Category: Fiber Transceivers

DWDM network has been widely accepted as the most cost-effective and feasible solution to increase the fiber optic network capacity over long distance. Except the bandwidth, the transmission distance is also an important factor during the deployment of DWDM network. This post is to introduce how to ensure and extend the transmission distance in DWDM network.

Proper DWDM Fiber Optic Transceiver Is Essential

Generally, the fiber optic transmission distance is affected by the data rate, light loss, light source, etc. During the deployment, technicians usually need to select proper fiber optic transceivers to ensure the light source is strong enough to support the long transmission distances. For instance, 1G DWDM SFP modules provided by the market can usually support transmission distance up to 100km, while for 10G DWDM SFP+ modules this distance decrease to 80km. If the longer transmission distance is to achieve, proper fiber optic devices should be added in the DWDM network to ensure the transmission quality. The following part will take the examples of 10G DWDM network which uses DWDM SFP+ modules supporting transmission distance up to 80km on both ends of the fiber link. This 10G DWDM network will be required to support fiber optic links up to 40km, 80km, 120km and 200km separately.

Case Study One: 40km DWDM Network

In this first case, this 10G DWDM network is required to support 40km transmission distance. As we are using the 80km DWDM SFP+ modules, if there are no other locations deployed between the two ends of this network, generally no other devices are required to be installed between the two DWDM MUX/DEMUXs. The light source of 80km DWDM SFP+ modules can support 10G transmission over 40km.

Case Study Two: 80km DWDM Network

If this DWDM network is required to support 80km transmission distance, we will still use the 80km DWDM SFP+ modules. The light source of these 80km DWDM SFP+ modules might not be able to support such long transmission distance, as their might have light loss during transmission. In this case, pre-amplifier (PA) is usually deployed before the receiver to improve the receiver sensitivity and extend signal transmission distance. Meanwhile, the dispersion compensation module (DCM) can be added in this link to handle the accumulated chromatic dispersion without dropping and regenerating the wavelengths on the link. The following diagram shows the deploying method of this 80km DWDM network.

Case Study Three: 120km DWDM Network

It is known that the light power will decrease with the increasing of transmission distance. More fiber optic devices should be added in the 120km DWDM network to amplify the optical signal transmission from the 80km DWDM SFP+ modules. The following diagram shows how to deploy this 120km DWDM network. Except the above mentioned pre-amplifier and dispersion compensation module, a booster EDFA (BA) is suggested to deploy before at the beginning of the transmitting side to further ensure optical signal can achieve 120km.

The above cases just simply illustrate the deployment of 40km, 80km and 120km 10G DWDM network that uses 80km DWDM SFP+ modules as light source. Related products in the above mentioned cases are listed in the following table. Please note that during the deployment of these long haul DWDM network, the light loss and compensation dispersion should be well calculated.

fiber-mart.com.COM Long Haul DWDM Solution

In fact, DWDM technologies and products can achieve transmission distance much longer than 120km, like 170km DWDM and 200km DWDM. If you are interested, kindly visit our Long Haul DWDM Network page where you can find specific details for complete DWDM network deployment solutions.

LC-LC patch cable has already become the main force of high density cabling network infrastructure. To future increase the profits of LC-LC fiber patch cable, manufactures has invented LC-LC patch cables of different features to meet various requirements in data center and increase the network performance.

What Kind of Fiber Patch Cable Is Required in Data Center?

Data center is a place of thousands fiber links. The selection of fiber patch cables will directly affect the network performance. More and more data centers choose to select fiber patch cable of high performance. Generally, insertion loss and return loss of connectors terminated on patch cable and light loss of optical fiber used for fiber patch cable are three most basic factors for fiber patch cable selection. To satisfy the increasing demands for higher density and easier management in data center, the optimization of fiber patch cable has never stopped. The following introduces several popular LC-LC fiber patch cables which represent the trends of fiber patch cable that data center is asking for.

Low Insertion Loss and Bend Loss LC-LC Patch Cable

When a length of fiber patch cable is connected in network, optical light loss occurs at the optical fiber and the connectors terminated on it. There are different optical light losses, among which insertion loss at the connectors and bend loss in fiber optic cables are the two most commonly light losses that technicians are trying to overcome. Manufactures provides LC-LC fiber patch cables which can minimize these losses to the most.

