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Armored Fiber Optic Cable

Definition of armored fiber optic cable
Armored Fiber Optic Cable, just as the name implies, is that there is a layer of additional protective metal armoring of the fiber optic cable.
Function
Armored fiber cable plays a very important role in long-distance line of fiber optic cable. A layer of metal armoring in the scarf-skin of fiber optic cable protects the fiber core from rodent, moist and erosion.

Classification
According to the place of use, there are indoor armored fiber optic cables and outdoor armored fiber optic cables.

Indoor armored fiber optic cable
Indoor armored fiber optic cable is mainly used in interior, so it must be flexible and can be installed in the corner and some narrow places. Besides, indoor armored fiber optic cable experiences less temperature and mechanical stress, but they have to be fire retardant, emit a low level of smoke in case of burning. And indoor armored fiber cables must allow a small bend radius to make them be amendable to vertical installation and handle easily.

Indoor armored fiber optic cable can be divided into simplex armored fiber optic cable and duplex armored fiber optic cable. The main difference is that simplex armored fiber optic cable is the cable that not contains stainless steel wire woven layer, and duplex armored fiber optic cable is the cable that contains stainless steel hose and stainless steel wire woven which are of compressive property, resistance to deflection, rodent resistance, anti-torque and so on.

Outdoor armored fiber optic cable
Outdoor armored fiber optic cables are made to protect the optical fiber to operate safely in complicated outdoor environment. Most armored outdoor fiber cables are loose buffer design, with the strengthen member in the middle of the whole cable, the loose tubes surround the central strength member.

Outdoor armored fiber optic cable can be divided into light armored fiber optic cable and heavy armored fiber optic cable. Light armored fiber optic cable is with steel tape and aluminium tape which can strengthen rodent protection. Heavy armored fiber optic cable is equipped with a circle of steel wire, and usually used in riverbed and seabed.

Installation
There are two installation methods of armored fiber optic cable. One is buried directly in the ground, and the other is aerial optical cable.

For direct burial fiber cable, armored fiber optic cable is in the position to resist external mechanical damage, prevent erosion and resist rodent. In addition, because of different soil and environment, the depth of burying under the ground is about between 0.8m-1.2m.

On the other hand, aerial optical cable is the optical cable that hanging on the pole. This kind of installation way of armored fiber optic cable can prevent fiber core from any kind of severe environment, such as typhoon, ice, and people or animals. Aerial armored optical cable mostly uses central loose tube armored fiber optic cable (GYXTW) and stranded loose tube armored fiber optic cable (GYTA). The features of GYXTW are that can contain up to 12 fiber cores, the loose tube is centrally situated with good excess length and minimizes the influence of lateral crush, and double wire as strength member provides excellent strain performance. GYTA is suitable for installation for long haul communication and LANs, especially suitable for the situation of high requirements of moisture resistance. GYTA is with compact structure; the cable jacket is made of strong Polyethylene. This armored fiber optic cable features the good mechanical and temperature performance. GYTA is also with high strength loose tube that is hydrolysis resistant and the optical cable filling materials ensure high reliability, its APL makes the cable crush resistant and moisture proof. The GYTA fiber optic cable is available from 2 cores to 144 cores.

The Introduction of Optical Power Meter

What Is an Optical Power Meter?
An Optical Power Meter usually knows as Fiber optical power meter is a device that used to measure the absolute optical signal and relate fiber optic loss. The term usually refers to a device for testing average power in fiber optic systems. Fiber optical power meter is a tool for telecommunication and CATV network. Optical power meter consists of a calibrated sensor, measuring amplifier and display. The sensor primarily consists of a photodiode selected for the appropriate range of wavelengths and power levels. On the display unit, the measured optical power and set the wavelength are displayed. Power meters are calibrated using a traceable calibration standard such as a NIST standard.

When to Use Optical Power Meter?
When you install and terminate fiber optic cables, you need to test them. A test should be conducted for each fiber optic cable plant for three main areas: continuity, loss, and power. In order to do this, you’ll need a fiber optic power meter.

How to Use Optical Power Meter?
When you measure fiber optic power with a power meter, you should attach the meter to the cable. Turn on the source of power, and view the meter’s measurement. Compare the meter measurement with the specified correct power for that particular system to make sure it have proper power not too much or too little . Correct power measurement is so important to fiber optic cables because the system works similar to electric circuit voltage, and the power must be just the right amount to work properly.

