Tunable Optical Transceivers – When To Use?

Already for some time tunable optical transceivers for use in DWDM systems, such as XFP and SFP+ are available for optical networking industry. Current evolution of tunable optical transceivers typically support full ITU-T C-band, allowing dynamically tune transmitter wavelength with 50GHz steps. However, even longer time conventional or fixed wavelength DWDM transceivers are in market. We feel that some of our customers are puzzled about choosing between fixed and tunable optical transceivers. I will try to shed some light on this by expressing my opinion.

 

 

What I believed when first heard about tunable optical transceivers? Well, I was thinking that it is revolutionary and that tunable transceivers will be part of future Metro Ethernet and Optical Transport Networks. I was imaging that in ecosystem of Software Defined Networks network intelligence will make decisions about required bandwidths in different directions, will dynamically add or drop some wavelengths and that essential part of that will become tunable optical transceivers. What is reality now, after some years with tunable optics in market?

 

At first Metro Ethernet. Nowadays metro Ethernet mainly consists of IP nodes, such as switches and routers interconnected by numbers of 10G interfaces. Main use case of DWDM in metro networks is economy of black fiber. Usually operators implement DWDM by using colored transceivers directly in 10G ports and connect to line trough Passive optical multiplexers. These IP nodes focusing on L2/L3 packet processing, but their optical network functionality is quite limited. From currently popular IP platforms, only few actually support tuning of wavelengths by CLI commands.

 

Then is Optical Transport Networks (OTN) which is focusing on carrying payload and multiplexing, switching and supervising networks in optical Layer 1 domain. Focus of current systems is packaging of payload in most effective transport containers and for Layer 1 management OTN use packages of Wavelength Selective Switches (WSS) called also ROADM (reconfigurable optical add-drop multiplexer), which allow switching wavelengths in multi-direction nodes from ring to ring, branch to branch. WSS/ROADM technologies allow rapid implementations of backup hot standby transport optical routes. But what about tunable optical transceivers in OTN..? Still – mainstream is conventional fixed wavelength DWDM transceivers.

 

How many optical ports from total implemented actually are with tunable optical transceivers? Hard to say about this research precision, but we found out such graph online, saying that from all optical ports shipped only about 0.5% are tunable and we tend to believe it:

 

Number of Tunable Ports

 

So – what is current use case for tunable optical transceivers? When to consider implementation of all DWDM network based on tunable transceivers? Take in account – tunable transceivers are much more expensive compared to conventional fixed wavelength DWDM transceivers. I see two main applications:

 

Spare Part – when You running big DWDM network with high number of nodes and let’s say use up to 80 (50GHz spacing) different wavelengths, spare part management quickly could become nightmare. You need to have couple of transceivers of each wavelength and possibly in different locations, as You wish that Your field technicians can access network nodes quickly enough. In this case few tunable modules in place of few hundred fixed ones are very good and cost efficient idea. If Your platform supports in-port tuning it’s excellent – if no, You additionally will need special programming board allow to tune module to necessary wavelength. (As us – we can deliver compatible tunable optical XFP and SFP+ modules and corresponding boards).

 

Really big transport network with 400G or 1T applications on horizon. Yes, with already now available coherent optical technologies, such as Dual-Polarization Quadrature Phase Shift Keying (DP-QPSK) is possible to fit 100G transmission bandwidth within DWDM 50 GHz channel. So if 100G is too less for you, then future 400G and 1T transmission formats are expected to be bulky and not fit within 50GHz spacing. These future new data rate formats require that channel plan/spacing is flexible, that Your OTN system can adapt to new rates and can re-arrange channel spacing to find place for new rates in it.

What is DWDM and Why is it Important?

It has been almost 20 years since DWDM came on the scene with Ciena’s introduction of a 16 channel system in March of 1996, and in the last two decades it has revolutionized the transmission of information over long distances.  DWDM is so ubiquitous that we often forget that there was a time when it did not exist and when accessing information from the other side of the globe was expensive and slow.  Now we think nothing of downloading a movie or placing an IP call across oceans and continents.  Current systems typically have 96 channels per optical fiber, each of which can run at 100Gbps, compared to the 2.5Gbps per channel in the initial systems.  All of this got me thinking about how it often takes two innovations coupled together to make a revolution.  Personal computers did not revolutionize office life until they were coupled with laser printers.  Similarly, the benefits of DWDM were enormous because of erbium doped fiber amplifiers (EDFAs).

DWDM stands for Dense Wavelength Division Multiplexing, which is a complex way of saying that, since photons do not interact with one another (at least not much) different signals on different wavelengths of light can be combined onto a single fiber, transmitted to the other end, separated and detected independently, thus increasing the carrying capacity of the fiber by the number of channels present.  In fact non-Dense, plain old WDM, had been in use for some time with 2, 3 or 4 channels in specialized circumstances.  There was nothing particularly difficult about building a basic DWDM system.  The technology initially used to combine and separate the wavelengths was thin film interference filters which had been developed to a high degree in the 19th Century.  (Now a ’days photonic integrated circuits called Arrayed Waveguide Gratings, or AWGs are used to perform this function.)  But until the advent of EDFAs there was not much benefit to be had from DWDM.

