Improving the performance of Mach-Zehnder interferometer with the dispersion response of the add-drop ring resonator

We use the add-drop ring resonator (ADRR) to produce the normal and anomalous dispersion simultaneously and apply these two dispersion responses to enhance the sensitivity of the Mach-Zehnder interferometer (MZI). To estimate the sensing ability of the ADRR assisted MZI, the dispersion sensitivity of the structure is theoretically and experimentally demonstrated. For two equal amplitude coupling coefficients, a 19.2-fold increase in the dispersion sensitivity is experimentally achieved, a little lower than 19.5-fold predicted in theory. This value can be futher increased by minimizing the attenuation or by choosing different amplitude coupling coefficient settings at different coupling regions. To acquire better dispersion sensitivity, only output port one should be utilized at the over-coupling region, and two output ports should be adopted at the under-coupling region.