Classification of Optical Power Meter
There are two types of Optical Power Meter: Ordinary Optical Power Meter and PON Optical Power Meter. Ordinary optical power meter measures the optical power in the fiber link, typically an absolute power value 850/1300/1310/1490/1550/1625nm optical wavelength. While PON Optical Power Meter is more suitable for measuring the fiber to the home (FTTH) networks. Specific measurement: PON Optical Power Meter can send three wavelengths from a single laser output port (1310 nm, 1490 nm, 1550 nm), of which 1310nm can measure upstream transmission direction, 1490 nm and 1550 nm measure downstream direction. Upstream associated with your upload data, downward is download data.

Tips for Selection and Operation

Choose the best probe type and interface type.
Evaluation of calibration accuracy and manufacturing calibration procedures, and your fiber and connectors to match the required range.
Make sure the type and the range of your measurement and display resolution is consistent.
With immediate effect db insertion loss measurements.
Wear eye protection when working with high-power cables. Even with low-power layouts, it’s wise to check the connectors with your power meter before looking.

Some Common Types of Indoor Cables

Optical fiber cables for indoor cabling are used for the construction of horizontal subsystem and SCS building backbone cabling subsytems. They differ form cables used for outdoor cabling by two key parameters.

Indoor fiber optic cable is tight buffer design, usually they consist of the following components inside the cable, the FRP which is non-metallic strengthen member, the tight buffer optical fiber, the Kevlar which is used to further strength the cable structure, making it resist high tension, and the cable outer jacket. The trend is to use LSZH or other RoHS compliant PVC materials to make the cable jacket; this will help protect the environment and the health of the end users.

Indoor Cables

Cables for indoor applications include the following:

* Simplex cables
* Duplex cables
* Multifiber cables
* Heavy-, light-, and plenum-duty cables
* Breakout cables
* Ribbon cables

Although thes categories overlap, they represent the common ways of referring to fibers. Figure 7-5 shows cross sections of several typcial cables types.

Simplex Cables

A simplex fiber cable consists of a single strand of glass of plastic fiber. Simplex fiber is most often used where only a single transmit and/or receive line is required between devices or when a multiplex data signal is used (bi-directional communication over a single fiber).

Duplex Cables

A duplex fiber cable consists of two strands of glass or plastic fiber. Typically found in a “zipcord” construction format, this cable is most often used for duplex communication between devices where a separate transmit and receive are required.

Duplex cable is used instead of two simplex cables for aesthetics and convenience. It is easier to handle a single duplex cable, there is less chance of the two channels becoming confused, and the appearance is more pleasing. Remember, the power cord for your lamp is a duplex cable that could eaily be two separate wires. Does a single duplex cord in the lamp not make better sense? The same reasoning prevails with fiber optic cables.

Loose Tube Cables

The loose tube variety contains one or more hard buffer tubes, which house between 1 and 12 coated fibers. The hard buffer tubes are also filled with a gel to provide vibration and moisture protection for the fibers. The fibers lie loosely in the tubes, which are wound into the cable in a reversing helical fashion and are actually longer than the outer sheath of the cable. This arrangement allows for a small amount of stretch in the outer sheath when installing the cable. Loose tube cable is used most often in OSP construction because it is designed for a tough outdorr environment use. See Figure-1 for the physical make-up of a typical loose tube cable.

Breakout Cables

Breakout cabke

Breakout cables have several individual simplex cables inside an outer jacket. The breakout cables shown in Figure 2 use two dielectric fillers to keep the cables positioned, while a Mylar wrap surrounds the cables/fillers. The outer jacket includes a ripcord to make its removal fast and easy. The point of the breakout cable is to allow the cable subunits inside to be exposed easily to whatever length is needed. Breakout cables are typically available with two or four fibers, although larger cables also find use.

Ribbon Cables

ribbon cable

Ribbon cable uses a number of fibers side by side in a single jacket. Originally, Ribbon fiber cable was used for outdoor cables (see Figure 3). Today they also find use in premises cabling and computer applications. The cables, typically with up to 12 fibers, offer a very small cross section. They are used to connect equipment within cabinets, in network applications, and for computer data centers. In addtion, they are comatible with multifiber array connectors. Ribbon cables are available in both multimode and single-mode versions.

The Application and Types of Armored Fiber Cable

What Is Armored Fiber Cable?
Armored fiber optic cable consists of a cable surrounded by a steel or aluminum jacket which is then covered with a polyethylence jacket to protect it from moisture and abrasion. It may be run aerially, installed in ducts, or placed in underground enclosures with special protection from dirt and clay intrusion.

armored fiber optic cable

Armored fiber optic cable is often installed in a network for added mechanical protection. Two armored fiber cable types exist: interlocking and corrugated. Interlocking armor is an aluminum armor that is helically wrapped around the cable and found in indoor and indoor/outdoor cables. It offers ruggedness and superior crush resistance. Corrugated armor is a coated steel tape folded around the cable longitudinally. It is found in outdoor cables and offers extra mechanical and rodent protection.