Fiber optic data transmission began in the 1970s with the discovery that certain glasses had very low optical loss in the near infrared spectral region, and that these glasses could be formed into fibers which would guide the light from one end to the other, keeping it confined and delivering it intact, although reduced by loss and dispersion.  With much development of fibers, lasers and detectors, systems were built which could transmit optical information for 80km before it was necessary to “regenerate” the signal.  Regeneration involved detecting the light, using an electronic digital circuit to reconstruct the information and then retransmitting it on another laser.  80km was much farther than the current “line of sight” microwave transmission systems could go, and fiber optic transmission was adopted on a wide scale.  Although 80 km was a significant improvement, it still meant a lot of regeneration circuits would be needed between LA and New York.  With one regeneration circuit needed per channel every 80 km, regeneration became the limiting factor in optical transmission and DWDM was not very practicable.  The then expensive filters would have to be used every 80 km to separate the light for each channel before regeneration and to recombine the channels after regeneration.

Since full regeneration was expensive, researchers began to look for other ways to extend the reach of an optical fiber transmission system.  In the late 1980s Erbuim Doped Fiber Amplifers (EDFAs) came on the scene.  EDFAs consisted of optical fiber doped with Erbium atoms which, when pumped with a laser of a different wavelength, created a gain medium which would amplify light in a band near the 1550nm wavelength.  EDFAs allowed amplification of the optical signals in fibers which could counter the effects of optical loss, but could not correct for the effects of dispersion and other impairments.  As a matter of fact, EDFAs generate amplified spontaneous emission (ASE) noise and could cause fiber nonlinearity distortions over a long transmission distance.  So EDFAs did not eliminate the need for regeneration completely, but allowed the signals to go many 80 km hops before regeneration was needed.  Since EDFAs were cheaper than full regeneration, systems were quickly designed which used 1550nm lasers instead of the then prevailing 1300nm.

Then came the “ah ha” moment.  Since EDFAs just replicated the photons coming in and sent out more photons of the same wavelength, two or more channels could be amplified in the same EDFA without crosstalk.  With DWDM one EDFA could amplify all of the channels in a fiber at once, provided they fit within the region of EDFA gain.  DWDM then allowed the multiple use of not only the fiber but also the amplifiers.  Instead of one regeneration circuit for every channel, there was now one EDFA for each fiber.  A single fiber and a chain of one amplifier every 40~100 km could support 96 different data streams. Regenerators are still needed today, every 1,200~3,500km, when the accumulated EDFA ASE noise exceeds a threshold that a digital signal processor and error correction codec can handle.

Of course, since the gain region of the EDFA was limited to about 40 nm of spectra width, great emphasis was placed on fitting the different optical wavelengths as close together as possible.  Current systems place channels 50GHz, or approximately 0.4 nm, apart, and hero experiments have done much more.

In parallel, new technologies have increased the bandwidth per channel to 100 Gbps using coherent techniques that we have discussed in other blog posts.  So a single fiber that in the early 1990s would have carried 2.5Gbps of information, now can carry almost 10 Terabits/sec of information, and we can watch movies from the other side of the globe.

How important is cleaning your optical fibers?

A high percentage of fiber optic transmission problems are the result of contaminated connectors and couplers. Dirt not only impacts the speed and performance of a network, but also damages equipment.

 

As a manufacturer of fiber optic cables Datcom is keenly aware of the implications of improper cleaning of end faces and recommends the following points to ensure that your fiber networks are always up and running. 

 

Dust caps are for protection only and do not mean that the fiber inside is clean. 

Inspection of ferrules with a scope is a must and if possible used with an analysis software. Even the most experienced technician cannot visually determine the cleanliness of a fiber. 

 

Do not use alcohol when cleaning fiber. It is hygroscopic which means it attracts water molecules from the air. 

Use a wet to dry cleaning process to avoid electrostatic attraction. 

Use an optical grade cleaning fluid for the static to dissipate. 

 

Use optical grade lint free wipes that have high absorbency and strength. 

Use cleaning sticks that are made from multiple fibers and can spread and contact the entire surface of the end face when port cleaning. 

 

Proper installation practices, coupled with advanced inspection procedures and professional cleaning products will not only save a technician repeated onsite visits and time. But also eliminate customer complaints along with loss of confidence and money. 

A Simple Guide on Choosing A Sex Doll

Sexual stimulation is provided by silicone love doll. They provide hands-free penetration whose feeling will be same as that you will do with your partner. You will get the real feeling of sex. Many people want to explore the experience of sex with real life sex dolls. You will get confused while choosing the range of sex dolls. Please do some research before buying in case you want to avoid disappointment. There are two unique types of sex dolls which are blow up sex dolls and advanced lifelike sex dolls. You will get immense help from this guide on choosing the perfect sex doll for you.

Blow Up Sex Dolls
Blow up sex dolls are very basic products. They don’t have any masturbators attached to them. Instead, in the doll’s design, plain holes are made. After using a good amount of sexual lubricant to the dolls, you can use them without any makeup. You can also pair up pocket pussy or realistic dildo with the dolls. Buy a basic blow up doll to enhance your sexual pleasure. If you want to buy sex dolls for the first time then you can opt for inflatable sex dolls as it will cut costs. You will get familiar with the doll’s sexual simulation. You will get a more realistic sensation with these dolls. Once your work is over with these dolls, you can deflate them and store them inside the box.

