Design of on-chip hybrid plasmonic Mach-Zehnder interferometer for temperature and concentration detection of chemical solution

Abstract

Highlights• A novel metal strip loaded horizontal slot hybrid plasmonic waveguide with a refractometric sensitivity of 1.13 is proposed.• Optimized waveguide design shows a high 59.23% and 82.04% quasi-TM field confinement in the slot and sensing (slot + clad) region, respectively.• A compact Mach-Zehnder interferometer is designed for detection of temperature and volume concentration of isopropanol/water solution, although it is also suitable for any other liquid chemical.• Asymmetric power splitting scheme enhances the interference fringe visibility to the ideal value ( ′ ≃ 1).• A single on-chip sensor design shows a high temperature sensitivity of 243.9 pm/ o C and volume concentration sensitivity of 437.3 nm/RIU.• The device incorporates a simple design scheme which is highly resilient to the fabrication tolerances. AbstractWe report a compact lab-on-chip design of a Mach-Zehnder interferometer (MZI) incorporating a novel metal strip loaded horizontal slot hybrid plasmonic waveguide (HSHPW) in the sensing arm and a dielectric horizontal slot (DHS) waveguide in the reference arm. The HSHPW is optimized to confine a high ~60% and ~82% evanescent optical field in the low index dielectric slot and an active sensing region, respectively which enhance the device sensitivity with a comparative lower propagation loss than a typical plasmonic waveguide. We report here a single MZI configuration which not only exhibits an excellent temperature sensitivity of 243.9 pm/ o C but also liquid concentration sensitivity of 437.3 nm/RIU for a 40 m long HSHPW. To mitigate loss arising from each section such as butt coupling and plasmonic modal losses, the HSHPW has been optimized by incorporating an asymmetric power splitter which shows a considerable improvement in the fringe visibility and device insertion loss. Thus, the proposed single MZI design shows an excellent response to the temperature and liquid concentration sensing with a maximum total loss and extinction ratio of 2.56 dB and >25 dB, respectively. A much simpler CMOS friendly compact design is also found to have a great robustness to the fabrication tolerances.

Refractive Index Sensing Performances of a Mid-Infrared Asymmetric Mzi Based on Suspended Gaas Waveguides

“…Year RI Sensitivity (nm/RIU) Yongjiao Wen et al [33] 2019 500 Souvik Ghosh et al [34] 2019 437.3 La Xiang et al [35] 2020 494 Bahram Azizi et al [36] 2021 600 Hongling Zhang et al [37] 2021 847 Our proposed sensors 2022 854.5…”

Ultrahigh Sensitivity Mach−Zehnder Interferometer Sensor Based on a Weak One-Dimensional Field Confinement Silica Waveguide

“…As a comparison, the polymer waveguide in [ 16 ] has an evanescent field ratio of 10.8%, at most. The hybrid plasmonic waveguide in [ 17 ] confines ~60% and ∼82% of the evanescent field in the dielectric slot and an active sensing region. The electric field discontinuity still introduces a larger R of TM mode than TE mode, but the distinction is not large between them as revealed in Figure 2 b due to the small ∆ n .…”

An Ultra-High Sensitivity Optical Fiber Refractive Index Sensor Based on Plasmonic Mach-Zehnder Interferometer

“…MZI is a kind of the wellknown label free optical sensing devices, which can achieve high sensitivity [20,21] and which is not limited by the working wavelength. Recently, plasmonic MZI has been proposed [22,23] and is believed to be promising for sensitive lable-free sensing [24,25]. SPR sensors with different configurations, such as metal-insulator (MI), insulator-metal-insulator and metal-insulator-metal (MIM), can be used to form plasmonic MZI.…”