Fiber Optic Blog

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 optic polisher 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 fusion splicer, among other network crimping tool 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.

Conclusion

Fiber polishing is a science but much like an art. The science of polishing is crystallized in a well designed machine while the art of polishing reside in the procedure and the continuous effort for improvement by the individual user. The procedure and the training are just as valuable as the polishing machine.

In previous articles, we have mentioned of the connector cleaning. And we know any contamination in the fiber connection can cause failure of the component or failure of the whole system. Fiber optic connector is an important component in fiber connection. And today, I want to introduce the fiber optic polishing in this article. As we know, fiber optic cables require end-surface treatment for proper light transmission. Polishing is an essential step for almost all glass-based fibers with cladding and diameters larger than 200 microns and all fiber optic connectors also need polishing. So, why do we need fiber optic connector polishing and what types are there of fiber optic connector polishing? We will describe in the following.

Why We Need Fiber Optic Connector Polishing?

It is known that, once the fiber optic cable is terminated with a particular connector, the connector end-face preparation will determine what the connector return loss(we generally call back reflection) will be. The back reflection is the ratio between the light propagation through the connector in the forward direction and the light reflected back into the light source by the connector surface.

It is very important to minimize the back reflection in high-speed and analog fiber optic links, utilizing narrow linewidth sources such as DFB lasers, which are prone to mode hopping and fluctuations in their output. Polishing is one of the essential procedure to make fiber optic connector work perfect. That’s why we need fiber optic connector polishing.

Fiber Connector Polishing Ways

There are several different polish options on the fiber connectors. Due to the extreme accuracy requirement of today’s fiber connections, polishing is mostly done by a machine, especially for the production. But there are also some of non-production types of terminations still done by hand.

The common machine polishing tools, such as fiber optic polishing machines and other fiber optic polishing machine kits including fiber polishing fixture for all types of fiber optic connectors. while the manual fiber optic connector polishing will need polishing paper and  fiber optic polishing puck or some cleanser. Some of the fiber optic polishing tools look as the following picture.

1. Flat Polished(Flat)

A flat polished connector has zero dome-shaped geometry.

flat-polish

2. Physical Contact(PC)

PC connector is polished in a dome-shaped geometry to maximize the signal transmitted at the connection.

Physical contact

3. Ultra Physical Contact (UPC)

The ultra physical contact describes connectors that undergo extended polishing to render the fiber end-face more suitable for optical contact with another fiber than an ordinary PC connector.

ultra physical contact

4. Angled Physical Contact (APC)

Angled physical contact connector is polished on an 8° angle. When compared with a normal “physical contact” (PC) connector, an APC connector exhibits better reflected properties, because the angled polish reduces the amount of light reflected at the connector interface. Connector types available with an angled polish include SC, ST, FC, LC, MU, MT, and MTP.

angled physical contact

Conclusion

Fiber polishing is as much a science as it is an art. To a certain extent, proper polishing of fiber optic polishing is critical for optimum results. However, it also depends on your polishing machine or your own technique. So do not just working like horse, select the right machine or the right company for your fiber optic connector and polishing tool.

Fusion splicer is a device using an electric arc to melt two optical fibers together at their end faces and form a single long fiber. The resulting joint, or fusion splice, permanently joins the two glass fibers end to end, so that optical light signals can pass from one fiber into the other with very little loss. There are numerous well-known brands of fusion splicer such as Fujikura, CLETOP, EXFO, Noyes, AFL ect. The most famous brand of these is Fujikura. This text mainly introduces Fujikura fusion splicer.

Fujikura Ltd. is a global, Tokyo-based electrical equipment manufacturing company. It develops and manufactures power and telecommunication systems products, including devices for optical fibres, like cutters and splicers. As the leading splicer brand in the world, Fujikura achieves and maintains the leading splicer brand in the world by providing quality products, extensive knowledge to telecommunication, photonics research and manufacturing application.

