Slow light is emerging as a promising approach for applications where the dynamic control of the delay is required, such as data synchronization, time multiplexing, and data storage . Coupled-resonator optical waveguides (CROWs)  have exhibited advantageous features like on-chip integration, delay tunable, large bandwidth, and transparency to modulation format, and so on. The numerical simulation for CROWs from the device level requires too much simulation resource and is not realistic. It is mainly done with circuit-level tools, such as OptSim, based on analytical or measurement coupling coefficients. Using the S-Matrix utility combined with OptSim Circuit, the design and optimization of CROWs can be realized with a device-level numerical approach.
Figure 1 shows a top view of fabricated CROWs . It consists of eight ring resonators with a radius of 20µm. The silicon waveguide has a 480x220nm^2 cross-section and is buried in a silica cladding. Note that the yellow parts depict the heating wire for modulation (not modeled in this simulation).