Understanding Fiber Optic Based Light Source

by www.fiber-mart.com

Each piece of active electronics will have a variety of light sources used to transmit over the various types of fiber. The distance and bandwidth will vary with light source and quality of fiber. In most networks, fiber is used for uplink/backbone operations and connecting various buildings together on a campus. The speed and distance are a function of the core, modal bandwidth, grade of fiber and the light source, all discussed previously. Light sources of the fiber light source are offered in a variety of types. Basically there are two types of semiconductor light sources available for fiber optic communication – The LED sources and the laser sources.

 

Using single mode fiber for short distances can cause the receiver to be overwhelmed and an inline attenuator may be needed to introduce attenuation into the channel. With Gigabit to the desktop becoming commonplace, 10Gb/s backbones have also become more common. The SR interfaces are also becoming common in data center applications and even some desktop applications. As you can see, the higher quality fiber (or laser optimized fiber) provides for greater flexibility for a fiber plant installation. Although some variations ( 10GBase-LRM SFP+ and 10GBASE-LX4) support older grades of fiber to distances 220m or greater, the equipment is more costly. In many cases, it is less expensive to upgrade fiber than to purchase the more costly components that also carry increased maintenance costs over time.

 

Light sources of the fiber light source are offered in a variety of types. Basically there are two types of semiconductor light sources available for fiber optic communication – The LED sources and the laser sources.

 

In fiber-optics-based solution design, a bright light source such as a laser sends light through an optical fiber, called laser light source . Along the length of the fiber is an ultraviolet-light-treated region called a “fiber grating.” The grating deflects the light so that it exits perpendicularly to the length of the fiber as a long, expanding rectangle of light. This optical rectangle is then collimated by a cylindrical lens, such that the rectangle illuminates objects of interest at various distances from the source. The bright rectangle allows line scan cameras to sort products at higher speeds with improved accuracy.

 

The laser fiber-based light source combines all the ideal features necessary for accurate and efficient scanning: uniform, intense illumination over a rectangular region; a directional beam that avoids wasting unused light by only illuminating the rectangle; and a “cool” source that does not heat up the objects to be imaged. Currently employed light sources such as tungsten halogen lamps or arrays of light-emitting diodes lack at least one of these features.

Knowledge About GPON SFP Transceivers

by Fiber-MART.COM

GPON stands for Gigabit Passive Optical Network. GPON is one of the key technologies that are being used in fiber-based (FTTx) access networks, including fiber to the home (FTTH), fiber to the business (FTTB), fiber to the curb (FTTC), etc. GPON system contains two main active transmission components, namely optical line termination (OLT) and optical network termination (ONT) or optical network unit (ONU). Modern OLT and ONT/ONU use compact fiber optic modules to achieve the triple-play GPON services. These modules are known as GPON SFP transceivers. This post will give a comprehensive introduction to GPON SFP modules.

 

What Is GPON SFP?

GPON SFP is one type of gigabit optical transceivers that are used in GPON system, which is compliant with ITU-T G.984.2 standard. It is a bidirectional module that has SC receptacle and works over simplex single-mode fiber optic cable. A GPON SFP module transmits and receives signals of different wavelengths between the OLT at the Central Office side and the ONT at the end users side. GPON SFPs utilize both the upstream data and downstream data by means of Optical Wavelength Division Multiplexing (WDM).

 

GPON SFP: Class B+ vs. Class C+

GPON SFP transceivers are categorized into GPON OLT SFP and GPON ONT SFP or GPON ONU SFP depending on the devices they are used in. And there are Class B+ GPON SFP and Class C+ GPON SFP. The major differences between them are the transmit power and the receive sensitivity. The table below lists the Tx power and Rx sensitivity of Class B+ GPON SFP and Class C+ GPON SFP.

 

By using Class B+ or Class C+ GPON OLT SFP, it can support up to 32 or 64 ONTs at customer premises respectively. And a C+ OLT SFP can be used with B+ ONT SFP as long as the loss budget of the link is appropriate.

 

How’s the GPON SFP Different From Conventional BiDi SFP?