Fujikura fusion splicer is one of the most widely used device in the world, and known for its performance, productivity and reliability. Fujikura fusion splicer keeps good condition as master’s tool to maintain good quality. And all Fujikura’s fusion splicers are backed by Fujikura’s Technical Support team. Fujikura has over 80 of authorized distributors all over the world. They stand by you and give the best and the quickest support, not only after service, but also before. You can depend on them for a solution to your every problem.

According to different splicing applications, Fujikura fusion splicer can be classified into three types: core alignment splicer, ribbon fiber fusion splicer and special fiber fusion splicer. Core alignment splicer is mostly used in practice, which includes 70S, 19S. Ribbon fiber fusion splicer is an essential tool to work effcient, which includes 70R, 19R and 12R. Special fiber fusion splicer includes fiber-martM-100 series, specialty accessories and recoater.

Fujikura has developed a comprehensive range of fusion splicer products to satisfy for every application. Although Fujikura constantly keep improving and innovating, it has invented the fiber-martM-80S Alignment Fusion Splicer succeeding to Fujikura FMS 60s fusion splicer. The main features of Fujikura fiber-martM-80S  in comparison with the fiber-martM-60S as following:

New Li-Ion battery now allows you to make up to 200 splicing cycles-shrinking

High speed welding of fiber (7c for single-mode fiber)

High speed shrink (14c CRSS 60mm)

Increased lifetime of electrodes – up to 3000 splices

Splicing with a length of just 5mm cleavage for use with any welded connectors or for micro-CRSS (20mm, 30mm)

Review System without mirrors

Automatic closing windproof lid when downloading and opening the fiber at the end of the welding

It is obvious that fiber-martM-80S has plenty of advantages over older ones in many aspects. Today, fiber-martM-80S splicer is the new standard model to cover  varied splicing needs in those fields. Also, it is just one of the  typical device of Fujikura fusion splicer.

FTTH (fiber to the home) networks are installed in many areas covering indoor section, outdoor section, as well as the transition in between. To fulfill the cabling requirements from different areas, different types of fiber optic cable are well developed. Drop cable as an important part of FTTH network forms the final external link between the subscriber and the feeder cable. This blog post will focus on this special outdoor fiber optic cable.

The Basic of FTTH Drop Cable

Drop cables, as previously mentioned, are located on the subscriber end to connect the terminal of a distribution cable to a subscriber’s premises. They are typicality small diameter, low fiber count cables with limited unsupported span lengths, which can be installed aerially, underground or buried. As it is used in outdoor, drop cable shall have a minimum pull strength of 1335 Newtons according to the industry standard. Drop cables are available in many different types. The following part introduces three most commonly used drop cables divided according to the cable structure.

Flat Type Drop Cable, also known as flat drop cable, with a flat out-looking, usually consists of a polyethylene jacket, several fibers and two dielectric strength members to give high crush resistance. Drop cable usually contains one or two fibers, however, drop cable with fiber counts up to 12 or more is also available now. The following picture shows the cross section of a flat drop cable with 2 fibers.

Figure-8 Aerial Drop Cable is self-supporting cable, with the cable fixed to a steel wire, designed for easy and economical aerial installation for outdoor applications. This type of drop cable is fixed to a steel wire as showed in the following picture. Typical fiber counts of figure-8 Drop Cable are 2 to 48. Tensile load is typically 6000 Newtons.

Round Drop Cable usually contains a single bend-insensitive fiber buffered and surrounded by dielectric strength members and an outer jacket, which can provide durability and reliability in the drop segment of the network. The following shows the cross section of a round drop cable with one tight buffered optical fiber.

Drop Cable Connectivity Method: Splice or Connector?

It’s necessary to choose a right architecture for FTTH network from overall. However, drop cable as the final connection from the fiber optic network to customer premises also plays an important role. Thus, finding a flexible, efficient and economical drop cable connectivity method becomes a crucial part of broadband service. Whether to use a fiber optic connector, which can be easily mated and un-mated by hand or a splice, which is a permanent joint? The following will offer the answer and the solutions for your applications.

