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Semiconductor lasers (520nm, 445nm, 635nm) Semiconductor lasers (660nm, 532nm, 405nm) ... it yields the correct linewidth for any temperature or excitation density ...
A laser diode (LD, also injection laser diode or ILD or semiconductor laser or diode laser) is a semiconductor device similar to a light-emitting diode in which a diode pumped directly with electrical current can create lasing conditions at the diode's junction. [1]: 3
This allows quantum dot lasers to be fabricated to operate at wavelengths previously not possible using semiconductor laser technology. [1] One challenge in the further advances with quantum dot lasers is the presence of multicarrier Auger processes which increases the nonradiative rate upon population inversion. [ 2 ]
Laser material is radioactive. Once demonstrated in use at LLNL in 1987, room temperature 4 level lasing in 147 Pm doped into a lead-indium-phosphate glass étalon. Chromium-doped chrysoberyl (alexandrite) laser Typically tuned in the range of 700 to 820 nm Flashlamp, laser diode, mercury arc (for CW mode operation)
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.
Lasers are used in fiber-optic and free-space optical communications, optical disc drives, laser printers, barcode scanners, semiconductor chip manufacturing (photolithography, etching), laser surgery and skin treatments, cutting and welding materials, military and law enforcement devices for marking targets and measuring range and speed, and ...
If the temperature of a semiconductor Fabry–Perot laser changes, the wavelengths that are amplified by the lasing medium vary rapidly. At the same time, the longitudinal modes of the laser also vary, as the refractive index is also a function of temperature. This causes the spectrum to be unstable and highly temperature-dependent.
Essentially a narrow laser pulse generated either by semiconductor or solid state lasers is sent into the fibre and the backscattered light is analysed. From the time it takes the backscattered light to return to the detection unit it is possible to locate the location of the temperature event.