Crystal oscillators are loosely divided because of the frequency they work at and whether or not they are fundamental oscillators—get the job done in the frequency marked over the can or at even multiples of that (overtone oscillators). We existing a Nd:GdVO4 bulk crystal oscillator with >70 WTEM00 laser output https://www.hxcrystals.com/seokeywords/bulk-crystal-oscillator.html