The working principle of a laser is what is the principle of a laser

The working principle of a fiber laser is as follows: the pump light emitted by the pump source is coupled into the gain medium through a mirror, because the gain medium is doped with rare earth elements.

The optical fiber, so the pump light is absorbed, absorbing the photon energy.

The energy level transition of rare earth ions occurs.

The number of particles is reversed, and the reversed particles pass through the resonator, transition back to the ground state from the excited state, release energy, and form a stable laser output. The working principle of fiber lasers is mainly based on the special structure of fiber lasers. The laser is composed of three parts: the working substance, the pump source and the resonant cavity, and the specific functions are as follows:

1. The gain fiber is the gain medium for generating photons. 2. The function of pumping light is to use the external energy to make the gain medium reach the number of particles to be reversed, that is, the pump source. 3. The optical resonator is composed of two mirrors.

With the exception of free-electron lasers, the basic operating principle of all lasers is the same. The indispensable conditions for the generation of laser light are the inversion of the number of particles and the gain is greater than the loss, so the indispensable components of the device are the excitation (or pumping) source and the working medium with metastable energy level. Excitation is the excitation of the working medium after absorbing external energy into the excited state, creating conditions for achieving and maintaining the inversion of the number of particles.

The excitation methods include optical excitation, electrical excitation, chemical excitation and nuclear excitation. The working medium has a metastable energy level that makes stimulated radiation dominant, thus achieving light amplification. The common component of the laser is also the resonator, but the resonator (see optical resonator) is not an essential component, the resonant cavity can make the photons in the cavity have the same frequency, phase and running direction, so that the laser has good directionality and coherence.

Moreover, it can well shorten the length of the working substance, and can also adjust the mode of the generated laser (i.e., mode selection) by changing the length of the resonator, so the general laser has a resonator.

The principle of laser:

The interaction between light and matter is essentially the manifestation of the microscopic particles that make up matter absorbing or radiating photons and changing their own motion at the same time. Microscopic particles all have a specific set of energy levels (usually these levels are discrete).

At any one time, a particle can only be in a state corresponding to a certain energy level (or simply expressed as being at a certain energy level). When interacting with photons, Heqing chain particles jump from one energy level to another and absorb or radiate photons accordingly. The energy value of the photon is the energy difference between the two levels e, and the frequency is = e h (h is Planck's constant).