Author: Fiber-MART.COM

eShop of Fiber Optic Network, Fiber Cables & Tools

Bridge Copper to Fiber With PoE Media Converter

It’s common to see in modern society that many enterprise networks must support a wide range of installation environments located indoors and out. Considering this, a wide range of media converters and power supply options are important. And with the great benefits of fiber optic cables being accepted widely, PoE media converter seems to be a better choice for enterprise networks. Today this article intends to explain what PoE media converter can bring for managers and its applications.

PoE Media Converter Basis

PoE media converter is a type of fiber-to-copper media converter. It enables enterprises to power their network devices over the existing copper connections. With its PoE injector, PoE media converters can power devices like IP phones, video conferencing equipment, IP cameras and Wi-Fi devices over copper UTP cabling. Besides, they are available in a variety of multi-port configurations, including dual RJ-45 and dual fiber ports, and they can support fixed fiber connectors or SFP (Small Form Pluggable) transceivers.

Once PoE media converters are connected into network systems, they are usually close to the PDs (Power devices) like IP cameras and wireless access points. And when they work, fiber is run to the power source via the SFP socket, and PoE is distributed over UTP cabling to the power devices via RJ45 port.

Network Design Options Provided by PoE Media Converter

PoE media converters bring great benefits for network deployments. For example, they eliminate the need for power supply devices, power cables and outlets that would be required for remote device. In addition, they also provide flexible network design options. Here are some examples.

PoE Media Converter with Single Fiber Ports

As shown in the following picture, single fiber ports are deployed in star topologies with a point-to-point style layout with the fiber switch in the center of the network.

PoE Media Converter with Dual Fiber Ports

Option 1: daisy chain design. This design uses dual fiber ports to support connections in a liner daisy chain configuration. It suits long-haul applications along subways and rail lines.

Option 2: fiber ring design. In this fiber ring architecture, traffic can flow in both directions. In the picture below, a switch connects three PoE media converters to form a ring. If a fiber

failure occurs in it, the switch can reroute the traffic in the opposite direction.

Option 3: redundant fiber design. This network structure uses two fiber connections. One is active and carries the data traffic. The other is a protection fiber port that back-up a fiber failure switch-over of less than 50 milliseconds.

Applications of PoE Media Converter

As we all know, in order to break out the distance and bandwidth limitations of copper cables, fiber optic cable is a good alternative. PoE media converters can convert copper to fiber and provide power at the same time, making it popular among enterprise networks. There are three main applications of PoE media converters.

Fiber to IP cameras. The PoE media converters have fiber uplink ports and downlink ports. And in most applications, two IP cameras at each location can be connected through the dual RJ-45 ports of a PoE media converter.

Fiber to wireless access points. PoE media converters enable wireless access points to be installed in office buildings, airport, hotels, public areas or other places needed.

Fiber to the desktop. The PoE media converters provide fiber to copper media conversion, and they send data and power to desktop items such as IP phones and video conferencing equipment.

Summary

PoE media converters provide a cost-effective way to extend distances over fiber optic cabling to PoE powered devices (PDs). In this article, four network designs with PoE media converters and three applications of them are illustrated simply. If you want to know more details about PoE media converters, please visit fiber-mart.COM.

Why Not Use Raman Amplifier to Extend the CWDM Network Reach?

In comparison with the long-haul DWDM network that uses the thermo-electric coolers to stabilize the laser emissions essential, the CWDM network is a more economical solution that features wider wavelength spacing, allowing the wavelength fluctuation of uncooled directly modulated laser diodes (DMLs). But on the other hand, the CWDM network exists the limitation for the uncooled DMLs’ output power and the additional loss of CWDM Mux Demux and optical add/drop modules. These make the CWDM loss budget limited to < 30 dB and the CWDM reach within 80 km. Moreover, when the insertion loss of the dark fiber is higher than our expectation, a decreasing transmission distance may occur. Hence, here offers the Raman amplifier (see the following figure) to extend the CWDM network reach, as an ideal solution.

