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Laser types with distinct laser lines are shown above the wavelength bar, while below are shown lasers that can emit in a wavelength range. The height of the lines and bars gives an indication of the maximal power/pulse energy commercially available, while the color codifies the type of laser material (see the figure description for details).
A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The word laser originated as an acronym for light amplification by stimulated emission of radiation.
Diagram of a simple VCSEL structure. The vertical-cavity surface-emitting laser (VCSEL / ˈ v ɪ k s əl /) is a type of semiconductor laser diode with laser beam emission perpendicular from the top surface, contrary to conventional edge-emitting semiconductor lasers (also called in-plane lasers) which emit from surfaces formed by cleaving the individual chip out of a wafer.
The laser diode chip removed and placed on the eye of a needle for scale A laser diode with the case cut away. The laser diode chip is the small black chip at the front; a photodiode at the back is used to control output power. SEM (scanning electron microscope) image of a commercial laser diode with its case and window cut away. The anode ...
Light is generated in a semiconductor laser by radiative recombination of electrons and holes. In order to generate more light by stimulated emission than is lost by absorption, the system's population density has to be inverted, see the article on lasers. A laser is, thus, always a high carrier density system that entails many-body interactions.
Albert Einstein proposed the stimulated emission in 1916, [1] [2] which contributed to the first demonstration of laser in 1961. [2] [3] From then on, people have been pursuing the miniaturization of lasers for more compact size and less energy consumption all the time. Since people noticed that light has different interactions with matter at ...
A distributed feedback (DFB) quantum cascade laser [25] is similar to a Fabry–Pérot laser, except for a distributed Bragg reflector (DBR) built on top of the waveguide to prevent it from emitting at other than the desired wavelength. This forces single mode operation of the laser, even at higher operating currents.
The free-electron laser FELIX Radboud University, Netherlands. A free-electron laser ( FEL ) is a fourth generation light source producing extremely brilliant and short pulses of radiation. An FEL functions much as a laser but employs relativistic electrons as a gain medium instead of using stimulated emission from atomic or molecular excitations.