Insertion loss refers to the fiber optic light loss caused when a fiber optic component insert into another one to form the fiber optic link. To provide low insertion loss patch cable, LC connectors terminated on the patch cable has been optimized. Standard LC-LC patch cable usually has an insertion loss less than 0.3 dB. However, for upgraded LC-LC patch cable, the insertion loss is usually lower than 0.2 dB. To decrease the bend loss, a type of bend insensitive fiber (BIF) has been used in fiber patch cable. With optimized LC connectors and bend insensitive fiber, LC-LC fiber patch cable could provide lower light loss during network transmission.

High Density LC-LC Patch Cable

LC connector was invented for higher cabling density. standard duplex LC-LC fiber patch cable can provide much higher cabling density than other duplex fiber patch cables. To further increase cabling density in data center, the connectors and cable diameter of LC-LC patch cable are becoming smaller. Uniboot LC-LC patch cable is a typical example. This kind of fiber patch cable designed the two fibers of the duplex patch cable into a single cable. In adding the two connectors terminated at each end of the duplex patch cable share the same boot. With less using cable counts, uniboot patch cable can provide higher cabling density and better cooling environment in data center.

Polarity Switchable LC-LC Patch Cable

The development of patch cable won’t stop at low loss and high density. Making fiber patch cable easier-to-use is also important. Polarity of fiber patch cable matters a lot during installation of fiber patch cable, especially for duplex fiber patch cable and MTP patch cable. It is common to change the polarity of a duplex patch cable during deployment. Technicians might need tools to change the polarity of patch cable. However, a polarity switchable LC-LC patch cable can make things much easier. Without any tools you can polarity reversal could be really easy. The following picture shows the polarity reversal of a special designed LC-LC patch cable.

Conclusion

LC-LC patch cable has been designed into many different types. A high performance fiber patch cable should not only provide low insertion loss and bend loss, but also higher cabling density and easy-to-use features. This is also the trend of data center development.

Due to the rapid increase of communication traffic, the requirement for core networks to handle larger capacity and longer distance on their links has led to a spread of 100G optical networks. For this environment, service providers are adopting coherent transceivers for their 100G DWDM backbone applications. Until recently, coherent CFP/CFP2 DWDM optical transceivers had been the technology of choice for transporting 100G traffic over long distances or as part of a DWDM network. This paper will mainly discuss 100G coherent CFP module for metro network application.

Coherent Technology: Making 100Gb/s Available

Moving from 10Gb/s to 100Gb/s line speeds comes with technical challenges. Coherent technology had been investigated for optical transmission since the 1980s as a means to increase transmission distances. By 2010 to 2011, the technology had reached a point of market maturity. At this time, it could genuinely allow 100G coherent signals. This result forms the foundation of the industry’s drive to achieve transport speeds of 100G and beyond, which helps to deliver Terabits of information across a single fiber pair at a lower cost. Until now, coherent technology has been mainly deployed in long-haul networks, and it is now starting to be deployed in metro networks.

Metro Requirements for 100G

100G rates were initially deployed in the long-haul and core networks. In the Metro, 10G is still the most dominant rate. In the coming years, the trend toward aggregation into 100G in the larger metro areas or data center connectivity will become more significant. The metro covers a broad range of distances: the metro regional and metro core cover distances of 500-1000 km and 100-500 km respectively, while the metro access links are generally point-to-point connections shorter than 100 km. Although these distances are shorter than long-haul links, the characteristics of metro network- including flexible protocol support, higher granularity of signal rates and increased number of nodes- create the requirements for 100G rates.

100G Coherent CFP Module for Metro Network Applications

While metro and long haul applications have different requirements, the lower-cost 100G technology for the metro is demanded for service providers. To achieve this feat, equipment vendors consider coherent CFP modules as the ultimate solutions for metro 100G deployments. Coherent 100G CFP can overcome optical transmission impairments and still achieve acceptable performance.

since the 100G rates are more susceptible to dispersion, they would require extra dispersion compensation and optical power boost. Thus an extra 100GHz DWDM multiplexer is first used to combine all the 100G rates together followed by a combined dispersion compensation and amplification stage. This architecture conveniently supports the ‘pay-as-you-grow’ model for service providers. When the bandwidth is exhausted, the existing legacy 10G channels may be seamlessly interchanged with 100G services. The same remaining components can even be reused to extend the data rate up to 2.4 Tb/s.

