KDP (Potassium dihydrophosphates, KH2PO4)
Potassium dihydrogen phosphate (potassium phosphate, dibasic potassium, KDP crystal) KH2PO4 is a synthetic colorless crystal grown from aqueous solutions of the KH2PO4 salt by the method of slowly lowering T in static and dynamic modes.
KDP is a uniaxial negative single crystal, it is a ferroelectric with a TCurie of 122 K. It has a high linear electro-optical effect when an electric field is applied along the Z (001) axis.
It dissolves well in hot water, gasoline, ethyl alcohol. Does not dissolve in acetone.
It is used to create oriented elements for light modulators, light gates for generating giant pulses of solid-state lasers, orthogonal switches for polarization light, discrete light deflectors, nonlinear laser radiation frequency converters, etc. (up to 10 GHz, then tg e increases significantly).
Disadvantages: KDP - low mechanical strength; high hygroscopicity; do not work at l>1.5 microns; low crystal growth rate, about 5·10-2 mm/hour.
optical axes = 21.020 ( f =102 108), tg from 0.0170 to 0.0005;
optical axes = 44.544.3 (f = 102 108), tg from 0.0098 to 0.0005, with lworks = 0.41.5 µm.