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From: Winfield Hill
Subject: laser diode operating range
Date: 18 Nov 2002 18:42:56 -0800
Organization: Rowland Institute
X-Newsreader: Direct Read News 4.11
Generally laser diodes are used with light-feedback servo-mode circuits.
That is mandated because of the rather dramatic increase in light level
that occurs above the "threshold" voltage, where true lasing begins and
takes over the light emission from simple LED action.
Consider applications where a variable range of light is required. Using
laser diodes with light servos tempts one to use the servo mode to achieve
the needed variable light intensity. However, often the laser diode's
threshold is a substantial fraction of the maximum power, 25% or more.
This can create possible unpredictable operation. If one servos close
to the threshold where coherent narrow-wavelength emission ceases, one
might as well have purchased an inexpensive LED. :-)
So one question is, what are typical lasing thresholds as a fraction of
the full laser power? How about for different laser diode wavelengths?
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