# Design of Novel Fiber Optical Flexible Routing System
## 2 Configuration and Operating Principle of the Proposed Optical Routing System  
The diagram of the proposed optical routing system is shown in Figure 1. In this configuration, two pairs of \(8\times 8\) AWGs with 100 GHz channel spacing, \(11\)\(2\times 2\) cross/bar optical switches (SWs), two optical couplers, and eight optical circulators (OCs) were used to construct the all optical routing system. Table 1 lists the spectral routing rule of \(8\times 8\) AWG. In the proposed router, we can adjust the status of optical switches SW1, SW2 and SW3 to implement the interleaver, OXC, or ROADM functions. The optical switch statuses of the various functions of the proposed optical routing system are shown in Table 2. Then we placed eight optical switches and corresponding signal wavelength channels on the right side of the AWG3 and AWG4 to determine the optical wavelength routing function that is allowed to pass through or be dropped. For optical switches numbered SW4 to SW11, when the optical switch is in the cross status, the signal will be dropped to drop port. If the optical switch is in the bar status, the signal will be passed to the output port. From Table 2, if we want the router to perform the functions of interleaver and de-interleaver, we must set SW1, SW2, and SW3 to the bar statuses. In Figure 1, when channel 1 (\(\lambda_{1}\)) to channel 8 (\(\lambda_{8}\)) are input from input port 1 of AWG1, the odd and even channels will come out from port 8 and port 2 on the right side of AWG2, respectively. Then, the odd channels will pass through SW1, OC3, \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multicolumn{8}{c}{Input Port} \\ \hline  & 1 & 2 & 3 & 4 & 5 & 6 & 7 & 8 \\ \hline  & 1 & 3\({}_{1}\) & 3\({}_{2}\) & 3\({}_{3}\) & 3\({}_{4}\) & 3\({}_{4}\) & 3\({}_{4}\) & 3\({}_{4}\) \\  & 2 & 3\({}_{1}\) & 3\({}_{2}\) & 3\({}_{3}\) & 3\({}_{4}\) & 3\({}_{4}\) & 3\({}_{4}\) & 3\({}_{4}\) \\ Output Port & 4 & 3\({}_{1}\) & 3\({}_{2}\) & 3\({}_{3}\) & 3\({}_{4}\) & 3\({}_{4}\) & 3\({}_{4}\) & 3\({}_{4}\) \\  & 5 & 3\({}_{2}\) & 3\({}_{3}\) & 3\({}_{4}\) & 3\({}_{4}\) & 3\({}_{4}\) & 3\({}_{4}\) \\  & 6 & 3\({}_{2}\) & 3\({}_{3}\) & 3\({}_{4}\) & 3\({}_{4}\) & 3\({}_{4}\) & 3\({}_{4}\) \\  & 7 & 3\({}_{1}\) & 3\({}_{2}\) & 3\({}_{3}\) & 3\({}_{4}\) & 3\({}_{4}\) & 3\({}_{4}\) \\  & 8 & 3\({}_{1}\) & 3\({}_{2}\) & 3\({}_{2}\) & 3\({}_{2}\) & 3\({}_{2}\) & 3\({}_{2}\) & 3\({}_{2}\) \\ \hline \hline \end{tabular}
\end{table} 
Table 1: \(8\times 8\) cyclic AWG routing rule. Figure 1: The configuration of proposed optical routing system. OC = optical circulators, AWG = arrayed waveguide gratings, SW = optical switches. \begin{table}
\begin{tabular}{c c c c} \hline \hline \multicolumn{2}{c}{**Routing Function**} & \multicolumn{3}{c}{**Switch Status**} \\ \cline{2-4}  & **SW1** & **SW2** & **SW3** \\ \hline Interleaver & Bar & Bar & Bar \\ \hline OXC\({}^{*}\) & Cross & Bar & Bar \\ \hline ROADM\({}^{**}\) & Bar & Cross & Cross \\ \hline \hline \end{tabular} \({}^{*}\)Optical cross-connect, **Reconfigurable optical add/drop multiplexers.**  
\end{table} 
Table 2: Optical switch statuses of the proposed optical routing system. and SW3 to reach the output port 2, and the even channels will reach the output port 1 via SW1, OC1, and SW2 to implement the de-interleaver function. When we want to combine two sets of even and odd channels, we can input even and odd channels from input port 2 and input port 3 of the AWG2, respectively. These channels will be combined at output port 3 of AWG1 for interleaver functionality. As can be seen from Table 2, when SW1 is in the cross status and SW2 and SW3 are in the bar statuses, we can perform the OXC function. Because the even channels from port 2 on the right side of AWG2 will reach the OC3 by the cross status of SW1, and then go to output port 2 from the bar status of SW3.