“…Lithium niobate has become an important optical material because of its numerous advantages, such as high electro-optic coefficient, high second-order nonlinear coefficient and can be fabricated into waveguide et al [2][3][4] . Therefore, it has been widely used in electro-optic modulating [5][6][7] , signal processing [8][9][10][11][12][13][14] and electromagnetic field sensing [15][16][17][18] . Particularly, the optical parametric amplifiers (OPAs) based on second-order optical nonlinear effects have attracted great attention, owing to the advantages of all-optical amplifying, low noise and easy to integrate [19][20][21] .…”