Pockels effect
The effect Pockels is the appearance of a Biréfringence in a medium created by a Electric field static or variable. The birefringence which appears is proportional to the electric field, contrary to the Effet Kerr where it is proportional to the square of the field. The Pockels effect appears only in the crystals without symmetry compared to an axis, like the Niobiate of lithium or the Gallium arsenide.
Friedrich Carl Alwin Pockels studied this effect, which bears its name now, in 1893.
The Pockels cell
The Pockels effect is used to make cells Pockels . They are blades with delay controlled thanks to the electric field applied to the crystal.
This control makes it possible to carry out a Modulation Luminous intensity crossing the cell with a characteristic time about the Nanoseconde.
These Pockels cells, because of their Constant dielectric raised, behave like a condensing .
Applications of the Pockels effect
The Pockels cells have a current application and perhaps a future application:
- the return of the light in a laser Cavité can be eliminated by using a polarizing prism. That makes it possible to obtain a very short and very intense laser impulse.
- a Pockels cell has also applications in quantum Cryptographie.
See too
- Modulating electro-optics
- Modulating acousto-optics
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