What’s Raman Amplifier?

Raman amplifier, also referred to as RA, is a kind of optical fiber amplifier based on Raman gain, which is used for boosting optical signals and finally achieving a longer transmission distance. Different from the erbium-doped fiber amplifier (EDFA) and semiconductor optical amplifier (SOA), the RA intensifies the signals through the nonlinear interaction between the signal and a pump laser within an optical fiber, as shown in the figure below.

At present, two kinds of Raman amplifiers are available on the market, the distributed and lumped Raman amplifiers. As for the distributed Raman amplifier (DRA), it uses the optical fiber as the gain medium to multiplex the pump wavelength with signal wavelength, so that the optical signals can be boosted. With regard to the lumped one (LRA), it requires a shorter length of optical fiber for the signal amplification. Both of these two Raman amplifiers are suitable for amplifying CWDM signals and extending the CWDM network reach.

Why Raman Amplifier Is Used for Amplifying CWDM signals?

As we know, the EDFA and SOA are able to strengthen the CWDM signals. But why it is not recommendable for the CWDM network? In fact, they can not perform as well as the RA in the CWDM network for some limitations, which can be learned from the following figure.

The figures above shows various gain bandwidths of these three optical fiber amplifiers for CWDM network, but only the gain bandwidth the RA offers meet the CWDM network demands. To fully serve the CWDM network, the RA usually optimizes the pumping lightwave spectrum to extend the usable optical bandwidth. As for the EDFA, its gain bandwidth can not match well with the channel spacing of the CWDM network requirements. And for the SOA, although it offers the gain bandwidth fit enough for the CWDM network, it is still not suggested for the inherent technical limitations. In details, the SOA has a relatively low saturation power but a high noise figure and polarization sensitivity, compared to other two amplifiers. Hence, the RA is undoubtedly the best choice to strengthen the CWDM signals and lengthen the CWDM network reach.

How Does Raman Amplifier Benefit CWDM Network?

In order to study the benefit of RA for the CWDM network, here offers two sets of research data about the receiver sensitivity, for a bit-error rate (BER) of 10-9 using a pseudo-random bit sequence (PRBS) with a 231-1 word length.

From the figure above, we can learn that the first set of data is resulted from the four channel CWDM network without use of the RA, while the second utilizes the RA. In order to check whether the Raman amplifier benefits the CWDM network, we can take the data of 100km CWDM transmission through singlemode fiber (SMF) as an example. The power penalty of the transmission with a RA are separately -34.4 dBm, -34.2 dBm, -33.2 dBm and -32.3 dBm. It is 0.3 dBm better than the power penalty of the transmission without a RA, at least. Except that, we can also learn that the CWDM network with a RA can transmit the signals through the SMF at lengths up to 150m without any repeater stations, while the network without the RA cannot.

Conclusion

The Raman amplifier is an ideal alternative to the repeater in CWDM network, for intensifying the CWDM signals and extending the CWDM network reach. By using the Raman amplifier, the loss budget of the CWDM network can be increased, which finally achieves a longer transmission. Meanwhile, from the view of cost, the RA and the repeater are almost the same, but the repeater stations should cost much more for constructing and maintaining. Moreover, using the RA in the CWDM network can also gain the loss compensation of OADM. Then, why not use Raman amplifier to extend your CWDM network reach?

How to Install a QSFP28 Transceiver

In recent years, QSFP28 transceivers have been highly favored by many Ethernet users. The modules are hot-swappable input/output (I/O) device that connect the system’s module port electrical circuity with either a copper or a fiber-optic network. Transceiver installation attaches great importance to the whole Ethernet connectivity. This article provides the installation tips of 100 Gigabit QSFP28 optical transceivers.