Although GPON SFP belongs to the gigabit BiDi SFP family, it differs from “normal” BiDi SFPs in some aspects. Here’s a comparison between GPON SFP transceiver and conventional BiDi SFP transceiver.

 

Signal Transmission Mode

In terms of conventional gigabit BiDi SFP transceivers that are mainly used in backbone network, the optical transmission mode is point to point (P2P), i.e., they must be used in matched pair. A BiDi usually has LC receptacle instead of SC receptacle. Here’s an illustration of P2P transmission mode.

 

The transmission mode of GPON SFP is point to multi-point (P2MP). One GPON OLT SFP at the Central Office communicates with multiple GPON ONT SFPs with the help of fiber optic splitters. This is why we usually see a GPON infrastructure is in a tree shape or a tee shape.

 

Transmission Distance

The transmission distance of conventional gigabit BiDi SFP can be up to 160 km over single-mode fiber cable when using 1590nm/1510nm and 1510nm/1590nm wavelengths. GPON OLT and ONT/ ONU SFP transceivers support a transmission distance up to 20 km with 1490nm/1310nm and 1310nm/1490nm wavelengths.

 

Benefits of Using GPON SFP

Using GPON SFP is considered a more convenient and cost-effective solution for the end customers. And it also reduces the devices that need to be provided by the Internet service provider (ISP). Before the GPON ONT SFP was released and used in GPON networks, the ISP usually needs to install at least an optical modem (a type of ONT with a fiber optic port) and an IP access router, and a Set-Top-Box or video recorder might also be needed if IPTV services are required. The separation of different devices inevitably increased the cost for GPON services.

 

The newly used GPON SFP is in smaller size and integrates the triple-play services. It has lower consumption as well. The ISP provides a GPON ONT SFP to the customer. This module is usually installed in the hub/router handed to the customer by the ISP. The customer is also able to unplug the fiber optic patch cable and the GPON ONT SFP from the ISP’s hub/router, and then plug them in his own router/switch that is white-listed by the ISP.

 

Conclusion

GPON SFP transceivers are typically used in the two main active transmission components OLT and ONT/ONU in GPON optical networks. They are essential in keeping the high-bandwidth communication between the service provider and the end users over a distance up to 20 km. GPON SFPs are classified into Class B+ and Class C+ and the main differences are their Tx power and Rx sensitivity. This module has simplified the implementation of GPON services. It benefits both the service providers and the end users to some degree.

How Does Fiber Identifier Work In Your Fiber Optic Network

by Fiber-MART.COM

Fiber Optical Identifier is an essential installation and maintenance instrument which can identify the optical fiber by detecting the optical signals transmitted through the cables, during this process the fiber optic identifier do no harm or damage to the fiber cable and it also don’t need opening the fiber at the splice point for identification or interrupting the service.During fiber optic network installation, maintenance, or restoration, it is also often necessary to identify a specific fiber without disrupting live service.

 

The Fiber optic identifier have a slot on the top. The fiber under test is inserted into the slot, then the fiber identifier performs a macro-bend on the fiber. The macro-bend makes some light leak out from the fiber and the optical sensor detects it. The detector can detect both the presence of the light and the direction of light.

 

A fiber optic identifier can detect “no signal”, “tone” or “traffic” and it also indicates the traffic direction. The optical signal loss induced by this technique is so small, usually at 1dB level, that it doesn’t cause any trouble on the live traffic.

 

Fiber optic identifiers can detect 250um bare fibers, 900um tight buffered fibers, 2.0mm fiber cables, 3.0mm fiber cables, bare fiber ribbons and jacketed fiber ribbons. Most fiber identifiers need to change a head fiber optic adapter in order to support all these kinds of fibers and cables. While some other models are cleverly designed and they don’t need to change the head adapter at all. Some models only support single mode fibers and others can support both single mode and multimode fibers.

 

Most high end fiber optic identifiers are equipped with a LCD display which can display the optical power detected. However, this power measurement cannot be used as a accurate absolute power measurement of the optical signal due to inconsistencies in fiber optic cables and the impact of user technique on the measurements.

