All About Various Optical Attenuator (EDFA, FRA, and SOA)

Optical Amplifier

The transmission loss of the light that passes through optical switch fiber is the very small value of less than 0.2 dB per km with a light wavelength in the 1,550 nm band.

An optical amplifier is an extremely important device that supports the long-distance optical communication networks of today and it amplifies light as it is without converting the optical signal to an electrical signal. The main type of optical amplifiers includes an EDFA(Erbium-Doped Fiber Amplifier), FRA(Fiber Raman Amplifier), and SOA(Semiconductor Optical Amplifier).

FRA (Fiber Raman Amplifier)

An FRA is a type of OFA. When strong excitation light enters the optical attenuator fiber it causes stimulated emission based on SRS. In a wavelength range about 100 nm longer than the excitation light wavelength, the light is then amplified. It has a wide amplification wavelength region, and it can be freely set by the wavelength of the excitation light.

DFA (Erbium-Doped Fiber Amplifier)

An EDFA is 1 type of OFA and is an optical amplifier that consists of erbium ions added to the core of the optical fiber. It can amplify optical signals in the 1.55 μm band or 1.58 μm bands, features high gain and low noise, and is polarization independent.

Previously it was important to use an optical repeater to temporarily convert attenuated light into an electrical signal, then electrically amplify it and regenerate the waveform, then convert back to light and resend it.

SOA (Semiconductor Optical Amplifier)

An SOA is a semiconductor element. On the cleavage plane of a semiconductor laser by performing antireflective processing and eliminating the resonator structure, light can easily enter from outside the semiconductor and amplify light via stimulated emission.

In a compact size, you can make an SOA, and compared to an EDFA its lower running costs mean it is more economically efficient. Till recent years, the input light of an SOA was highly polarization-dependent but in recent years research into low polarization, dependency has proceeded. Furthermore, at data centers, optical amplifier EDFA is being replaced by SOAs, and their use is expected to expand in future optical communication.

FBT and PLC Fiber Optic Splitters Differences

To share the optic network with multiple users, fiber splitter is an important component in PON and FTTx architectures. Splitting one optic light beam into several parts at a certain ratio is the basic principle of fiber optic splitter. Fiber optic splitters can be divided into FBT and PLC splitters as per different manufacturing technologies. When choosing between them, you may wonder about the differences between the two splitter types.

FBT & PLC Splitters Differences 

PLC and FBT splitters still have many differences although they may look similar to each other when it comes to actual applications. Here we are going to compare them from several other aspects.

Wavelength Range

Ranging from 1260 nm to 1620 nm, the PLC splitter has a wider operating wavelength. Thus to most of the applications in PON and FTTx networks, it can be applied. Only to be used for 1550nm, 1310nm, and 850nm wavelengths, and FBT splitter has a limitation on the contrary.

Splitting Ratio

By the outputs and inputs of a splitter, the Splitting ratio is decided. With the splitting ratio of 1:64, A PLC splitter is available which means into 64 splits, one light beam can be separated at a time. However, for networks requiring the splitter configuration of fewer than 4 splits, and FBT splitter is used typically. It will cause a higher failure rate and more errors will occur when its splitting ratio is larger than 1:8. Thus to the number of splits in one coupling, the FBT splitter is more restricted. The fiber coupler is also useful.

Price

Its cost is generally higher than the FBT type Owing to the complicated manufacturing technology of the PLC splitter. FBT splitter is a cost-effective solution if your application is short of funds and simple.

Temperature-Dependent Loss

By the sensitivity of the device and manufacturing process, Temperature-dependent loss (TDL) of the splitter is affected. Insertion loss will influence the performance of the fiber splitter and increase once the working temperature of the splitter is out of range. At the temperature of -40 to 85 Celsius degrees, the PLC splitter can work while at -5 to 75 Celsius degrees, the FBT splitter can only work.

Everything About Fiber Optic Couplers

Optical fiber coupler have the same functionality as electronic couplers: The signal is split into multiple points(devices). For tapping (monitoring the signal quality) or more complex telecommunication systems, fiber optic couplers are required which need more than simple point-to-point connections, such as ring architectures, bus architectures, and star architectures.

Passive couplers and active couplers

Fiber optic couplers are either active or passive devices. Between active and passive couplers the major difference is that a passive coupler without optical-to-electrical conversion redistributes the optical signal. Active couplers are electronic devices that split or combine the signal electrically and they make use of fiber optic detectors and sources for input and output.

Electronic couplers are easy to make because as long as you have physical contact between the conductor’s there is the flow of electric current. Fiber optic coupler types are defined by their input and output port numbers. They are designed to fulfill different applications.

wavelength-selective couplers

Wavelength selective couplers are WDM (wavelength division multiplexer). fiber splitter split the signal, not based on their power but rather based on their wavelengths.