Types Of Armored Fiber Cable

Armored fiber cable can be divided into indoor armored fiber cable and outdoor armored fiber cable. With the fast development of fiber optic communication technology and the trend of FTTX, indoor fiber optic cables are more and more required to be installed between and inside buildings. Typical indoor armored fiber cable types include GJFJV, GJFJZY, GJFJBV, GJFJBZY, GJFDBV and GJFDBZY. Compared with outdoor use fiber cable, indoor fiber cable experiences less temperature and mechanical stress, but they have to be fire retardant, emit a low level of smoke in case of burning. And indoor armored fiber optic cable allows a small bend radius to make them be amendable to vertical installation and handle easily.

Features of Indoor Armored Fiber Cable

* Good mechanical property and environment property.
* Soft, agility, convenience for connect.
* Flexible and Easy to Handle
* Cables with Improved Attenuation Available
* Adapt to harsh environments and man-made damage.

Outdoor armored fiber cable is made to protect the optical fiber to operate safely in complicated outdoor environment. Most Outdoor Armored fiber cables are loose buffer design, with the strengthen member in the middle of the whole cable, the loose tubes surround the central strength member. Inside the loose tube there is waterproof gel filled, whole cable materials used and gels inside cable between the different components (not only inside loose tube) will help make the whole cable resist of water.

Features

* Excellent attenuation performance
* Dry water blocking for moisture protection
* Polyethylene jacket for weather and UV protection
* Breakout kits available
* Corrugated Steel Tape
* Rodent Resistant
* Waterblock gel available

Application of Armored Fiber Cable

Armored fiber cable is used in direct buried outside plant applications where a rugged cable is needed and/or for rodent resistance. Armored fiber optic cable withstands crush loads well, for example in rocky soil, often necessary for direct burial applications. Cable installed by direct burial in areas where rodents are a problem usually have metal armoring between two jackets to prevent rodent penetration. Another application for armored fiber cable is in data centers, where cables are installed under the floor and one worries about the fiber cable being crushed. Indoor armored fiber optic cables may have nonmetallic armor. Metallic armored fiber cable is conductive, so it must be grounded properly. As with other fiber optic components, there are different names or meanings used. “Armor” in some companies’ jargon denotes a twisted heavy wire rope type cable surrounding the entire poly cable sheath/jacket. Single or double armor (two opposite ply layers of the steel wire) is typically used underwater near shore and shoals. Inner metallic sheath members of aluminum and/or copper are used for strength and for buried cable locating with a tone set.

What’s Difference Between CFP and CXP Transceivers?

Two years ago, though everyone is talking about the 100G Ethernet as the next generation, it had still faced a lot of problems to be solved, seeming to be a long way off. But, technologies are developed very rapidly, and now 100G Ethernet is becoming more and more closer to us. Fiber connectivity in higher-speed active equipment is being condensed and simplified with plug-and-play, hot-swap transceiver miniaturization. Thus, optical transceiver technology is one of the basic but important technology to achieve the realiable and effective 100G Ethernet. Interfaces for 100G active equipment include CFP and CXP. So, what are CFP and CXP? And what’s the difference between CFP and CXP? Is CXP transceiver designed to replace the CFP? … You might be interested in them and have a lot of questions in your mind. Today, you will find the answer in this post.

About CFP
CFP, short for C form-factor pluggable, is a multi-source agreement to produce a common form-factor for the transmission of high-speed digital signals. The c stands for the Latin letter C used to express the number 100 (centum), since the standard was primarily developed for 100 Gigabit Ethernet systems. In fact, CFP also supports the 40GbE. When talking about CFP, we always define it as multipurpose CFP, compared to the CXP which is discussed later.

The CFP MSA was formally launched at OFC/NFOEC 2009 in March by founding members Finisar, Opnext, and Sumitomo/ExceLight. The CFP form factor, as detailed in the MSA, supports both single-mode and multi-mode fiber and a variety of data rates, protocols, and link lengths, including all the physical media-dependent (PMD) interfaces encompassed in the IEEE 802.3ba standard. At 40GE, target optical interfaces include the 40GBase-SR4 for 100 meters (m) and the 40GBase-LR4 for 10 kilometers (km). There are three PMDs for 100 GE: 100GBase-SR10 for 100 m, 100GBase-LR4 for 10 km, and 100GBase-ER4 for 40 km.

