communication and lasers

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 lasers..

(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 1870 John Tyndall, a natural philosopher living in England, demonstrated one of the first guided light systems to the Royal Society. His experiment involved using water as a medium to prove that light rays bend. He filled a container with water and allowed the water to escape through a horizont..