Or just an HR@532nm rear coating on the KTP?
(From: Bob.) It’s not very likely you will find a piece of KTP with that kind of coating on it. To get one custom made, even if you used a ‘cheap’ piece of flux grown material, would probably be over $1,000. The dielectric optic in the pic you referenced is normally what is used to get green light out of the cavity. (From: Simon.