Optimizing Superposition of Laser Beams Using Polarizing Beam Splitters

[cks]

I want to superpose two laser beams to create the beat frequency.

I design the system to be like this .

Two laser beams come from A and B meet at the center of the PBS, so that two laser beams going out to C and D. I tune the laser beams A and B such that the laser output at C and D superimpose. In mathematical terms.

E1=Aexp[i(k1x-w1t)]
E2=Bexp{i(k2x-w2t)]

So, the superimposed state is

E=E1+E2.

My problem is, I use a polarizing beam splitter. so the output laser beam have electric field that are orthogonal to each other. It'd be nice if I can get parallel E field so that the superposition would be much better.

How can I do that. How can I make the two orthogonal electric field to be parallel to each other?

 

[Redbelly98]

Use a non-polarizing, 50/50 beam splitter. And adjust the beams so that they have the same polarization.

 

[cks]

I have found the solutions.

Just put a half-wave plate and a PBS after the PBS.

 

[Redbelly98]

So the wave plate rotates the polarization to be at 45 degrees before going into the 2nd PBS? Nice.