It is known that splice, which eliminates the possibility of the connection point becoming damaged or dirty with a permanent joint, has better optical performance than fiber optic connector. However, splice lack of operational flexibility compared with fiber optic connector. Fiber optic connector can provide an access point for networking testing which cannot be provided by splicing. Both methods have their own pros and cons.

Generally, splice is recommended for drop cables in the places where no future fiber rearrangement is necessary, like a greenfield, new construction application where the service provider can easily install all of the drop cables. Fiber optic connector is appropriate for applications which flexibility is required, like ONTs which have a connector interface.

Choosing the Right Splice Method

For splice, there are two methods, one is fusion splicing, the other is mechanical splicing. Fusion splicers have been proved to provide a high quality splice with low insertion loss and reflection. However, the initial capital expenditures, maintenance costs and slow installation speed of fusion splicing hinder its status as the preferred solution in many cases. Mechanical splicing are widely used in FTTH drop cable installation in countries, as a mechanical splice can be finished in the field by hand using simple hand tools and cheap mechanical splicer (showed in the following picture) within 2 minutes. It’s a commonly used method in many places, like China, Japan and Korea. However, in US mechanical splicing is not popular.

Choosing the Right Connector

For fiber optic connector, there are two types connector for drop cable connection. Field terminated connector, which contains fuse-on connector and mechanical connector, and pre-terminated drop cable, which is factory terminated with connector on the end of drop cable.

Fuse-on connector uses the same technology as fusion splicing to provide the high optical connection performance. However, it requires expensive equipment and highly trained technician, and more time like fusion splicing. Mechanical connector could be a replacement of fuse-on connector (showed in the following picture), if the conditions do not fit the mentioned ones. It could be a time-save and cost-save solution for drop cable termination.

If you have no limits in cost and want high performance termination in a time-save way, pre-terminated drop cable could be your choice. Many factories can provide you customized drop cables in various fiber types, fiber optic connector and lengths.

Conclusion

Customer demand for higher bandwidth will continue to drive the development of FTTH as well as its key component like drop cable. Choosing the right drop cable and drop cable termination method is as important as choosing the right network architecture in FTTH.

Loopback

Loopback is a commonly used term in telecommunications. It refers to the process of transmitting electronic signals or digital data streams and returning to their sending point without any intentional processing or modification. Therefore, by comparing transmitting signals with the receiving signals, the loopback test is used to debug physical connection problems. But what a loopback test means for fiber optic network and how to make use of it will be the issues that we will explore in this post.

Why Need Fiber Loopback Test?

To conduct a fiber loopback test, the communication devices will be involved, like the transceivers and the switch. As you know, the transceiver is the basic component of fiber optic communication network equipment. We can take the transceiver as a case. Conventionally, a transceiver has a transmitting port and a receiving port, in that way, the loopback test can be applied to test the ports to diagnose whether the transceiver is working well and the configuration of the switch is right. For its unique working mode, the test is a convenient way to maintain transceivers. In the next part, we will deliver how to do the fiber loopback test on the transceiver.

How to Conduct Loopback Test?

In this part, we will introduce two types of tests to troubleshoot transceiver and switch port: single-port test and dual-port test.

Tools You Need to Prepare

To perform tests, things you need to prepare are listed below:

Transceivers (2pcs), such as 10G SFP+ SR transceiver.

Simplex fiber cable (1 pc).

Switch (1 pc), like Cisco switch.

Duplex fiber cable (1 pc).

Two loopback cables (optional), like LC or SC loopback cable. To know more about loopback cable, you can move to the article: What Is Loopback Cable And How to Use It?

1. Connect your transceiver with one simplex fiber cable or loopback cable, such as LC fiber cable or LC loopback cable. At this step, you can examine whether the port and transceiver parameters are normal.

2. Check the software version of the switch.

3. Review the interfaces status to confirm the working status of all ports on the switch.

4. Check the working status of the port you are connecting, such as the port 50 in the following figure.

5. Go over the DDM information to review whether the transceiver works in normal status.

1. Connect two transceivers with one duplex fiber cable or two loopback cables. At this step, you can examine whether the port and transceiver data rate are matching as well as the link is normal or not.

