Category: Fiber Tester & Tools

Fiber optic testers, fiber optic tools, fiber splicing, fiber polishing, copper testers and tools.

Fiber Optic Fusion Splicing – Arc Checking and Maintenance

Working with fiber optics takes a delicate hand and some patience. One of the most used pieces of equipment is a fusion splicer. A fusion splicer uses an electric arc to fuse two pieces of optical fiber (glass) together so that light can pass through with no scatter of light or light reflected back (backscatter) by the splice. Fusion splicing helps to reduce loss in your network. Typical loss through a fusion splice is .01dB to .05dB. When using these machines there are some important things that you need to do, as well as steps to maintain them. There are a few different types of splicers, as well as a couple of different concepts of splicing. We will discuss these and some other key points about splicing.
Different Types of Fusion Splicers
There are several different types of splicers. We have V-Groove splicers. These splicers typically only have one camera and align the fiber using the grooves that help to make sure that the cladding of both sides is matched up. These tend to be the low cost splicers which do not have sophisticated motors in them.
Then there is the active cladding alignment splicer. This type does have motors that move on the X and Y axis but it is still aligning the fibers by the cladding and not the core. These tend to be priced about a couple thousand higher than the V-Groove splicers.
Finally, you have a core alignment splicer that uses more than one camera to align your glass fibers by the core or center of your fiber. These were the first splicers that were on the market. This was due to early fiber having very poor concentricity of the core of fiber. These machines are also the most expensive of the splicers because of the advanced technology that is needed to align the fibers up by the cores.
Arc Checks
When you are splicing, there are certain things that need to be done every time before you start splicing your fibers together. The main thing is known as an arc check. This process is to make sure that your splicer is ready and able to help you complete your job without any hiccups. Arc checking will help to make sure a fusion splicer is tuned up for environmental conditions as well as that your machine settings are ideal for you to splice. One thing that is always brought up when performing this operation, is that when doing an arc check, single mode fiber should always be used whether you are splicing multimode or single mode that splicing session. Go to your splicer’s menu and click on the “Arc Check” setting. While doing this the splicer is looking at several different factors that can play a role that affects the splicer’s performance. Weather is a big part of this. It looks at the humidity, temperature and overall performance of the machine to have the perfect formula for the conditions at your job site. This process may need to be repeated several times before your machine is ready to splice. I have heard as many as fifteen times before it was ready, but usually one or two works. So – one thing most people don’t realize is, when splicing throughout the day – as the temperature changes another arc check may need to be performed later in the day. So you start splicing at ten in the morning and it is 65 degrees. You take a break for lunch around noon. When you get back the temperature is now 75 degrees and it has become more humid. Before you start splicing, an arc check should be performed as the temperature and humidity difference will cause your splicer to not be properly ready to splice in the different conditions.
Maintenance of the Splicer
There are a couple of things that can be done with your splicer to make sure it is well maintained and running to help complete important jobs. One of the most important pieces of your splicer is the heart of your fusion splicer. That piece being the electrodes. The electrodes are a pair of conductors that electricity flows through and this is what fuses your two pieces of fiber together. The electrical arc does wear them down over a period of arcs. The recommended number of arcs before these should be changed is typically a thousand. Now, there are some others out there that are trying to extend this amount by three times this. In this case, just keep an eye on your splice losses to determine when to change the electrodes. As the splice loss estimates get higher, your machine is closer to needing the electrodes to be changed. Another key part of splicing that needs to be maintained is your precision cleaver. A cleaver is the tool that you will use to score and cut the fiber so it can make a good splice. A cleaver has a wheel that rotates – this is known as the blade. This blade wears down and also needs to be managed with a certain number of good cleaves per position on the blade. Without good maintenance of your electrodes and cleaver your equipment can shut down a job or cause problems with your splicer.
Different Methods of Splicing
When splicing, there are a couple of different reasons why you do optical fiber splicing. In the end, it is all the same concept but there are different reasons to splice. The first one is to extend a fiber cable. This is where you will splice two different lengths together. This happens when a break occurs and you will use some of the excess fiber cable originally pulled to put your link back together. This can also be in a new deployment when you need to go a greater distance over what is the max length of fiber optic cabling that can be placed on a spool. When doing the long haul applications the core alignment splicer is the recommended machine.
The next two are the same concept just a different approach. This concept is to terminate the ends of your fiber. The first one is splicing on pigtails. Pigtails are a piece of fiber that is blunt on one side and has a factory polished connector on the other end. So you are splicing fiber to fiber and putting a splice protection sleeve (a heat shrinkable tube that contains a ceramic or stainless steel strength member) on to protect the splice. These will typically require a splice tray to put your splices in to protect them. The other concept is a splice on connector. This is also a pigtail but it is a lot shorter and uses a holder that is placed in the splicer. This allows your splice protection sleeve to be covered by the connector boot and does not require any splice trays.
So remember, always arc check using single mode fiber before beginning any splicing session, whether you are splicing single mode fiber or multimode fiber that day. Maintain your fusion splicer and your precision cleaver on a regular basis and your jobs will go much smoother. A fusion splicing machine can be a tech’s best friend, or his worst nightmare!

