Ta'eed Vahid, Moss D, Eggleton B, Freeman D, Madden S, Samoc M, Luther-Davies B, Janz S, Xu D
Opt Express. 2004 Oct 18;12(21):5274-84. doi: 10.1364/opex.12.005274.
We report the first Bragg gratings fabricated by Focused Ion Beam milling in optical waveguides. We observe striking features in the optical transmission spectra of surface relief gratings in silicon-on-insulator waveguides and achieve good agreement with theoretical results obtained using a novel adaptation of the beam propagation method and coupled mode theory. We demonstrate that leaky Higher Order Modes (HOM), often present in large numbers (although normally not observed) even in nominally single mode rib waveguides, can dramatically affect the Bragg grating optical transmission spectra. We investigate the dependence of the grating spectrum on grating dimensions and etch depth, and show that our results have significant implications for designing narrow spectral width gratings in high index waveguides, either for minimizing HOM effects for conventional WDM filters, or potentially for designing devices to capitalize on very efficient HOM conversion.
我们报道了首次通过聚焦离子束铣削在光波导中制造的布拉格光栅。我们在绝缘体上硅波导中的表面浮雕光栅的光传输光谱中观察到显著特征，并与使用光束传播方法和耦合模理论的新颖改编获得的理论结果取得了良好的一致性。我们证明，即使在名义上的单模脊形波导中通常大量存在（尽管通常未被观察到）的泄漏高阶模（HOM），也会极大地影响布拉格光栅的光传输光谱。我们研究了光栅光谱对光栅尺寸和蚀刻深度的依赖性，并表明我们的结果对于在高折射率波导中设计窄光谱宽度光栅具有重要意义，这既可以用于最小化传统波分复用（WDM）滤波器的HOM效应，也可能用于设计利用非常高效的HOM转换的器件。