Blow Up Realistic Sex Dolls
These dolls are the latest version of inflatable basic sex dolls. Instead of permanent holes, they have a removable vagina of their own. These dolls have a vibrator which will enhance your sensation. Some dolls can suck, lick and even talk. Realistic blowup sex dolls are more attractive than basic blow up sex dolls. Generally, they have their own moulded hands and own hair which will provide the more realistic feature. If you can spend more money, then a real life blow up sex doll will be great for you.

The lifelike sex dolls have their own disadvantages. There is a large price difference between the realistic blow dolls and these dolls. These real-feel dolls are very heavy. Sometimes, you can feel difficulties to move or store them. The materials of these dolls can degrade much more. A lot of cleaning and powder sprinkling are required if you want to keep these dolls in a good shape. For a dedicated buyer, these disadvantages mean nothing to them. They buy these dolls to get an ultra realistic sexual simulation.

Life Size Silicone Sex Doll -7 Things That Will Turn Your World Upside Down

Sexual interaction has been a way of entertainment or to be more precise a way to fulfil the sexual desires of human beings (both males and females). But with the change of time, sexual interaction between humans has also taken a drastic turnaround. The use of life-size silicone sex doll has raised new debatable thoughts and topics among certain sections of the society.

Societies at large have the opinion that people who use life size silicone sex dolls are perverts and are destroying God’s greatest gift to mankind.  With the invention of technology and innovative solutions, different logics have come into play in the minds of people using the silicone lovers. Some of the things that these people do with a life size silicone sex doll are eye-popping and are sure to stunt you.

Why life size silicone sex doll is worth it?
(1)Due to the advancement of technology, people in Japan have started using full-size sex doll on the 3D platform. Which makes the owner feel like having sex with a real partner. You can enjoy numerous 3D games with virtual sex dolls flooding the internet.

(2) This life size silicone sex doll is available in full size as well as in different body parts as per the customers’ requirement so that the client can fulfil his or her sexual desire to the climax.

(3) These life size sex toys that are used for having sex and are available in adjustable parts so it can be positioned in different directions by the user while having sex.

(4) Since the life size silicone sex doll is bit heavier than other sex dolls photographers usually uses these sex toys as their models for various photo shoots.

(5) Due to its Low thermal conductivity, toxicity, ability to repel water and form watertight seals, they are resistance to oxygen, ozone, and ultraviolet light(UV). They have great durability, cleaning ability and are non-degraded by petroleum-based lubricants.

(6) These dolls are almost like that of plastic. They can be differently shaped or formed and softened or hardened into practically anything. The only thing that is unique about these dolls is that they are much more temperature resistant.

(7) The life size silicone sex doll basically represent the perfect replicas of real life woman. Since they are non-reactive material chances of anyone getting an allergic reaction by using her is almost negative.

The above-mentioned facts are some of the main reasons that made these dolls famous throughout the globe. It helps to fulfil every desire of the sexually frustrated men. It also in a way provides self-satisfaction, self-esteem, and confidence in its users. Overall, these life size silicone love dolls are gaining prime importance in today’s world. They are even entering into the lives of couples who want to have something more in their sexual relationship.

Type of different sex dolls that are available in the market

In fact, the real sex dolls have become so popular that they are available at online sites where you can buy them after comparing the various dolls and their prices.

Thousands of blogs are posted every day regarding realistic sex dolls. A huge number of forums are present on the web where people share images and experiences of new sex doll. In short, we can say the market of this real playful doll is getting bigger day by day. With the increased demand and interest that’s getting into the heads of people, manufacturers are thinking of introducing new models of sex dolls that promise to give you a far better sexual experience than the normal ones do.

Let’s see the different types of dolls available in the market or are ready to hit the market soon. Silicone sex dolls- They are most common sex dolls, one can find today’s date.  It looks like a real person, made out of best silicon quality. In fact, you can buy them at My-Doll.com at great affordable prices. They are very useful to fulfill all your fantasies and desires.  They are tough to take about 80 pounds of flesh on them. These real sex dolls have their skin that resembles a real human, so you get the feeling of being intimate with a real human being. The manufacturers developed them in such way that the owner gets the best feeling ever. 

Advanced sex dolls– The real doll manufacturers have recently proposed the launch of their new sex doll models which are really advanced. They promise to keep both men and women happy. It is not a simple doll, manufacturers built them with the latest technology which enables them to respond to postures and talk dirty as well. A special program installed on them can make them talk like real women. You can buy real sex dolls as they are now available in the market soon. The approximate price of the latest sex doll is between $5000-$10000.

Sexbots– The manufacturers of sex dolls are going deeper into presenting a doll that has the least difference from the real women.  What more are you get the option to customize the realistic dolls according to your taste and choice. For example, you can order black hair, manipulate the size of their bodily features, or order for a celebrity lookalike. So if you fantasize about someone, the opportunity to have similar looking doll is now possible.

The future will see sex robots that can blink their eyes, even make a sound during the intimate moments. Day by day the sexbots are becoming more realistic.  Some of the sex robots will have temperature control in their bodies which will adjust according to the needs. They will have an orgasm and respond to you. It seems ver interesting, isn’t it?