This scenario would require 24 differently colored CFP modules deployed together with the already existing 48 channel 100 GHz DWDM multiplexer. All the 100G services are first multiplexed together such that only one dispersion compensation and amplification stage suffices. Clearly, such a network architecture provides higher density with capability to reuse existing infrastructure with flexibility while remaining cost friendly.

In this scenario, the switch was tested with SFP+ OEO transponders for simple distance extension solutions. The 100G output signals from the switch are converted to DWDM signals that can be transmitted over longer distance. The solution removes the distance limitations by using a coherent CFP module to connect the output signal to the line fiber and carry the signal over longer distances.

to achieve higher cabling density with Cisco CFP 100G optics, the architecture mixed a 16 channels dual fiber DWDM Mux Demux which can be used for CWDM/DWDM hybrid and 8 channels dual fiber CWDM Mux Demux, by adding MTP harness cable and WDM SFP+ OEO converter to transfer the regular SR wavelength to DWDM wavelengths. Therefore, building a long distance 2500km DWDM networks in 100G coherent CFP modules and cost effective way will be achieved.

Conclusion

100G coherent CFP modules provide cost-effective electronic equalization of fiber impairments and extensive performance monitoring capabilities that enable easy installation and network management. These benefits help service providers meet bandwidth demand growth while reducing the total cost of ownership.

10G connection in telecommunication network is gradually moving from the backbone to layer 2 and layer 3. Both technology and market of 10G SFP+ transceiver modules are mature: the 10G transceiver modules have advanced from XENPAK which is the first generation of 10G transceiver to SFP+ which is now the most popular 10G optics. In addition, the price of 10G modules is getting lower. 10G modules are becoming affordable. Some genius guys even buy 10 SFP+ modules online to DIY private point to point 10G network. This article will offer basic information about 10G SFP+ transceiver modules and their connection instructions.

Basic of 10G SFP+ Transceiver Module

10G SFP+ transceiver has the same form factor of Gigabit SFP transceiver. Thus, many 10G modules can support 1/10G data rate to increase its flexibility during practical using. A SFP+ transceiver usually has two LC ports (as shown in the following picture). While 10G BiDi SFP+ transceiver, which transmitting and receiving signals from the same fiber optic cable, only has one LC port.

Except fiber optical transceivers, there are also various factory terminated copper-based or fiber optic based cables which are terminated with a SFP+ module on each end of the cable. There are mainly three types of these 10G cables: 10G SFP+ passive direct attached copper cable, 10G active direct attached copper cable and 10G SFP+ active optical cable. These 10G SFP+ cables eliminate the used of additional patch cable and can be directly plugged into the 10G SFP+ ports on switches. It is acceptable that these cables are an cost-effective and reliable solutions for 10G connections in short distance.

Optical Standards of 10G SFP+ Transceiver

According to IEEE standards, there are a variety 10GBASE SFP+ transceivers. For short distance transmission, 10GBASE-SR SFP+ and 10GBASE-LRM SFP+ can support transmission distance up to 300 meters and 220 meters over multimode fiber optic cables separately. 10GBASE-SR SFP+ modules is the most commonly used transceiver for short distance. It is suggested to work over wavelength of 850 nm.

There are a lot of 10G SFP+ transceivers that support long distance, like 10GBASE-LR SFP+, 10GBASE-ER SFP+, 10GBASE-ZR SFP+, CWDM SFP+, DWDM SFP+, BiDi SFP+, etc. These transceivers can support transmission distances ranging from 10 km to 120 km over single-mode fiber optic cables.

There is another special type of 10G transceivers which has been mentioned in this post, which is known as dual-rate SFP+. For example, dual-rate 1000BASE-LX and 10GBASE-LR SFP+ transceiver can be adjusted to support both 1G and 10G data rate up to 10 km over wavelength of 1310 nm.

