Category Archives: Fiber Optic Connectors

Know Enough About Fiber Connectors?

As there exists a wide range of splice options for fiber network available on the market, selecting the right connector for your application can sometimes be tough and confusing. While choosing the fiber connector, various factors like cost and availability should be considered, which naturally lead to even less thought goes to connector itself. Since each connector has its own unique design as well as merits and demerits, it can pose a significant influence on deployment speeds and costs in the long run. So before making your decision, you’d better have an overall understanding of fiber connectors, and this is what we will talk about.

Fiber Connectors Overview

In this part, we will introduce some fiber connectors that are commonly used in the network applications. The following diagram directly explains the differences among them in performance.

Name Mating Cycles Ferrule Size Typical Insertion Loss (db) Application Features
SC 1000 2.5 mm Ceramic 0.25-0.5 Mainstream, Reliable, Fast deployment, Field fit
LC 500 1.25 mm Ceramic 0.25-0.5 High density, Cost effective, Field fit
FC 500 2.5 mm Ceramic 0.25-0.5 High precision, Vibration environments, Field fit
ST 500 2.5 mm Ceramic 0.25-0.5 Military (legacy), Field fit
MTP/MPO 1000 6.4*2.5 mm molded 0.25-0.75 High density, Aggregate networking, Fast deployment
SC Connector

SC connector was one of the first connectors presented on the market following the advent of ceramic ferrules. It has a push-pull coupling end face with a spring loaded ceramic ferrule. Initially intended for Gigabit Ethernet networking, it became increasingly popular as manufacturing costs came down. The SC connector has held a dominated position in fiber optics for over a decade with only the ST rivaling it. And it still remains the second most common connector for polarization maintaining applications. The SC is ideally suited for datacoms and telecoms applications including point to point and passive optical networking.

SC fiber connectors

LC Connector

Considered to be the modern replacement of the SC connector, LC connector is also a push-pull connector, but it utilizes a latch as opposed to the SC locking tab and with a smaller ferrule it is known as a small form factor connector. LC connector shares huge popularity in datacoms and other high-density patch applications. And its small size and latch feature make it an ideal alternative for densely populated racks and panels. Since LC compatible transceivers and active networking components have been introduced, LC connector is likely to continue to grow steadily.

LC fiber connectors

FC Connector

FC connector leads the trend to use a ceramic ferrule, but unlike the plastic bodied SC and LC, it utilizes a round screw-type fitment made from nickel-plated or stainless steel. In spite that the manufacturing and installation of FC connector are much more complex, it’s still an optimum option for precise measuring equipment such as OTDRs. Moreover, FC connector is particularly effective in high vibration environments, ensuring that the spring-loaded ferrule is firmly mated.

FC connectors

ST Connector

ST connector looks much like FC connector, but it uses a bayonet fitment rather than a screw thread. Deployed predominately in multi-mode datacoms, it is most common in network environments such as campuses, corporate networks and in military applications where the quick connecting bayonet had its advantages at the time. However, it cannot be terminated with an angled polish, which limits use in single mode fiber and FTTH applications.

ST connectors

MTP/MPO connector

MTP and MPO connector falls into the category of multiple fiber push-on/pull-off connector. It is larger than other connectors since it can support up to 24 fibers in a single ferrule. It is currently extensively used in high density patch environments such as data centers, both at single mode and multi-mode wavelengths. MTP/MPO connector is often supplied with a fan-out assembly at the opposing end (such as LC, SC FC etc.). This allows the operator to change channels simply by re-patching the fanned-out side of the cable.

MTP/MPO connectors

Conclusion

Getting to know the differences between various types of fiber connectors simply contribute to the primary stage of selecting the right one. And when it comes to the planning process of fiber deployments, the differences can be much more clearly. So, make sure to invest enough time to select the right fiber connector, which will do you a good return in the long run.

Fiber Optic Connector Cleaning

With the deployment of 40G and 100G systems in the data center, reliable and efficient fiber installations are critical to the high performance network. Contaminated fiber optic connectors can often lead to degraded performance. Any contamination on the fiber connectors can cause failure of the component or failure of the whole system. So it’s important to keep fiber connectors clean.

Contamination Sources

There are two most important forms of contamination on fiber connectors and they are oils and dust. Oils from human hands will leave a noticeable defect easily seen with a fiberscope. The oil will trap dust against the fiber and bring scratches to the fiber connector. Inserting and removing a fiber can create a small static charge on the ends, which can attract airborne dust particles. Simply removing and re-inserting a fiber may also contaminate the end of the connector with a higher level of dust. Fiber caps, which are used to prevent fiber ends from being contaminated while not seated in a connector, will collect dust, dirt, oil and other contaminants to the fiber when used. Except oil and dust, there also other types of contamination, such as film residues condensed from vapors in the air, powdery coatings leaving after water or other solvents evaporating away. These contaminates tend to more difficult to remove and can also cause damage to equipment if not removed.

Contamination Inspection Tools

To inspect whether a fiber connector is contaminated, one should use fiberscope, clean and resealable container for the endcaps, bulkhead probe. A fiberscope is a customized microscope for inspecting optical fiber components. The fiberscope should provide at least 200x total magnification. The bulkhead probe is a handheld fiberscope used in order to inspect connectors in a bulkhead, backplane, or receptacle port. It should provide at least 200x total magnification displayed on a video monitor.

Contamination Inspection Steps

With contamination inspection tools, you should know how to inspect fiber connectors. The following introduces the inspection steps:

  • Make sure that the lasers are turned off before you begin the inspection. Be careful: Invisible laser radiation might be emitted from disconnected fibers or connectors. Do not stare into beams or view directly with optical instruments.
  • Remove the protective cap and store it in a clean resealable container. Verify the style of connector you inspect and put the appropriate inspection adapter or probe on your equipment.
  • Insert the fiber connector into the fiberscope adapter, and adjust the focus ring so that you see a clear endface image. Or, place the tip of the handheld probe into the bulkhead connector and adjust the focus.
  • On the video monitor, see if there is contamination present on the connector endface (See the following figure).

clean-connector-and-connectors-with-contamination

Connector Cleaning Tools

If there is contamination inspected on the fiber connector, then you need to clean it with proper tools. These tools can be divided into four types based on the cleaning method.

fiber-optic-cleaner-one-push

  • Wet cleaning: Optic cleaning with a solvent.
  • Non-Abrasive cleaning: Cleaning without abrasive material touching the fiber optic connector end face.
  • Abrasive cleaning: The popular lint free wipes, such as fiber optic mini foam swabs.
Connector Cleaning Steps

How to clean the fiber connector? Here is about the cleaning steps with abrasive cleaning tools.

  • Gently wipe endface with lint-free pad in one direction.
  • Using a can with compressed gas held upright and approximately 2 inches from the connector end, release a stream of gas on the connector endface for no more than 5 seconds.
  • Gently wipe the ferrule and the end-face surface of the connector with an alcohol pad. Making sure the pad makes full contact with the end-face surface. Wait 5 seconds for the surface to dry.

After finishing the cleaning steps, you should better inspect again to make sure there is definitely no contamination on the connector. Remember never touch the end face of the fiber connector and always install dust caps on unplugged fiber connectors. Do not re-use optic cleaning swabs or lens paper (lint free wipes).