Fiber optics applications to Internet of things

Those days you didn't have breakfast at home because you forgot to buy eggs are in the past. Nowadays your refrigerator sends you an alert telling you you are running out of products. And that's possible thanks to the Internet of Things. 

 

The Internet of Things has many years being a hot topic, but what exactly is it?

 

It can be defined as a future in which everyday objects will be connected to Internet and will be able to communicate with each other.  Jacob Morgan describes The Internet of Things on Forbes as “the concept of basically connecting any device with an on and off switch to the Internet (and/or to each other). This includes everything from cell phones, coffee makers, washing machines, headphones, lamps, wearable devices and almost anything else you can think of.”

 

And yes, it is going to impact the way you live and the way you work. Ericcson estimates 50 billion devices will be connected to Internet by 2020, while Gartner predicts there will be roughly 500 networked devices in a typical family house.

 

#IoT Tweets

Cars, refrigerators, lamps, clocks, phones and wearables devices will be embedded with sensors that will make them possible to gain intelligence and the ability to communicate with other objects and with people. So, in the future the communication will be machine-to-machine (M2M), machine-to-person (M2P) and person-to-person (P2P).

 

So your car is going to be able to alert you if the tire pressure is low and tell you places you can go to solve that problem. Or your clock will tell your coffee maker to start making that delicious beverage because is almost time for you to wake up. Sounds cool, right?

 

And how exactly is the Internet of Thing related with optical fiber?

 

When all your gadgets and devices are connected and communicate with each other, data transmission needs to be fast, and there is no other transmission media able to reach higher speeds than optical fiber. Therefore, the Internet of things needs optical fiber broadband to reach wirelessly 100Gpsb speeds and reproducing 4K videos in just seconds.

 

Billions of devices connected with each other put a big issue on the spotlight: security. Will anybody be able to hack your phone and have access to your house? Is it going to bring more security and privacy threats? It probably will. But then again, optical fiber networks will be the solution because they are the most secure ones as it is really hard to hack them without being detected.

 

Also, with fiber there aren’t going to be interference issues as it is immune to electromagnetic currents and can be installed basically everywhere, from underwater to high-temperature places.

 

As Kyle Hollifield, senior vice president at Magellan Advisors, said at CES 2016 FTTH networks needs to be prepared for the added traffic, because network capacity will be critical for the success of smart cities and homes when everything is connected with everything.

Optical fiber beyond telecommunication

are more a necessity than a luxury, but they also have an excellent throughput in other fields beside telecommunications, since they are used from non-invasive surgeries to pool illumination.

 

Optical fiber made it possible for surgeries to be minimally invasive and to have advanced diagnostic technologies due to implements like optical fiber cameras. Medical optical fiber applications also include X-ray imaging, ophthalmic lasers, light therapy, dental head pieces, surgical microscopy and endoscopy. The study “Global Market Study on Medical Fiber Optics: Asia to Witness Highest Growth by 2019” says that medical fiber global market will reach a value of USD 1,336.1 million by 2019.

 

Optical fiber is used in the decoration field because it provides an attractive and economical way of illumination. It is used at museums exhibitions due to their heat-free attribute and in underwater lighting because they don't conduct electricity. 

 

Optical fibers also provide extremely focused light, they are long-lasting, look like neon, colors can change according to the applied filter and their installment and maintenance is easy. Also they look really cute, don't they?

 

Lighting applications with optical fiber are being used in the automotive industry too because they it can be installed in reduced spaces and it transmits cold light. Companies like Volvo, Audi, BMW, Jaguar and Saab use fiber to build the communication system that connects sensors with airbags and traction control devices in order to increase passenger’s safety.

 

Roll Royce’s trademark “Starlight headliner” is built with over 1300 optical fibers which make Phantom’s ceiling look like a starlight night.

 

Optical fiber sensors measure, pressure and strain. But they are also used to look for displacements, vibrations and rotations in civil structures such as highways, buildings and bridges or smart structures like airplanes wings and sport equipment. They are also very helpful for monitoring oil, power cables and pipelines in places that are really hard to reach.

 

Sensors work with a detector arrangement that measures the subtle changes that happen in the light as it travels through an optical fiber.  They offer a lot of advantages because they don’t require electrical cables, therefore can be safely used in high-voltage and electrical environments.

New hardware could make FTTH expansion cheaper

by www.fiber-mart.com

A new way to solve the “last mile problem” and provide real fiber connections to households was developed by scientists and researchers from the UCL Optical Networks Group and UNLOC program in London as they designed a simplified optical receiver that could be mass-produced cheaply.

 

Although current networks are mostly composed with optical fiber, they usually terminate in cabinets away from the user premises and that last mile that goes from the cabinet to the end user is mostly made with copper, which slows down connections, because it is really expensive to install in every home the optical receiver needed to read the optical signals.

 

“We have designed a simplified optical receiver that could be mass-produced cheaply while maintaining the quality of the optical signal. The average data transmission rates of copper cables connecting homes today are about 300 Mb/s and will soon become a major bottleneck in keeping up with data demands, which will likely reach about 5-10 Gb/s by 2025. Our technology can support speeds up to 10 Gb/s, making it truly futureproof”, said Dr Sezer Erkilinc, lead researcher from UCL Electronic & Electrical Engineering.

