# Design and Modelling of a Novel Integrated Photonic Device for Nano-Scale Magnetic Memory Reading
## 3 Results and Discussion  
In order to demonstrate the magnetic memory reading capabilities of our devices, the mathematical model described in Section 2.2 was used. As explained in Section 2.1, the chosen \begin{table}
\begin{tabular}{c c} \hline \hline
**Parameter** & **Value** \\ \hline \(\lambda\) & 1465–1495 nm \\ \(Loss_{\text{avg}}\) & 3 dB/cm \\ \(n_{\text{TE}}\) & 2.012 \\ \(n_{\text{TM}}\) & 1.809 \\ \hline
**Parameter** & **Value** \\ \hline \(L_{1}\) & 1386 \(\upmu\)m \\ \(L_{2}\) & 462 \(\upmu\)m \\ \(x_{\text{PC}}\) & 200 \(\upmu\)m \\ \(x_{\text{clad}}\) & 100 \(\upmu\)m \\ \hline
**Parameter** & **Value** \\ \hline \(Loss_{\text{clad.}}\) & 0.13 dB/50 nm \\ \(Loss_{\text{GCTE-TTE}}\) & 1.5 dB \\ \(\phi\) & \(\pm\)0.2\({}^{\circ}\) \\ \(\phi\) & \(\pm\)0.2\({}^{\circ}\) \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Showing generic parameters that are valid for all devices. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Parameter** & **Standard Device** & **Reduced Performance** & **Noise + Reduced Performance** \\ \hline \(\alpha\) & 90\({}^{\circ}\) & 45\({}^{\circ}\) & 45\({}^{\circ}\) \\ \(Loss_{\text{GCTM-TM}}\) & 1.5 dB & 7 dB & 7 dB \\ \(Ext_{\text{GCTM-TTE}}\) & 50 dB & 28 dB & 28 dB \\ Noise & none & none & 10.7 dB (SNR) \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Showing parameters that are dependent on the device performance. devices were unbalanced interferometers that contain built-in ferromagnetic memory components as their top claddings. The model predicted the output light intensity vs. wavelength plots of the devices with opposing memory bits (bit '1' and '0'). Later these plots were analyzed by the Fourier transformation technique to determine the memory bit type, thus realize'reading' of the magnetic information. Recall that since the magneto-optic interaction which enables the determination of the memory bit type is only extractable from the phase of the \(TM\) mode (when \(TE\) mode is used as input), Fourier technique greatly reduced the noise and enhanced the sensitivity. In Figure 2, the left column plots present output light intensity vs. wavelength data. Note that plots depict the intensity after a windowing function is applied. The right column plots show the Fourier transformation of the left column in blue color and the phase difference between two memory bit states for each oscillatory components in red color. Figure 2a,c,e represent the standard, reduced-performance and noisy reduced-performance devices, respectively. The standard device shown in Figure 2a demonstrate a clear 180\({}^{\circ}\) phase shift between the two signals which correspond to the opposite memory states. The Fourier transformation in Figure 2b (right side y-axis) show a single peak which correspond to the \(TM\) mode (see Equation (2)). The fact that there is only \(TM\) mode is thanks to the well-performing \(TM\)-selective out-couplers in the standard devices that have a negligible out-coupling of the \(TE\) mode. As expected, the phase difference plot in Figure 2b (left side y-axis) indicate 180\({}^{\circ}\) difference at the region which correspond to \(TM\) peak. Note that the plots depicting phase difference between two memory states convey meaningful information only at the locations where a correspondent Fourier peak is present. To stress this aspect visually in the graph, the points corresponding to a peak are shown in black, whereas the rest is left grey. In Figure 2c, the'reduced-performance device' is seen. This device has only 45\({}^{\circ}\) conversion at the polarization converter and the \(TE\)-mode couples out from the \(TM\)-selective out-coupler (see Table 3). Due to coupling out of the \(TE\) mode that does not carry information on the memory bit's state, it impossible to observe a 180\({}^{\circ}\) phase shift in the intensity vs. wavelength plot upon a change in the memory bit type. As expected, Figure 2d reveals two Fourier peaks that correspond to \(TE\) and \(TM\) modes.