Information About QSFP28 Transceiver

100 Gigabit (QSFP28) transceiver module is a hot-swappable, parallel fiber-optical module. The interconnect offers four channels of high-speed differential signals with data rates ranging from 25 Gbps up to potentially 40 Gbps, and will meet 100 Gbps Ethernet (4×25 Gbps) and 100 Gbps 4X InfiniBand Enhanced Data Rate (EDR) requirements. These channels can terminate in another 40G QSFP+ transceiver. The QSFP+ transceiver connects the electrical circuity of the system with an optical external network.

The following figure shows the 100G QSFP28 SR4 transceiver. The transceiver is used primarily in short reach applications in switches, routers and data center equipment where it provides higher density than SFP+ modules.

Required Tools and Equipment

To install the 100G QSFP28 transceiver, you need the following tools :

Wrist strap or other personal grounding device to prevent ESD occurrences.

Antistatic mat or Antistatic foam to set the transceiver on.

Fiber-optic end-face cleaning tools and inspection equipment.

Installing 100G QSFP28 Transceiver

The QSFP28 transceiver can have either a bail-clasp latch or a pull-tab latch. Installation procedures for both types of latches are provided.

Caution: The QSFP28 transceiver is a static-sensitive device. Always use an ESD wrist strap or similar individual grounding device when handling QSFP28 transceivers or coming into contact with system modules.

Installation Steps:

Step1: Attach an ESD wrist strap to yourself and a properly grounded point on the chassis or the rack.

Step2: Remove the QSFP28 transceiver from its protective packaging.

Step3: Check the label on the QSFP28 transceiver body to verify that you have the correct model for your network.

Step 4: For QSFP28 transceiver, remove the optical bore dust plug and set it aside.

Step 5: For QSFP28 transceiver equipped with a pull-tab, hold the transceiver so that the identifier label is on the top.

Step 6: For QSFP28 transceiver equipped with a bail-clasp latch, keep the bail-clasp aligned in a vertical position.

Step 7: Align the QSFP28 transceiver in front of the transceiver’s socket opening and carefully slide the QSFP28 transceiver into the socket until the transceiver makes contact with the socket electrical connector.

Step9: For optical QSFP28 transceiver, reinstall the dust plug into the QSFP28 transceivers optical bore until you are ready to attach the network interface cable. Do not remove the dust plug until you are ready to attach the network interface cable.

Conclusion

Through this passage, we are clear the basic installation procedures of 100G QSFP28 transceivers and please keep the cautions and tips in mind in case of accident. If you need any of 100G QSFP28 transceiver, fiber-mart.COM is a good choice.

What Are MPO Fiber Connectors?

MPO fiber connector is a passive component for optical fiber cable connection. It has been widely used in many projects and plays an important role in the optical fiber transmission system. In order to give full play to the role of MPO fiber connector in engineering applications, technicians should pay attention to the main structure and features of this connector, and master the basic working principle of MPO fiber connector so that the application of MPO fiber connector can be better put in practice and the development and innovation of optical fiber transmission system can be better promoted.

You may also see the term MTP used interchangeably with MPO. The term MTP is a registered trademark of the MPO connector offered by US Conec. The MTP is fully compliant with MPO standards and is described by US Conec as an MPO that has been engineered to very tight tolerances for improved performance. For the purpose of this discussion, we will refer to only MPO connectors since MTP connectors are considered to be MPO connectors.

Structure of MPO Fiber Connector

MPO is short for the industry acronym— “multi-fiber push on”. The MPO connector is a multi-fiber, and multichannel pluggable connector which is most commonly defined by two documents: IEC-61754-7 (the commonly sited standard for MPO connectors internationally) and EIA/TIA-604-5 (also known as FOCIS 5, is the most common standard sited for in the US). It is made up of a male plug , a female plug, and an adapter. The end of the male plug has two guide pins and a maximum of 72 guide holes, but the most common are 12 holes. When mating the connector, the spring mounted at the end of the core insert will provide a thrust on the core insert to lock it up with the adapter. The guide pins of the plug can restrict the relative position between the connectors, and ensure the optical fiber mating sequence is correct.

