Plastic Optical Fiber (POF) is also known as Polymer or Consumer Optical Fiber. It is an optical material made up of polymer (plastic). Plastic optical fiber is used for data and non data communication fields. It is becoming more popular with time. It is creating a challenge to glass optical fiber because it is able to transmit huge amount of data for long distances.

The plastic fibers are transparent at specific wavelengths that allow the fiber to efficiently guide the light. It is also possible to made POF more thin and long. At the lower index part, the fiber is made with a core having a high index surrounding with a layer of cladding. The core part is constructed with polystyrene or polymethylmethacrylate while the cladding is mostly made up of silicone or Teflon. There are three basic types of plastic fiber optics: Step Index (SI) POF, Graded Index (GI) POF and Perfluorinated POFs.

The main material used now days for SI-plastic optical fibers is Poly-Methyl-Methacrylate (PMMA) SI-POF. It is based on CH material.

It is mostly used for data communication in industrial automation field and multimedia communication in cars. It is very easy to install and connecting. It is able to with stand mechanical stress and electromagnetic interference. It is low in weight and price. Its diameter ranges from 300 µm to 1mm. Cable having a diameter of 1mm allows more light to enter with larger angle due to large numerical aperture of 0.5 that results in large tolerances to bending and alignment. Its attenuation is around 130 dB/km. Its operation is limited to 650. Its band width is limited to 50MHz × 100m which is showing a negative chances of Gigabit transmission over SI-POF and it has short link i.e. upto 50m.

The material used in Graded Index POF is Poly-Methyl-Methacrylate (PMMA). It provides a high band width of approximately 3GHz upto 50m that allows a higher transmission rate. The commercial GI-POF is available with core diameter from 0.5-1mm. The major disadvantage is that its bending loss is high and hence high attenuation values of 200dB/Km. It is able to provide giga bit communication.

The third basic type is Perfluorinated POF (Teflon, Cytop). It is based on CF material.

It attenuation is low i.e. 20dB/km. It operates at 650,850 and 1300 nm. It has long link i.e. upto 1km.It provides high speed of about ≥10Gb/s. Core diameter of about 50-62.5m upto 120 m. Easy installation with low cost and a small bending radius of 5mm. It has ability of higher tolerance to stress and load. It is easy to connect.

POF has also a high band width type. This type includes a bandwidth of above 1Gbps.The high band width GI POF facilitates us by transmitting high speed optical signals to a short range network which was not covered by step index type POF commercially available. The high band width GI POF will provide more advantages in high speed multimedia network.

The main advantages of POF high bandwidth are that it supports all the wavelengths i.e. 510, 650, 850, 1300 nm ,all application like high and low speed, existing light sources used for silica fiber.

Generally the attenuation in plastic optical fibers is about 1 dB/m @ 650 nm. This is a larger value as compared to conventional optical fibers in which the attenuation as low as 4dB/km has been achieved by using germanium dioxide. This is one of the major disadvantages of plastic optical fibers that there are larger losses associated with them.

If we look at the above figure, it is showing the attenuation curve for different wavelengths in SI-POF which is mainly due to the spectral attenuation characteristics of PMMA material. According to this figure the least attenuation transmission windows are near to 520 nm that is blue, 570 nm that is green and 650 nm that is red in SI-POF that tells us that SI POF can be operated in visible wavelength region that helps the inspection of system easily. The typical source of SI POF is LEDs that are available in variety of wavelengths.

Numerical aperture is a dimensionless quantity specifying the range of angles of light that can enter or leave an optical device. It can be calculated by using the following formula
N.A= n.sin.ɵ
Where,
N.A= Numerical aperture
n= Refractive index of the optical material
ɵ = The angle range with which the light can enter or leave the device

A distinguishing feature of plastic optical fibers is their high numerical aperture. This means that a high quantity of light (can be visible) can pass through it with ease and hence a high propagation capacity. A lot of light means a lot of information being transferred with every pulse.

Dispersion is a process associated with optical fibers where a signal that is being transmitted is dispersed and the waveform somewhat becomes longer (horizontally). This results in bits being broader and having less defined boundaries between them. Dispersion causes more error at the receiving end and makes the decoding a difficult process.

POFs are low cost solution for low speed and short distance applications like automobile makers are making use of plastic optical fibers for interfacing between different systems present within an automobile, industrial network, appliances and home networks. Due to the light weight of plastic optical fibers, it finds a lot of application in airlines and space shuttles because weight is crucial for anything that flies. Any setup where interface between different systems or devices is required, they can find their applications with the added advantage of strength, flexibility and durability.