Tree couplers

Tree couplers make use of only one input and split it into multiple (more than two) outputs. As a combiner, you can use tree couplers as backward (bidirectional). Multiple output signals (now function as the input actually) are then combined to a single input (now as the output actually).

Star couplers

From tree couplers, star couplers are very much different as they have multiple inputs and multiple outputs. The fibers then radiate from the central point like a star.

T couplers

T couplers are also called Y couplers which are based on their look. T couplers are three-port devices with one input and two output ports.

Manufacturing technologies of Fiber optic coupler

For fiber optic coupler there are majorly three types of manufacturing technologies: micro-optics, fused-fiber, and planar waveguide.

Individual optic elements such as lens, prism, mirrors, etc. are used by micro-optics technologies to construct an optical route that functions as a coupler. This is quite an expensive approach and not as popular as the other two types. Fuse- fiber coupler makes use of the most basic material - optical fibers.

Overview of Multimode Fiber Pigtail

Optical fiber networks are the clear technology leaders among the different technologies of today that attempt to transfer high volumes of data at high speed. Today across the world fiber pigtail is the technology that drives most of the significant data transfers, including the Internet-scale data transfer that happens across the world. To integrate well into the devices these cables need high-quality interface support. It is because the devices need to run the applications with the best possible performance and efficiency.

Multimode fiber patch cable

It is a patch that is used to connect the backend optical network to the front-end device running the applications. For carrying the data signal to the device, the backend high-speed network is responsible. From the wire, the fiber adapter patch is then used to pick up the signal and feed that into the device.

So, the characterization of a multimode fiber patch cable is done by the following-

Fiber: Glass and plastic are the materials used to make these cables. They are never made by using any metal. These materials are not ferromagnetic or paramagnetic. They are diamagnetic.

Patch: These are patch cables. These are not the mainline cables that are intended for the long-distance carriage of data.

Multimode: These cables are highly capable of carrying more than one signal over its length at the same time, such that no two signals can interfere with each other. Enhancing the bandwidth and data transfer rate of the cables helps significantly.

It is interesting to note that these cables are very much capable of handling multiple protocols. Ethernet protocol, the Internet protocol, the ATM protocol, and telecommunication network protocols are a few of the protocols supported by these devices. Ethernet protocols are an example that is used to support local area computer networks that support several users exchanging data at the same time.

In summary, a multi mode fiber patch cable may prove to be exactly what you are looking for if you know your requirements in a multi-user or multi-channel system and are looking for high bandwidth, low attenuation, and high-speed data transfer.

Get to know about the MPO Cable

MTP MPO Cable is interchangeably used nowadays. An enhanced version of MPO cable is MTP. Firstly allowing changing, re-working, and polishing connector heads, the MTP connector has a removable housing. Secondly, to ensure that the cable is not easily broken inside the connector housing, it has a more advanced mechanical support system.

Nevertheless, many MPOs provide breaking resistance from extensive bending force and have implemented similar mechanical support, but a removable housing is not guaranteed.

One of the contributors that led the migration to 40/100GbE is MMPO/MTP technology, which is of reliability, flexibility, and high density with upgradeable as well as scalable properties. However, another challenge is faced by the network designers. Using multi-fiber MPO/MTP components from the end-to-end, proper polarity of these array connections is assured. A transmit signal from any type of active equipment will be directed, which is ensured by maintaining the correct polarity across a fiber network so that it can get a port of the second piece of active equipment.

The MTP Cable is in complete compliance with every MPO connector and is 100% inter-mate able. In generic, MPO connectors become limited in terms of performance and never provide high-performance levels.

MTP connector is superior to generic MPO connectors: Know why

The MTP connector has benefits and features. A few key distinctions are:

• To improve mechanical performance, The MTP has a floating ferrule. To maintain physical contact while under an applied load, this allows two mated ferrules.
• A removable housing is present in The MTP connector. The customer is allowed to re-polish and re-work the MT ferrule, scan the ferrule interferometrically after assembly and change the gender in the field or even after assembly by the feature.
• With features for centering the push spring, The MTP connector has a metal pin clamp. This feature eliminates fiber damage from spring, centers spring force, and eliminates lost pins.
• Tolerance stainless steel elliptical guide pin tips are held by The MTP connector used tightly. This reduces guide hole wear and improves guidance.
• For multi-fiber and twelve fiber ribbon applications, The MPO Cable spring design maximizes ribbon clearance to prevent fiber damage.

Meaning of UTP, S/UTP, FTP, STP, and CAT7

Selecting the right type of shielding you want the cable to have can prove a minefield of confusing acronyms when the question is about copper cabling.

