Crystal oscillators are loosely divided by the frequency they work at and whether they are fundamental oscillators—get the job done on the frequency marked on the can or at even multiples of that (overtone oscillators). We existing a Nd:GdVO4 bulk crystal oscillator with >70 WTEM00 laser output according to the https://nimmansocial.com/story8744627/what-does-bulk-crystal-oscillator-mean