 

The design of the optical receiver developed by UCL researchers is simplified because it contains a quarter of the connectors that are usually used in a conventional receiver. It is able to improve sensitivity and network reach compared to current technology. When commercialized, the cost of installing and maintaining a real FTTH network will be dramatically reduced.

 

 The laser stability of the receiver is currently being tested by the researchers, but Dr Erkilinc said once they it is quantified, they will be in a strong position to take the receiver design to trials and commercialize it.  

Best Practices for Handling Fiber Optic Cabling

Glass is very fragile. Evidence of this is in the plethora of options for shipping preparations and packing materials.

 

To ensure the product is in one piece upon delivery, lots of packing material is used with stickers added to the exterior of the box to alert people of the fragile contents inside.

 

Of course you know that fiber optic cables have glass in them, but it’s easy to be misled by the jacket surrounding the glass core; it would appear to be protected enough.

 

Don’t be fooled. You will need to handle this product with care. Here are some of the best practices for handling fiber optic cables.

 

Leave cable in a safe space

Leave your cable boxes in a safe place until your team is ready to use them. Don’t open, don’t unwrap. Err on the side of caution to avoid potentially damaging situations – like someone rolling a cabinet over it – crashing into it with a forklift  truck!

 

Keep the ends protected

When using the assembly, make sure to leave the protective end-caps on until you are ready to plug the cable into the patch panel or transceiver.

 

These caps protect the most sensitive part of the fiber assemblies. Once removed, the tiny core of the cable, the glass that runs through its center, is now exposed to the contaminants in the environment surrounding it.

 

Contaminants that find their way to these glass ends can cause the loss of light flow, which means less data passes through. To ensure you maintain a clean connection to the other fiber end piece, wait to remove those caps!

 

Don’t pinch the fiber

When handling fiber cable, never pinch or kink. While the glass inside is designed to be flexible, at a certain point it will snap, ruining your company’s expensive investment. Use Velcro to gather cables, never zip ties. Follow the manufacturer’s recommendations for bend radius and you’ll be fine.

An introduction to fiber cable pushing machines

Since they were first introduced in the 1980s, optical fiber cables have dramatically shrunk in size. A 96 fiber cable can now weigh 30kg/km (down from 300kg/km) and have a diameter of 7mm, compared to 20mm for first generation cables.

 

Similarly, 12 fiber drop cables used to connect individual FTTH customers now weigh less than 10kg/km and have a diameter of 1-3mm. These are normally installed into microducts, which typically range in outside diameter size from 3-18mm.

 

This leads to new challenges for installers when it comes to equipment. Previously cables would have been installed with heavy equipment, such as winches and capstans, or heavy compressors and blowing heads. However, this has four big disadvantages in the last drop:

 

1. People

It requires multiple operators, pushing up costs.

 

2. Disruption and mess

Customers don’t want bulky equipment in their buildings or apartments, particularly if it damages their homes.

 

3. Equipment cost

Operators need to invest in buying or hiring expensive machines to carry out installations.

 

4. Time

While the cable install itself may not take long, setting up (and dismantling machines) is time-consuming, limiting the number of installs that can be completed in a day.

What is a handheld pushing machine?

 

What is needed is a single operator, a self-contained installation head and low-cost, lightweight ancillary apparatus. For example, this handheld pushing machine caters for cables from 2 to 5.5m diameter and microducts from 5 to 12.7mm outer diameter.

 

It’s necessary to understand a little of the science behind "pushing" to see how it can be used. When pushing there is no cable tension, meaning that, unlike pulling, the challenge is not one of over-straining the cable, but in forcing the cable to buckle by over-pushing. Buckling the cable effectively locks it into the duct and can cause permanent damage.

 

This can be controlled by controlling and optimizing the cable stiffness and by reducing the coefficient of friction between the duct and cable. While low friction is always beneficial, stiffness is a compromise. It needs to be sufficient high to tolerate the push force exerted by the head, but low enough to enable to cable to flex around curves in the route.

 

a handheld pushing machine

Cable pushing machines typically exert around 40 to 50N of push force at the drive system, which can be a belt or driven wheels. Provided that the microduct’s internal diameter is a relatively close fit (for example no larger than a 6mm bore for a 3-4mm cable) there is no danger of the cable kinking at these force levels. This means that, for a low friction duct, a push distance of 100 to 200m is possible, depending on the degree of bend in the route.

 

In practice, this enables installers to deploy the majority of drop cable connections by using pushing machines.To meet these contrasting needs you need a cable designed specifically for pushing. The relatively hard polymer used as a jacket confers low friction properties when used with optimally lined microducts, providing the right level of stiffness to avoid the risk of buckling - while still having the flexibility to push around corners.

 

Of course, even a pushing machine requires a power source and in the interests of simplicity and cost many use a standard 10.8V Euro/12V Li-ion US unit.

 

Adding air assistance

Despite the optimization of pushable cables, there will always be instances where pushing alone is insufficient to deliver the required installation. For example, the route may curve unexpectedly or the actual install length may be longer than planned. In these situations air assistance will be required.

 

For this reason, most high quality pushing machines provide an optional inlet for compressed air sources of up to around 12-15 bar. Whereas pushing puts the cable into mild compression, the use of a high speed air flow brings a distributed force to bear on the cable, which eases it around any significant bends, meaning that the install length can be extended to over 1km. The good news is that the same ultra-low friction duct used for cable pushing provides the same excellent properties when used for air assisted deployments.

