Q Factor - Optical Systems

Optical Systems

In optics, the Q factor of a resonant cavity is given by


Q = \frac{2\pi f_o\,\mathcal{E}}{P}, \,

where is the resonant frequency, is the stored energy in the cavity, and is the power dissipated. The optical Q is equal to the ratio of the resonant frequency to the bandwidth of the cavity resonance. The average lifetime of a resonant photon in the cavity is proportional to the cavity's Q. If the Q factor of a laser's cavity is abruptly changed from a low value to a high one, the laser will emit a pulse of light that is much more intense than the laser's normal continuous output. This technique is known as Q-switching.

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