Pulse response of nonlinear multimode interference couplers
Pulse response of nonlinear multimode interference couplers
复制标题
非线性多模干扰耦合器的脉冲响应
DOI：
10.1109/jqe.2014.2307922
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发表时间：
2014
期刊：
影响因子：
--
通讯作者：
K. Ogusu and H. Li
中科院分区：
文献类型：
--
作者：
Tsubasa Tobe;Ryota Kojima,Yasuo Kimura;and Michio Niwano;K. Ogusu and H. Li
利用广义非线性薛定谔方程，数值研究了由克尔材料制成的多模干涉耦合器中短光脉冲的开关动力学。这些传播方程包含四波混频（FWM）以及自相位和交叉相位调制和不同阶的色散，以正确地描述多模波导部分中的非线性传播。四波混频效应比自相位调制和交叉相位调制效应更显著，导致波导中各模之间的功率交换。在数值模拟中，2 × 2 MMI耦合器被视为近双模干涉（TMI）耦合器。对于长TMI耦合器，在相对窄的输入功率范围内发生多个切换。还发现由于模色散（即，群延迟差）和当输入脉冲的持续时间极短（通常为亚皮秒）时的FWM效应。通常，非线性TMI耦合器的开关特性类似于非线性定向耦合器的开关特性。
The switching dynamics of short optical pulses in a multimode interference (MMI) coupler made of Kerr materials are numerically investigated using generalized nonlinear Schrödinger equations. These propagation equations contain four-wave mixing (FWM) as well as self-phase and cross-phase modulation and dispersion of different orders to properly describe the nonlinear propagation in the multimode waveguide section. The FWM effects are more dominant than those of self-phase and cross-phase modulation, which cause power exchange among the modes in the waveguide. In numerical modeling, a 2 × 2 MMI coupler is treated to operate as a nearly two-mode interference (TMI) coupler. For long TMI couplers, multiple switching takes place in a relatively narrow range of input powers. It is also found that the transmitted pulse becomes unstable because of the interplay between the modal dispersion (i.e., the group-delay difference) and the FWM effect when the duration of the input pulse is extremely short (typically sub-picoseconds). In general, the switching characteristics of the nonlinear TMI coupler are similar to those of a nonlinear directional coupler.