Bulk defect formations in KH₂PO₄ crystals investigated using fluorescence microscopy

Defect formations located in the bulk of KH₂PO₄ crystals are studied using a specially designed microscopic fluorescence imaging system. The concentration of the observed defect clusters varies depending on the crystal-growth method, the growth sector of the crystal, and the speed of growth. The experimental procedure involves acquisition of high-resolution fluorescence images of bulk defect cluster formations obtained under cw, 488-nm photoexcitation. Annihilation and/or passivation of these defects is observed under exposure of the crystal to high-power, 355-nm laser irradiation. This work suggests that native defects can influence the optical performance and characteristics of potassium dihydrogen phosphate.