For PLDD, the current mainstream wavelength choice is 980nm because 980nm has been clinically proven for a long time in terms of tissue absorption and widely accepted by physicians worldwide. However, more and more doctors are trying to apply 1470nm, because 1470nm has a better water absorption rate, and the water content in the nucleus pulposus of the disc is relatively high, and even trying the dual combination of 1470nm+980nm, which continues to be well accepted by the academic community.