Optical Power Meter – an Essential Tester for Fiber Optic Testing

by Fiber-MART.COM

In fiber optic network, whether installing new cable, or troubleshooting existing cable, cable testing always plays an important role in the process. Optical power meter which is widely used for power measurement and loss testing is well known to us. Today, we are going to talk about this familiar and essential fiber optic tester—optical power meter, in details.

 

As its name suggests, optical power meter is a meter which is used for testing optical power. So, what is optical power? And how to measure power by using optical power meter?

 

Optical Power

In simple terms, optical power is the brightness or “intensity” of light. In optical networking, optical power is measured in “dBm” which refers to a decibel relative to 1 milliwatt (mW) of power. Thus a source with a power level of 0 dBm has a power of 1 mW. Likewise, 3 dBm is 2 mW and -3 dBm is 0.5 mW, etc. And one more thing should be known is that 0 mW is negative infinity dBm.

 

Using Optical Power Meter for Power Measurement

 

Measuring power at the transmitter or receiver requires only an optical power meter, an adapter for the fiber optic connector on the cables used, and the ability to turn on the network electronics.

 

The optical power meter must be set to the proper range (usually dBm, but sometimes mW) and the proper wavelength when measuring power. When all are ready, attach the optical power meter to the cable at the receiver to measure receiver power, or to a short test cable that is attached to the system source to measure transmitter power. Mark the value, and compare it to the specified power for the system and make sure it is in the acceptable range for the system.

 

In addition to measuring optical power, optical power meter can be used to test optical lost by using together with light source. What is optical loss and how does the optical power meter achieve loss testing?

 

Optical Loss

When light travels through fiber, some energy is lost, e.g., absorbed by the glass particles and converted to heat; or scattered by microscopic imperfections in the fiber. We call this loss of intensity “attenuation”. Attenuation is measured in dB loss per length of cable. dB is a ratio of two powers. Even the best connectors and splices aren’t perfect. Thus, every time we connect two fibers together, we get loss. We called this loss as insertion loss which is the attenuation caused by the insertion of the device such as a splice or connection point to a cable. Actual loss depends on your fiber connector and mating conditions. Additionally, insertion loss is also used to describe loss from Mux since it is the “penalty you pay just for inserting the fiber”.

 

Using Optical Power Meter and Light Source for Loss Testing

 

Loss of a cable is the difference between the power coupled into the cable at the transmitter end and what comes out at the receiver end. But Loss testing requires not only optical power meter, but also a light source. In general, multimode fiber is tested at 850 nm and optionally at 1300 nm with LED sources. Single-mode fiber is tested at 1310 nm and optionally at 1550 nm with laser sources. The measured loss is compared to the loss budget, namely estimated loss calculated for the link. In addition, in order to measure loss, it is necessary to create reproducible test conditions for testing fibers and connectors that simulate actual operating conditions. This simulation is created by choosing an appropriate source and mating a launch reference cable with a calibrated launch power that becomes the “0 dB” loss reference to the source.

 

There are two methods used to measure loss which are called “single-ended loss” and “double-ended loss”. Single-ended loss works by using only the launch cable while the double-ended loss works using a received cable attached to the meter also. The method “signle-ended loss” is described in FOTP-171. By using this method, you can test the loss of the connector mated to the launch cable and the loss of any fiber, splices or other connectors in the cable you are testing. Thus, it is the best possible method of testing patchcords, since it tests each connector individually. The method “double-ended loss” is specified in Ofiber-martTP-14. In this way, you can measure loss of two connectors and the loss of all the cable or cables, including connectors and splices in between. The following picture shows these two methods to us. From left to right: Single-ended loss testing (Patch Cord), Double-ended loss testing (installed cable plants).