Features & Specifications

MPO connectors utilize precision molded MT ferrules, with metal guide pins and precise housing dimensions to ensure fiber alignment when mating. The MPO can be mass terminated in combinations of 4, 8, or 12 fiber ribbon cables. The MPO adapter comes standard in black. The single mode or multimode MPO products available from fiber-mart.COM are multifiber connections used in high-density backplane and Printed Circuit Board (PCB) applications in data and telecommunications system. The MPO connector, combined with lightweight ribbon cable, represents a huge technological advance over traditional multifiber cables. It’s lighter, more compact, easier to install, and less expensive, and it has lower insertion loss over traditional multifiber cables.

Application of MPO Fiber Connector

As mentioned, MPO connectors are compatible ribbon fiber connectors. MPO fiber connectors cannot be field terminated, thus MPO connector is usually assembled with fiber optic cable. MPO fiber optic cable is one of the most popular MPO fiber optic cable assemblies, which are now being widely used in data center to provide quick and reliable operation during signal transmission. MPO connectors can be found in the following applications:

Gigabit Ethernet

CATV and Multimedia

Active Device Interface

Premise installations

Optical Switch interframe connections

Interconnection for O/E modules

Telecommunication Networks

Industrial & Medical, etc.

Considerations to Select MPO Fiber Connector

With the drive of market requests. Various types of MPO connectors are being provided. Some basic aspects should be considered during the selection of a MPO connector. Firstly, pin option. MPO connectors have male and female design (as showed in the figure 1). Male connectors have two guide pins and female connectors do not. Alignment between mating ferrules of MPO connectors is accomplished using two precision guide pins that are pre-installed into the designated male connector. Secondly, fiber count. MPO connector could provide 4, 6, 8, 12, 24, 36, 64 or more interconnections, among which 12 and 24 are the most popular MPO connectors. In addition, like other fiber optic connectors, the selection of MPO fiber connectors should also consider fiber type and simplex or duplex design.

Conclusion

According to aforementioned introduction, we can see that MPO connector plays an important role in optical telecommunication as well as the high-density cabling solutions. If you are preparing to deploy network, it’s advisable that you can purchase quality MPO connector, MPO cables and MPO cassettes from fiber-mart.COM.

Comparison of Passive DWDM and Active DWDM System

DWDM (dense wavelength division multiplexing) technology is an ideal solution to address the capacity-hungry issue, which can simply fall into two types, passive DWDM and active DWDM. To greatly expand the bandwidth of the existing fiber system, both passive DWDM and active DWDM systems are designed to multiplex different wavelengths for carrying multiple signals over one single fiber. To better know the features of these two DWDM systems, the following will intend to learn what are the passive DWDM and active DWDM systems, and find their advantages and disadvantages.

Passive DWDM System Overview

Since there is no any active component used in the passive DWDM system, the performance of the passive DWDM link only depends on the optical budget of the DWDM transceivers used in the system. That’s to say, the transmission distance the passive DWDM system supports can’t be extended and is limited to the optical budget of the DWDM transceivers. We can learn from the figure below that shows a common passive DWDM system. Obviously, no active component like fiber amplifier and DCM module, but a pairs of 20 channels DWDM Mux are used. This design allows for high capacity transmission and makes capacity expansion possible. In short, it is very suitable to deploy passive DWDM system in metro networks and high speed and capacity communication lines.

Active DWDM System Overview

Unlike passive DWDM system, active DWDM system can be composed of fiber amplifier, DWDM Mux, DWDM transceiver, DCM module and OEO transponder, which can be also called transponder-based system. Due to its active feature, it is easier to manage and control the optical active DWDM network. Here offers the design of the active DWDM system for your reference.

