What is stimulated absorption in laser?

What is stimulated absorption in laser?

Stimulated Absorption is the starting point to achieve laser. It happens when a photon of light having energy E2 – E1 = hυ (as shown in the figure) is incident on an atom in the ground state, the atom in the ground state E1 may absorb the photon and jump to a higher energy state E2.

What is stimulated emission and absorption?

Stimulated emission (absorption) is a process, in which an incident electromagnetic field, comprising the energy of one photon, forces an atom in its excited (ground) state to oscillate and emit a second electromagnetic field, comprising the energy of one photon, that is in phase (anti-phase) with the incident field.

What are the important features of stimulated emission?

Stimulated emission of radiation generates monochromatic and coherent light with a determined wavelength. Absorption: When an atom of the active medium absorbs a photon, an electron jumps to an excited state. This process competes with the stimulated emission process.

What happens stimulated absorption?

ii. Stimulated absorption occurs when a photon strikes an atom with just exactly the proper energy to induce an electronic transition between two energy states.

Why stimulated emission is used for laser?

In laser action the stimulating emission triggers a chain reaction in which the radiation from one atom stimulates another in succession until all the excited atoms in the system have returned to normalcy. In doing so, coherent monochromatic light (light of a single wavelength) is emitted.

What is the stimulated absorption?

What is the difference between stimulated emission and stimulated absorption?

Absorption: An atom in a lower level absorbs a photon of frequency hν and moves to an upper level. Stimulated emission: An incident photon causes an upper level atom to decay, emitting a “stimulated” photon whose properties are identical to those of the incident photon.

Why is 4 level laser better than 3 level laser?

The pumping operation of a four level laser is similar to the pumping of a three level laser. The advantage of the four level laser is the low population of the lower laser energy level (E2). To create population inversion, there is no need to pump more than 50% of the atoms to the upper laser level.

What should be stimulated emission than stimulated absorption?

In normal media at thermal equilibrium, absorption exceeds stimulated emission because there are more electrons in the lower energy states than in the higher energy states.