What Fiber Optic Connectors Are Used for Non Standard Fiber Sizes?

The question I seem to be asked over and over is “What fiber optic connectors are used when I have non-standard size multimode and singlemode fiber”? The frequency of this question led me to write this blog. It can be very frustrating when installers and technicians are faced with this situation, the proper fiber has been identified, but what good is it to me if I cannot install connectors. Fortunately, there are answers and I hope to relieve some of the angst that you may have.
Most telecommunications projects utilize standard equipment and fibers that are readily available, but what happens when this is not the case? The standard LC, SC, ST and FC style optical fiber connectors with ferrule holes at or around 126um will suffice 99% of the time but, nonstandard applications such as medical, automotive, high power and others utilize specialty fibers where the standards will not work.
Non-Standard (Specialty, Large Core) Fiber
As most of us know, standard singlemode optical cable is made with a 9um optical glass core and a 125um cladding (9/125) with multimode standards being 50/125 and the old North American standard of 62.5/125. Many non telecommunication optical applications utilize non-standard fibers. Following is a list of just a few of these fibers:
100/140 – This fiber is identifiable by its green jacket color and has a typical attenuation of about 4 dB/km.
200/230 – 200/230 will typically have a blue jacket and has a standard attenuation of 6dB/km. You may notice that as the fiber cores increase in size, so does the standard attenuation.
960/1000 – This fiber is actually manufactured using plastic instead of the glass we usually find in fiber. Commonly black jacketed, this fiber is popular for optical audio cables; its 300 dB/km attenuation relegates it to short distance transmissions.
Large core fibers are also available: 300/330, 400/440, 500/550/ 600/660, 800/880 and many others too numerous to mention.
Precision-Drilled Connectors
Specialty fibers will not accept the standard 126um fiber connectors, so the technician must search out alternative solutions. Let’s first address the components that make up a fiber connector:
The Fiber Connector:
Strain Relief Boot
The strain relief boot allows the fiber exiting the connector to maintain its bend radius. A connector without a boot would kink the fiber causing attenuation (loss) or possibly a break in the fiber itself. It is important that the boot not be glued into place, gluing the boot will hinder the spring inside the connector, so the boot should be slip fit onto the connector body.
Connector Body
The body of the connector holds the ferrule in place and allows the connector to be crimped to the fiber and body via the use of a crimp sleeve. Connectors that only crimp to the fiber and not the body (like an ST) will allow the ferrule to piston when force is applied to the fiber, this is why LC, SC and FC connectors are dual crimp and have the advantage of non-optical disconnection.
The Ferrule
The most important component of any connector is the Ferrule. In the past, ferrules were made from stainless steel but due to performance issues most of today’s ferrules are made from ceramic (Zirconia). The ferrule’s primary function is to hold the fiber precisely to allow for the transmission of optical signal. Most standard ferrules have a hole size of 126um.
When specialty/uncommon (large core) fibers are used, many times ferrules with the larger hole sizes are not available. When larger size holes are needed, the ferrule must be drilled to accommodate these sizes.
When drilling a ceramic connector ferrule, issues occur that effect the hole tolerance and concentricity. During the drilling process, the ceramic material will chip and flake making the ferrule unusable. Because of these issues, the only ferrule type that can be consistently drilled is stainless alloy.
