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The lasing threshold is the lowest excitation level at which a laser's output is dominated by stimulated emission rather than by spontaneous emission. Below the threshold, the laser's output power rises slowly with increasing excitation. Above threshold, the slope of power vs. excitation is orders of magnitude greater.
The slope efficiency is an important property of a laser. It is obtained by plotting the laser output power against the input pump power. Above the lasing threshold, the resulting curve is usually close to a straight line. The slope efficiency is the slope of this line. Slope efficiency can similarly be defined in terms of output and input ...
In laser science, an output coupler (OC) is the component of an optical resonator that allows the extraction of a portion of the light from the laser's intracavity beam. An output coupler most often consists of a partially reflective mirror , allowing a certain portion of the intracavity beam to transmit through.
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 ...
Since the pump pulses are of short duration, optical gain is only present in the laser for a short time, which results in a pulsed output. Q-switching is more commonly used for producing pulsed output from these types of laser, as pulses with much higher peak power can be achieved.
The larger output aperture of VCSELs, compared to most edge-emitting lasers, produces a lower divergence angle of the output beam, and makes possible high coupling efficiency with optical fibers. The small active region, compared to edge-emitting lasers, reduces the threshold current of VCSELs, resulting in low power consumption.
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For the Hakki–Paoli method, [8] the semiconductor laser has to be operated below the laser threshold. Then, the spectrum of the emitted ASE is strongly governed by the Fabry–Pérot modes of the diode laser resonator. If the length of the device and the reflectivities of the facets are known, the gain can be evaluated from the maxima and the ...