 

When adding air, it is important to use the right type of source. Large, wheeled and towed petrol compressors provide ample air but aren't necessarily appropriate quality for installation.

 

The user needs to determine the air pressure and volume needed, although pushing equipment manufacturers can advise on this. Additionally, they need to set the degree of filtering and contaminant removal. This is because it is vital to remove moisture from the air supply using an after-cooler and water filter and to take out any residual hydrocarbons, since both of these contaminants interfere with effective blowing. One way to achieve this is to use an air cylinder which contains clean air under high pressure (alternatively a compressed nitrogen tank will work).

 

However, for those users who want to avoid the logistical issues associated with obtaining and returning a large number of cylinders, a small compressor remains the best option. Historically 10 bar and 15 bar compressors have provided relatively large air outputs (measured in cubic feet per minute (CFM) or cubic meters per minute (m3/min)). A substantial compressor will generate in excess of 1 m3/min but will weigh around 100kg. Such a size rules out single operator working and necessitates specialized vehicles to transport the compressor.

 

Coping with leakage

In the past, one of the reasons that users tended to opt for these large machines was that older style blowing heads lost a large volume of air through leakage. This meant that a modest air supply wouldn’t let cables be pushed "hard" enough to ensure they reached their destination.

 

However, recent work has led to the availability of one-person portable compressors. These weigh around 25kg in weight, meaning that the pushing machine and its ancillary compressor can be handled and transported by a single person in a standard commercial vehicle. This further brings down staff costs and makes pushing available for a wider range of installs.

 

Pushing to the future

Installers have three options when it comes to last drop deployments – blowing, pulling or pushing cables. Given the relatively short runs and often complex routes of the last drop, pushing cables is becoming much more common as an option. Using a pushing machine extends the usefulness and range of this technique, helping to bring down last drop install costs and speed up deployments. Particularly when used in combination with cable and microduct designed for pushing, they deliver major budgetary and time benefits. This means they should now be a standard part of every operator’s toolbox when carrying out FTTH deployments.

WHAT ARE OPTICAL FIBER ISOLATORS?

A fiber optic isolator lets light passing through in one direction with a low loss while blocking the light in the opposite direction with a high loss.

 

Isolators are placed in output circuits of devices with a high output light level such as laser diode transmitter and EDFAs, as shown in this picture.

 

Their function is to reduce the level of reflected light back into the laser diode or EDFA.

 

Most fiber optic isolators use the Faraday effect to achieve their function. Faraday effect governs the rotation of the polarization plane of the optical beam in a magnetic field. The rotation is in the same direction for light propagating either parallel or antiparallel to the magnetic field direction.

 

Optical isolators consist of a rod of Faraday material such as yttrium iron garnet (YIG), whose length is selected to provide 45° rotation. The Faraday material is sandwiched between two polarizers whose axes are tilted by 45° with respect to each other.

 

Light propagating in one direction passes through the second polarizer because of the Faraday rotation. By contrast, light propagating in the opposite direction is blocked by the first polarizer.

 

There are a few critical parameters that determine the performance of isolators.

 

Wavelength-dependence, especially for so-called narrowband isolators that are designed to operate in a spectral range narrower than 20nm. Isolators are described by peak reverse direction attenuation and by the bandwidth for which the isolation is within 3 dB of the peak value

 

Low insertion loss. The insertion loss should be less than 1 dB in the forward direction, and in excess of 35 dB (single-stage isolator) or 60 dB (double-stage isolator) in the reverse direction.

 

Polarization mode dispersion (PMD). Isolators are constructed using high birefringent elements; and they are very prone to PMD – typically 50 to 100 fs, especially for single-stage designs. Double-stage isolators can be designed so that the PMD induced by the first stage is largely cancelled by the second stage.

 

Polarization-dependent loss (PDL). This degrades the performance of an optical isolator.

MPO/MTP Trunk Cable Advantages

A specific lengths pre-assembled MTP/MPO Trunk cable with 12 or 24 fibers is delivered to data center for easy installation, because an It is impossible to manually to assemble MPO/MTP plug connector with 12 or 24 fibers on site during installation.MPO-MPO-Patch-cord-10m

 

The advantages of MPO/MTP Trunk cable with the following advantages

 

• Higher Quality

Higher quality is usually achieved through factory assembly and inspection of individual parts. A factory-prepared inspection certificate is also useful for longterm documentation and in turn quality assurance purposes.

 

• Minimum Skew

A crucial factor in achieving a successful parallel optical connection is keeping the signal offset (skew) between the four or ten parallel fibers to an absolute minimum. Only in this way can information be successfully re-synchronized and re-combined at its destination. Factory-assembled trunk cables allow skew to be measured, minimized and logged.

 

• Shorter Installation Times

Pre-assembled MPO cable systems provide plug-and-play advantages and can be inserted and set up immediately.

This reduces installation time enormously

 

• Better Protection

Because they are completely assembled at the factory, cables and plug connectors remain completely protected from

environmental influences. Optical fibers that lie open in splice trays are at a minimum exposed to ambient air and may age faster as a result.

