I have a couple of Nd:YVO4 laser crystals I think are taken out of Coherent Verde lasers. The end faces are not plane parallel. The Verde's are pumped with large multimode fibers so the pump beam has random polarization. Because Nd:YVO4 is birefringent, the angled end faces result in two slightly different beam angles for each polarization direction of the pump. So it seems they are doing this to reject the extraordinary polarization as the resonator is only aligned to one polarization.
I think I get the mechanics of this. But I'm wondering what are the reasons for it. While absorption is not as high for the non-dominant pump polarization it still exists and can contribute to lasing. Is there a thermal or beam quality advantage to doing this? The Verde's are also frequency doubled. Does this have any downstream improvement in the beam that's fed into the doubling crystal?
Thanks for any ideas.