Comparison of Two Optical Fibers: Glass Optical Fiber vs Plastic Optical Fiber

Posted on October 2, 2014
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High bandwidth networking has become a trend. As a transmission media widely used for telecommunication and computer networking, optical fiber has the unique advantage of high-speed data transmission over long distances. In fact, optical fiber has two types: glass optical fiber vs plastic optical fiber. This article will give an introduction to them and make a simple comparison.

What is Glass Optical Fiber?

Glass optical fibers are constructed of tiny strands of glass that are bundled together inside an application-specific sheathing like stainless steel for durability and high temperatures. They are attached to certain photoelectric sensors and guide light from the sensing head to the target. Glass optical fibers have an impressive temperature range, as low as -40°F and up to +900°F. The main applications for glass fiber are communication, sensor, and measurement system. Some types of glass optical fiber cables can also be used in harsh environments such as corrosive and wet environments.

Advantages and Disadvantages of Glass Optical Fiber

Advantages:


  • Glass fiber cables can be used in high-temperature applications like furnaces, ovens, and condensers in large engines, as well as in extremely low-temperature areas such as cold storage warehouses.

  • Since glass cores are efficient at transmitting light and allow for significantly higher transfer speeds, glass optical fibers can be used over long sensing distances.

  • Glass optical fiber enables you to use a photoelectric sensor in areas where you wouldn’t normally be able to use them. With this advantage, you can choose sensors with a wide range of housings, mounting styles, and features for your specific application.

  • Since glass fiber optic cables are thin and light, they are optimized for small spaces and small targets.

Disadvantages:


  • The installation of glass optical fibers requires highly trained technicians, and the tools and equipment for fiber termination are usually expensive.

  • The core diameter of glass fiber is very small, hence it has higher technology requirements to couple light into the core region, such as light sources.

  • Glass optical fibers are fragile and more possible to break if not handled properly.

What Is Plastic Optical Fiber?

Plastic optical fiber (POF) is introduced to optical links later than glass optical fiber. It is an optical fiber in which the core and cladding are both made out of plastic or polymeric materials rather than glass. It is typically made up of PMMA (acrylic), a general-purpose resin as the core material, thus it is also referred to as PMMA optical fiber. Similar to the glass optical fiber, POF transmits the light through the core of the fiber. POFs are usually multimode fibers with large core (diameter from 0.15-2 mm). Made from just one acrylic monofilament, plastic fiber optic cables are efficient when used with visible red status indicator light sources.

Advantages and Disadvantages of Plastic Optical Fiber

Advantages:


  • The materials which POF is made up of are low-cost and the installation with associated assemblies is not expensive.

  • It is flexible and solid, able to bend farther without breakage.

  • The network using plastic optical fiber can be installed by untrained personnel. Even home users can handle and install these fibers.

  • Plastic optical fibers use harmless green or red light that is easily visible towards the eye. They are safe when installed in a house without risk to inquisitive children.

Disadvantages:


  • The signal attenuation and dispersion of POF are typically very high, hence it is limited to short distances.

  • POF can not withstand the extreme temperature as glass optical fiber does.

What’s Difference Between Glass Optical Fiber and Plastic Optical Fiber?

From the introduction of glass optical fiber and plastic optical fiber below, you may have a clearer impression of the difference between these two terms. The following comparison chart which summarizes the parameters will help you better understand it.

Item Glass optical fiber Plastic optical fiber
Core diameter More narrow (about 50-100μm for multimode fiber and 8-10μm for single mode fiber) Wider (about 150-2000μm and even up to 20000μm)
Numerical aperture Larger More narrow
Cost More expensive Less expensive
Signal strength Poorer Better
Extreme temperatures Sustainable Unsustainable
Flexibility Less flexible More flexible
Consumability More complex Easier
Transmission distance Longer Shorter

For short-range connectivity and those who are lack of professional knowledge of glass fiber, POF is a better choice. For a challenging environment and higher transmission rate over a long distance, glass optical fiber should be considered.

Another Type of Optical Fiber

There is another type of optical fiber—plastic clad silica (PCS) fiber or sometimes called hard clad silica (HCS) fiber. It features a glass core and a plastic cladding but is used less than plastic optical fiber. Compared with all-glass fibers, it has significantly lower performance characteristics, providing higher loss and lower bandwidths. The main advantage is the big core (up to 200-300μm), which is advantageous in applications such as industrial and medical applications.

Conclusion

As transmission mediums, glass optical fiber and plastic optical fiber are both used for high-speed data transmission. However, they consist of different materials and have their own advantages and are suitable for different applications. When choosing the correct optical fiber for the application, you are recommended to take the factors listed above into account.