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What is Vπ?
(Half-Wave Voltage)
Vπ (Half-Wave Voltage) is the voltage required to produce a π radians (180°) phase shift in an optical signal passing through an electro-optic modulator. It is a key parameter used to characterize the efficiency of an optical modulator.
A lower Vπ means that a smaller electrical voltage is required to achieve the same phase shift, which can enable lower-power and more efficient modulation.
HOW Vπ Works
Vπ describes the relationship between the applied electrical voltage and the optical phase shift produced by an electro-optic modulator. It depends on the electro-optic material, device geometry, electrode design, and operating wavelength.
Voltage applied
An electrical voltage is applied to the electrodes of the modulator.
Phase shift
The resulting electric field changes the refractive index of the electro-optic material, modifying the phase of the propagating light.
π phase shift
When the applied voltage reaches Vπ, the relative optical phase shift reaches π radians, corresponding to a half-wave phase shift.