CFP was designed after the Small Form-factor Pluggable transceiver (SFP) interface, but is significantly larger to support 100Gbps. The electrical connection of a CFP uses 10 x 10Gbps lanes in each direction (RX, TX). The optical connection can support both 10 x 10Gbps and 4 x 25Gbps variants. CFP transceivers can support a single 100Gbps signal like 100GE or OTU4 or one or more 40Gbps signals like 40GE, OTU3, or STM-256/OC-768.

The CFP-MSA Committee has defined three form factors:

CFP – Currently at standard revision 1.4 and is widely available in the market
CFP2 – Currently at draft revision 0.3 is half the size of the CFP transceiver; these are recently available in the market
CFP4 – Standard is not yet available, is half the size of a CFP2 transceiver, not yet available

CFP transceiver today to future

The original CFP specification was proposed at a time when 10Gbps signals were far more achievable than 25Gbps signals. As such to achieve 100Gbps line rate, the most affordable solution was based on 10 lanes of 10Gbps. However as expected, improvements in technology has allowed higher performance and higher density. Hence the development of the CFP2 and CFP4 specifications. While electrical similar, they specify a form-factor of 1/2 and 1/4 respectively in size of the original specification. Note that CFP, CFP2 and CFP4 modules are not interchangable (but would be interoperable at the optical interface with approriate connectors).

About CXP
CXP is targeted at the clustering and high-speed computing markets, so we usually called it high-density CXP. Technically, the CFP will work with multimode fiber for short-reach applications, but it is not really optimized in size for the multimode fiber market, most notably because the multimode fiber market requires high faceplate density. The CXP was created to satisfy the high-density requirements of the data center, targeting parallel interconnections for 12x QDR InfiniBand (120 Gbps), 100 GbE, and proprietary links between systems collocated in the same facility. The InfiniBand Trade Association is currently standardizing the CXP.

The CXP is 45 mm in length and 27 mm in width, making it slightly larger than an XFP. It includes 12 transmit and 12 receive channels in its compact package. This is achieved via a connector configuration similar to that of the CFP. For perspective, the CXP enables a front panel density that is greater than that of an SFP+ running at 10 Gbps.

Typical applications of CXP in the data center include 100GE over Copper (CXP): 7m (23ft) and 100GE over multimode fiber: CXP for short reach applications (CFP is used for longer reach applications).

What’s the Difference Between CFP and CXP?
Despite having a similar acronym and emerging at roughly the same time, the CFP and CXP form factors are markedly different in terms of size, density, and intended application. The CFP and CXP optical transceiver form factors are hot pluggable, both feature transmit and receive functions, and both support data rates of 40 and 100 Gbps. But the similarities begin and end there. Aimed primarily at 40- and 100-Gigabit Ethernet (GbE) applications, the CFP supports both singlemode and multimode fiber and can accommodate a host of data rates, protocols, and link lengths. The CXP, by contrast, is targeted at the clustering and high-speed computing markets. The two are therefore complementary, not competitive, according to several sources. Thus, the existence of CXP does not mean the replacing of CFP.

However, things are never black and white. In some case, there is a competition between CFP and CXP, as CFP can also be used with multimode fiber. It becomes more of a choice for system vendors. Do they need to build a box that can adapt to any interface? If so, they would probably use CFP. If it’s a box that is just focused on the short-reach market, then they would probably use something more like CXP.

I hope this post will let you more understanding the 100GbE transceivers, whether CFP or CXP. Similarly, you could kown the 40GbE transceiver through this post as the CFP and CXP also support the 40GbE. If you want to have a further study on this subject, I suggest you to learn the related refference of MSA.

Article Source: http://www.fiber-optic-transceiver-module.com/whats-difference-between-cfp-and-cxp-transceivers.html

Ultra-High-Power Optical Amplifier for FTTH – EYDFA

Background

While the Cable Modem, xDSL, and other forms of broadband access are booming in recent years, Fiber To The Home (FTTH) access is also gradually becoming a project that people are very interested in. The FTTH will eventually realize the “three networks in one” of Telephone, CATV and Internet, when the speed of data transmission can be more than 100 Mbps (200 times faster than the commonly used dial-up Internet access) and bring homes high-definition TV movies and fast online office, etc. FTTH can also solve the problem such as the quality of phone calls, the definition of television and so on.

From the perspective of the world’s situation, the FTTH’s promotion of South Korea and Japan has entered a rapid growth period; North America and Europe has begun to start which brings an optimistic outlook; China, Russia, India and South America is following and speeding up the development. From the perspective of FTTH, the optical communications industry market’s growth potential is still very large.

