Just found this is quite interesting. We can use a $30 non-linear crystal to produce a green 532nm beam at high frequency with a simple fiber laser (this laser costed us $1000).
The energy per pulse is not much though; it is rated at 1mJ/pulse @ 1064nm and I reckon the conversion efficiency is sub-40% for this crystal setup.
Regardless, thought this would be interesting to share =)
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https://www.youtube.com/watch?v=qVVZ0Fgoc_g