This study introduces an accurate design and optimisation of a passive optical code division multiple access (OCDMA) network encoder using the coupled cavity waveguide (CCW) as an optical delay line. Such CCW has the capability of providing more time delay with minimum encoder size. The proposed design and analysis are based on the two-dimensional (2D) photonic crystal (PhC) structure. Additionally, two different 2D-PhC structures are studied, in which a silicon material with an effective refractive index of 3.487 is used. The first structure is a silicon bar in air background, whereas the second one is air holes in a silicon substrate. Furthermore, the behaviour of the proposed 2D-PhC structures is studied over the wavelength, ranging from 1300 to 1600 nm. Since the structure geometry is simple with a clear operating principle, it is sufficient to use in the photonic integrated circuits. Moreover, the performance analysis of such design is investigated in terms of the bit error rate (BER) calculations. Finally, the results showed that a 21% BER performance enhancement was achieved using the optimised silicon bars in air background encoder model and this model can be utilised for the multimedia applications in the OCDMA networks.

中文翻译：

---

基于优化2D PhC无源编码器的OCDMA系统的BER性能

这项研究介绍了使用耦合腔波导（CCW）作为光延迟线的无源光码分多址（OCDMA）网络编码器的精确设计和优化。这种CCW具有以最小的编码器大小提供更多时间延迟的能力。提出的设计和分析基于二维（2D）光子晶体（PhC）结构。另外，研究了两种不同的2D-PhC结构，其中使用了有效折射率为3.487的硅材料。第一种结构是空气中的硅棒，而第二种结构是硅衬底中的气孔。此外，在1300至1600 nm的整个波长范围内研究了所提出的2D-PhC结构的行为。由于结构几何简单，操作原理明确，在光子集成电路中使用就足够了。此外，根据误码率（BER）计算研究了这种设计的性能分析。最后，结果表明，在空中背景编码器模型中使用优化的硅棒可将BER性能提高21％，该模型可用于OCDMA网络中的多媒体应用。