Applications of High-Power Optical Amplifiers

High-power optical amplifier as one of the basic devices of modern optical communications, is not only the premise of the existence of large-capacity and long-distance all-optical communication networks, but also plays a more and more important role in the process of fiber optic networks’ constantly extending and expanding. At present, in the central office, it usually needs to install more than one optical amplifiers in order to cover larger scope and more users. To take CATV for example, if a medium-sized county needs to send high-quality first-level TV signals to the villages and towns, it generally needs 4 to 8 sets of optical amplifiers. However, if high-power optical amplifiers are used, then only one is enough, which can greatly reduce the cost.

Solutions of High-Power Optical Amplifiers

Traditional Solution using EDFA Technology

One of the solutions for high-power optical amplifiers is to use the traditional general EDFA technology. As shown in the figure below, the signal is amplified at the first stage and then divided into several parts into several EDFAs at the second stage to realize the further ascension of power. The power enlarged in the end can be allocated.

Traditional High-Power Solution using EDFAs

Theare are mainly four problems of this solution:

The adoption of multilevel structure will make the optical structure very complex, and due to the adoption of multiple lasers in the internal part, the corresponding control scheme is very complicated.
As the multilevel structure has a WDM between the two stages of optical amplifiers, equivalent to bring more insertion loss to the optical path, the noise figure of EDFA amplifiers will deteriorate.
In addition, the traditional EDFAs use single mode fiber core pump technology, but high-power single-mode pumped lasers have been greatly restricted on technical and cost.
The whole sets of EDFA’s cost is very high and is very expensive.

Better Solution using EYDFA Technology

This ultra-high-power amplifier technology is a multimode cladding pump technology—EYDFA technology, a recently developed new technology that uses the Yb³⁺ and Er³⁺ ions doped double-clad fiber. The technology results to the combination of a series of new technologies, new processes and new materials. It is the core technology of ultra-high-power amplifiers and represents the development direction of optical amplifier technologies. While traditional EDFA use single-mode fiber core pump technology to achieve higher output power (which has been greatly limited on the technical and cost), the Er/Yb-Doped Fiber Amplifier (EYDFA) multimode cladding pump technology is the best choice for large output power optical amplifiers. Here is a typical optical structure of EYDFA.

EYDFA Structure

The main advantages of EYDFA are as following:

Compared with the single mode fiber core pump technology, multimode cladding pump technology has obvious advantages. The multimode cladding pump technology is to input the pump light to the multimode double-cladding fiber whose cross section are hundreds to thousands of times the single-mode fiber. As a result, at the same input optical density, multimode cladding pump can allow hundreds to thousands of times the single-mode pumped input, easily realizing the optical amplifiers’ high output power or ultra-high output power.
Can be realized using a simple optical structure, so the application form is very simple (as shown in the figure below).
The overall cost of the pumps can be greatly reduced.

Fiberstore’s high-power optical amplifier module type products—FTTH-EYDFA series are featured with high output power (17–26 dBm), low noise figure (less than 6 dB @ 1550 nm, 5 dBm input power), wide range of working wavelength (1540–1565 nm), flexible control, high reliability, etc. The output power of high-power optical amplifier is nearing 32 dBm in the laboratory.

Conclusion

Predictably, the widely applications of the ultra-high-power optical amplifiers (EYDFA) will have a profound impact on the development of optical communication, and its market prospect and effectiveness to economic and social present a good trend.

Cable Selection for Your 10 Gbps Transmissions — Fiber or Copper?

The decision to deploy fiber or copper really depends on several factors. First is the length of time you think the data center will remain in the same physical location. Fiber-only or copper-only implementations are rare in comparison to mixed fiber and copper.

Fiber will remain the medium of choice for backbone (vertical) applications and increasingly for horizontal applications alongside copper. This is mainly due to the distance support, size of cable, high bandwidth, high density, immunity to EMI/RFI, security, and reliability of fiber. Fiber has been the medium of choice for Storage Area Network (SAN) implementations for many years and is thus a proven cabling component.

Structured Cabling

Copper, on the other hand, is currently being challenged with the recent ratification of 10GBASE-T. Companies are currently racing to market their “unique” copper-based structured cabling solutions for 10 Gbps devices. Cat6a copper cables made for 10 Gbps transmissions are approximately 50 percent thicker than Cat6 copper cables and certainly a lot thicker than fiber cables; the space available for the cable runs may influence the type of cable you deploy. Copper cabling is more suited for horizontal runs, but of course limited to 100 meters distance. It is advisable to install a higher category of cable if you plan to be at the same facility for a while.

