use these three wavelengths? Because the attenuation of the fiber is much less at those wavelengths. Therefore, they best match the transmission properties of available light sources with the transmission qualities of optical fiber. The attenuation of glass optical fiber is caused by two factors: absorption and scattering. Absorption occurs in several specific wavelengths called water bands due to the absorption by minute amounts of water vapor in the glass. Scattering is caused by light bouncing off atoms or molecules in the glass.

It is strongly a function of wavelength, with longer wavelengths having much lower scattering. From the chart below, we can obviously see that there are three low-lying areas of absorption, and an ever-decreasing amount of scattering as wavelengths increase. As you can see, all three popular wavelengths have almost zero absorption.



After reading this passage, you may know some basic knowledge of wavelengths in fiber optics. Since the attenuation of the wavelengths at 850 nm, 1300 nm, and 1550 nm are relatively less, they are the most three common wavelengths used in fiber optic communication. Fiberstore offer all kinds multimode and single-mode fiber optic transceivers which operate on 850 nm and 1310 nm respectively very well. For more information, please visit

Do You Know About Mode Conditioning Patch Cord?

The great demand for increased bandwidth has prompted the release of the 802.3z standard (IEEE) for Gigabit Ethernet over optical fiber. As we all know, 1000BASE-LX transceiver modules can only operate on single-mode fibers. However, this may pose a problem if an existing fiber network utilizes multimode fibers. When a single-mode fiber is launched into a multimode fiber, a phenomenon known as Differential Mode Delay (DMD) will appear. This effect can cause multiple signals to be generated which may confuse the receiver and produce errors. To solve this problem, a mode conditioning patch cord is needed. In this article, some knowledge of mode conditioning patch cords will be introduced.

What Is a Mode Conditioning Patch Cord?

A mode conditioning patch cord is a duplex multimode cord that has a small length of single-mode fiber at the start of the transmission length. The basic principle behind the cord is that you launch your laser into the small section of single-mode fiber, then the other end of the single-mode fiber is coupled to multimode section of the cable with the core offset from the center of the multimode fiber (see diagram below).

mode conditioning patch cord

This offset point creates a launch that is similar to typical multimode LED launches. By using an offset between the single-mode fiber and the multimode fiber, mode conditioning patch cords eliminate DMD and the resulting multiple signals allowing use of 1000BASE-LX over existing multimode fiber cable systems. Therefore, these mode conditioning patch cords allow customers an upgrade of their hardware technology without the costly upgrade of their fiber plant.

Some Tips When Using Mode Conditioning Patch Cord

After learning about some knowledge of mode conditioning patch cords, but do you know how to use it? Then some tips when using mode conditioning cables will be presented.

    • Mode conditioning patch cords are usually used in pairs. Which means that you will need a mode conditioning patch cord at each end to connect the equipment to the cable plant. So these patch cords are usually ordered in numbers. You may see someone only order one patch cord, then it is usually because they keep it as a spare.
    • If your 1000BASE-LX transceiver module is equipped with SC or LC connectors, please be sure to connect the yellow leg (single-mode) of the cable to the transmit side, and the orange leg (multimode) to the receive side of the equipment. The swap of transmit and receive can only be done at the cable plant side. See diagram below.

mode conditioning patch cord

  • Mode conditioning patch cords can only convert single-mode to multimode. If you want to convert multimode to single-mode, then a media converter will be required.
  • Besides, mode conditioning patch cables are used in the 1300nm or 1310nm optical wavelength window, and should not be used for 850nm short wavelength window such as 1000Base-SX.


From the text, we know that mode conditioning patch cords really significantly improve the data signal quality and increase the transmission distance. But when using it, there are also some tips must be kept in mind. Fiberstore offer mode conditioning patch cords in all varieties and combinations of SC, ST, MT-RJ and LC fiber optic connectors. All of the Fiberstore’s mode conditioning patch cords are at high quality and low price. For more information, please visit

Erbium Doped Fiber Amplifier (EDFA) Used in WDM System

The capacity of fiber optical communication systems has undergone enormous growth during the last few years in response to huge capacity demand for data transmission. With the available wavelength division multiplexing (WDM) equipment, commercial system can transport more than 100 channels over a single fiber. However, increasing the number of channels in such systems will eventually result in the usage of optical signal demultiplexing components with greater values of optical attenuation. Besides, when transmitted over long distances, the optical signal is highly attenuated. Therefore, to restore the optical power budget, it is necessary to implement optical signal amplification. This article may mainly tell you  why EDFA is used in WDM system and how does it work.

Why Use EDFA in WDM System?

EDFA stands for erbium-doped fiber amplifiers, which is an optical amplifier that uses a doped optical fiber as a gain medium to amplify an optical signal. EDFA has large gain bandwidth, which is typically tens of nanometers and thus actually it is enough to amplify data channels with the highest data rates. A single EDFA may be used for simultaneously amplifying many data channels at different wavelengths within the gain region. Before such fiber amplifiers were available, there was no practical method for amplifying all channels between long fiber spans of a fiber-optic link. There are practically two wavelength widows C-Band (1530nm-1560nm) and L-Band (1560nm-1600nm). EDFA can amplify a wide wavelength range (1500nm-1600nm) simultaneously, which just satisfies the DWDM application, hence it is very useful in WDM for amplification.

How Does EDFA Work ?

The basic configuration for incorporating the EDFA in an optical fiber link is shown in the picture below. The signals and pump are combined through a WDM coupler and launched into an erbium-doped fiber (EDF). The amplified output signals can be transmitted through 60-100km before further amplification is required.

Erbium-doped fiber is the core technology of EDFA, which is a conventional silica fiber doped with erbium ions as the gain medium. Erbium ions (Er3+) are having the optical fluorescent properties that are suitable for the optical amplification. When an optical signal such as 1550nm wavelength signal enters the EDFA from input, the signal is combined with a 980nm or 1480nm pump laser through a wavelength division multiplexer device. The input signal and pump laser signal pass through erbium-doped fiber. Here the 1550nm signal is amplified through interaction with doped erbium ions. This can be well understood by the energy level diagram of Er3+ ions given in the following figure.


Where to Buy EDFA for Your WDM System ?

To ensure the required level of amplification over the frequency band used for transmission, it is highly important to choose the optimal configuration of the EDFAs. Before you buy a EDFA, keep in mind that the flatness and the level of the obtained amplification, and the amount of EDFA produced noise are highly dependent on each of the many parameters of the amplifier. Fiberstore provide many kinds of EDFAs, especially the DWDM EDFAs (shown in the picture below), which have many output options (12dBm-35dBm). Besides, they are very professional in optical amplifiers. Whatever doubts you have, they can give a clear reply.