Ahn Tae-Jung, Azaña José
Department of Photonic Engineering, Chosun University, 375 Seosuk-dong, Gwangju, South Korea.
Opt Express. 2011 Apr 11;19(8):7625-32. doi: 10.1364/OE.19.007625.
Wavelength-selective directional couplers with dissimilar waveguides are designed for ultrafast optical differentiation within the femtosecond regime (corresponding to processing bandwidths > 10 THz). The theoretically proposed coupler-based differentiators can be produced by wavelength matching of the propagation constants of two different waveguides in the coupler at the center wavelength. A single directional coupler can be designed to achieve either a 2nd-order differentiator or a 1st-order differentiator by properly fixing the product of coupling coefficient and coupling length of the coupler. We evaluated the differentiation errors (2%) and energetic efficiency (11% for 1st order differentiation) of the designed optical differentiators through numerical simulations. The proposed design has a strong potential to provide a feasible solution as an integrated differentiation unit device for ultrafast optical signal processing circuits.
具有不同波导的波长选择定向耦合器专为飞秒范围内的超快光学微分而设计（对应于处理带宽>10太赫兹）。理论上提出的基于耦合器的微分器可以通过耦合器中两个不同波导在中心波长处的传播常数的波长匹配来制造。通过适当地固定耦合器的耦合系数和耦合长度的乘积，可以设计单个定向耦合器以实现二阶微分器或一阶微分器。我们通过数值模拟评估了所设计的光学微分器的微分误差（约2%）和能量效率（一阶微分为约11%）。所提出的设计具有很强的潜力，可为超快光信号处理电路提供一种可行的集成微分单元器件解决方案。
