Question

Name and briefly discuss 5 of the main advantages of optical fibre over conventional copper coaxial cable for use in communication systems. (5 ma A commercial laser diode (Sharp LT026MDO) has the following operating characteristics: Forward Bias 2.4 V Threshold current 35.1 mA Operating current 50.0 mA Wavelength 788 nm Total radiant flux 4.35 mW c.w. Calculate the efficiency (%) of the laser in terms of the optical power out / electrical power in, the quantum efficiency, QE, and the lasing response in W.A-'.

Answer 1

The advantages of optical fiber are in detail below:

1. Electromagnetic Interference (EMI) :

Instead of electrons, optical fiber transmits light, so it neither radiates EM (electromagnetic) fields nor is it susceptible to any EM fields surrounding it. This is important in a number of applications :

Industrial control, where cables run along factory floors in proximity to electrically noisy machinery. The optical medium permits the control signals to be carried error-free through the electrically noisy environment.

Telecommunications equipment manufacturers use optical fiber because it eliminates cross talk between the telecommunication lines.

Financial institutions and gaming equipment manufacturers require data security. Tapping into a fiber cable without being detected is extremely difficult.

2. High Bandwidth :

Optical fiber has a relatively high bandwidth in comparison to other transmission media. This permits much longer transmission distances and much higher signal rates than most media. For example, all undersea long-haul telecommunications cable is fiber - optic.

This technology is allowing worldwide communications (voice, video and data) to be available mainstream. With new technologies, such as VCSEL transmitters, parallel optics and wavelength division multiplexing (WDM), services such as video-on-demand and video conferencing will be available to most homes in the near future.

3. Voltage Isolation and Voltage Insulation :

Fiber isolates two different voltage potentials. and insulates in high-voltage areas. For example, it will eliminate errors due to ground-loop potential differences and is ideal for data transmission in areas subject to frequent electrical storms, and presents no hazard to the field installer.

4. Weight and Diameter :

A 100 meter coaxial cable transmitting 500 megabits of data per unit time is about 800 percent heavier than a plastic fiber cable and about 700 percent heavier than a hard-clad silica cable, all of equal length and transmitting at the same data rate.

The relative diameters of various types of fiber cable and coaxial copper cable for the same distance and data rate are shown in the illustration below.

5. Long lifespan :

Optical fibers usually have a longer life cycle for over 100 years.