U/FTP: UNSHIELDED WITH FOILED TWISTED PAIRS

Overall shielding is not provided by CAT7 trunk cable but the individual twisted pairs are wrapped in a foil screen. It then provides some protection from EMI and crosstalk from adjacent pairs and other cables.

F/UTP: FOILED WITH UNSHIELDED TWISTED PAIRS

Often referred to as FT. Overall foil shield wrapped around unshielded twisted pairs and a drain wire are listed out by this type of cable list. Unwanted noise is redirected to the ground when the drain wire is correctly connected, offering extra protection against EMI/RFI.

S/UTP: SHIELDED WITH UNSHIELDED TWISTED PAIRS

This cable is often referred to as ST. However, you have to use this term with caution as other shielded cables use this term. Compared to U/UTP, across long distances, SFTP trunk cable is quite capable of supporting higher transmission rates, and because of the braids; it gives better mechanical strength and grounding.

U/UTP: UNSHIELDED TWISTED PAIRS

It is also referred to as UTP. To date, it is the most common and basic method of cable construction, which consists of pairs of wires that are twisted together. There is no shielding provided; instead, a balanced transmission line is created by the symmetrical twist in the wires which then helps in reducing electrical noise and EMI.

S/FTP: SHIELDED WITH FOILED TWISTED PAIRS

Similar to F/FTP, before being wrapped in an overall flexible yet mechanically strong braid screens the individual twisted pairs are wrapped in foil tape. With adjacent pairs and other cables, the additional foil on the twisted pairs helps to reduce crosstalk.

F/FTP: FOILED WITH FOILED TWISTED PAIRS

These are quite similar to F/UTP cables. The designing of cable construction is done in a way that it can produce the assembly with greater protection from other cables.

SF/FTP: SHIELDED AND THEN FOILED WITH THE HELP OF FOILED TWISTED PAIRS

SFTP copper cable consists of both an overall braid shield and foil shield, with individually foil tape screened twisted pairs. From interference and better grounding due to the braid, this type of cable provides the best level of protection.

Things to Know About MPO Fiber Testing

For the ever-increasing data center, bandwidth requirements of MPO trunk cable have become the common cabling solution. The MPO fiber cable links have attributes of parallel transmission. They are pre-terminated, compact, and can handle bandwidth up to 100 Gbps. The testing, certification, and migration of the MPO fiber cables can turn into a nightmare. This article will provide you with a clear overview regarding the testing of MPO cables in the data center.

Challenges of MPO Cables

It is essential to understand MPO cables and how they are tested to get a better understanding of the challenges of MPO cable validation. An MPO connection is similar in size to a fingernail. It contains 12 optical fibers which are less when compared to the diameter of a human hair, and there is a need for them to be tested separately. Once you’re in the process the actual fiber test is quick enough, typically under 10 seconds per fiber.

The main challenge here is that the pre-terminated fiber provides a guarantee when it exists in the manufacturer’s factory. During installation in the data center, it must then be transported, stored, and later bent and pulled. Before MTP trunk cable is deployed there needs to be the introduction of all kinds of performance. After installation, proper testing of pre-terminated cables is the only way that a live application can guarantee performance. Another challenge is testing and determining fiber polarity. Providing a continuous connection from the link’s transmitter to the link’s receiver is the simple purpose of any polarity scheme. Deployment mistakes are quite common as these methods always require a combination of patch cords with different types of polarity.

To evolve at an ever-increasing pace the demand for fast and reliable delivery of critical applications is driving data center technology. The insatiable requirement for bandwidth keeps in mind that the integrity of the data center is linked to the strength of the fiber cabling infrastructure. The growing use of MPO trunk cables says that the time has arrived to stop the verification of individual fibers. After all, it’s a single MPO trunk cable connection.

Increasing Popularity of polarization-maintaining Fiber

Optical networks have become popular due to increasing demands for bandwidth. It becomes important to use existing fiber-optic networks very effectively because installation of new fiber-optic networks is very expensive. Dispersion and attenuation are the main parameters that limit the optical networks. The uses of two polarization axes are improved by the efficiency of optical networks which are very much similar to the technology used in radio technologies. The use of two polarization planes is allowed because of the use of polarization maintaining splitter.

Theoretically, there is no birefringence in an optical fiber with a circular core, and in such an optical fiber the polarization state does not change during propagation. However, in reality, due to external perturbations or manufacturing imperfection in an optical fiber, a small amount of birefringence is always present. Such birefringence is inherently random, and in an optical fiber between two polarization modes, it results in random power coupling. The output polarization state then becomes unpredictable and also differs with time.

