We use the nonlinear coupled-mode theory to theoretically investigate second-harmonic generation(SHG) in subwavelength x-cut and z-cut lithium niobate(LN) thin-film waveguides and derive the analytical formula to calc...We use the nonlinear coupled-mode theory to theoretically investigate second-harmonic generation(SHG) in subwavelength x-cut and z-cut lithium niobate(LN) thin-film waveguides and derive the analytical formula to calculate SHG efficiency in x-cut and z-cut LN thin-film waveguides explicitly.Under the scheme of optimal modal phase matching(MPM), two types of LN thin films can achieve highly efficient frequency doubling of a 1064 nm laser with a comparable conversion efficiency due to very consistent modal field distribution of the fundamental wave and second-harmonic wave with efficient overlap between them.Such a robust MPM for high-efficiency SHG in both the subwavelength x-cut and z-cut LN thin-film waveguides is further confirmed in a broad wavelength range, which might facilitate design and application of micro–nano nonlinear optical devices based on the subwavelength LN thin film.展开更多
基金supported by the National Natural Science Foundation of China (No.11974119)Guangdong Innovative and Entrepreneurial Research Team Program(No.2016ZT06C594)+1 种基金National Key R&D Program of China(No.2018YFA0306200)Dongguan Introduction Program of Leading Innovative and Entrepreneurial Talents,Guangdong Science and Technology Innovation Strategy Special Foundation (No.2019B090904007)。
文摘We use the nonlinear coupled-mode theory to theoretically investigate second-harmonic generation(SHG) in subwavelength x-cut and z-cut lithium niobate(LN) thin-film waveguides and derive the analytical formula to calculate SHG efficiency in x-cut and z-cut LN thin-film waveguides explicitly.Under the scheme of optimal modal phase matching(MPM), two types of LN thin films can achieve highly efficient frequency doubling of a 1064 nm laser with a comparable conversion efficiency due to very consistent modal field distribution of the fundamental wave and second-harmonic wave with efficient overlap between them.Such a robust MPM for high-efficiency SHG in both the subwavelength x-cut and z-cut LN thin-film waveguides is further confirmed in a broad wavelength range, which might facilitate design and application of micro–nano nonlinear optical devices based on the subwavelength LN thin film.
