Birefringent walk off question

[quackyneudle]

Hi,
I am having trouble wrapping my head around a simple (I think?) question about birefringent walkoff:

If the crystal is oriented at some angle such that walkoff is nonzero between e and o beams (in a nonlinear conversion process, for example), it seems to me that reflecting the light straight back after it exits should have the e beam walkoff in the opposite direction as before i.e. towards the o beam, and "compensated". But, I haven't been able to convince myself of this by drawing pictures. Can anyone help provide an explanation about whether this is correct of not, whether through math or visual argument?

Thanks!

 

[quackyneudle]

<Moderator's note: Post merged from another thread>

Hi,
I am trying to reason out whether when one reverses the sign of k, does the angle between k_e and S_e (wavevector experiencing extraordinary refraction, extraordinary Poynting vector) change in sign. In other words, if a reflect back with a normal-incidence mirror a beam experience extraordinary index of refraction, will it return to the same point at which it entered the crystal?

I am asking this in the context of nonlinear optics (OPG), and wondering whether double-passing a pump beam through a crystal will compensate for walkoff.

Thanks!

 

[Andy Resnick]

Hi,
I am having trouble wrapping my head around a simple (I think?) question about birefringent walkoff:

If the crystal is oriented at some angle such that walkoff is nonzero between e and o beams (in a nonlinear conversion process, for example), it seems to me that reflecting the light straight back after it exits should have the e beam walkoff in the opposite direction as before i.e. towards the o beam, and "compensated". But, I haven't been able to convince myself of this by drawing pictures. Can anyone help provide an explanation about whether this is correct of not, whether through math or visual argument?

Thanks!

If I understand your question, you are asking about 'reciprocity'. Some polarization-dependent devices, such as a Faraday isolator, are not reciprocal. Use of a phase-conjugate mirror instead of a 'normal' mirror restores reciprocity, and so that technology has been used, for example, to correct aberrations.

Does that help?