Concept of Laser Physics

Laser Physics:

Stimulated emissions-

The energy possessed by an electron that is revolving in the orbit around an atomic nucleus is larger in comparison to those orbits which is further from the nucleus of an atom. However, quantum mechanical effects force electrons to take discrete positions in orbitals. Therefore, only in the specific energy levels in the atom electrons are found. An electron resides in the atom is capable to absorb energy from light (photon) or heat (phonon) only if there is a transition between energy levels matching the energy carried by the photon or phonon.

In terms of light, only one particular wavelength of light will be observed by any given transition. Photons with the right wavelength can cause an electron to jump from a lower to a higher energy level. Photons are consumed in this process. When an electron gains some amount of extra energy and becomes excited from one state to that of a higher energy level having an energy difference, it will soon get restored to its original state. Furthermore, a photon will be created spontaneously from the vacuum having the energy equal to the energy difference.

Conserving energy, the electron transitions to a lower energy level that is not occupied, with transitions in different levels having different time constants. This whole process is known as “spontaneous emission”. Spontaneous emission is a type of quantum-mechanical effect that can be represented as a direct physical expression of the Heisenberg uncertainty principle. The emitted photon has a random direction, but its wavelength corresponds to the absorption wavelength of the transition. It is the mechanism of fluorescence and thermal emission. The process of whole product design and manufacture custom optical filters options requires single surface coated laser windows and custom lenses.

A photon that has a correct wavelength will get observed by a transition that can also make an electron fall from higher to the lower level, emitting a new photon. The photon which is emitted exactly matches the original photon in wavelength, phase, and direction. This process is called stimulated emission.

Quantum vs. classical emission processes

It all depends on the stimulated emission the whole mechanism of radiation generation in the laser, where energy is extracted from a transition in a molecule or an atom. However, atomic energy levels are not involved in the case of free-electron lasers; It appears that the operation of this rather exotic device can be explained without reference to quantum mechanics.