When drilling stainless alloy ferrules, sizes range typically from 250um to as large as 1550um, these sizes step in 10um increments (example 310um, 320um, 330um etc). When manufacturing these drilled ferrules, specifications for hole tolerance, concentricity, length and diameter are all measured and have pass/fail criteria. Some companies offer two options for their drilled ferrules, standard and premium. A standard drilled optical connector has a hole tolerance specification of -10µm/+50µm and a concentricity value of +/- 50µm. Premium drilled connectors will have tighter tolerances; so if higher performance (low attenuation) is required the premium product is the answer. Premium drilled optical ferrules have a hole tolerance specification of -4 µm/+10 µm and a concentricity value of +/- 25 µm. The premium ferrule will allow for better light transmission, which makes this the most popular of all drilled connectors.
Understand that the ferrule cannot be drilled while inserted inside of the connector body. All ferrules are drilled before the connecter is manufactured. Once the ferrule is drilled and passes all specifications then it is installed into the finished connector. Many times (like in medical devices) the ferrule is the only thing that is installed onto the fiber, leaving the body and strain relief boot out.
It is important to also note that the older SMA905 and SMA906 connectors can be drilled and are commonly used in military, medical, aerospace and research facilities where higher power lasers and heat dissipation are required. The SMA connector uses a larger 3mm ferrule, compared to the typical 2.5mm for SC, FC and ST and the 1.25mm ferrules used for LC connectors.
Installation of the optical connector
Once you have identified the correct connector style (ST, FC, SC, LC) and hole drill size the next question is “How to install these connectors?” When considering standard fiber optic connectors (dozens of manufacturers) it really boils down to only three options on how to install the connector on the optical fiber. These options are:
Hand/Machine Polishing
All fiber optic connectors are manufactured using this epoxy/polish procedure. The move in the fiber industry over the last decade has been to shy away from this process. Labor, consumables, skill level and overall quality is deeming this process obsolete for field connector terminations. The thought process is to let the industry manufacturing professionals handle the task.
Mechanical Connectors
A mechanical connector is manufactured and machine polished by the connector manufacturer with a small piece of fiber inserted into the connector, this fiber is precision cleaved inside the back of the ferrule and the end is then machine polished. The field installer simply cleaves his fiber and inserts it into the back of the mechanical connector and clamps it into place. Using mechanical connectors drastically reduces labor, and the required skill level of the technician. These connectors are more expensive than epoxy style connectors but the savings in labor costs tend to outweigh the expense.
Mechanical Splice
Fusion Spliced Connector
Most people believe that fusion splicers are used to lengthen and repair fiber optic cables. While this is true, the most common use of a fusion splicer is to attach premade pigtails or the newer Splice on Connectors (SOC). Although the perception is that the investment in the fusion splicer makes this process expensive, the reality is that fusion splicing a connector is the least expensive, lowest labor, highest quality way to install a factory manufactured connector.
Now that we have identified the field installation processes for fiber connectors how do we apply this to large core/specialty/Non Standard drilled connectors? Reality is that there are really only two options you have. Fusion splicers cannot splice these specialty fibers and there are no mechanical connectors made today that can be used with these larger core fibers. This leaves us with field installing these connectors using the epoxy/hand polishing procedure or purchasing the cable with the connectors installed by a fiber optic manufacturer. The obvious choice is having your cables manufactured by a company that is a reputable fiber assembly house. These pre-terminated cables will be professionally manufactured and tested; your job is to simply install the cable.
Remember that when using specialty/large core fibers there are solutions to your connectorization needs and most of the time the answer is a precision drilled fiber optic connector.

