Question

Explain the working of Ruby Laser with the help of an energy level diagram.

Answer 1

Hint: A ruby laser is a solid-state laser that emits light through a synthetic ruby crystal. Maiman's first successful laser, the Ruby laser, was invented in 1960. One of the few solid-state lasers that produces visible light is the Ruby laser. It produces a deep red light with a wavelength of \[694.3{\text{ }}nm.\]

Complete step by step answer:

Working of Ruby Laser: A single ruby crystal \[\left( {A{l_2}{O_3}:{\text{ }}C{r^{3 + }}} \right)\] in the shape of a cylinder serves as the laser media or active medium in a ruby laser. The sapphire host \[\left( {A{l_2}{O_3}} \right)\] in the ruby laser is doped with modest amounts of chromium ions \[\left( {C{r^{3 + }}} \right)\] to serve as the laser medium. The thermal characteristics of ruby are excellent.

The pump source in a ruby laser system is the component that provides energy to the laser medium. To achieve laser efficiency, this type of laser requires population inversion. The laser medium must be provided with energy in order to produce population inversion. As a power source for the ruby laser, we employ a flash tube. The laser medium receives energy from the flash tube. Lower-energy electrons in the laser medium will transition to an excited state once they gain enough energy from the flash tube.

The cylindrical ruby rod's ends are flat and parallel. The ruby rod is positioned between two mirrors in a cylindrical shape. The optical coating is applied to both mirrors. Silvering is the process of placing tiny layers of metals on glass substrates to generate mirror surfaces. The mirrors are silvered or coated in different ways.

At one end of the rod, the mirror is totally silvered, whereas at the other end, the mirror is only slightly silvered. The fully silvered mirror reflects the light, whereas the partially silvered mirror reflects the majority of the light but permits a little percentage of it to be converted into laser light.

Energy level diagram: Consider a ruby laser medium with three energy levels \[{E_1},{\text{ }}{E_2},\] and \[{E_3}\] and \[N\] number of electrons. The energy levels are \[{E_1} < {\text{ }}{E_2} < {\text{ }}{E_3}\] . The ground state is designated by the energy level\[{E_1}\] , the metastable state by the energy level \[{E_2}\] , and the high energy state by the energy level \[{E_3}\] . Assume that the majority of electrons are in the lower \[{E_1}\] state at first, with only a small number in the \[{E_2}\] and \[{E_3}\] states.

The electrons in the \[{E_1}\] state accumulate enough energy to transition to the \[{E_3}\] state as the laser medium absorbs light energy. Because the lifetime of the pump state \[{E_3}\] is only \[{10^{ - 8}}{\text{ }}seconds\] , the electrons in the \[{E_3}\] do not stay for long. They collapse into the metastable state \[{E_2}\]by releasing radiationless energy after a short time. The metastable state \[{E_2}\] has a lifespan of \[{10^{ - 3}}seconds\] , which is substantially longer than the \[{E_3}\] state. As a result, electrons reach \[{E_2}\] far more quickly than they leave \[{E_2}\].

The electrons in metastable state \[{E_2}\] sink into the lower energy state \[{E_1}\] after a period of time, releasing energy in the form of photons. Spontaneous radiation emission is the term for this. When an emitted photon interacts with an electron in a metastable state, the electron is forced into the state. As a result, it produces two photons. It's known as stimulated radiation emission, and millions of photons are created because the process is constant.

Note: In an active medium, light is created via a process known as spontaneous emission. The light emitted by the laser medium will bounce back and forth between the two mirrors. Other electrons descend into the ground state as a result of the release of light energy. It's referred to as stimulated emission. It also causes millions of electrons to release light in the same way. And now the light gain has been achieved.