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.

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.

Optical attenuators are used to reduce the power level of optical signal, either in free space or in an optical fiber. They are often used in optical communication systems where the optical signal is too strong and needs to be reduced, in which the attenuation, also called transmission loss, helps with the long-distance transmission of digital signals.

Optical attenuators can take a number of different forms and are typically classified as fixed or fiber optic variable attenuator. Fixed attenuators can be broken down into either build out style or incorporated into a patch cord. The build out variety is a small (~ 1.25 inch long) attenuator with a male connector interface on one end and a female interface connector on the opposite end. The build out style is typically fabricated with either air gap attenuation or doped fiber attenuation.

Fiber optic attenuators can be designed to use with various types of fiber optic connectors. Commonly used fiber optic attenuators are the female to male type, which is also called a plug fiber attenuator. Another type inline fiber optic attenuator is designed with a piece of fiber optic cable at any length and connectors are installed as the customers request. Fixed value fiber optic attenuators can reduce the optical light power at a fixed level, for example, a 10dB SC fiber optic attenuator will reduce the optical power 10dB and utilize a SC male to female attenuator. Variable fiber optic attenuators are with adjustable attenuation range. There are also attenuation fiber optic patch cables available, their function is the same as attenuators and are used inline.

Variable Attenuator (or ajustable fiber optic attenuator) is a need to provide different under construction decline. The reduction of precision devices for a wide variety of fiber optic transmission lines to carry out scheduled, the amount of light intensity attenuation. There are also handheld variable fiber optic attenuators which are used as test equipment.

Typical attenuation values are between 3 and 20 dB. It is used in optical systems where the optical power from a source is too high for the test equipment in use. Fixed plug type fiber attenuator provides a connector plug (male) and an adapter socket (female) to connect between fiber patch cord and fiber adapter. Fixed plug type optical attenuator introduces an in-line fixed loss that will reduce the source power to an acceptable detection level. The attenuation level should be stable with temperature and wavelength for a stable reliable system.

An optical attenuator uses a segment of attenuating fiber interposed in the optical path. The attenuating fiber is produced by using a solution doping technique to introduce transition or rare earth elements into the fiber’s core. The dopant reduces the transmission of the fiber. The degree of attenuation depends upon the material used as the dopant, the dopant level, and the length of the attenuation segment. In a specific embodiment, an optical attenuator is provided having a first and second signal carrying optical fibers and an attenuating fiber segment, each of which has a core, a cladding substantially coaxial with the core, and a substantially planar end face. The attenuating fiber segment is fusion spliced between the first and second signal carrying optical fibers. In a second embodiment a portion of the cladding of the attenuating fiber is chemically etched.

Wide range variable & inline fiber optic attenuator and the inline fiber optic attenuator are with more accurate attenuation compared with traditional connector type fiber optic attenuators. Variable optical attenuators from FiberStore are specifically designed for use in DWDM networks with individual channel source elements such as add drop multiplexer.

Unlike electrical wires, optical fibers require end-surface treatment for proper light propagation. The two most common ways of surface preparations are cleaving and polishing. While fiber cleavage is very effective on fibers with small diameters such as 125 microns, polishing is essential for almost all glass-based fibers with cladding deameters larger than 200 microns. Furthermore, all fiber connector require polishing.

When it is time to purchase a mechanical polishing machine there are a number of questions that should be asked:

1. Are the operating functions simple to use?
2. Does the unit offer easy connector interchangeability?
3. Are the polishing platens easy to access?
4. Is there a pressure-setting feature?
5. Does the polishing motion attack the connectors from all sides equally?
6. Can the machine perform angle polishes?
7. Does the manufacturer have the capability to supply custom fixturing if needed?
8. Are the end results meeting and/ or exceeding current end-face standards?

A quality production polisher will answer "yes" to all of these questions.

In detail, a fiber optic polisher will have:

1. Timer - a settable timer allows a pre-defined timed sequence of operations techniques to be used. Timing has proven to be critical in obtaining connector performance specifications. A timer should have time settings ranging from 0 to 60 seconds.

2. Pressure setting device - a polishing machine must have adjustable pressure loading capability. Pressure combined with the hardness of the polishing surface will allow the machine to produce the connectors' required end-face geometry. This device should have a setting tool that has clearly marked divisions of measurement.

