How Do Pockels Cells Differ from Faraday Rotators in Polarization Control?

[SchroedingersLion]

Greetings,

another question to the Pockels Effect, maybe someone can answer this.

Pockels Cells are called "voltage controlled waveplates", since the voltage changes the birefringence of the material, leading to the same birefringence induced change of total polarisation plane than in wave plates.
However, it is known that waveplates, unlike Faraday Rotators, are reciprocal, meaning if you send a beam of light through a waveplate, let it reflect somewhere and let it pass through the plate once more, the total effect is zero.

However, in a Pockels Cell, this seems not to be the case, as one lecture slide to Q-switching of lasers via Pockels cells imply:

The lefthand side picture does imply that the effect is not reversed. So the comparison of Pockels cells with waveplates is not 100% accurate?
SL

 

[eljose79]

Dear SL,

Thank you for your question regarding the Pockels Effect. You are correct in noting that Pockels Cells are often referred to as "voltage controlled waveplates" due to their ability to change the polarization of light passing through them via the application of an electric field. However, as you have observed, there are some differences between Pockels Cells and traditional waveplates.

One key difference is that Pockels Cells are not completely reciprocal, meaning that the effect is not fully reversed when the light passes through the cell multiple times. This is due to the fact that the birefringence induced by the electric field in the Pockels Cell is not completely reversible, unlike the birefringence induced by the physical structure of a traditional waveplate.

This difference is important to consider when comparing Pockels Cells to traditional waveplates. While they both have the ability to manipulate the polarization of light, they do so in slightly different ways. Pockels Cells are better suited for applications that require fast switching of the polarization state, such as Q-switching in lasers, while traditional waveplates are better for precise control of polarization.

I hope this helps to clarify the comparison between Pockels Cells and waveplates. If you have any further questions, please don't hesitate to ask.