Cat6 Cables

Cat6a Cables

Until recently, copper was the clear winner in a straight cost comparsion. However, recent technology advances are closing the cost gap, especially in the high-performance arena. Fiber-based solutions are dropping in cost, but the main differentiation is in the cost of the active electronic components (e.g. transceivers, converters, amplifiers, etc.), and not in the actual cabling. In parallel, the cost for copper-based solutions is on the rise, due primarily to the stringent implementation and testing requirements imposed by TIA/ISO for 10 Gbps transmissions. Note also that in support of “Greener” data center environments, certain vendors are choosing, designing, and promoting active cabling components and media that consume the least power without compromising performance. 10GBASE-T consumes about 5 to 10 times more electrical power than optical solutions.

Another area that plays an important role in cable selection is the network components that are planned in the data center. Is their interface fiber or copper? And do they support 10 Gbps transmissions? Upgrading the cabling may include swapping out the connectors and other existing cabling components for the ones slated for 10 Gbps.

Note: If you want to deploy Power over Ethernet (PoE), then your choice is limited to copper—carring power over fiber is not yet possible.

Conclusion

In most cases, the end result will be a Combination of Cable Types for the Different Segments of the Infrastructure. Most likely fiber for the backbone, fiber and/or twisted pair for the horizontal runs, and fiber and/or copper for the final patching (since this will be governed by the interface of the equipment that you will be connecting to). When selecting cableing consider the pros and cons for each cable type in each segment of the infrastructure using the following criteria:

- Existing implementation
- Installation difficulty
- Termination difficulty
- Reliability
- Distance required
- Compatibility

Wavelength Selective Couplers and Splitters

Wavelength Selective Couplers (or Splitters) are used to either combine or split light of different wavelengths with minimal loss. Light of two different wavelengths on different input fibers can be merged (combined) onto the same output fiber. In the reverse direction light of two different wavelengths on the same fiber can be split so that one wavelength goes to one output fiber and the other wavelength is output onto the other output fiber. The process can be performed with very little loss.

As the coupling length is wavelength dependent, the shifting of power between the two parallel waveguides will take place at different places along the coupler for different wavelengths. All we need to do is choose the coupling length carefully and we can arrange for loss free wavelength combining or splitting. These functions are shown in the figure below. The graph of power transfer shows how power input on one of the fibers shifts back and forth between the two waveguides. The period of the shift is different for the two different wavelengths. Thus in the left-hand section of the diagram (combining wavelengths) there will be a place down the coupler where all of the light is in only one waveguide. If we make the coupler exactly this length then the signals have been combined. On the right-hand side of the diagram the reverse process is shown where two different wavelengths arrive on the same input fiber. At a particular point down the coupler the wavelengths will be in different waveguides so if we make this the coupling length then we have separated the wavelengths exactly. In fact both the processes described above are performed in the same coupler—the process is Bi-Directional (BiDi). Thus the coupler on the left can operate in the opposite direction and become a splitter and the splitter on the right can operate in the opposite direction and become a coupler (combiner). Note that each coupler or splitter must be designed for the particular wavelengths to be used.

Wavelength Selective Coupling and Splitting

Commercial devices of this kind are commonly available and are very efficient. The quoted insertion loss is usually between 1.2 and 1.5 dB and the channel separation is quoted as better than 40 dB. “Wavelength flattened” couplers or splitters of this kind operate over quite a wide band of wavelengths. That is a given device may allow input over a range of wavelengths in the 1310 nm band up to 50 nm wide and a range of wavelengths in the 1550 nm band also up to 50 nm wide.

Power Input to an EDFA

On the left-hand side of the figure we see an example of coupling two different wavelengths into the same output fiber. At the input of an EDFA you want to mix the (low level) incoming signal light with (high level) light from the pump. Typically the signal light will be around 1550 nm and the pump will be 980 nm. In this case it is possible to choose a coupling length such that 100% of the signal light and 100% of the pump light leaves on the same fiber. A major advantage of this is that there is very little loss of signal power in this process.

Splitting Wavelengths for CWDM Systems

On the right-hand side of the figure we show an example of CWDM demultiplexing. A mixed wavelength stream with one signal in each of the 1300 and 1550 nm bands is separated into its two component wavelengths. A CWDM system like this might be used in a system for distributing CATV and advanced VOD services to people in their homes. One signal stream might be carried at 1310 nm and the other at 1550 nm. A resonant coupler is shown here operating as a splitter separating the two wavelengths. Note that an identical splitter could also be used to combine the two wavelengths with very little loss.

Adding the Management Channel in DWDM Systems

In DWDM systems where many channels are carried in the 1550 nm band there is often a requirement to carry an additional relatively slow rate channel for management purposes. A convenient way to do this is to send the management information in the 1310 nm band and the mixed DWDM stream in the 1550 band. Wavelength selective couplers are commonly used for this purpose. A management signal (a single wavelength) in the 1310 band is coupled onto a fiber carrying many wavelengths between 1540 nm and 1560 nm. Another similar device (wavelength selective splitter) is used to separate the signals at the other end of the link.

