KTiOPO4, referred to as KTP, crystal grown by the hydrothermal method is a very good performance of nonlinear optical crystal, with large nonlinear coefficient, Broad range of temperature and angle compatibility, High laser damage threshold, High stability of chemical, mechanical, and other characteristics. It can be used in laser frequency doubling, sum frequency, difference frequency, parametric oscillation, optical waveguide devices, electro-optical modulators, etc., and is widely used in military scientific research, bio-medical, Submarine optics, Military and environmental remote sensing, and other fields.