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发表于 2008-10-17 14:18:36
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© Dr. Rüdiger Paschotta
Last update: 2008-06-30
Four-level and Three-level Gain Media previous | next | feedback
Ask RP Photonics for advice on any aspects of quasi-three-level lasers. Definition: laser gain media without/with reabsorption from the lower laser level
Optical amplification in the gain medium of a laser or laser amplifier arises from stimulated emission, where the input light induces transitions of laser-active ions from some excited state to a lower state.
Three-Level Systems
In a three-level system, the laser transition ends on the ground state. The unpumped gain medium exhibits strong absorption on the laser transition. Only by pumping more than half of the ions (or atoms) into the upper laser level do a population inversion and consequently net laser gain result; the threshold pump power is thus fairly high.
从这段话看不像是电子阿 |
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发表于 2008-10-16 11:45:53