How to Test Optical Splitter Loss With Optical Power Meter & Light Source

Before discussing the details of splitter loss testing, here is a fact that we should know about it. Attenuation of signal through an optical splitter is symmetrical which means it is identical in both directions. Whether an optical splitter is combining signal in the upstream direction or dividing signals in the downstream direction, it still introduces the same attenuation to an optical input signal. Thus, the principle of optical splitter loss testing is to follow the same directions for a double-ended loss test.
Now, we test the simplest 1×2 optical splitter as the picture shown below. First, attach a launch reference cable to the optical light source of the proper wavelength (some splitters are wavelength dependent), and then calibrate the output of the launch reference cable with the optical power meter to set the 0dB reference. Attach to the light source launch to the splitter and attach a receive launch reference cable to the output and the optical power meter, and then measure the loss. Similarly, to test the loss to the second port—move the receive launch cable to the other port and read the loss from the meter. For the other direction from all the output ports, we should reverse the direction of the test.
For other 1xN optical splitters, e.g. 1×32 splitter, this test method can also be used. Just set the light source up on the input and use the power meter and reference cable to test each output port in turn. But for upstream, we have to move the light source 32 times and record the results on the meter.
So, how about the 2X2 splitter? In this case, a lot of data are involved sometimes but it needs to be tested. We would need to test from one input port to the two outputs, then from the other input port to each of the two outputs. In the same way, we can test other 2xN splitters.
Warm Tips: What you are measuring is the loss of the splitter due to the split ratio, excess loss from the manufacturing process used to make the splitter and the input and output connectors. So the loss you measure is the loss you can expect when you plug the splitter into a cable plant. Once installed, the splitter simply becomes one source of loss in the cable plant and is tested as part of that cable plant loss for insertion loss testing.
Conclusion
Optical splitters used in PON architecture are a very important type of passive optical components. Loss testing, as a necessary testing item of optical splitters can be done by using an optical power meter and light source. This tutorial illustrated the details of using optical power meter and light source to test optical splitter loss. Related products such as high-quality PLC splitters and testing tools such as optical power meter, light source and test cord are available in fiber-mart.COM with very affordable prices. For more details, please contact us over sales@fiber-mart.com.

How to determine the quality of a PLC splitter?

