Amplification assisted difference frequency generation for efficient mid-infrared conversion based on monolithic tandem lithium niobate superlattice

We report the investigation on the performance of an amplification assisted difference frequency generation(AA-DFG) system driven by pulsed pump and continuous-wave primary signal lasers. A monolithic tandem lithium niobate superlattice was employed as the nonlinear crystal with a uniform grating section for the DFG process, followed by a chirp section for the optical parametric amplification process. The impacts of pump pulse shape, primary signal power, input beam diameter, and crystal structure on the pump-to-idler conversion efficiency of the AA-DFG system were comprehensively studied by numerically solving the coupled wave equations. It is concluded that square pump pulse and high primary signal power are beneficial to high pump-to-idler conversion efficiency. In addition, tighter input beam focus and smaller DFG length proportion could redeem the reduction in conversion efficiency resulting from wider acceptance bandwidths for the input lasers. We believe that such systems combining the merits of high stability inherited from cavity-free configuration and high efficiency attributed from the cascaded nonlinear conversion should be of great interest to a wide community,especially when the pulse shaping technique is incorporated.

Lu Xun, Shin Eon-jun, and Karashima Takeshi

Shin Eon-jun and Karashima interacted with Lu Xun during a similar period but their relationships with him proceeded in different directions. Shin Eon-jun participated in the independence movements in Korea, introduced Lu Xun from the progressive position, and actively reported the political situation and philosophical trends in China. On the other hand, Karashima put his major focus on Lu Xun and left wing literature, when introducing the new literature of China, but gradually revealed an opportunistic attitude and actively participated in promoting Japan＇s ＂National Policy.＂