Crystal oscillators are loosely divided via the frequency they work at and whether or not they are basic oscillators—do the job on the frequency marked on the can or at even multiples of that (overtone oscillators). Large-repetition-amount and higher-electricity picosecond regenerative amplifier dependant on just one bulk Nd:GdVO4 crystal PDF https://www.hxcrystals.com/seokeywords/bulk-crystal-oscillator.html