These objects sometimes use mode-locking or Q-switching. They require that more molecules be in an excited state than a lower energy state, which is known as population inversion. They also contain a 
These objects sometimes use mode-locking or Q-switching. They require that more molecules be in an excited state than a lower energy state, which is known as population inversion. They also contain a substance such as titanium sapphire which is used as a gain medium inside a resonator cavity, which typically has a fully reflecting mirror on one side and partially transmitting mirror on the other. This technology, whose red type was first introduced in 1960, is now ubiquitous, used in communication, printers, and data storage on CDs and DVDs. Name these devices that emit coherent light.
These objects sometimes use mode-locking or Q-switching. They require that more molecules be in an excited state than a lower energy state, which is known as population inversion.
Laser(s)