 

• Smaller Cable Volumes

Smaller diameters can be realized in MPO cabling systems that are produced from loose tube cables. The results are

correspondingly smaller cable volumes, better conditions for acclimatization in the data center and a lower fire load.

 

• Lower Overall Costs

When splice solutions are used, a few factors that are not always foreseeable boost total costs: time-intensive,

equipment-intensive splicing, needs for specialty works, bulk cables, pigtails, splice trays, splicing protection, holders. In contrast, pre-assembled trunk cables not only bring technical advantages, but usually result in lower total costs than splicing solutions.

Understanding MPO- MTP fibre optic connectivity in cabling applications

As the quest for greater bandwidth continues and fibre optic connections within data centres and optic fibre networks increase, these challenges must be met by choosing the right type of connectivity. This is all driven by requirements for additional switching and routing, storage, virtualization, convergence, video-on-demand (VoD) and high performance cloud computing. All of these applications plus other bandwidth intensive applications increase the need for transmission speed and data volume over short distances.

 

Optic fibre 10G transmission systems are becoming more widely used and accepted and migration paths to 40G and 100G have been specified for optical fibre.

 

The IEEE 802.3ba 40G / 100G Ethernet standard provides guidance for 40G / 100G transmission with multimode fibre. OM3 and OM4 are the only multimode fibres included in the standard.

 

Parallel optics technology has become the transmission option of choice in many data centres and labs as it is able to support 10G, 40G, and 100G transmission. For parallel optics to work effectively, it requires the right choice of cable and connector.

 

Parallel optic interfaces differ from traditional fiber optic communication in that data is simultaneously transmitted and received over multiple optical fibres. In traditional (serial) optical communication, a transceiver on each end of the link contains one transmitter and one receiver. For example, on a duplex channel the transmitter on End A communicates with the receiver on End B and another optic fibre is connected between the transmitter on End B and the receiver on End A.

 

In parallel optical communication, the devices on either end of the link contain multiple transmitters and receivers, e.g. four transmitters on End A communicate with four receivers on End B. This spreads the data stream over the four optical fibres. This configuration would allow for the operation of a parallel optics transceiver which uses four 2.5 Gb/s transmitters to send one 10 Gb/s signal from A to B. In essence, parallel optical communication is using multiple paths to transmit a signal at a greater data rate than the individual electronics can support. This type of connectivity utilises a ribbon cable type design with all fibres aligned in a straight array, in either a 12 fibre or 24 fibre configuration.

 

In addition to the cable performance, the choice of physical connection interface is also important. Since parallel-optics technology requires data transmission across multiple fibres simultaneously, a multifibre connector is required. Factory terminated MPO / MTP connectors which have either 12 fibre or 24 fibre array, will support this solution. For example, a 10G system would utilise a single MPO / MTP (12 Fibre) connector between the 2 switches. Modules are placed on the end of the MPO connector to transition from a MPO connector to a 12 Fibre breakout LC duplex or SC duplex cable assembly. This enables connectivity to the switch. 40G and 100G systems require a slightly different configuration.

 

Difference between MPO and MTP connectors

From the outside there is very little noticeable difference between MPO and MTP connectors. Infact, they are completely compatible and inter-mateable. For example, an MTP trunk cable can plug into an MPO outlet and vice versa.

 

The main difference is in relation to its optical and mechanical performance. MTP is a registered trademark and design of UsConnec, and provides some advantages over a generic MPO connector. Since MPO / MTP optic fibre alignment is critical to ensure a precise connection there are some benefits in utilising the MTP connector. The MTP connector is a high performance MPO connector with multiple engineered product enhancements to improve optical and mechanical performance when compared to generic MPO connectors.

 

The MTP optic fibre connector has floating internal ferrule which allows two mated ferrules to maintain contact while under load. In addition, The MTP connector spring design maximizes ribbon clearance for twelve fibre and multifibre ribbon applications to prevent fibre damage.

 

Overall it provides a more reliable and precise connection.

 

In addition, it is also important when specifying an MPO/MTP system to ensure the correct polarity options and which cables and outlets have female or male pins.

What are MPO connectors?

MPO—Multi-fiber Push On—is a type of optical connector that has been the primary multiple fiber connector for high-speed telecom and data communications networks. It has been standardized within the IEC 61754-7 and TIA 604-5. This connector and cabling system first supported telecommunications systems especially in the Central and Branch offices. Later it became the primary connectivity used in HPC or high-performance computing labs and enterprise datacenters. It has also been heavily used in cloud datacenters but is now being replaced with the lower cost MXC optical connector and cabling systems because of a much more controlled, benign environment versus the rugged Telcordia testing and validation requirements.

 

Over the years, the MPO connector family has evolved to support a wider range of applications and system packaging requirements. Now there are several more suppliers investing and developing products with new features and fiber counts. Originally a single row 12-fiber connector, there are now 8 and 16 single row fiber types that can be stacked together to form 24, 36 and 72 fiber connectors using multiple precision ferrules. However, the wider row and stacked ferrules have had insertion loss and reflection issues due to the difficulty of holding alignment tolerances on the outer fibers versus the center fibers. USCONEC, a primary MPO supplier, and others offer a higher precision ferrule and alignment version called MTP Elite versus their MTP standard ferrule and connector housing, but at a higher cost/price level.

