Why does the small spot size for the case (A) have small efficiency as the others? I thought the efficiency goes diverged to infinity as the radius of the cylinder gets smaller.
With a 30mm PPKTP crystal the conversion efficiency from 1064nm to 532nm is expected to 3.7 %/W.
Therefore we will have a green beam of more than 2mW by putting 700mW NPRO.
Last a couple of weeks I performed a numerical simulation for calculating the conversion efficiency of PPKTP crystal which we will have.
Here I try to mention about just the result. The detail will be followed later as another entry.
The attached figure is a result of the calculation.
The horizontal axis is the waist of an input Gaussian beam, and the vertical axis is the conversion efficiency.
You can see three curves in the figure, this is because I want to double check my calculation by comparing analytical solutions.
The curve named (A) is one of the simplest solution, which assumes that the incident beam is a cylindrical plane wave.
The other curve (B) is also analytic solution, but it assumes different condition; the power profile of incident beam is a Gaussian beam but propagates as a plane wave.
The last curve (C) is the result of my numerical simulation. In this calculation a focused Gaussian beam is injected into the crystal.
The numerical result seems to be reasonable because the shape and the number doesn't much differ from those analytical solutions.