 

Optical Power Meter Selection Guide

As described above, optical power meter is very useful and necessary for fiber optic testing such as optical power measurement and loss testing. Thus, to select a suitable optical power meter is very important. According to the user’s specific application, several points should be considered when choosing an optical power meter:

 

Choosing optical power meter with the best type of detector and interface

Evaluation of calibration and precision as well as the manufacturing calibration procedures should match your fiber and connector requirement

Make sure that the model of the meter is consistent with your measurement range and the display resolution

Whether have a direct insertion loss (dB) measurement function

In addition to optical power meter and light source, other tools such as launch cable, mating adapters, visual fault locator or fiber tracer, cleaning and inspection kits as well as other testers are also required for fiber optic testing. Fiberstore offers a comprehensive solution of fiber optic testers and tools which help you achieve a reliable and valuable fiber optic system. Contact us via sales@fiber-mart.com for more information.

Fiber Optic Tool Kits From fiber-mart.com

The fiber-mart’s Basic fiber optic tool kits provide you with dozens of basic tools that are essential for fiber optic termination, construction, splicing, polishing and testing. The kit includes strippers, cable slitters and other precision hand tools, consumable products, and much more. All of the contents are packed in a durable case, keeping the items you need within easy reach. For example, the fiber optic termination tool kit provided by fiber-mart.

The traditional Erpoxy and Polish Connector Termination Tool Kit:

This type of kit sometimes is also called universal connectorization epoxy tool kit. They include all the tools necessary for hand-polishing termination of epoxy optic connectors such as FC, SC, ST, LC, etc. The following list shows all essentials tools that should be included.

a. Fiber cable jacket stripper to remove outer jacket from optical cables;

b. Fiber stripper to remove fiber coatings (900um tight buffer or 250um UV coating layer) to expose the bare fiber cladding;

c. Kevlar scissors to cut the yellow strength member inside fiber jacket;

d. Fiber connector crimp tool for FC, SC, ST, LC;

e. Fiber scribe tool to scribe the bare fiber;

f. Epoxy for fixing the fiber inside the connector, empty syringes for epoxy dispensing into the connector;

g. Glass polish plate so you can place rubber polish pad on top of it;

h. Rubber polish pad so you can place the lapping films on top of it;

i. Lapping films (several grits included, typically 12um, 3um, 1um and 0.5um);

j. Connector hand polish pucks for FC, SC, ST, LC;

k. Inspection microscope so you can inspect the quality of your work;

l. Heat cure oven to cure the epoxy (either 220V or 110V);

m. Other misc. items for cleaning such as Kimwipes, Isopropyl alcohol, etc.

Quick Termination Connector Tool Kit

90 percent of quick termination connectors don’t require polishing. They have a factory pre-polished fiber stub inside the connector body, all you need to do is strip your fiber, clean, cleave the fiber and then insert the cleaved fiber into the connector body, with or without assembly tool assistance, then finally crimp the connector with specialized tool.

There is no universal quick termination connector tool kit, since each connector is designed differently by their manufacturers and requires proprietary assembly tool.

The fiber optic tools come in a range of colours, designs and features — from subtle to spunky. For the ones who like to keep it simple, there are designs, such as a portable and practical crimping tool. For someone who like it sophisticated, there are designs, such as the Multi-Function F-Type, RJ-12 and RJ-45 Cable Tester. With affordable pricing, these tools do meet the expectations of as many customers as possible.

Fiber Optic Termination Kits provide field engineers with a low cost and highly portable solution. fiber-mart has provided four different options for the consumer. The basic Fiber Optic Termination Kit includes adhesives and primers, a fiber scraps bin, polishing pads, pre-saturated IPA wipes, lint free wipes, syringes and needles, a cleave tool, and a polishing puck. The other three models contain the tools of the basic kit and options such as light meter and fiber microscope, maximizing the functionality and flexibility of the Kits. And the Fiber Connector Termination Tool Kit contains all of the latest popular fiber optic tools and consumable material necessary for epoxy and polish connector terminations(SC/ST/FC and LC connectors).

WHY IT PROFESSIONALS PREFER FIBER OPTICS

More and more IT professionals are choosing to install fiber optic cables over the copper cables that have traditionally been used to create networks. Why is that? Well, for one, fiber optic cables have proven to transmit data substantially faster than copper cables. Fiber optic cables use light to move data around, and that makes them quicker. But that’s not the only reason why IT professionals are choosing fiber optic cables. Here are several other reasons.

