Crystal oscillators are loosely divided via the frequency they do the job at and whether or not they are essential oscillators—work at the frequency marked around the can or at even multiples of that (overtone oscillators). We existing a Nd:GdVO4 bulk crystal oscillator with >70 WTEM00 laser output determined by https://macrobookmarks.com/story19094005/the-2-minute-rule-for-bulk-crystal-oscillator