2. Check the interfaces status to confirm the working status of all ports on the switch.

3. Check the working status of the two ports you are connecting, such as the ports 50 and 52 in the following figure.

4. Go over the DDM information to review whether the transceiver works in normal status.

Summary

To troubleshoot the circuit connectivity as well as the transceiver and the switch port, loopback test is a cost-effective way. In this post, we have an overview of loopback and make a demonstration of how to conduct the loopback test on a switch to debug the transceiver and the switch port.

As a passive technology, CWDM allows for any protocol to be transported over fiber optic link at specific wavelengths. CWDM technology is a cost-effective and simple method to increase the capacities of fiber optic network, by using different wavelengths to carry different signals over a single optical fiber. The wide deployment of CWDM network is greatly driven by its affordable cost.

What Is Need for A 10G CWDM Network?

The deployment of a 10G CWDM network is relaying on the exiting fiber optic network. Adding some components on the existing network can largely increase its capacity for data transmission. Here will introduce the key component and an important step during 10G CWDM network deployment.

A Key Component—CWDM Mux/Demux

A key component should be deployed is CWDM Mux/Demux, which combines different wavelength signals from different optical fibers into a single optical fiber, or separates different wavelength signals coming from a single optical fiber to separate optical fibers. The Channel number of a CWDM Mux/Demux is an important factor to divide this device. Standards have identified 18 CWDM Channels. Most of the CWDM Mux/Demux are provided with Channel number range from 2 to 16. However, fiber-mart.COM provides a 18-Channel CWDM Mux/Demux which can increase capacity of CWDM network to the most. CWDM Mux/Demuxs also come into a variety of package form factors. The most commonly used are LGX design, rack design and pigtail design.

An Important Step—Connecting CWDM Mux/Demux With 10G Switch

Connecting CWDM Mux/Demux with a 10G switch, is the most important step to build a 10G CWDM network. In simple, to add more devices on the fiber optic network by CWDM technology is to connect the CWDM Mux/Demux with the 10G switches which are linked to the end users. To link CWDM Mux/Demux with the switches, fiber patch cable and 10G CWDM SFP+ transceiver are needed. 10G CWDM SFP+ transceiver should be installed on the switch SFP+ port (some switches use XFP port, then 10G CWDM XFP transceiver is required). Then a length of fiber patch cable should be used to link the transceiver and CWDM Mux/Demux.

How to Select to Right 10G CWDM SFP+ Transceivers?

Choose the Right Working Wavelength: To ensure the right connection, the specific wavelength port should be connected to the same wavelength CWDM SFP+ transceivers. For example, the port on the CWDM Mux/Demux marked with 1270 nm, should be connected to a CWDM SFP+ transceiver that working over wavelength of 1270 nm. As there are 18 different CWDM wavelengths, 10G CWDM SFP+ transceivers that are provided in the market also can 18 different versions for these wavelengths.

Choose the Compatible CWDM SFP+: It is common sense that the fiber optic transceiver should be compatible with the switch which it works on. For instance, if you are using a Cisco switch, the fiber optic transceivers that you used with this switch should be original Cisco transceivers or Cisco compatible transceivers which are provided by third party vendors. The latter is usually the choice of many companies, this is because third party transceivers are usually more cheap than the original brand transceivers. Fiber optic transceivers provided by third party vendor like fiber-mart.COM are all fully tested on original brand switch to ensure their compatibility and quality. What’s more, most of fiber-mart.COM fiber optic transceivers support same day shipping. Select the right SFP do not only cut your cost and time, but also provide high network performance.

Choose the Transmission Distance According to Your Needs: CWDM network is usually deployed for long distance transmission. Thus the 10G CWDM SFP+ transceiver that are provided in the market usually support transmission distance longer than 20 km, some can support link length up to 80 km or more. You can select the 10G CWDM SFP+ according to your requirements.