by http://www.fiber-mart.com

There are five main specifications that are outlined in this standard. The following section outlines each of the specification and their importance for a fully functional optical splitter.
1. Optical Bandpass
For a fiber optic network, there are six nominal optical bandpass ranges.
A PON system has a downstream transmission (data sent from a server to a user) using the 1490nm wavelength while the upstream transmission (data sent from a user to a server) is a 1310nm wavelength. In addition, there needs to be consideration for any requirement for RF video overlay and network testing/maintenance. RF video overlay is generally transmitted through the 1550nm wavelength.
According to the ITU L.41 recommendation, the 1550nm or 1625nm wavelength is used for network for testing and surveillance. With these considerations, the required optical band needs to be determined.
The standard operating wavelength for a PON splitter is the 1260-1650nm which covers most of the optical bands.
The optical bandpass can be tested by connecting the optical splitter to an optical spectrum analyzer with a high powered light source having a central wavelength of the required bandpass. The attenuation across the required bandpass shall meet the splitter requirements.
2. Optical insertion loss
The optical splitter is the component with the largest attenuation in a PON system. The optical insertion loss is the loss of an optical signal resulting from the insertion of a component such as connector or splice in an optical fiber system. In order to conserve the power budget of a PON system, the insertion loss from the splitter needs to be minimized.
Based on the GR-1209 standard, the maximum allowable insertion loss for an optical splitter used in a PON system can be determined by using the calculations outlined in the below table.
1×N Optical Splitter 0.8 + 3.4 log2N
2×N Optical Splitter 1.0 + 3.4 log2N
Note: ‘N’ denotes the number of output ports.
The insertion loss is tested by using a light source and power meter(or) by using an insertion loss meter.The reference power level is obtained and each of the output port of the optical splitter is measured.
3. Optical return loss
The return loss is the loss of power in the light signal returned or reflected by a discontinuity in an optical fiber or transmission line. A high return loss reduces the power reflected back to the transmitting port thus minimizing noise which may result in a system power penalty.
The return loss is tested by using a return loss meter. The input port of the splitter is connected to the return loss meter and all the output ports are connected to a non-reflective index matching gel.
4. Uniformity
Uniformity is the maximum insertion loss value between one input port and any two output ports or between two input ports and one output port. This requirement ensures that for a PON system, the transmission power at each splitter output port is the same, thus simplifying the network design.
Custom optical splitters with non-uniform coupling ratio can be manufactured for specific network deployment. In such a situation, this criteria is not applicable. The usage of a non-uniform splitter in a PON system increases the complexity in testing, design and maintenance while reducing the network flexibility.
The uniformity of the splitter can be determined by referring to the results from the insertion loss test to ensure that the difference between the highest loss and the lowest loss is within the acceptable uniformity value (≤0.5 dB).
5. Directivity
Directivity is the fraction of power transferred from one input port to another input port or from an output port to another output port. For a 2×N optical splitter, when light is injected into one of the input ports, light does not only propagate out of the output ports. Some of the light propagates back through the second input port. Similarly, when light is injected into one of the output ports, some of the light propagates back through the other output ports.
In a bidirectional transmission system such as a PON, directivity is important to reduce the power back to the transmitting port to reduce signal cross talk. In addition, a high directivity value will also cause a higher insertion loss due to the loss in optical power. So it is important to reduce the directivity as much as possible.
Directivity can be measured in a manner similar to the insertion loss test. However, the light source and power meter are connected to each of the input ports of two output ports.

What is the OADM Multiplexer?

The OADM, optical add drop multiplexer, is a gateway into and out of a single mode fiber. In practice, most signals pass through the device, but some would be “dropped” by splitting them from the line. Signals originating at that point can be “added” into the line and directed to another destination. An OADM may be considered to be a specific type of optical cross-connect, widely used in wavelength division multiplexing systems for multiplexing and routing fiber optic signals. They selectively add and drop individual or sets of wavelength channels from a dense wavelength division multiplexing (DWDM) multi-channel stream. OADMs are used to cost effectively access part of the bandwidth in the optical domain being passed through the in-line amplifiers with the minimum amount of electronics.
OADMs have passive and active modes depending on the wavelength. In passive OADM, the add and drop wavelengths are fixed beforehand while in dynamic mode, OADM can be set to any wavelength after installation. Passive OADM uses WDM filter, fiber gratings, and planar waveguides in networks with WDM systems. Dynamic OADM can select any wavelength by provisioning on demand without changing its physical configuration. It is also less expensive and more flexible than passive OADM. Dynamic OADM is separated into two generations.
A typical OADM consists of three stages: an optical demultiplexer, an optical multiplexer, and between them a method of reconfiguring the paths between the optical demultiplexer, the optical multiplexer and a set of ports for adding and dropping signals. The optical demultiplexer separates wavelengths in an input fiber onto ports. The reconfiguration can be achieved by a cross connection panel or by optical switches which direct the wavelengths to the optical multiplexer or to drop ports. The optical multiplexer multiplexes the wavelength channels that are to continue on from demultipexer ports with those from the add ports, onto a single output fiber.
Physically, there are several ways to realize an OADM. There are a variety of demultiplexer and multiplexer technologies including thin film filters, fiber Bragg gratings with optical circulators, free space grating devices and integrated planar arrayed waveguide gratings. The switching or reconfiguration functions range from the manual fiber patch panel to a variety of switching technologies including microelectromechanical systems (MEMS), liquid crystal and thermo-optic switches in planar waveguide circuits.
CWDM and DWDM OADM provide data access for intermediate network devices along a shared optical media network path. Regardless of the network topology, OADM access points allow design flexibility to communicate to locations along the fiber path. CWDM OADM provides the ability to add or drop a single wavelength or multi-wavelengths from a fully multiplexed optical signal. This permits intermediate locations between remote sites to access the common, point-to-point fiber message linking them. Wavelengths not dropped, pass-through the OADM and keep on in the direction of the remote site. Additional selected wavelengths can be added or dropped by successive OADMS as needed.