 

FIBER OPTIC CABLES DON’T LOSE THEIR SIGNAL STRENGTH AS QUICKLY AS COPPER CABLES.

When copper cables are forced to transmit data over a long distance, they end up losing a lot of their signal strength. IT professionals refer to this as low attenuation, and it can obviously be problematic for companies that need cables capable of carrying data over longer distances. Data doesn’t break down in fiber optic cables like it does in copper cables, which, outside of speed, is one of the biggest benefits of using them.

 

FIBER OPTIC CABLES AREN’T A FIRE HAZARD LIKE COPPER CABLES.

When companies use copper cables, they are relying on electricity to transmit data. Anytime you count on electricity for anything, there is obviously a fire risk that comes along with it. This same fire risk is not present when fiber optic cables are utilized since light will not catch on fire when transmitting data.

 

FIBER OPTIC CABLES DON’T BREAK AS OFTEN AS COPPER CABLES DO.

Fiber optic cables and copper cables can both wear down and break over time. But despite the fact that fiber optic cables are comprised of glass, they break a whole lot less often than copper cables do. This means that IT professionals won’t be forced to make unnecessary repairs when they go with fiber optic cables.

 

There are so many different advantages to using fiber optic cables over copper cables. It’s why many IT professionals have started to turn their attention to fiber optic cables. If your company would like to find out more about the benefits of using fiber optic cables over copper cables, Connected Fiber can help. Call us at 1-862786-1199 today and ask about the fiber optic services we can provide for you.

QSFP+ to 4xSFP+ AOC and QSFP+ MTP Breakout Cable Solution

Migration from 10G to 40G is an inevitable trend in data center. Migration means you need new QSFP+ transceiver modules, fiber patch cables and other equipment. Common two methods to migrate from 10G to 40G for short distance are QSFP+ to 4xSFP+ AOC and QSFP+ MTP breakout cable solution. When you come across this issue, it’s hard to tell which one is better. This article will introduce their difference and tell you how to make the right decision.

40G QSFP+ to 4xSFP+ AOC (active optical cable) is composed of a QSFP+ connector on one side and four individual SFP+ connectors on the other side. The QSFP+ connector (40Gbps rate) offers four parallel, bidirectional channels and each operates at up to 10.3125 Gbps. The QSFP+ connector can be installed into QSFP+ port on the switch and feed up to four 10G SFP+ links. And the link lengths can reach 100 meters on OM3 fiber. It’s a cost-effective interconnect solution for 40G and 10G switches and servers.

QSFP+ MTP Breakout Cable

The other common solution for 10G to 40G short distance migration is to use breakout cable and of course corresponding transceivers. How to achieve the connection? You’re gonna need 40GBASE-SR4 QSFP+, MTP to LC breakout cable and 10GBASE-SR SFP+. Here we are going to explain 40GBASE-SR4 QSFP+ and MTP-LC breakout cable in details.

First, 40GBASE-SR4 QSFP+ is designed for 40 Gigabit data center and can support the link length of 100 m and 150 m respectively on laser optimized OM3 and OM4 fiber cables. This module offers 4 independent channels for transmitting and receiving. Each lane is capable of running 10Gbps signal and is compliant to IEEE 10GBASE-SR specification. Connecting with 12-fiber MTP/MPO cables, it can support 40Gbps network. Or combine 40GBASE-SR4 QSFP+ with 4x10G breakout cable and send data to four 10GBASE-SR SFP+.

Second, MTP to LC breakout cable is suitable for high density network. It’s specifically designed for fast Ethernet, fiber channel, data center and gigabit Ethernet application. QSFP+ MTP to LC breakout cable is used for a direct connection between QSFP+ to 4xSFP+ ports with no patch panels or intermediate trunks in between. On one side, it’s an MTP connector with 8 or 12 fibers. On the other side, there are 4 duplex LC connectors. Each fiber cable transmits 10Gbps.

