Monthly Archives: July 2011

Fiber Optic Connectors & Adapters

The most common connectors used in the fiber optic telecommunications industry consists of the LC, SC, ST, FC, MTRJ, and MU. The purpose of these connectors is to provide a reliable mechanical connection to couple and align the fiber cores so that the laser light can pass through to a network or device. Most optical fiber connectors are spring-loaded allowing the two endfaces to press together firmly resulting in a direct glass or plastic contact, depending on the type of fiber. It’s important to avoid air gaps or contamination. SC connectors are a popular connector used with multimode fiber. Includes a 2.5 mm ferrule, and a square shaped connector with a push-pull latching mechanism allowing it to be used in tighter spaces ST connectors are used with multimode fiber, and have a 2.5mm shaft and bayonet locking ring for twist-connect and disconnect of a 125 micron multi-mode fibre. It is similar in appearance to a BNC connector. The connector is keyed which prevents rotation of the ceramic ferrule. LC connectors are used in single and multimode applications. The LC connector is often found on small form-factor pluggable transceivers. FC connectors are the most widely used fiber optic connector in the telecommunications industry. Includes a floating ferrule and threaded body to provide good mechanical isolation in high-vibration environments. MT-RJ Connectors (Mechanical Transfer Registered Jack) uses a form factor and latch similar to the RJ-45 connectors. Two separate fibers are included in one unified connector. The smaller size allows twice the port density on a face plate than ST or SC connectors do. Fiber Optic Adapters are a mechanical device used to align and join two or more fibers with different connection types.

SC connectors

SC connectors use a round 2.5mm ferrule to hold a single fiber. They use a push-on/pull-off mating mechanism which is generally easier to use than the twist-style ST connector when in tight spaces. The push-pull design also reduces the chance of fiber endface damage when connection is made. Two SC connectors are usually held together with a plastic clip (this is referred to as a duplex connection). Developed in Japan by NTT (the Japanese telecommunications company), the SC connector is believed to be an abbreviation for Subscriber Connector, or possibly Standard Connector.

ST Connectors

  • Rugged metal bayonet coupling ring
  • Keyed for repeatable performance
  • Precision ceramic ferrule and metal ferrules.
  • Low insertion loss: <0.5 dB Max, < 0.3 dB Typical
  • Connector mating using bulkhead feed-through adapters

The ST connector was one of the first connector types widely implemented in fiber optic networking applications. Originally developed by AT&T, it stands for Straight Tip connector. ST connections use a 2.5mm ferrule with a round plastic or metal body. The connector stays in place with a “twist-on/twist-off” bayonet-style mechanism. The single index tab must be properly aligned with a slot on the mating receptacle before insertion; then the bayonet interlock can be engaged, by pushing and twisting, locking at the end of travel which maintains spring-loaded engagement force on the core optical junction. Although extremely popular for many years, the ST connector is slowly being supplanted by smaller, denser connections in many installations.

LC Simplex/Duplex

  • Single mode 6/125, 9/125 and Multimode 50/125, 62.5/125
  • Pull-proof design
  • RJ-45 style latching mechanism
  • PC and APC end face geometries available
  • LC Duplex includes 2 connector bodies + duplex clip * Low insertion loss: -0.20 dB (Typical)
  • Low return loss (Single mode): min. -45 dB

One popular Small Form Factor (SFF) connector is the LC type. This interface was developed by Lucent Technologies (hence, Lucent Connector) and is replacing SC connectors in corporate networking environments due to their smaller size, uses approximately 50% less space in a panel. It uses a retaining tab mechanism, similar to a phone or RJ45 connector, and the connector body resembles the squarish shape of SC connector. LC connectors are normally held together in a duplex configuration with a plastic clip. The ferrule of an LC connector is 1.25mm.

FC Connectors

  • Threaded metal coupling ring – excellent stability
  • Available in PC and APC end face geometries
  • Pull proof design
  • Designed to the NTT-FC standards
  • Precision keyed ceramic ferrule; metal ferrules available
  • Low insertion loss: <0.5 dB max, < 0.34 dB typical
  • Connector mating using bulkhead feed-through adapters
  • Low cost

The Fixed Connection (FC) connector has a threaded body which was designed for use in high-vibration environments and needs to be mated more carefully than the push-pull types due to the need to align the key, and due to the risk of scratching the fiber endface while inserting the ferrule into the jack.

