PC, UPC or APC – Selecting the Right Fiber Connector

When describing fiber connectors, we often use terms like “LC UPC simplex single-mode fiber connector” or “ SC APC simplex single-mode fiber connector”. Then have you ever wondered what “UPC” and “APC” stand for? Or is there any difference between them? This is what we are going to talk about in this article.

Introduction to Different Kinds of Fiber Connector

Firstly, let’s take a look at how connectors evolve from the original flat fiber connector into the physical contact (PC) connector and then onto ultra physical contact (UPC) connector and angled physical contact (APC) connector.

Flat Fiber Connector

When two flat fiber connectors are mated together, a small air gap is left between the two ferrules. This is partly because the relatively large endface of the connector allows for numerous slight but significant imperfections to gather on the surface. However, it is not much use for single-mode fiber cables with a core size of just 8-9 um, hence there naturally comes to the necessary evolution to physical contact (PC) connectors.

Physical Contact Connector

The PC connector is similar to the flat fiber connector but it is polished with a slight spherical (cone) design to reduce the overall size of the endface. Which helps to decrease the air gap issue faced by regular flat fiber connectors, resulting in lower optical return loss (ORL), with less light being sent back towards the power source.

Ultra Physical Contact Connector

Ultra physical contact connector (UPC) is built on the convex endface attributes of the PC, but with an extended polishing method, which creates an even finer fiber surface finish. This results in lower back reflection (ORL) than a standard PC connector, allowing more reliable signals in digital TV, telephony and data systems, where UPC today dominates the market. UPC connectors do have a low insertion loss, but the back reflection will depend on the quality of the fiber surface and, following repeat matings/unmatings, it will begin to deteriorate.

Angled Physical Contact Connector

The tendency is that the industry needs a connector with low back reflection, that could sustain repeated matings/unmatings without ORL degradation. And this brings us the angled physical contact (APC) connector.

Although PC and UPC connectors have a wide range of applications, some instances require return losses in the region of one-in-a-million (60dB). Only APC connectors can consistently achieve such performance. This is because adding a small 8-degree angle to the endface allows for even tighter connections and smaller endface radii. Combined with that, any light that is redirected back towards the source is actually reflected out into the fiber cladding, again by virtue of the 8-degree angled end-face. What to mention is that other three connectors are all inter-mateable, whereas the APC isn’t.

Differences Between UPC and APC

Currently, with UPC and APC connectors dominating the market, these two types are the most commonly seen connectors employed in the fiber optic industry. In this part, we will mainly explain the difference between them. Besides the more obvious difference that UPC connectors are blue while APC connectors are green, the main difference actually lies in the fiber endface.

APC connectors feature a fiber endface that is polished at an 8-degree angle, while UPC connectors are polished with no angle. UPC connectors are not exactly flat however, they have a slight curvature for better core alignment. With UPC connectors, any reflected light is reflected straight back towards the light source. However, the angled endface of the APC connector causes reflected light to reflect at an angle into the cladding versus straight back toward the source. This causes some differences in return loss, which is a measurement of reflected light that is expressed as a negative dB value (the higher the value, the better). Industry standards recommend that UPC connector return loss should be -50dB or greater, while APC connector return loss should be -60dB or greater.

Selecting the Right Fiber Connector

With APC connectors being used by most cable companies, other FTTX providers in outside plant applications, and passive optical applications (both GPONs and passive optical LANs). Future higher-speed passive optical networks and other WDM applications that will use higher wavelengths via singlemode fiber will also likely require the reduced return loss of APC connectors. What should be noted is that APC and UPC connectors cannot be mated, in case to cause poor performance or to destroy both connectors. However, when choosing the right connector for your specified application, factors like cost and simplicity should also be considered seriously, not just optical performance. So, it actually depends on the real circumstances and various factors.

Conclusion

It is generally accepted that all of these connector options capture a place in the current market, and we cannot say anyone is better than the others since whether to choose UPC or APC in fact depend on your particular need. Whereas for those applications which high precision optical fiber signaling matters, APC should be the optimum alternative, but for less sensitive digital systems, UPC and APC can both perform equally well.

First published: http://www.china-cable-suppliers.com/pc-upc-apc-selecting-right-fiber-connector.html

An Overview of Fiber Optic Connector Cleaning

A fiber optic connector works to terminate the end of an optical fiber, as the name indicates, it is generally adopted to join optical fibers where a connect or disconnect capability is required. The connector mechanically couples and aligns the cores of fibers to enable light passing from one fiber to another. Thus it provides much more convenience and flexibility to operators with a connecting speed quicker than fiber splicing. Fiber optic connector is widely employed in the telephone company central office, at installations on customer premises and in outside plant applications to connect equipment and cables. Besides, it also captures an essential position when cross-connect cables are required. As an indispensable component in cable installation that can affect the performance and reliability of the whole system, the cleanliness of fiber optic connector cannot be ignored. This article aims to raise the awareness of connector cleaning and offer some constructive suggestions to clean fiber optic connector.