Differences of Two Solutions

Two methods of 10G to 40G migration over short distance have been introduced in above content. Comparing the two different solutions, you can find some obvious differences. The following lists some points for your convenience to make suitable decision.

Price—The second solution needs at one QSFP+, 4 SFP+ and an MTP-LC breakout cable. The price of these devices is higher than 40G QSFP+ to 4xSFP+ AOC. So 40G QSFP+ to 4xSFP+ AOC is cheaper.

Complexity—The second solution seems more complicated since it needs more optical equipment. You need to order and manage cables.

Distance—40G QSFP+ to 4xSFP+ AOC can only support the distance up to 100 m. While using MTP-LC breakout cable, the link distance can reach 150 m over OM4 cable.

Conclusion

You must have a full understanding of these two solutions. 40G QSFP+ to 4xSFP+ AOC is easier and cheaper than MTP to LC breakout cable. If you’re a new technician and have tight budget, you can buy AOC cable. But if you don’t care too much about money, you can select 40GBASE-SR4 QSFP+ and MTP to LC breakout cable to get a little longer link length. Hope this article can help you make the right decision.

Introduction to Simplex, Half Duplex and Full Duplex

Introduction to Simplex, Half Duplex and Full Duplex

by Fiber-MART.COM

Simplex, half duplex and full duplex are three kinds of communication channels in telecommunications and computer networking. These communication channels provide pathways to convey information. A communication channel can be either a physical transmission medium or a logical connection over a multiplexed medium. The physical transmission medium refers to the material substance that can propagate energy waves, such as wires in data communication. And the logical connection usually refers to the circuit switched connection or packet-mode virtual circuit connection, such as a radio channel. Thanks to the help of communication channels, information can be transmitted without obstruction. A brief introduction about three communication channel types will be given in this article.

Three Types of Communication Channel

1) Simplex

A simplex communication channel only sends information in one direction. For example, a radio station usually sends signals to the audience but never receives signals from them, thus a radio station is a simplex channel. It is also common to use simplex channel in fiber optic communication. One strand is used for transmitting signals and the other is for receiving signals. But this might not be obvious because the pair of fiber strands are often combined to one cable. The good part of simplex mode is that its entire bandwidth can be used during the transmission.

 

2) Half duplex

In half duplex mode, data can be transmitted in both directions on a signal carrier except not at the same time. At a certain point, it is actually a simplex channel whose transmission direction can be switched. Walkie-talkie is a typical half duplex device. It has a “push-to-talk” button which can be used to turn on the transmitter but turn off the receiver. Therefore, once you push the button, you cannot hear the person you are talking to but your partner can hear you. An advantage of half-duplex is that the single track is cheaper than the double tracks.

 

 

3) Full duplex

A full duplex communication channel is able to transmit data in both directions on a signal carrier at the same time. It is constructed as a pair of simplex links that allows bidirectional simultaneous transmission. Take telephone as an example, people at both ends of a call can speak and be heard by each other at the same time because there are two communication paths between them. Thus, using the full duplex mode can greatly increase the efficiency of communication.

 

 

Simplex Fiber Optic Cable vs. Duplex Fiber Optic Cable

A simplex fiber optic cable has only one tight-buffered fiber inside cable jacket for one-way data transmission. The aramid yarn and protective jacket enable the cable to be connected and crimped to a mechanical connector. It can be used for both single-mode and multimode fiber optic cables. For instance, single-mode simplex fiber optic cable is suitable for networks that require data to be transmitted in one direction over long distance.

 

Different from simplex fiber optic cable, the duplex one has two fibers constructed in a zipcord style. It is often used for duplex communication between devices to transmit and receive signals simultaneously. The duplex fiber optic cable is required for all sorts of applications, such as workstations, fiber switches and servers, fiber modems and so on. And single-mode or multimode cable is also available with duplex cables.

Conclusion

The concept of communication channel is important for understanding the operation of networking. Simplex, half duplex and full duplex are three modes of communication channels. Each of them can be deployed for different applications. It is more cost-effective to choose the right fiber optic cable according to its channel mode.