MT-RJ Connectors

  • Small 2 fiber design (conforms to SFF)
  • Multimode applications 50/125 um, 62.5/125 um
  • Single mode applications 6/125, 9/125 um
  • Reduces required space by 50% throughout the network
  • RJ-45 latching mechanism, small 2 fiber design
  • PC and APC end face geometries
  • Low insertion loss: -0.35 dB Typical Multi-Mode, -0.25 dB Typical Single mode
  • Low return loss (Single mode): > -35 dB

The MTRJ connector closely resembles an RJ-style modular plug, even getting part of its name from the resemblance. MTRJ connectors are always duplex in that they hold two fibers. MTRJ This is another popular SFF connector. Based on a specification by NTT, it was developed by AMP/Tyco and Corning, and stands for Mechanical Transfer-Registered Jack. The body and ferrule are normally made from plastic or plastic composite, and lock into place with a tab (just like a modular RJ-style plug). It is easier to terminate and install than ST or SC connectors.

Fiber Optic Adapters

SC-Simplex-Adapters Housing material: Plastic (UL 94V-0) Sleeve: Phosphor-Bronze; Ceramic Spring plate: Stainless steel Dust caps. SC-Duplex-Adapters Housing material: Plastic (UL 94V-0) Sleeve: Phosphor-Bronze; Ceramic Spring plate: Stainless steel Dust caps. ST-Simplex-Metal LC-Duplex-Adapters Housing material: Plastic (UL 94V-0) Sleeve: Ceramic, Phosphor-bronze Spring plate: Stainless steel Dust caps. Adapters Housing material: Zinc diecast Plating: Nickel Sleeve: Phosphor-Bronze; Ceramic Dust caps. FC-Simplex-Metal Adapters Housing material: Metal Plating: Nickel Dust caps Sleeve: Phosphor-Bronze; Ceramic.

Fusion Splicer Electrodes

Is it time to have the electrodes replaced in your fusion splicer? Electrodes need cleaning due to buildup of silica oxide and other contaminants. Cleaning fusion splicer electrodes can be done through the menu on the splicer. Electrode cleaning is part of the essential maintenance of your fusion splicer. As the electrodes wear from use, cleaning by using the splicer’s menu option will not be enough and they will need to be replaced. Higher splice loss is the result of worn electrodes. Fujikura®, FITEL®, Sumitomo®, Ilsintech®, Emitor®, Corning/Siecor®, and Ericsson® all specify differing lengths of time between replacing splicer electrodes. Refer to your user manual for when to replace them. Replacing electrodes is a normal, and important, part of your splicers’ maintenance. Always replace electrodes as a pair. For optimal performance, electrodes should also be aligned when they are replaced to maximize the performance of your splicer. Replacement fusion splicer electrodes from FiberTool™ last as long as the original equipment electrodes but for half the price. Each electrode is manufactured to exceed the specifications required for the Fiber Optic industry. Every fusion splicer electrode is 100% individually inspected to ensure that they adhere to our stringent tolerances. We also stock a full range of replacement Fibre Optic Cleaver Blades.