Fiber Patch Cable Selection Guide for 10G SFP+ Transceivers

As 10G SFP+ DAC and AOC eliminate the using of additional patch cords. This part will introduce the selection guide for 10G SFP+ transceivers. During the selection of fiber optic patch cables for 10G SFP+ transceivers, the transmission distance is the first element to be considered. Single-mode patch cable is used for long distance transmission and multimode is designed for short distance transmission. Then the ports on the transceiver for receiving and transmitting should be considered. As mentioned, most 10G transceiver use duplex LC port, while BiDi SFP+ use simplex port (as shown in the above picture). Thus, simplex LC patch cords or duplex LC patch cords are used according to the port type on the transceiver. The following chart introduces detailed cabling information for 10G SFP+ transceivers.

This post just introduced the basic information of 10G optics and cabling information. For more specific information, please visit fiber-mart.COM, where you can find a variety of 10G SFP+ optics modules.

PLC splitter is a simple passive component which plays an important role in the applications of technologies like GPON, EPON and BPON. It allows a strand of fiber optic signal being equivalently splitted into several strands of optical signal, which can support a single network interface to be shared by many subscribers. When selecting it, split ratios should always be considered. However, with the network cabling environment becoming increasingly complex, various PLC splitters with different package form factors are being invented. Now the package form factor of it is also a key factor to be considered. This post will introduce the most commonly used PLC splitters in different package form factors for your reference during selection.

Bare Fiber PLC Splitter

Bare fiber PLC splitter is commonly used in FTTx projects. It leaves bare fiber on all its ends. Thus, they can be spliced by network engineer freely according to the applications. Meanwhile, it requires the least space during cabling. They can be installed in fiber optic splicing closure easily to provide FTTH signal distribution.

Blockless PLC Splitter

A blockless PLC splitter looks like a bare fiber splitter. The main differences are that the blockless one is usually terminated with fiber optic connectors and it uses a compact stainless tube package. It is also common that many bare fiber PLC splitters also use stainless tube package for the split chip.

Fanout PLC Splitter

Fanout PLC splitter generally uses 0.9mm buffer fiber, added with a length of ribbon fiber terminated with fanout kit behind the PLC split chip. The splitter ratios of it also come in various types. The following picture shows a 1:8 fanout version which is terminated with SC/APC connectors.

ABS PLC Splitter

ABS PLC splitter uses ABS plastic box to holding the splitter chip. The inbound fibers and distribution fibers are arranged on the same plate of this ABS box, which can provide easier and more flexible cabling. Except providing reliable protection, it can also be installed in a variety of boxes or enclosures. It is very commonly to install a it in a standard 19-inch rack unit.

LGX Box PLC Splitter

LGX Box PLC splitter looks like a MTP LGX cassette. It houses the whole splitter inside a metal box and leave fiber optic adapters for both inbound fibers and distribution fibers on its front panel. The LGX splitter can be used stand alone or be installed in the standard rack unit or fiber enclosures for better cabling.

Mini Plug-in PLC Splitter

Mini plug-in PLC splitter is now widely used in FTTx project, especially at the distribution points near the end users of the FTTx networks. It provides fast installation and low space requirement helping to alert the deployment of FTTs projects. Fiber pigtails for input and output can be directly connected with this passive component easily.

Tray Type PLC Splitter

Tray type PLC splitter also uses a space saving package form factor for better cable management. However, it uses a international 19-inch design which can be deployed in ODF for compact cable management and signal distribution. With this design, the ports on tray type splitter are clearly marked, which can reduce the faults caused by wrong connections.

Rack Mount PLC splitter

Rack mount PLC splitter is designed to meet the requirement of high cabling density for data centers or server room. It can be firmly installed on the data center or server racks. It is an ideal solution for high density cabling environment. fiber-mart.COM can provide PLC splitter ports up to 64 in 1U 19-inch rack. The following picture shows the details of a 1:8 rack mount one provided in fiber-mart.COM.

fiber-mart.COM PLC Splitter Solution

PLC splitter is a cost-effective passive optical component enabling a single network interface to be shared by two or more users. Selecting the right package form factor for it can help a lot during both the network deployment and maintaining. The above mentioned splitters in different package form factors are all being provided in fiber-mart.COM. Customized ones are also available in fiber-mart.com. Kindly contact sales@fiber-mart.com for more details if you are interested.

