lasers used in communication

The smallest lasers used for telephone communication over optical fibres have as their active medium a semiconducting gallium arsenide crystal about the size of a pin-hea..

The development of the laser has opened many avenues of investigation and improved many others. The important characteristics that have contributed to its usefulness in these many areas are tile coherence, monochromaticity and great intensity of its radiation. (i) The smallest h..

(in the ruby, at the desired frequency). Such an arrangement is called a Fabry-Perot resonator. Pumping process is carried with the help of flash tube. The spiral flash tube pumps light energy into the ruby in pulses, which are generated by the charge and discharge of a capacito..

The below figure shows schematically how a population inversion can be achieved so that laser action-or lasing us it is called can occur. Atoms from the ground state E 1 are "pumped" up to an excited state E 3 , for example by the absorption of light energy from an intense continuous spec..

The figure shows the elements of a type of laser that is often found in student laboratories. The glass discharge tube is filled with a 80%-20% mixture of the inert gases helium and neon. Helium is the "pumping" medium and neon is the "lasing" medium. The above figure is a simplified vers..

in the following way. The system can be a solid, liquid or gas but is taken in the form of a cylinder. A system is chosen which has a lower energy E 1 , a higher energy E 2 . Using some technique the number of atoms in state E 2 is made higher than that in state E 1 . In this situation..

Communication Systems..

Microsurgery is any operation done with the aid of microscopes. Surgeons work with spectacle - mounted magnifiers or with microscopes. Using this technique, surgeons can remove adenoma, tumours of the pituitary gland, without damaging the gland itself. Neurosurgeons, ear and eye surgeons ..

Lasers-An Introduction - The laser is an acronym for Light Amplification by Stimulated Emission of Radiation. The laser has been invented and developed in 1959 and 1960. In the laser, the maser principle has been extended to optical or visible light frequenci..

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