A Pockels cell, also known as an electro-optic modulator, is a device commonly used in optics and photonics for manipulating the polarization of light. The half-wave voltage (V_π) of a Pockels cell refers to the applied voltage at which the Pockels cell introduces a phase shift of exactly half a wavelength (π phase shift) to an incident light beam passing through it. It is typically measured in volts (V).

When the voltage applied to the Pockels cell reaches the half-wave voltage, the device has the ability to rotate the polarization of the light passing through it by 90 degrees, effectively causing a phase shift of half a wavelength. This property is crucial in various applications such as optical communication, laser technology, and optical instrumentation, where precise control over the polarization state of light is required.

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