title: Direct quasi-phase-matched fourth-harmonic generation.
abstract: We have theoretically demonstrated direct fourth-harmonic generation (FHG) based on a quasi-phase-matching (QPM) configuration in periodically poled lithium niobate. The wavelength dependence of period of FHG QPM gratings is calculated. Bandwidths of fundamental wavelength, temperature, and incident angle are also studied. We find a very wide bandwidth, as large as 115 nm, of fundamental wavelength near the wavelength of 3797 nm with the QPM period of 9.73 microm. The numerical calculation shows that the conversion efficiency for QPM FHG and cascading QPM by two-step second-harmonic generation is almost identical.
authors.affiliation: Institute of Optics and Photonics, Department of Physics, Shanghai Jiao Tong University, Shanghai 200240, China. xfchen@sjtu.edu.cn
authors.forename: Xianfeng
authors.initials: X
authors.lastname: Chen
authors.forename: Yuping
authors.initials: Y
authors.lastname: Chen
authors.forename: Yuxing
authors.initials: Y
authors.lastname: Xia