Article Source: http://www.fiberopticshare.com/wavelength-selective-couplers-and-splitters.html

A Complete Guide of Installing or Removing Transceiver Modules (Part III)

Monday again, welcome to my blog. This week, we are going to finish the topic “A Complete Guide of Installing or Removing Transceiver Modules”. As we know, we continue this topic for almost three weeks, and today, we will explain the Part III, ie. the last part. The Part III is explaining mainly the installation and remove of QSFP/QSFP+ and CFP.

After learning the Part I and Part II, you may have a better understanding of installing or removing transceiver modules, such as SFP, X2, GBIC, XENPAK or XFP etc. You may also find that the different transceivers are similar in the installing or removing steps. Nonetheless, there is unique feature of different transceiver modules which affect the installing and removing, so that we should be carefully and understand each type of transceiver. OK, now we are return to today’s main topic – How to Install or Remove the QSFP/QSFP+ and CFP.

How to Install or Remove QSFP/QSFP+ Transceiver Module

QSFP/QSFP+ Installing Steps
step 1: Attach an ESD wrist strap to yourself and a properly grounded point on the chassis or the rack.
step 2: Remove the QSFP+ transceiver module from its protective packaging.
step 3: Check the label on the QSFP+ transceiver module body to verify that you have the correct model for your network.
step 4: For optical QSFP+ transceivers, remove the optical bore dust plug and set it aside.
step 5: For transceivers equipped with a bail-clasp latch:
a. Keep the bail-clasp aligned in a vertical position.
b. Align the QSFP+ transceiver in front of the module’s transceiver socket opening and carefully slide the QSFP+ transceiver into the socket until the transceiver makes contact with the socket electrical connector.

step 6: For QSFP+ transceivers equipped with a pull-tab:
a. Hold the transceiver so that the identifier label is on the top.
b. Align the QSFP+ transceiver in front of the module’s transceiver socket opening and carefully slide the QSFP+ transceiver into the socket until the transceiver makes contact with the socket electrical connector.

step 7: Press firmly on the front of the QSFP+ transceiver with your thumb to fully seat the transceiver in the module’s transceiver socket.
Please Note: If the latch is not fully engaged, you might accidentally disconnect the QSFP+ transceiver module.

step 8: For optical QSFP+ modules, reinstall the dust plug into the QSFP+ transceivers optical bore until you are ready to attach the network interface cable. Please Note: Do not remove the dust plug until you are ready to attach the network interface cable.

QSFP/QSFP+ Removing Steps
step 1: For optical QSFP+ transceivers, disconnect the network interface cable from the QSFP+ transceiver connector.
step 2: For QSFP+ transceivers equipped with a bail-clasp latch.
a. Pivot the bail-clasp down to the horizontal position.
b. Immediately install the dust plug into the transceivers optical bore.
c. Grasp the sides of the QSFP+ transceiver and slide it out of the module socket.

step 3: For QSFP+ transceivers equipped with a pull tab latch
a. Immediately install the dust plug into the transceiver’s optical bore.
b. Grasp the tab and gently pull to release the transceiver from the socket.
c. Slide the transceiver out of the socket.

step 4: Place the QSFP+ transceiver into an antistatic bag.

How to Install or Remove CFP Transceiver Module

CFP Installing Steps
step 1: Remove the CFP transceiver from its protective packaging.
step 2: Check the label on the CFP transceiver body to verify that you have the correct model for your network.
step 3: Remove the dust plug from the CFP transceiver module optical port and set it aside.
step 4: Align the CFP device into the transceiver port socket of your networking module, and slide it in until the CFP transceiver EMI gasket flange makes contact with the module faceplate.
step 5: Press firmly on the front of the CFP transceiver with your thumb to fully seat it in the transceiver socket.
step 6: Gently tighten the two captive installation screws on the transceiver to secure the CFP transceiver in the socket.
step 7: Reinstall the dust plug into the CFP transceiver’s optical bore until you are ready to attach the network interface cable.
step 8: When you are ready to attach the network cable interface, remove the dust plugs and inspect and clean fiber connector end faces, and then immediately attach the network interface cable connectors into the CFP transceiver optical bores.

CFP Removing Steps
step 1: Disconnect the network fiber-optic cable from the CFP transceiver connectors. Immediately reinstall the dust plugs in the CFP transceiver optical bores.
step 2: Loosen the two captive installation screws that secure the CFP to the networking module.
step 3: Slide the CFP transceiver out of the module socket. Immediately place the CFP transceiver in antistatic protective packaging.

