Research On The Electro-Optic Effect And Nonlinear Optical Frequency Conversion Technology Of KTP Crystal

KTiOPO4 (KTP) crystal is a well-known nonlinear optical crystal. With the excellent merits of large nonlinear optical coefficients, high damage threshold, high optical transmission in the visible and near-infrared spectral regions, thermally stable phase-matching, wide acceptance angle and nonhygroscopy, KTP crystal is widely used in nonlinear optical fields such as second harmonic generation (SHG), sum frequency generation (SFG), difference frequency generation (DFG) and optical parametric oscillation (OPO). On the other hand, KTP crystal is a superior electro-optic (EO) medium, which has large linear EO coefficients, low dielectric constant, and no piezoelectric effect. It is also used successfully in EO modulators, Q-switches, and EO waveguides. The main content and innovative points in the dissertation can be summarized as follows:1. The development and growth methods of KTP crystal are introduced. Make a detailed summary of various nonlinear optical applied areas for the KTP crystal, such as SHG, SFG, DFG, OPO and electro-optic devices.2. An analysis is made for KTP crystal about its linear electro-optic effect and frequency doubling. A method of precisely calculating the external applied voltage and the optimum type-II phase matching angles for KTP crystal, which is simultaneously used as Q-switch and SHG device, is presented.3. We have studied the dynamical properties of the intracavity optical parametric oscillator. The temporal evolutions of the population inversion and of the pump and signal intracavity powers are modeled by a simple system of coupled equations. Numerical simulations show that the optical parametric oscillator can produce one or several pulses, depending on the signal cavity reflective, which provides the basis for realizing high power in the cavity and the high energy conversion efficiency.4. A simple V-fold cavity is analyzed by transmission matrix and numerical calculation. We have selected a set of proper cavity parameters for Nd:YVO4/KTP V-fold cavity structure which can be used readily by operating at high power levels with low threshold and high efficiency. 2.93W continuous-wave green laser has been obtained at a 12.9W pumping power and with an optical-optical conversion efficiency of 22.7%.