any laser guru's here?

[otispunkmeyer]

trying to do some past exam papers and there is a question about how a birefringent material can be used t stabilise a HeNe laser.

typically the notes given to us by the lecture (with the guarantee that this is all we need for the exams) dont cover birefringent materials at all, and only very briefly gloss over how a HeNe laser works.

i know that the cavity length is what determines the frequency of the light and that more than one freq is generated (althought they are modes or harmonics of the first freq) and that frequency will change slighty as it heats up.

does the birefringent material use its two refractive indexes to split off the other modes or something?

 

[jagec]

I should probably know this, but I use 'em, I don't build 'em.

A mode locker maybe? They might not work for a HeNe because it emits over such a narrow range, and it will change your CW output to a string of higher-energy pulses...