Why It Is Critical to Ensure Fiber Connector Cleaning

It is important to know the fact that every fiber optic connector should be inspected and cleaned before mating, because a clean fiber optic connector is a necessary requirement for quality connections between fiber optic equipment. And One of the most basic and important procedures for the maintenance of fiber optic systems is to clean the fiber optic equipment. However, any contamination in the fiber connection can cause failure of the component itself, or even worse, failure of the whole system.

In addition, even microscopic dust particles can cause various problems for optical connections. A particle that blocks the core, either partially or completely, could generate strong back reflections, which can cause instability in the laser system. Dust particles trapped between two fiber faces can scratch the glass surfaces. Even if a particle is only situated on the cladding or the edge of the endface, it can cause an air gap or misalignment between the fiber cores which significantly degrades the optical signal. Besides dust, there still exists other kinds of contamination such as oil, human touch, film residues, vapors in the air and so on, which are proved to be more difficult to remove than dust particles. If not removed properly, they may also result in great damage to equipment.

Contaminated fiber optic connectors can often lead to degraded performance and costly, but preventable failures. So, to ensure proper performance and reliability, care must be taken with the installation and maintenance of fiber connectors. Cabling industry best practices recommend that both field and pre-terminated connections should be inspected and cleaned prior to mating to other connectors or equipment.

Common Contamination Conditions of Fiber Connector

In this part, this article intends to show several common contamination conditions of fiber connector through the following picture:

Figure 1 shows a clean single mode ceramic endface.

Figure 1

Figure 2 shows a connector with dust particles spread across the surface of the endface that needs cleaning.

Figure 2

Figure 3 shows a connector with liquid contamination that needs cleaning.

Figure 3

Figure 4 shows a connector with alcohol residue that needs cleaning.

Figure 4

Figure 5 shows a connector with a dry residue that needs cleaning.

Figure 5

Figure 6 shows a connector with an oil residue that needs cleaning.

Figure 6

The Methods of Fiber Connector Cleaning

Based on the cleaning method, generally there are four types of fiber optic cleaning kit on the market nowadays:

Dry cleaning: Optic cleaning without the use of any solvent.
Wet cleaning: Optic cleaning with a solvent. Typically IPA (isopropyl alcohol). Non-Abrasive cleaning: Cleaning without abrasive material touching the fiber optic connector end face. Examples are air dusters or pressured solvent jet used in automated in-situ connector cleaners.
Abrasive cleaning: The popular lint free wipes, reel based fiber connector cleaners and optic cleaning swabs such as the sticks are all abrasive cleaning types.

The Process of Fiber Connector Cleaning

In this part, let’s move to describe the connector cleaning process. For general fiber optic connector cleaning, it is necessary for you to complete the following steps:

• Step 1: Clean the fiber optic connectors with a dry cleaning technique.
• Step 2: Inspect the connector.
• Step 3: If the connector is dirty, repeat the dry cleaning technique and inspect the connector again.
• Step 4: Clean the connector with a wet cleaning technique if it’s still dirty.
• Step 5: Inspect the connector again.
• Step 6: Repeat these steps until the connector is clean.

If you are using resealable containers, you should store the end caps in separate containers and store all of the cleaning tools as well. The inside of the containers should be clean and the lid should be kept tight to avoid contamination. Do not allow the cleaning alcohol to evaporate slowly. This may leave a residue on the cladding or fiber core. It is often difficult to clean and can be more difficult to remove than the original contaminant.

Conclusion

As the demand for increased bandwidth, more data and better quality audio/video grows rapidly, the use of fiber optics around the globe has increased greatly. That need for more and better data means more fiber optic cable and more high density, reliable optical connectors. It is thus nature that cleaning consideration is the number one issue in fiber optic cable technology today, with the proper method and process implemented in connector cleaning, the fiber optic connector will perform flawlessly for years in your fiber cable infrastructure. FS.COM provides cost-efficient and high-quality fiber optic cleaners that ensure you high-performed fiber connector cleaning. Supported by large quantities of products in stock, you can enjoy really fast delivery in FS.COM. For more detailed information, please visit www.fs.com or contact sales@fs.com.

First Published: http://www.china-cable-suppliers.com/an-overview-of-fiber-optic-connector-cleaning.html