Cool thx for the help. Ya i couldnt pass that 3.5x3.5x6mm high efficiency ktp up. Only $26 so im happy about that. Afew more quick questions. I get the corner to corner thing so can I put my open can diode right super close to the corner for efficiency? Also can I have my two crystal touching just like a DPM style? Also what do you mean by output coupler?
Ok so here's the deal. If you use a bonded crystal set you can only get so much power. I think 200mW is about the maximum if you get a good set and pump them hard. The 'mirrors' on these bonded crystal sets are just coatings at one end of the ktp and one end of the vanadate (ND:YVO4). These 'coatings' are equivalent to flat mirrors, or mirrors without any radius of curvature. In the case of these tiny crystal sets, flat mirrors work becuase the cavity is so short that your energy density stays fairly high because the beam doesn't get much of a chance at all to diverge. Overall cavity length is only about ~2.5mm.
When you start using bigger components, such as a longer KTP and a thicker ND:YVO4, you can start making much more power. Unfortunately these do NOT come in 'bonded' sets with 'mirrors' (reflective coatings) built in (well, the high reflective mirror is built in, more on this later). The only coatings these larger crystals have are anti-reflective coatings to allow light to pass without losses.
So since these larger crystals will have a much longer cavity length, usually somewhere around 1-2cm on your 'averge' linear cavity design which can make up to around 500mW, your 1064nm beam (from the YVO4) will be able to diverge within the cavity and lose it's power density, which is bad for frequency doubling. The way to overcome this is to use an output coupler with a radius of curvature, rather than a flat mirror or coating. This output coupler allows 532nm light to exit, but it keeps the 1064nm light in the cavity to allow lasing to continue. ALso, since it is radiused, it focuses the light back down to maintain a higher energy density inside the doubling crystal. In this type of cavity design, you can still use one flat mirror. The flat mirror (or HR mirror) is built into the back of the ND:YVO4 in the form of a coating, much like the bonded crystal sets. It allows the 808nm pump light to enter, but is high reflective for 1064nm and 532nm, forming the high reflective end of the cavity.
I hope that helps!!! The hardest part about this kind of cavity is getting your output coupler aligned. It is VERY VERY VERY VERY VERY sensitive and requires some sort of precision adjustable mount.
Oh yeah, you do not want your crystals touching. They should be spaced apart. By corner to corner, I just mean that you USUALLY want your crystals tilted 45 degrees from the plane of the pump diode.
What kind of diode do you plan on using to pump these? I can tell you now that the KTP you have may be a bit too big for the power you are wanting to make. I mean it will still probably work, but something like 2x2x4mm might be better. Those big KTP's are meant for making a lot of power, and if that is your goal you are going to need a much more complicated cavity design.
