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Introduction to Fiber Optic Sensor

In recent years, fiber optic sensor has been deployed successfully in the supervision of structures. Because it is immune to electromagnetic interference and can handle extreme conditions, so it is gaining popularity as the sensor of choice for many industries. Fiber optic sensor is a sensing device that converts light rays into electronic signals. It is usually used for measuring physical quantities such as temperature, pressure, strain, voltages and acceleration etc. This blog is to introduce fiber optic sensor’s classification, characteristics and applications.

Classification
Fiber optic sensor can be mainly classified by sensing location, operating principle and applications. Depending on location of sensor, there are intrinsic and extrinsic fiber optic sensors. Considering the operating principle and demodulation technique, fiber optic sensors can be further divided into intensity, phase, frequency and polarization sensors. Based on application, fiber optic sensors can be classified in physical, chemical, bio-chemical sensors.

Characteristics
Fiber optic sensor offers unique characteristics that make it very popular and sometimes become the only viable sensing solution. Some inherent characteristics of fiber optic sensor are shown as following:

Harsh environment stability to strong electromagnetic interference immunity, high temperature and chemical corrosion, as well as high pressure and high voltage etc.

Very small size, passive and low power.

Excellent performance such as high sensitivity and wide bandwidth.

Long distance operation.
High sensitivity.

Multiplexed or distributed measurements – which are used to offset their major disadvantages of high cost and end-user unfamiliarity.

Applications
Fiber optic sensor has a variety of applications that can be found in equipment from computers to motion detectors. Several applications are specifically shown as following:

Mechanical Measurement – such as rotation,acceleration, electric and magnetic field measurement, temperature, pressure, acoustics,vibration, linear and angular position, strain, humidity, viscosity etc.
Electrical & Magnetic Measurements

Chemical & Biological Sensing
Monitoring the physical health of structures in real time.
Buildings and Bridges – concrete monitoring during setting, crack monitoring, spatial displacement measurement, neutral axis evolution, long-term deformation monitoring, concrete-steel interaction and post-seismic damage evaluation.

Tunnels – multipoint optical extensometers, convergence monitoring, shotcrete vaults evaluation, and joints monitoring damage detection.

Dams – foundation monitoring, joint expansion monitoring, spatial displacement measurement, leakage monitoring, and distributed temperature monitoring.

Heritage structures – displacement monitoring, crack opening analysis, post-seismic damage evaluation, restoration monitoring, and old-new interaction.

Detection of Leakage

MPO/MTP Fiber Cabling Basics

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With the ever increasing need for even greater bandwidth in data centers, multi-mode fiber cables (MMFs) have proven to be a practical optical solution to support such fast-changing and fast-growing bandwidth demand. MTP/MPO fiber cabling, ideal for quick and reliable MMF connectivity, provide an effective way for 40GbE network solutions, ensuring a high-performance and high-speed network. This blog includes basic information about MPO/MTP fiber cabling solutions.

MTP/MPO Connector Background
The term MTP is a registered trademark of US Conec used to describe their connector. The US Conec MTP product is fully compliant with the MPO standards. As such, the MTP connector is a MPO connector.

MTP/MPO Fiber Cabling System Introduction
MTP/MPO fiber cables, as an important part of the MPO/MTP cabling system, are designed to go on reliable and quick operations for the multi-fiber connection system in data centers. Each MTP fiber cable contains 12 fibers or 6 duplex channels in a connector, thus requiring less space. Besides, MTP/MPO fibers are manufactured with outstanding optical and mechanical properties, which makes them able to offer more improved scalability. What’s more, it is easy to have cable management and maintenance on them. Generally speaking, MTP/MPO fiber cables can save a lot of money and space to some extent.

MTP/MPO Fiber Cabling Categories
When it come to types, MTP/MPO fiber cables fall on MTP/MPO trunk cables and MTP/MPO harness cables.

MTP/MPO trunk cables, available in 12-144 counts, are intended for high-density application. By using MTP/MPO trunk cables, the installation of a complete fiber optic backbone is accessible without any field termination.

MTP/MPO harness cables, also called MTP/MPO breakout cables or MTP/MPO fanout cables, available in 8-144 counts, are used for breaking out the MTP into several connections. They provide connection to equipment or panels that are terminated with other standard connectors. As terminated with MTP/MPO connectors on one end and standard LC/FC/SC/ST/MTRJ connectors (generally MTP to LC) on the other end, these cable assemblies can meet a variety of fiber cabling requirements.

