One of the mysteries of the English language finally explained.
The process of pumping a laser that has a low Q, and so cannot oscillate, and then suddenly increasing the Q so that the stored energy is released in a single pulse of very high power; the use of a Q-switch.
1960s; earliest use found in Journal of Applied Physics. Partly from Q + switching, and partly from either Q-switch or Q-switch + -ing.
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