Theoretical analyses and optimizations for wavelength conversion by quasi-phase-matching difference frequency generation
Theoretical analyses and optimizations for wavelength conversion by quasi-phase-matching difference frequency generation
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DOI：
10.1109/50.964081
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发表时间：
2001-11
影响因子：
4.7
通讯作者：
Xueming Liu;Hanyi Zhang;Yili Guo
中科院分区：
文献类型：
--
作者：
Xueming Liu;Hanyi Zhang;Yili Guo
在未耗尽泵浦近似下，对基于准相位匹配差频产生（DFG）的转换效率/spl eta/和带宽/spl Delta//spl lambda/进行了详细的理论研究，并得到了它们的表达式。理论结果表明，对于均匀光栅，/spl λ /随L的对数增加，而在完全相位匹配下/spl δ //spl λ /减小。相反，当/spl δ /达到最小值时，在不完全相位匹配下，与二阶非线性、泵浦和信号功率无关的带宽/spl δ //spl λ /达到最大值。本文首次得到了典型DFG过程中任意啁啾QPM光栅的/spl eta/表达式。分别给出了二段、三段和四段啁啾光栅的优化实例。数值优化结果表明，啁啾光栅中的泵浦和信号带宽/spl δ //spl λ /均有明显的增宽，但/spl δ //spl λ /可能略有减小，并且随着段数的增加，/spl δ //spl λ /会增大。
Under the undepleted-pump approximation, the conversion efficiency /spl eta/ and bandwidth /spl Delta//spl lambda/ based on quasi-phasematching (QPM) difference frequency generation (DFG), are theoretically studied in detail and their expressions are obtained. The theoretical results show that, for the uniform grating, /spl eta/ logarithmically increases with L, whereas /spl Delta//spl lambda/ decreases under the perfect phase matching. Contrarily, when /spl eta/ reaches the minimum, the bandwidth /spl Delta//spl lambda/, which is independent of the second-order nonlinearity, the pump, and the signal power, reaches the maximum under the imperfect phase matching. The expression of /spl eta/ for the arbitrary chirp QPM grating in the typical DFG process is obtained in this paper for the first time. Optimized examples for two-, three-, and four-segment chirp grating are given, respectively. The numerically optimized results show that both the pump and signal bandwidth /spl Delta//spl lambda/ can apparently be widened in the chirp grating although /spl eta/ may decrease a little, and that, with the adding of segment numbers, /spl Delta//spl lambda/ can increase.