FTTH (fiber to the home) networks are installed in many areas covering indoor section, outdoor section, as well as the transition in between. To fulfill the cabling requirements from different areas, different types of fiber optic cable are well developed. Drop cable as an important part of FTTH network forms the final external link between the subscriber and the feeder cable. This blog post will focus on this special outdoor fiber optic cable.

The Basic of FTTH Drop Cable

Drop cables, as previously mentioned, are located on the subscriber end to connect the terminal of a distribution cable to a subscriber’s premises. They are typicality small diameter, low fiber count cables with limited unsupported span lengths, which can be installed aerially, underground or buried. As it is used in outdoor, drop cable shall have a minimum pull strength of 1335 Newtons according to the industry standard. Drop cables are available in many different types. The following part introduces three most commonly used drop cables divided according to the cable structure.

Flat Type Drop Cable, also known as flat drop cable, with a flat out-looking, usually consists of a polyethylene jacket, several fibers and two dielectric strength members to give high crush resistance. Drop cable usually contains one or two fibers, however, drop cable with fiber counts up to 12 or more is also available now. The following picture shows the cross section of a flat drop cable with 2 fibers.

Aerial Drop Cable is self-supporting cable, with the cable fixed to a steel wire, designed for easy and economical aerial installation for outdoor applications. This type of drop cable is fixed to a steel wire as showed in the following picture. Typical fiber counts of figure-8 Drop Cable are 2 to 48. Tensile load is typically 6000 Newtons.

Round Drop Cable usually contains a single bend-insensitive fiber buffered and surrounded by dielectric strength members and an outer jacket, which can provide durability and reliability in the drop segment of the network. The following shows the cross section of a round drop cable with one tight buffered optical fiber.

Drop Cable Connectivity Method: Splice or Connector?

It’s necessary to choose a right architecture for FTTH network from overall. However, drop cable as the final connection from the fiber optic network to customer premises also plays an important role. Thus, finding a flexible, efficient and economical drop cable connectivity method becomes a crucial part of broadband service. Whether to use a fiber optic connector, which can be easily mated and un-mated by hand or a splice, which is a permanent joint? The following will offer the answer and the solutions for your applications.

It is known that splice, which eliminates the possibility of the connection point becoming damaged or dirty with a permanent joint, has better optical performance than fiber optic connector. However, splice lack of operational flexibility compared with fiber optic connector. Fiber optic connector can provide an access point for networking testing which cannot be provided by splicing. Both methods have their own pros and cons.

Generally, splice is recommended for drop cables in the places where no future fiber rearrangement is necessary, like a greenfield, new construction application where the service provider can easily install all of the drop cables. Fiber optic connector is appropriate for applications which flexibility is required, like ONTs which have a connector interface.

Choosing the Right Splice Method

For splice, there are two methods, one is fusion splicing, the other is mechanical splicing. Fusion splicers have been proved to provide a high quality splice with low insertion loss and reflection. However, the initial capital expenditures, maintenance costs and slow installation speed of fusion splicing hinder its status as the preferred solution in many cases. Mechanical splicing are widely used in FTTH drop cable installation in countries, as a mechanical splice can be finished in the field by hand using simple hand tools and cheap mechanical splicer (showed in the following picture) within 2 minutes. It’s a commonly used method in many places, like China, Japan and Korea. However, in US mechanical splicing is not popular.

Choosing the Right Connector

For fiber optic connector, there are two types connector for drop cable connection. Field terminated connector, which contains fuse-on connector and mechanical connector, and pre-terminated drop cable, which is factory terminated with connector on the end of drop cable.

Fuse-on connector uses the same technology as fusion splicing to provide the high optical connection performance. However, it requires expensive equipment and highly trained technician, and more time like fusion splicing. Mechanical connector could be a replacement of fuse-on connector (showed in the following picture), if the conditions do not fit the mentioned ones. It could be a time-save and cost-save solution for drop cable termination.

If you have no limits in cost and want high performance termination in a time-save way, pre-terminated drop cable could be your choice. Many factories can provide you customized drop cables in various fiber types, fiber optic connector and lengths.

Conclusion

Customer demand for higher bandwidth will continue to drive the development of FTTH as well as its key component like drop cable. Choosing the right drop cable and drop cable termination method is as important as choosing the right network architecture in FTTH.