Why are rubies used in lasers?

Ruby has very broad and powerful absorption bands in the visual spectrum, at 400 and 550 nm, and a very long fluorescence lifetime of 3 milliseconds. This allows for very high energy pumping, since the pulse duration can be much longer than with other materials.

Read more

What is the relation between Einstein's A and B coefficients?

The Einstein A coefficients are related to the rate of spontaneous emission of light, and the Einstein B coefficients are related to the absorption and stimulated emission of light. Then, what is quantum emission? Spontaneous emission is the process in which a quantum mechanical system (such as a molecule, an atom or a subatomic particle) transits from an excited energy state to a lower energy state (e.g., its ground state) and emits a quantized amount of energy in the form of a photon.

You can also ask is white light monochromatic?

This means the light contains only one wavelength. Why laser is not perfectly monochromatic? That being said, however, the laser light is not exactly monochromatic. Since the wavelength of the light is extremely small compared to the size of the laser cavities used, then within that tiny spectral bandwidth of the emission lines are many resonant modes of the laser cavity.

Thereof, why is laser light not monochromatic?

Laser light is not perfectly monochromatic. All the photons are not the same wavelength and they are not all in phase. What is the difference between intensity and brightness of the laser? Brightness : When taken reference of a picture with another you can find out the brightness amongst them. Intensity : It is a numerical value of how intense the light needs to be bright.