Choosing the Right Fusion Splicer

There comes a time in every telecommunications company’s life when new fusion splicers need to be purchased.  With hundreds of options to choose from, this task can become very difficult in choosing the right splicer for the job.  Currently there are over 20 different manufacturers of fusion splicers and more are popping up as I am writing this.  Here is some information on the most common types of fusion splicers which include single fiber splicers, ribbon splicers and the differences between them. Single fiber splicers usually splice 250 micron fiber, but can also hold 900 micron jacketed fiber, flat drop cable and splice on connectors also known as (SOC or splice-on-connectors) used mostly for FTTH applications as well.  One piece of fiber is stripped, cleaned, cleaved then inserted into the fiber holder.  Another fiber repeats the same process to lay in the opposite fiber holder.  Most newer models can splice in less than ten seconds and estimate attenuation (loss of light).  Of course this is only an estimation and the fiber should be tested more accurately with an OTDR.  There are also different types of single fiber splicers that are used. Core alignment simply means they look at the core and use it’s diameter to align the fiber up.  Fixed V-groove splicers use “V” shaped fiber holders and rely on the outside parameters to align the fiber.  Generally, core alignment splicers are more expensive but fiber is becoming so precise and consistent when manufactured that using v-groove splicers is becoming more economical while providing similar splice loss.   Also, there are polarization maintaining a.k.a. “P.M.” splicers.  They use rotating motors on the fiber holders to align the endfaces up by looking at their cleaved ends.  These machines are not as common in outside telecom uses. Ribbon splicers can splice 1 to 12 fibers all at once.  The fiber holders usually have twelve spots for fiber on the v-grooves, some may only have four such as the Fitel S121M.  These machines are not nearly as popular as the single fiber machines, but if used on cable where more than one fiber needs to be spliced they are extremely efficient.  When fiber counts of over 96 are needed, there can be up to a 65% savings on per splice costs.  Let’s say on average a single fiber splice costs $25 and a ribbon splice is $110 each.  At a location that needs 144 splices, the single fiber machine would run a cost of $3600.  A ribbon machine would only perform 12 splices at a total of $1320.  The savings would be $2,280 respectively; please keep in mind a slight difference may be due to cost of ribbon cable versus loose tube. When it comes to choosing a splicer, many different factors such as budget, brand loyalty, and specific job requirements are all deciding factors in making an informed decision.  There are more and more companies becoming splicer resellers with no experience or history.  Buyer should be wary of small new companies that do not offer repairs and/or long term support for their products.   Many people are purchasing directly from small distributors and are left abandoned when they need repairs or service.  When doing your research, always shop around, weighing out price, warranties and how confident you feel in purchasing from that company. One company that can help you decide which machine is the best fit for you is eFiberTools.com, Inc.  The supportive staff will help narrow down the choices of equipment to fit your particular needs based on application and budget.  Visit their site www.efibertools.com for live chat or to download brochures, manuals and pdf files pertaining to equipment you want, need or currently own.  Also, contact them directly via phone, 623-582-5560 or toll free 877-773-3423 to talk to a friendly and knowledgeable staff member that can assist you without the high pressure sales pitches used by many of eFiberTools.com’s competition.  

Cleaning Products for Fiber Splicing

The best choices for proper cleaning of fiber optic bare fiber prior to fusion splicing are the Sticklers® Benchtop CleanWipes, which are lint-free wipes for use on bare fiber wet or dry. Use the wipes to thoroughly clean the bare fiber prior to splicing. Each mini-tub contains 90 perforated lint-free wipes, each wipe being 4″ x 2″ (10 cm x 5 cm) clean up to six fiber optic connectors or one bare fiber. You can get a case of 24 mini-tubs, and they have an unlimited shelf life with a 12-month warranty. The fabric is very strong and resists shredding and tearing, even on LC connector end-faces. They are also ideal for cleaning fiber optic connector end-faces, plus lenses, mirrors, diffraction gratings, prisms and test equipment. For best results dampen the wipes with Sticklers® Fiber Optic Splice & Connector Cleaner. This is an optical-grade liquid which easily removes fingerprints, oils, dust, lint and surface films, and is fast drying. The Cleaning Fluid is packaged in a small metal pump spray can (not an aerosol). Each can is equipped with a 3-way dispenser, so you can wet a wipe, dampen a cleaning stick or swab or even spray a burst of fluid. It is nonflammable and can be shipped without hazmat fees or paperwork. Can is good for more than 400 cleaning events, unlimited shelf life and available in case of 12 cans each. It’s important to note that although you can use  isopropanol alcohol when cleaning fiber optics you must use  only 99.9% alcohol. Using  what you find in the local drug store may contains 30% water which leaves a thin residue on the surface if it’s the 70% bottle. Alcohol draws moisture from the air so even if you start with 99.9% and leave the cap off the bottle you will increase the alcohols’ water content significantly, depending on the ambient humidity. Even by repeatedly opening the bottle can contaminate it. These are further reasons why you should use Sicklers Fiber Optic Splice & Connector Cleaner with the 3-way dispenser.