3. Inter - changeability of connector holders - connector holders that can be removed quickly and easily offer increased output, less downtime and improved production. A machine that offers connector holders for all connector types adds flexibility to production.

4. Availability of the connector holders - In evaluating the equipment, it is important to consider the available connector holders. It is important that the manufacturer has available holders for the standard connectors used around the world - SC, FC, ST - for both PC and APC configurations.

Also, the manufacturer should have the capability to provide a range of connector holders beyond the "standard" used - versatility in this area will minimize lost opportunities and maximize the ability to meet potential customer requests.

5. Removable Polishing Platens - polishing platens carry the polishing films that act upon the connector end-face. These should be easily removed and replaced. This minimizes contamination,increases connector output and maximizes polishing film life.

6. Polishing Motion - A key element of a high quality polishing system is the motion of the surface that performs the polishing. If the polishing action is not balanced evenly from all sides, connector performance will suffer and costs will increase because of rejected material and excessively rapid wear of the polishing films. To obtain consistent high quality results, the machine must provide an orbital polishing motion - a circular oscillation.

7. Can the Machine perform Angle Polishes - Though new polishing techniques, such as MPC (Maximum Physical Contact), allow PC finished connectors to achieve APC (Angled Physical Contact) results, the need to perform angle polishing is a must. Angle polishing (typically polished to 8 degree) is necessary when Backrelection readings of <-65dB are demanded.

A polisher should offer the option to polish connectors Flat, with a PC finish, or an APC finish. Different machines should not be purchased for different types of polishes. A quality polisher will have the capability to perform all types of polishing.

8. A "Recipe" for meeting the standards - Standards for today's connectors are stringent. It is important that the machine manufacturer provides, along with a good, preferably illustrated operation manual, specific polishing "recipes" for obtaining the connector specifications (described in the section below) - and, that you have open lines of communication with the manufacturer to keep you up to date in this developing technology.

Polished - end acceptance criteria for fiber optic connectors

Within the communications field, high standards are needed for Telephone transmission and even higher standards for CATV transmission - with the apparent movement to the higher standards being influenced by the logic of using telephone lines for CATV. Singlemode connectors are used to assure optimal results - and these optimal results are a function of the quality of the polished connector end - face surfaces - specifically, these are the measurable performance characteristics that are controlled in connector polishing. the characteristics that a polishing machine must provide are:

1. Backreflection
2. Insertion Loss
3. Apex Offset
4. Radius of Curvature
5. Fiber Undercut/ Protrusion
6. Connector End - face Inspection

Polishing Techniques

Critical to proper polishing is the applied process - the technique - that result in meeting the various specifications.

The following is a list of polishing techniques for singlemode & multimode polishing.

Fiber polishing is as much a science as it is 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. Therefore, the buyer of a polisher is really buying both the hardware and the know-how of the polisher company. So do not just select the right machine, select the right company.

It is important to understand the different varieties of core characteristics that are available within the fiber optic cabling itself, as each of these different characteristics will have different effects on your ability to transmit information reliably. Have a look at the most common fiber optics cores used in the industry nowadays.

Simplex Fiber Optic Cable

Simplex means this cable is with only one thread of fiber optic glass inside the single core. And simplex cables are with one single outer jacket. Simplex fiber optic cable is used in applications that only require one-way data transfer. For instance, an interstate trucking scale that sends the weight of the truck to a monitoring station or an oil line monitor that sends data about oil flow to a central location. There are singlemode and Simplex Fiber Cable available. Single-mode simplex fiber optic cable is a great option for anyone setting up a cable network that will require data to travel in one direction over long distances. Since this type of cable only carries one ray of light at a time, it’s better for long-distance transmissions. Single-mode fiber itself has a high-carrying capacity, is very reliable, and has lower power consumption than other options.

Analog to digital data readouts, interstate highway sensor relays, and automated speed and boundary sensors (for sports applications) are all great uses of Simplex fiber optic cable. This form of fiber cable can be cheaper than Duplex cables, because less material is involved. Simplex cable is compatible with any HDMI extender.

Duplex Fiber Optic Cables

Duplex fiber cable can be regarded as two simplex cables, either single mode or multimode, having their jackets conjoined by a strip of jacket material, usually in a zipcord (side-by-side) style. Use duplex multimode or singlemode fiber optic cable for applications that require simultaneous, bi-directional data transfer(One fiber transmits data one direction; the other fiber transmits data in the opposite direction). Duplex fiber is available in singlemode and multimode.