 

Optical loss budgets and the number of connections between active equipment types affect and determine the choice of premium or standard MPO connectors. Telecom infrastructure connectivity systems usually have many more passive optical connections versus newer cloud datacenters that have mostly short intra-rack and intra-row between just two devices. Cloud datacenter racks and row of racks have higher density packaging systems that leave much less space for connector plugs versus telecom wiring cabinets and racks. So there are mini-MPO and micro-MPO connector housings to compete against the smaller MXC housing. At this year’s OFC conference and exhibition, Senko and other suppliers had introduced new smaller MPO products. Combined with more flexible strain-reliefs and newer bend insensitive fiber types for both SMF and MMF these new cable assemblies support more confined routing channels.

 

Industrial automation systems and datacenters also have benefitted from newer designs using circular and rectangular plastic over-shells. Mining and military use MPOs embedded inside circular metal shells.

There are many newer fiber types like 10G performance MMF OM4 that are using color-coded housings like aqua to more easily discern within the rack.

 

Besides the MXC system, other competing connector and cabling systems now include using a single multi-core fiber with the LC connector. There are up to 12 or more cores within some newer fiber types. Also competing is the Valdor circular 7 fiber ferrule that fits within the SC or LC connector housing and newer E-Shield 19 and 37 fiber circular ferrules that fit within a SC or LC housing. The circular multi-fiber bundle geometry and multi-core fiber solutions help to provide better insertion loss versus the linear single row 16 fiber MPO system.

 

MPO connectors will still thrive in many market segments while newer multi-fiber connector will also expand their usages and product features and application options.

How the Fiber Optics Attenuators work?

An optical attenuator is a passive device used to reduce the power level of an optical signal, either in free space or in an optical fiber. There are various types of them from the fixed ones, step-wise variable, and continuously variable.

 

Attenuators are usually used when the signal arriving at the receiver is too strong and hence may overpower the receiving elements. This may occur because of a mismatch between the transmitters/receivers, or because the media converters are designed for a much longer distance than for which they are being used.

 

Sometimes attenuators are also used for stress testing a network link by incrementally reducing the signal strength until the optical link fails, determining the signal’s existing safety margin.

 

Although fiber optic attenuators are normally used in SM (Single Mode) circuits, because this is where the stronger lasers are used for distance transmission, there are also multi mode attenuators available.

 

The most common version of attenuators are male to female units, often called plug-style or buildout style. These plug-style attenuators simply mount on one end of a fiber optic cable, allowing that cable to be plugged into the receiving equipment or panel.

 

There are also female to female (bulkhead) attenuators, often used to mount in patch panels or for connecting two fiber optic cables together. More expensive, but useful for testing, are variable attenuators which are adjustable between 1dB and 30dB.

 

Fiber optic attenuators are usually used in two scenarios.

 

The first case is in power level testing. Optical attenuators are used to temporarily add a calibrated amount of signal loss in order to test the power level margins in a fiber optic communication system. In the second case, optical attenuators are permanently installed in a fiber optic communication link to properly match transmitter and receiver optical signal levels.

 

How many types of Optical Attenuators (OA) can you find?

 

There are four different types of OA and they can take a number of different forms and are typically classified as fixed or variable attenuators. What's more, they can be classified as LC, SC, ST, FC, MU, E2000 etc. according to the different types of connectors.

 

1. Fixed Attenuators: Fixed optical attenuators used in fiber optic systems may use a variety of principles for their functioning. Preferred attenuators use either doped fibers, or misaligned splices, or total power since both of these are reliable and inexpensive.

 

 

 

Inline style attenuators are incorporated into patch cables. The alternative build out style attenuator is a small male-female adapter that can be added onto other cables. 

 

Non-preferred attenuators often use gap loss or reflective principles. Such devices can be sensitive to modal distribution, wavelength, contamination, vibration, temperature, damage due to power bursts, may cause back reflections, may cause signal dispersion etc.

 

2. Loopback Attenuators: Loopback fiber optic attenuator is designed for testing, engineering and the burn-in stage of boards or other equipment. Available in SC/UPC, SC/APC, LC/UPC, LC/APC, MTRJ, MPO for single mode application. 

 

 

3. Built-in Variable Attenuators: Built-in variable optical attenuators may be either manually or electrically controlled. A manual device is useful for one-time set up of a system, and is a near-equivalent to a fixed attenuator, and may be referred to as an "adjustable attenuator". In contrast, an electrically controlled attenuator can provide adaptive power optimization.

 

Attributes of merit for electrically controlled devices, include speed of response and avoiding degradation of the transmitted signal. Dynamic range is usually quite restricted, and power feedback may mean that long-term stability is a relatively minor issue.

 

The speed of response is a particularly major issue in dynamically reconfigurable systems, where a delay of one millionth of a second can result in the loss of large amounts of transmitted data.

 

Typical technologies employed for high-speed response include liquid crystal variable attenuator (LCVA), or lithium niobate devices.

 

There is a class of built-in attenuators that is technically indistinguishable from test attenuators, except they are packaged for rack mounting, and have no test display.

 

4. Variable Optical Test Attenuators: this type generally uses a variable neutral density filter. Despite the relatively high cost, this arrangement has the advantages of being stable, wavelength insensitive, mode insensitive, and offering a large dynamic range.