MPO/MTP Fiber Cabling for 40GbE
The Institute of Electrical and Electronics Engineers (IEEE) 802.3ba 40 Ethernet Standard was ratified in June 2010. The IEEE 802.3ba standard specifies MPO connectors for standard-length MMF connectivity. MMF employs parallel optics using MPO interconnects for 40GbE transmission. More specifically, 40G is implemented using eight of the twelve fibers in a MPO connector. Four of these eight fibers are used to transmit while the other four are used to receive. Each Tx/Rx pair is operating at 10G.

fiber-mart MPO-based fiber cabling solutions provide a fast , simple and economical way for 40G applications. Certainly, fiber-mart 40G fiber cabling solutions are not limited to MPO/MTP fiber cables. Copper cables are also recommended. Take CAB-Q-Q-1M for example, Arista CAB-Q-Q-1M is the QSFP+ to QSFP+ passive copper cable assembly for 40G links. Or one of other fiber-mart 40G fiber cabling products: JG329A, fiber-mart compatible HP JG329A runs over passive breakout copper cable for 40-gigabit links.

MTP/MPO Jumpers
The MTP jumpers serve to create the connection between the device ports and the structured cabling via the connector panel.

Ruggedized Fiber Optic Cables for Harsh Environment

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As a perfect choice for today’s telecommunication which requires a larger bandwidth, fiber optic cables have been widely put into use and get more popularity. However, when optical cables are increasingly used in different applications with diverse environments, for example, from indoor to tough environments, new and demanding requirements also have been put forward for them. Before deployment, several considerations may occur. For instance, can they resist the erosion of oil or chemicals? Can they still work normally in changeable weather? Do they have rodent-resistant ability? The answer of all the questions is yes. Today’s fiber optic cables possess various abilities to meet different requirements. Here is a brief introduction several ruggedized fiber optic cables that can work in different harsh environments, providing more conveniences and extra protection for network systems.

Armored Fiber Optic Cable
Armored fiber optic cable is one of the most commonly used cables to offer protection for fibers. Generally, armored fiber optic cable contains a helical stainless steel tap over a buffered fiber surrounded by a layer of aramid and stainless steel mesh with an outer jacket. With this unique construction, it can withstand the toughest environments—high temperatures, high pressures, and harsh vibrations as well as animals rodent and moisture. In a word, with the protection of flexible and durable steel tube, armored fiber patch cable will ensure the excellent operation of networks.

IP67 Waterproof Fiber Optic Cable
IP67 waterproof fiber optic cable is another kind of ruggedized cables used for outdoor applications. They are with strong PU jacket and stainless steel armor inside for future protection. “IP” in this term is a type of protection rating defined by International Standard IEC 60529. The number “6” and “7” mean this kind of cable possesses a good ability to resist dust and water. According to the connector types, the IP67 waterproof fiber optic cables have several types including IP67 MTP/MPO fiber cables, IP67 LC waterproof fiber cable and so on. IP67 waterproof fiber optic cables will not get damage even stepped, and are anti-rodents and suitable for use in harsh environment like communication towers and CATV (Community Antenna Television), providing protection for your networks. Here is a picture of IP67 LC component details.

Military Grade Fiber Optic Cable
Military grade fiber optic cable is the last type of ruggedized fiber cable to be introduced. They are manufactured with specialized military tactical fiber cable that has excellent impact and crush resistance characteristics, which comply with military requirements. Generally, they have an outdoor-rated polyurethane jacket that resists UV radiation, cuts, abrasions and chemicals, which is an ideal choice for military vehicles and field deployed communications equipment.

Guide To Fiber Optic Polishing

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Optical fibers require end-surface treatment for proper light propagation and that includes polishing their ends. Polishing is essential for almost all glass-based fibers with cladding diameters larger than 200 microns. Furthermore, all fiber connectors require polishing. The process of fiber optic polishing can occur in the field or in a technical lab, it employs a range of tools and products used to create precision fits and finishes in the delicate glass ends.

