One of the biggest revolutions in human history was the start of the use of electromagnetic waves for modern communication. Modern communication means the exchange of digital information. The use of electromagnetic waves for modern communication has started about one hundred years ago.
For electromagnetic waves do not necessarily require a conductive medium for propagation. Avoidance of conductive wires saves a lot of work and ensures a lot of safety. In fact, the use of electromagnetic waves ensured high speed, low loss transmission of information.
Electromagnetic waves can travel in a vacuum, air, and in an electrically non-conducting medium such as copper wires, and aluminum wires. Electric non-conducting medium is also known as a dielectric medium.
The electromagnetic spectrum is the range of frequencies of electromagnetic radiation and their respective wavelengths and photon energies. The electromagnetic spectrum covers electromagnetic waves with frequencies ranging from below one hertz to above 1025 Hertz. This frequency range corresponds to wavelengths from thousands of kilometers to a fraction of the size of an atomic nucleus.
The electromagnetic spectrum is divided into separate bands. The electromagnetic waves within each frequency band are called by different names. The classification of these frequency bands begins with the low frequency or long-wavelength and ends with high frequency or short wavelength.
Frequency Bands in Electromagnetic Spectrum
Radio wave including Microwave (Wavelength ranging from 1mm to 100,000 km and Frequency ranging from 300 GHz to 3 Hz)
Infrared Rays (Wavelengths ranging from 1 micrometer to 1 millimeter and corresponding frequencies from 300 THz to 300 GHz)
Visible light (380 nm to 700 nm corresponding to 789 THz to 370 THz)
Ultraviolet 10 nm to 380 nm corresponding to frequencies from 30 PHz to 789 THz.
X-rays (Wavelength ranging from 10 pm to 10 nm corresponding to frequencies of 30 EHz to 30 PHz)
Gamma rays (Wavelength ranging from 1 pm to 10 pm corresponding to frequencies of 300 EHz to 30 EHz)
As you can see in the above list, Radio waves have longer wavelengths low frequency and Gamma rays have shorter wavelengths and high frequency.
For optical transmission in telecommunication purposes, wavelengths ranging from 850nm to 1650nm are used. However, for practical reasons, these wavelength ranges are further divided into different windows.
Windows for Optical Communication
850 nm – First Window
1310nm – Second Window
1530 nm to 1565 nm (Conventional Band) – Third Window
1565 nm to 1625 nm (Long-wavelength band) – Fourth Window
1380 nm to 1525 nm – Fifth Window
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