Advantages and Disadvantages of FBT Splitter and PLC Splitter

Fiber optical splitter is also known as “non-wavelength selective optical branching device”. It is a fiber optic device used to achieve a particular band optical signal power splitter and redistribution.
Optical splitter can be used as a stand-alone device in the OLT node, the light distribution point and the FTTH point. It can also be placed in the central office wiring facilities, the light distribution points and FTTH points within the facility (integrated design or plug-in).
In accordance with the production process, optical splitters are divided into Fused Bi-conical Taper (FBT Splitter) and Planar Lightwave Circuit (PLC Splitter).
FBT Splitter (FBT Coupler)
Fused Bi-conical Taper technique is tied to two or more fibers, and then melted in a cone machine, pull tensile and real-time monitoring of changes in splitting ratio, the splitting ratio to meet the requirements after the end of the melt stretching, and wherein one end of a fiber optic reserved ( The remaining cut off) as the input terminal and the other end a multitude of road outputs. Mature tapering process can only pull 1 × 4. 1 × 4 or more devices, with a plurality of 1 × 2 connected together. Then the overall package in the splitter box.
Advantages
(1) pull taper coupler over twenty years of history and experience, many equipment and processes simply follow the only development funds only a few of the PLC tenth or hundredth of a few
(2) Raw materials only readily available quartz substrate, fiber optics, heat shrink tubing, stainless steel pipe and less plastic, a total of not more than $ 1. Investment in machinery and equipment depreciation costs less, 1 × 2,1 × 4 and other low-channel splitter low cost.
(3) splitting ratio can be real-time monitoring, you can create unequal splitter.
Disadvantages
(1) Loss of light sensitive wavelength ships according to the wavelength selection device, in this triple-play during use is a fatal defect, since the triple play of light transmitted signal 1310nm, 1490nm, 1550nm, and other multiple-wavelength signal.
(2) poor uniformity, 1×4 nominal about 1.5dB away, 1 × 8 or more away from larger, can not ensure uniform spectroscopic, which may affect the overall transmission distance.
(3) Insertion loss varies with temperature variation is greater (TDL)
(4) multi-demultiplexer (e.g., 1 × 16,1 × 32) volume is relatively large, the reliability will be reduced, the installation space is restricted.
PLC Splitter
Planar waveguide technology is the optical waveguide branching device with a semiconductor production process. The branching function is completed on the chip. On one chip to achieve up to 1X32 splitter, then, at both ends of the chip package input terminal and an output terminal respectively coupled multi-
Channel optical fiber array.
Advantages
(1) The loss of transmission is not sensitive to the wavelength of light, to meet the transmission needs of different wavelengths.
(2) spectroscopic uniform signal can be uniformly allocated to the user.
(3) compact structure, small size, can be installed directly in the existing junction box, no special design leave a lot of space for installation.
(4) only a single device shunt channel can achieve much more than 32 channels. (5) The multi-channel, low cost, stars ones more and more obvious cost advantages.
Disadvantages
(1) Device complex production process, high technical threshold, the chip is several foreign companies to monopolize domestic bulk package production companies only Borch rarely several.
(2) relative to the higher cost of Fused Splitter more at a disadvantage, especially in the low channel splitter.