There is typical fiber polishing machine for fiber optic polishing. Fiber Optic Polishing Machines are used to polish the end faces of fiber optic products (cables, connectors, adapters, etc.) in order to minimize signal losses due to scattering. Polishing machines can increase productivity by providing rapid polishing of many different connector styles.

When selecting a fiber polishing machine, there are several features to consider, including adjustable pressure, changeable holders, a timer, and the ability to request custom specifications. Most polishing machines do not offer the flexibility of speed adjustment. This is partially due to the fact that most users only need to handle one type of ferrule material such as zirconia. A slight speed variation does not have significant impact on connector polish result. However, a versatile polisher should have the capability to change speed according the ferrule and polishing film material.

The polishing job typically involves fiber optic fusion splicer, among other cable crimping tools and connectors are needed. It also requires 99% isopropyl alcohol, polishing (lapping) film and pad, a polishing puck, and epoxy or adhesive. Some technicians also find needle, syringe, and piano wire useful.

Several Different Polish Options On Fiber Connectors

The different polish of the fiber optic connector ferrules result in different performance of them, mainly on the back reflection (return loss). Generally, PC type is required at least 40dB return loss or higher, UPC is 50dB or higher, APC is 60dB or higher. (As we know, the higher the return loss, the better the performance). Insertion loss of them all should be less than at least 0.3dB, the lower the insertion loss the better the performance.

Things You Need To Mind During Fiber Optic Polishing

It is important not to dwell on any polishing film longer than necessary. Too much polishing can result in undesirable ferrule length, unnecessary polish film wear, and degraded polish finish due to particle accumulation. Make proper adjustments to the recommended polishing time in each step in case they are less than ideal.

Eye protection is always necessary to protect against powerful industrial lasers used in long-distance single-mode networks. Supporting tools may include a visual fault locater to troubleshoot fiber faults and breaks. A fiber-optic inspection microscope permits precision analysis of hair-fine fibers. Additionally, technicians rely upon jacket strippers, cutters, cable slitters, and fusion splicers.

Things You Should Know about Fiber Optic Connector Polishing

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Optical fiber is utilized for high-speed and error-free data transmission across connector assemblies. So the connector end faces need to be polished to optimize performance. And also the connectors must follow acceptance criteria related to insertion and back reflection loss as well as end-face geometry specifications. This article will talk about the fiber optic connectors polishing.

Polishing Process
Early physical contact connectors required spherical forming of their flat end faces as part of the polishing procedure. It involved a four-step process: epoxy removal, ferrule forming, and preliminary and final polishing. These steps utilized aggressive materials for epoxy removal and ferrule forming, generally accomplished with diamond polishing films. Now the polishing process has developed into a sequence of epoxy removal, followed by rough, intermediate and final polishing cycles because almost all connectors are manufactured with a pre-radiused end face. One goal is to avoid excessive disruption of the spherical surface,

while still producing a good mating surface.

Polishing Specifications
Polishing specifications for fiber connectors fall into two categories related to performance and end-face geometry. Back reflection and insertion loss specifications are the most critical measures of polished end functionality. The insertion loss is the amount of optical power lost at the interface between the connectors caused by fiber misalignment, separation between connections (the air gap) and the finish quality of each connector end. The current standard loss specification is less than 0.5 dB, but less than 0.3 dB is increasingly specified. Back reflection is the light reflected back through the fiber toward the source. High back reflection can translate to signal distortion and, therefore, bit errors in systems with high data transfer rates.

Polishing Material
Today several types of connectorized fibers are available, the most common of which are 2.5 mm, 1.25 mm and multifiber. Connector end faces must first be air-polished to ensure a proper mating surface. This will be followed by a sequence of polishing steps depending on the type of connector, the back reflection and the insertion loss specifications. Regardless of the connector type, most polishing sequences begin with aggressive materials, including silicon carbide to remove epoxy and diamond lapping films for beginning and intermediate polishing. These remove both surrounding material and fiber at the same rate. But the last polishing step needs a less aggressive material to attack only the fiber, such as silicon dioxide. Using a material for final polishing that is too aggressive could result in excessive undercut. The wrong final-polish material can cause excessive protrusion, leading to fiber chipping and cracking during the connector mating process.

