bassurgery use optical pickups on there basses, have a look at there site. Ive never heard of them being used for guitars tho.
I would reccomend EVERYONE to look at that site - there instruments are increadable, and the guy makes them all (electronics included) and they are without doubt the best playing basses I have ever tried - shame they start at about £7,000 (or $12,500). Go and druel people