DWDM (dense wavelength division multiplexing) technology is an ideal solution to address the capacity-hungry issue, which can simply fall into two types, passive DWDM and active DWDM. To greatly expand the bandwidth of the existing fiber system, both passive DWDM and active DWDM systems are designed to multiplex different wavelengths for carrying multiple signals over one single fiber. To better know the features of these two DWDM systems, the following will intend to learn what are the passive DWDM and active DWDM systems, and find their advantages and disadvantages.

Passive DWDM System Overview

Since there is no any active component used in the passive DWDM system, the performance of the passive DWDM link only depends on the optical budget of the DWDM transceivers used in the system. That’s to say, the transmission distance the passive DWDM system supports can’t be extended and is limited to the optical budget of the DWDM transceivers. We can learn from the figure below that shows a common passive DWDM system. Obviously, no active component like fiber amplifier and DCM module, but a pairs of 20 channels DWDM Mux are used. This design allows for high capacity transmission and makes capacity expansion possible. In short, it is very suitable to deploy passive DWDM system in metro networks and high speed and capacity communication lines.

Active DWDM System Overview

Unlike passive DWDM system, active DWDM system can be composed of fiber amplifier, DWDM Mux, DWDM transceiver, DCM module and OEO transponder, which can be also called transponder-based system. Due to its active feature, it is easier to manage and control the optical active DWDM network. Here offers the design of the active DWDM system for your reference.

Active DWDM

In the active DWDM system, the transponder usually utilizes short wave 850nm or long wave 1310nm to do the optical-electrical-optical (OEO) DWDM conversion. When the long distance is required in the active DWDM system, several EDFA fiber amplifiers will be inserted along the active DWDM link. What should be noted is that the active DWDM link can’t be extended infinitely, because the number of fiber amplifiers for an active DWDM link is limited to the optical cable type, the channel count, the data transmission rate of each channel, and permissible OSNR value, etc.

Furthermore, the chromatic dispersion occurring in the optical transmission also makes an influence on the transmission distance of the active DWDM link. Hence, when designing the active DWDM system, we should also take the permissible chromatic dispersion values of the link into consideration. If needed, we can insert the dispersion compensators (dcm modules) into the active DWDM link to enhance the optical signals for a longer transmission.

Passive DWDM vs Active DWDM System

It is well known that the passive DWDM system doesn’t need fiber amplifiers or dispersion compensators, which may saves you a lot of time and money. Meanwhile, it is also very easy to deploy due to the uncomplex installation. However, there are also several disadvantages of passive DWDM system. Firstly, the scalability is not so good as the active one. With the development of the passive DWDM system, more passive devices are required. Meanwhile, the passive DWDM system will be difficult to manage with the increasing of passive devices. What’s worse, if a wavelength or connection needs to be changed in the link, the only option is to take it out of link and disconnect the connection.

As for the active DWDM system, it can multiplex more wavelengths over a single fiber pair. Hence, more bandwidth can be provided by the active DWDM system. Furthermore, the active setups make the optical system management easier. And you can directly change the wavelengths or connections in the link without dropping connections. Finally, the active DWDM system is more scalable than the passive one, which makes more wavelengths to be multiplexed over the fiber. But one the other hand, there are also two main disadvantages of active DWDM system. One is the high cost of the active DWDM devices, and the other one is the complex installation.

In conclusion, the active DWDM system can offer greater capacity and higher scalablity, while the the passive DWDM system needs less cost and is easy to deploy. If the passive DWDM system meets your need, you’d better not to choose the active one as it will cost you very high. All in all, there is no the best, but the most suitable for your system. Just choosing the most suitable DWDM for your system according to what your network needs.

BiDi Fiber Optic Transceiver Overview

As we all know, common optical transceivers, like SFP+, SFP, normally require two fibers to achieve data transmission between switches, firewalls, servers, routers, etc. The first fiber is dedicated to receiving data from networking equipment, while the other is to transmit data to the equipment. With the development of technology, a new class of pluggable optical transceiver—BiDi fiber optic transceiver has been developed to combine the transmit and receive functions onto a single fiber (single-mode or multimode). The image below shows the differences between common optical transceiver and BiDi transceiver. How does BiDi transceiver achieve the transmission of optical channels on a fiber propagating simultaneously in both directions? What are the most commonly used BiDi transceivers available on the market? Is it worthwhile to use this kind of transceiver which is much more expensive than standard transceiver? The following test will provide more details from these three aspects.