PM fibers need to meet critical optical and mechanical specifications, such as attenuation and tensile strength. In characterizing their birefringence properties polarization maintaining isolator have two specifications – beat length and holding (H) parameter. These are complex measurements, but characterizing how well the fibers maintain the two polarization modes they are necessary.

By intentionally inducing uniform birefringence along the entire fiber length a polarization-maintaining Fiber (PM Fiber, PMF) maintains two polarization modes, hence they prohibit random power coupling between two polarization modes.

In a single-mode fiber, the transmission of a source laser’s output is done with two linear polarization modes that propagate at right angles to each other. For a moment imagine that this fiber is an ideal single-mode waveguide:

• the fiber and source laser temperatures always remain constant;
• Polarization maintaining circulator does not have bends and no loss;
• there is perfect uniformity in the core material;
• Compared to the cut off wavelength the laser wavelength is greater, and all the laser energy is concentrated in the core;
• Lateral stress is zero (no external stress from cabling, placement, supports, etc., or even, hypothetically, no gravity or air pressure).

Know about the Working of Fiber optic splitter

Working of fiber optic splitter

Whenever in a network there is the transmission of the light beam it needs to be divided into two or more light beams and for this purpose, a fiber splitter is used.

Whenever there is the transmission of the light signal, the light energy cannot entirely concentrate in the fiber core. Through the cladding of the fiber, a small amount of energy will be spread. The transmitting light in an optical fiber can enter into another optical fiber if two fibers are close enough to each other. Therefore, you can achieve the reallocation technique of optical signals in multiple fibers.

Splitter never generates power nor do they need it. Hence, it is a passive device. Splitters do not even contain any electronic components. It is a simple device. A fiber optic splitter is also referred to as a beam splitter.

In most fiber optic networks splitters are widely used. It consists of numerous input and output terminals, which are majorly applicable to a passive optical network like GPON, BPON, FTTX, EPON, FTTH, etc.

Into two types there is a division of the fiber optic splitters: Fused Biconical Taper (FBT) splitter and PLC splitter.

The most commonly used splitters are the FBT splitters. FBT splitters are accepted everywhere and are mainly used in passive networks.

PLC Splitter

PLC refers to a planar lightwave circuit. PLC splitter makes use of an optical chip as a micro-optical device so that the input signal can be split into various outputs. At the edge of the chip, there is the presence of a light circuit in ribbon form that is mounted on a carrier and fibers. PLC splitter divides the incident light beam (input light signal) into two or more light beams (output light signal) with the use of a fiber splitter chip. As the material of the lightwave circuit PLC splitter adopts silica glass. In PLC splitter the substrate, waveguide, and lid are three basic layers. PLC splitters can be further categorized into different types for various applications which include LGX box PLC splitters, block less PLC splitters, ABS PLC splitters, tray-type PLC splitters bare PLC splitters, mini plug-in type PLC splitters, and 1U rackmount PLC splitters.

Simulating Multi-Fiber and MPO Cable Links

Multi-fiber cabling is used both inside data centers and across vast field networks in today’s advanced fiber-optic networks because deploying large counts of fibers using as little physical space as possible provides the most efficient approach. On a basic level, MTP breakout cable consists of a ribbon cable that is then surrounded by a protective outer jacketing. When it comes to fiber counts this ribbon and/or multi-fiber cables are available with several options.

In a data center between racks, one can have 12 or 24 fiber patch-style cables that connect devices. 

Across the network between sites, a larger field cable in the ground will have several of these resulting in larger fibers counts like 72, 144, 288, and so on. At the ends of some links, fibers may be individually terminated but those between the gear inside the data center often make use of MPO style connectors to reduce the number of total connections.

NEED TO SIMULATE MULTI-FIBER MPO LINKS

There are some primary applications where there is a simulation of multi-fiber links in the lab environment:

Device certification – is provided by the manufacturer or those deploying the equipment

Latency/delay validation – replicates expected network

Simulating real-world conditions is a critical part of the quality assurance process particularly for transceiver and device manufacturers who are designing or certifying their technology. In case an engineering team is designing a new 100G transceiver with a 500m distance specification and MPO connectivity then it needs to be tested over a real 500m MPO breakout cable to make sure that before going into production it is optically functioning as expected over that distance. The QA team may run a final test over the simulated link once a finished product is in production just to make sure that before shipping to the customer the product passes its final inspection.

Secondly, while validating or certifying the necessary equipment before purchase, engineers at service providers and data centers tasked with selecting and deploying MPO breakout cable in their network may wish to replicate their unique fiber links. Spending a large sum of money on equipment is the last thing any network engineering team wants to do and later gets to know that it doesn’t meet all of the needs.