Impact Factor
Issues to be examined include the polishing films used, the type of epoxy and lubrication. Films are the most significant impact because the gradations and quality vary from supplier to supplier. End users should pay attention on selecting film type. Excessively aggressive films can destroy a 125-μm fiber and the end-face radius. Epoxy removal is also essential to contamination-free polishing. Some types of epoxies can be removed more easily with specific grades of silicon-carbide polishing films. The films to use in this step depend on the size of the epoxy bead mounted on the connector end face and the epoxy type. Epoxies have different varieties. Some will be tacky, some firm. In all, a contamination-free environment is essential to optimizing connector polishing.

Polishing may be an old art form, but for the immediate future, it’s here to stay. Undoubtedly inspection criteria will increase. Polishing procedures will be driven to change, and new connector style will also make us continuously strive to reinvent our approach to polishing. Fiberstore has various products about fiber optic polishing. For more details, please visit fiber-mart.COM.

Four Questions You May Ask About Fiber Optic Connector Cleaning

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Fiber optic connectors, as one of important linking components, can be found everywhere in fiber optic networks. With fiber optic connectors, you can easily add, drop, move and change the networks. And it’s also well known that a clean and reliable optical connector can provide high performance fiber infrastructure and extend the life of network. Then how much do you know about fiber optic connectors cleaning? Today, these questions may help you know more about it.

Why Fiber Optic Connector Should Be Cleaned?
Cleaning consideration is a crucial issue in fiber optic cable technology today. If not cleaned properly, the ferrule in connectors is easy to be damaged when connecting, which can result in high costs. What’s more, it’s known to us that the fiber ferrules in the connectors make physical contact with another within the connectors alignment sleeve. Any contamination or dirt on one of the ferrules can easily be transferred to the mating ferrule, which can cause physical damage to the fiber’s end-face and further lead to information transmission failures. Hence, fiber optic connectors should be cleaned carefully.

How to Clean Fiber Optic Connectors?

Generally, there are two ways to clean fiber optic connectors. One is dry cleaning, and another is wet cleaning. Following is a brief introduction.

Usually, dry cleaning is to use a reel-based cassette cleaner to wipe the connector end-face against a dry cleaning cloth in one direction. For APC (angled physical contact) polished connectors, it’s essential to ensure the end-face surface mates with the cleaning cloth. Generally, dry cleaning can remove airborne contamination.

As for wet cleaning, first wipe the end-face against the wet area and then onto a dry area to clean potential residue from the end-face. Wet cleaning is more aggressive than dry cleaning, and can remove both airborne contamination and light oil residue.

What Types of Fiber Optic Cleaners Are There?
With more and more fiber optic components widely used, fiber optic cleaning is required for an optimum connection between both active fiber equipment and passive fiber equipment. Without cleaning, your network performance and reliability can be influenced. Here recommends two common types of fiber optic cleaners.

One-Push Cleaner
One-push cleaner is designed to clean male connectors, female bulkhead adapters, fiber patch cables and test equipment. It cleans the ferrule end-face by removing dust, oil and other contamination without scratching the end-face. FS provides several kinds of this cleaners such as one-push cleaner for LC/MU 1.25mm ferrules, one-push cleaner for SC/ST/FC/LSH 2.5mm ferrules, one-push cleaner for MTP/MPO connector and so on.

How to Clean Fiber Optic Connectors?
Generally, there are two ways to clean fiber optic connectors. One is dry cleaning, and another is wet cleaning. Following is a brief introduction.

What Types of Fiber Optic Cleaners Are There?

With more and more fiber optic components widely used, fiber optic cleaning is required for an optimum connection between both active fiber equipment and passive fiber equipment. Without cleaning, your network performance and reliability can be influenced. Here recommends two common types of fiber optic cleaners.

What Should Be Noticed When Cleaning Fiber Optic Connectors?
There are various ways to clean fiber optic connectors. But we still should be careful when cleaning fiber optic connectors because they are easily damaged. Following are some helpful notes that should be given attention to when cleaning connectors.

Do not forget to inspect the fiber optic connector, component, or bulkhead before starting cleaning.

Do not allow the end of the fiber optic connectors to contact with any surface including fingers.

Do not use alcohol or wet cleaning if no residue left on the end-face. It can do harm to the equipment.

Do not push it with heavy pressure. Use the fiber optic cleaner correctly by inserting it at the correct angle and clean connectors carefully.
Do not forget to reinspect the connectors when cleaning has been finished.

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