How Does BiDi Fiber Optic Transceiver Work?

BiDi fiber optic transceiver is also called as WDM transceiver, since it is fitted with WDM coupler, which helps to combine and separate data transmitted over a single fiber based on the wavelengths of light. Unlike common optical transceivers use two fibers for duplex transmission, BiDi transceiver uses two different wavelengths to carry the duplex signals separately. The optical signals for transmitting and receiving are separately converted into signals of specific wavelengths as shown in the following image. This is why BiDi transceiver module can achieve the transmission of optical channels on a fiber propagating simultaneously in both directions.

Three Commonly Used BiDi Transceiver Types

Currently, there are a lot of fiber optic transceivers designed with BiDi technology available on the market, but the most commonly used ones are BiDi SFP, BiDi SFP+ and BiDi QSFP+. The following part will introduce them one by one.

BiDi SFP: BiDi SFP (shown in image below), compliant with the SFP multi-source (MSA), is specially used for the high-performance integrated duplex data link over a single optical fiber. It uses a long wavelength DFB laser diode, enabling data transmission up to 80 km on a single fiber. Generally, BiDi transceiver can be produced with LC simplex port which is used both for transmitting and receiving. Nowadays, it is one of the most popular industry formats supported by many fiber optic component vendors.

BiDi SFP+: Like BiDi SFP, BiDi SFP+ (see following image) is also connected by simplex LC fiber cable. Currently, BiDi SFP+ transceivers using 1270 nm and 1330 nm for transmission are most commonly used for 10G transmission. And it can achieve 10G data rate for the link lengths of 10 km, 20 km, 40 km, and 80 km. When you select BiDi transceivers, please take these two factors into consideration.

BiDi QSFP+: BiDi QSFP+ transceiver is a latest product used for 40G short-reach data communication and interconnect applications. Compliant with the QSFP MSA specification, it is terminated with a duplex LC connector interface to transmit data over laser-optimized OM3 and OM4 multimode fiber cables for the length of up to 100 m and 150 m respectively, that is the same as the traditional QSFP-40G-SR4. This 40G transceiver has two 20G channels, and each channel transmits and receives two wavelengths over a single multimode fiber strand. The following picture is a BiDi QSFP+ transceiver.

Why Should We Use BiDi Fiber Optic Transceiver?

Generally, BiDi fiber optic transceivers are much more expensive than common fiber optic transceivers. From fiber-mart.com, a Cisco SFP-10G-SR is 16 dollars, while a cheapest Cisco BiDi SFP+ transceiver is 50 dollars. Is it worthwhile to use this kind of transceiver? The answer is definitely yes.

As we have mentioned above, compared to traditional optical transceivers, BiDi transceivers uses fewer fibers (about 2 fibers) to support signal transmission, which can save an amount of money for you. Take BiDi QSFP+ transceiver as an example, if you are building a new 40G data center fabric in the traditional way, you would need to run 8-multimode fiber strands between your access and aggression layer: a cost of $2000 per port. However, with BiDi QSFP+ transceivers, you can get 40G performance using just 2 fiber strands: a quarter of cabling. For a standard server rack (384 ports), that translates to a savings of more than $550,000.

Summary

Although the label price of BiDi fiber optic transceiver is higher than standard optical transceiver, it is of much more value in practical applications. With the existence of BiDi fiber optic transceiver, the cost of fiber infrastructure will reduce, while the network capacity will increase. But keep in mind that BiDi transceiver is usually deployed in matched pairs to get the work most efficiently, since it uses two different wavelengths for transmission.