Electro-optic coefficient measurement of a K(H_1−xD_x)₂PO₄ crystal based on χ⁽²⁾ nonlinear optical technology

Abstract

We present a novel method utilizing the χ(2) nonlinear optical technology, which can realize high precision measurement of linear electro-optic (EO) coefficients of nonlinear materials. By applying the linear EO effect to the nonlinear optical process, the theoretical model of this measurement method was established, and the calculation formula of the linear EO coefficient was given. In the proof-of-principle experiment, by introducing an external electric field into the fourth harmonic generation (FHG) process, we comprehensively obtained the linear EO coefficients of K(H1−xD x )2PO4 crystals and revealed the relationship between deuterium content (x) and EO coefficient (γ63): γ63 = −9.789 − 16.53x. Meanwhile, the stability of FHG was greatly improved, and the angular range of efficiency stability was increased to 4.4 times in maximum. This work not only systematically demonstrates the FHG characteristics of KDP-family crystals, which provides a good reference for the deep ultraviolet laser generation, but also offers a new way to measure the basic parameters of nonlinear optical materials.

Electro-Optic Modulation of Higher-Order Poincaré Beam Based on Nonlinear Optical Crystal

“…In simulation and experiments, two 98% KD 2 PO 4 (DKDP) crystals (10 × 10 × 20 mm, θ = 90 • , ϕ = 45 • ) were employed as EO modulator [27,28]. The EO coefficient of DKDP crystal used in experiments is γ 63 = 25.8 pm/V [29]. Those optical surfaces were polished and coated antireflection films at a wavelength of 633 nm.…”

Phase Compensation Method in OPA System Based on the Linear Electro-Optic Effect

“…Measurements of the electro-optic coefficient of DKDP have been previously reported. The relationship between the deuterium content (D) and linear electro-optic coefficient (γ 63 ) is γ 63 = −9.789 − 16.53D [15]. According to the principle of linear electro-optic effect and DKDP crystal refractive index ellipsoid equation, the new principle polarization axes x' and y' are rotated 45 • around the z-axis from the original polarization axes with a constant electric field applied to DKDP along the z-direction, and thus [16] n…”

Research on the Nonlinear Absorption Coefficient of 98% Deuterated DKDP Crystal at Fourth-Harmonic-Generation Wavelength

“…KDP and deuterated DKDP crystals are one of the nonlinear optical and electro-optic crystal materials with outstanding performance such as low half-wave voltage, large nonlinear electro-optic coefficient, wide transparency range, relatively high laser-induced damage threshold (LIDT), and the unique ability to grow into a single crystal with large size, making them the only nonlinear optical crystal materials that are used in a high-power laser system for inertial confinement fusion (ICF) [1][2][3][4][5][6]. Compared with KDP crystals, DKDP crystals have a better electro-optic performance.…”