Duplex Fiber Optic Cable and Singlemode duplex cable alike are used for two-way data transfers. Larger workstations, switches, servers, and major networking hardware tends to require duplex fiber optic cable. Duplex cables can be more expensive than Simplex cables, and are compatible with any HDMI extender.

Simplex and duplex are with various cable structure types; they are different from single mode and multi mode which are related to fiber optic glass types.

Multi Fiber Cables

Both multi fiber cables and simplex cables are with a single outer jacket, but simplex only has one thread fiber glass inside the core, while multi fiber has many threads of fiber optic glass inside the core. For example, an 8-core multi fiber cable. There are ribbon type and bundle type multi fiber cables.

Single-mode fiber cables and multi-mode fiber cables are similar in many ways, with the main difference being that the glass center of single-mode cables is significantly smaller, at about 10 microns in diameter. The smaller size is what allows these cables to transmit data up to 40 miles with a bandwidth of 1Gbs.

Only need a simplex fiber cable if data will be traveling in one direction, such as with a security camera or truck weigh station. And if your data will be traveling a long distance – for instance between buildings or from one station to another – then you’re better off with a single-mode fiber cable.

SFP modules(Small form factor pluggable) is prefered to  easier to change and easier for maintenance rather than traditional modules and is expected to perform at data speeds of up to five gigabits per second (5 Gbps), and possibly higher.

SFP interfaces between communication devices like switches, routers and fiber optic cables, and performs conversions between optical and electrical signals. SFP transceivers support communications standards including synchronous optical networking (SONET)/synchronous digital hierarchy (SDH), gigabit ethernet and fiber channel. They also allow the transport of fast Ethernet and gigabit Ethernet LAN packets over time-division-multiplexing-based WANs, as well as the transmission of E1/T1 streams over packet-switched networks.

SFP Transceivers have a wide range of detachable interfaces to multimode/single-mode fiber optics, which allows users to select the appropriate transceiver according to the required optical range for the network. Signal transmitting rate of SFP modules range from 100Mbps up to 4Gbps or more, working distance of these SFP transceiver modules can be from 500 meters to 100 kilo meters, working wavelength of different SFP modules are typically 850nm, 1310nm and 1550nm, there are also CWDM type SFP transceivers available. There are SFP product numbers below:

Cisco GLC-ZX-SM SFP, SFP-GE-F, SFP-GE-S, SFP-GE-L, SFP-GE-Z, GLC-SX-MM, GLC-LH-SM, GLC-T, CWDM-SFP-1470, CWDM-SFP-1490, CWDM-SFP-1510, CWDM-SFP-1530, CWDM-SFP-1550, CWDM-SFP-1570, CWDM-SFP-1590, CWDM-SFP-1610.

GLC LH SM is the Cisco 1000Base LX/LH SFP transceiver module, it is one of the most commonly use SFP. SFP units like the GLC-LH-SM in general have different transmitter and receiver types that allow the consumer to select the best option for their specific situation. Its primary function is to interface with a networking cable and increase the connectivity between two network devices such as mother boards, routers and media converters.

There are many options when it comes to finding a GLC-LH-SM. The GLC-LH-SM SFP Transceiver from the reseller is a Cisco brand mini-GBIC but can be used to work with anyone that builds SFP ports such as HP, Finistar, and Juniper among many others. Finding a compatible transceiver can eat up valuable time for IT pros who are upgrading networks and T3 systems provides the best value and support.

Cisco GLC-LH-SM SFP transceiver is a tool utilized to join Cisco machines like wan interfaces or network switches that make use of sfp transceiver module technological expertise. It is characterized by an LC type interface with a higher density as well as a smaller fiber optic connecter. It is suitable for both single and multimode use and has a working distance of 10 kilometers or 550 meters over MMF. It is compliant to IEEE standards in line with Gigabit Ethernet and comes in a variety of styles to ensure users have the exact choice for their needs.

The GLC-LH-SM is a SFP fiber optic transceiver works at a 1300nm wavelength. When utilized as GLC-SX-MM SFP, the unit has a tier-one laser of 1,300nm for medium range fiber applications. In MMF configuration, the maximum distance is 1,800 ft and on SMF the max distance is 10 Km (6.2 miles).