Author’s Note
Up to here, the topic “A Complete Guide of Installing or Removing Transceiver Modules” has already finished. Thanks all the reader for continued focusing. In fact, the installing or removing steps of the mentioned transceiver modules are the general case. Different transceiver modules of different brands have their own features. We should ask the vendor to get more informations when you face a problem that we do not mentioned here. In addition, to save more money, we suggest that compatible 3rd transceiver modules may be another good choice but you should ensure that your vendor is reliable. Fiberstore‘s fiber optic transceivers are 100% compatible with major brands like Cisco, HP, Juniper, Nortel, Force10, D-link, 3Com. They are backed by a lifetime warranty so that you can buy with confidence. Additionally, customize optical transceivers to fit your specific requirements are available. If you have any requirement of transceivers, Fiberstore will be a good choice for you.

Article Source: http://www.fiber-optic-transceiver-module.com/a-complete-guide-of-installing-or-removing-transceiver-modules-part-iii.html

Advanced Optical Components – Optical Isolator

Connectors and other types of optical devices on the output of the transmitter may cause reflection, absorption, or scattering of the optical signal. These effects on the light beam may cause light energy to be reflected back at the source and interfere with source operation. To reduce the effects of the interference, an Optical Isolator is used. Many laser-based transmitters and Optical Amplifiers use an optical isolator because the components that make up the optical circuit are not perfect.

The optical isolator comprises elements that will permit only forward transmission of the light; it does not allow for any return beams in the fiber transmission routes or in the optical amplifiers. There are a variety of optical isolator types, such as Polarized (dependent and independent), Composite, and Magnetic.

Polarized Optical Isolator

As mentioned, the Polarized Optical Isolator transmits light in one direction only. This is accomplished by using the polarization axis of the linearly polarized light. The incident light is transformed to linearly polarized light by traveling through the first polarizer. The light then goes through a Faraday rotator; this takes the linearly polarized light and rotates the polarization 45 degrees, then the light passes through the exit polarizer. The exit polarizer is oriented at the same 45 degrees relative to the first polarizer as the Faraday rotator is. With this technique, the light is passed through the second polarizer without any attenuation. This technique allows the light to propagate forward with no changes, but any light traveling backward is extinguished entirely.

The loss of backward-traveling light occurs because when the backward light passes through the second polarizer, it is shifted again by 45 degrees. The light then passes through the rotator and again is rotated by 45 degrees in the same direction as the initial tilt. So when the light reaches the first polarizer, it is polarized at 90 degrees. And when light is polarized by 90 degrees, it will be “shut out.” The figures below show the forward- and reverse-transmitted light in a dependent polarized optical isolator.

Forward-Transmitted Light through a Polarized Optical Isolator

Reverse-Transmitted Light through a Polarized Optical Isolator

It should be noted that these figures depict the dependent type of polarized optical isolator. There is also an independent polarized optical isolator. The independent device allows all polarized light to pass through, not just the light polarized in a specific direction. The principle of operation is roughly the same as the dependent type, just slightly more complicated. Tips: The Independent Optical Isolators are frequently used in EDFA Optical Amplifiers.

Composite Optical Isolator

In fact, Composite Optical Isolator is a type of polarization independent isolator used in the EDFA optical amplifier. The EDFA optical amplifier is comprised of Erbium-Doped Fiber, Wavelength-Division Multiplexer, Pumping Diode Laser, Polarization Independent Isolator, and other passive components. Because the polarization independent isolator is composited with the others components into a single EDFA module, it is called a Composite Optical Isolator.

Magnetic Optical Isolator

Magnetic Optical Isolator is another name for polarized optical isolator. The magnetic portion of any isolator is of great importance. As mentioned, there is a Faraday rotator in the optical isolators. The Faraday rotator is a rod composed of a magnetic crystal having a Faraday effect and operated in a very strong magnetic field. The Faraday rotator ensures that the polarized light is in the correctly polarized plane, thus ensuring that there will be no power loss. Here is a figure that shows a basic magnetic optical isolator.

Magnetic Optical Isolator

Optical isolators are used to ensure stabilization of laser transmitters and optical amplifiers as well as to maintain good transmission performance. Ultra speed and large capacity optical fiber trunk systems are expanding as a result of the development of optical amplifiers. In parallel, the demand for optical isolators is increasing. Demand is also expected to increase as LAN and other subscriber fiber optic networks expand. It is therefore imperative that optical isolators be further improved to achieve higher performance, smaller size, and lower price. Luckily, you can now find the best optical isolators solution in Fiberstore, a Manufacturer & Supplier of Fiber Optic Network Solutions focus on Professional Customization.

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