Surface Plasmon Polariton Band Gap-Enabled Plasmonic Mach–Zehnder Interferometer: Design, Analysis, and Application

In this paper, we propose a design for surface plasmon polariton band gap (SPPBG)-enabled plasmonic Mach–Zehnder interferometer (PMZI) comprising of array of silver nanorods embedded upright into silicon on insulator (SOI) substrate and analyze its potential in sensing, intended for cancer therapy. Periodic arrangement of nanorods embedded into SOI substrate grants strong spatial confinement and assist waveguidance to the propagating plasmon mode due to the SPPBG effect. This arrayed system triggers local field enhancement promoting sensing proficiency of the device and is assessed in terms of wavelength and phase shift. Proposed design of SPPBG-enabled PMZI sensor is successfully employed for detection and classification of various cancerous cells. The structural parameters of PMZI are optimized in compliance with the plasmonic band gap in the range of 400–800 nm yielding exceptionally high sensitivity at input wavelength of 633 nm. Volumetric analysis of the analyte reveals that very small analyte volume of the order of 10−15 cc is sufficient to yield significant phase shift. Phase shift obtained for the breast adenocarcinoma and blood cancer cell lines are 1.2357radian and 0.3351radian, respectively, which read very high value of phase shifts to identify extremely small changes in refractive index of the analyte. Figure of merit calculated thereby expose impressive device performance outdoing preceding plasmonic sensors leading to validation of proposed ultra-compact-sensitive PMZI design.