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Q-switching, sometimes known as giant pulse formation or Q-spoiling, [1] is a technique by which a laser can be made to produce a pulsed output beam. The technique allows the production of light pulses with extremely high peak power, much higher than would be produced by the same laser if it were operating in a continuous wave (constant output) mode.
They are used in lasers for Q-switching, telecommunications for signal modulation, and in spectroscopy for frequency control. A piezoelectric transducer is attached to a material such as glass. An oscillating electric signal drives the transducer to vibrate, which creates sound waves in the material.
In practice, L is usually much greater than λ, so the relevant values of q are large (around 10 5 to 10 6). Of more interest is the frequency separation between any two adjacent modes q and q + 1; this is given (for an empty linear resonator of length L) by Δν = c / 2L, where c is the speed of light (≈ 3×10 8 m/s).
In this mode, the operating principle is described by the plots in figure 4: [2] When the switch pictured above is closed (top of figure 2), the voltage across the inductor is =. The current through the inductor rises linearly (in approximation, so long as the voltage drop is almost constant).
A cavity switch is a device that modulates cavity properties in the time domain. It is known as Q switching if the quality factor of cavities is under modulation. There are other properties such as the cavity mode volume, resonant frequency, phase delay, and optical local density of states can be switched or modulated.
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Space vector modulation (SVM) is an algorithm for the control of pulse-width modulation (PWM), invented by Gerhard Pfaff, Alois Weschta, and Albert Wick in 1982. [1] [2] It is used for the creation of alternating current (AC) waveforms; most commonly to drive 3 phase AC powered motors at varying speeds from DC using multiple class-D amplifiers.