Abstract
A high-sensitivity Mach-Zehnder interferometer (MZI) biochemical sensing platform based on Silicon-in-insulator (SOI) rib waveguide with large cross section is proposed in this paper. Based on the analyses of the evanescent field intensity, the mode polarization and cross section dimensions of the SOI rib waveguide are optimized through finite difference method (FDM) simulation. To realize high-resolution MZI read-out configuration based on the SOI rib waveguide, medium-filled trenches are employed and their performances are simulated through two-dimensional finite-difference-time domain (2D-FDTD) method. With the fundamental EH-polarized mode of the SOI rib waveguide with a total rib height of 10 μm, an outside rib height of 5 μm and a rib width of 2.5 μm at the operating wavelength of 1550 nm, when the length of the sensitive window in the MZI configuration is 10 mm, a homogeneous sensitivity of 7296.6%/refractive index unit (RIU) is obtained. Supposing the resolutions of the photoelectric detectors connected to the output ports are 0.2%, the MZI sensor can achieve a detection limit of 2.74 × 10−6 RIU. Due to high coupling efficiency of SOI rib waveguide with large cross section with standard single-mode glass optical fiber, the proposed MZI sensing platform can be conveniently integrated with optical fiber communication systems and (opto-) electronic systems, and therefore has the potential to realize remote sensing, in situ real-time detecting, and possible applications in the internet of things.
Highlights
With the capability of efficiently transforming chemical or biological reaction into measurable signal, biochemical sensors are widely used in chemical industry, biological process, medical diagnostics, healthcare, environmental monitoring, military defense, and scientific research
Supposing the resolutions of the photoelectric detectors connected to the output ports are 0.2% of the optical power for the intensity measurement, the Mach-Zehnder interferometer (MZI) sensor can achieve a detection limit of 2.74 × 10−6 refractive index unit (RIU)
An MZI biochemical sensing platform based on an SOI rib waveguide with a large cross section is proposed in this paper
Summary
With the capability of efficiently transforming chemical or biological reaction into measurable signal, biochemical sensors are widely used in chemical industry, biological process, medical diagnostics, healthcare, environmental monitoring, military defense, and scientific research. SOI-based nanowire waveguide [9,10] and slot waveguide [11,12] have been employed to realize high-sensitivity biochemical sensors. An SOI rib waveguide with large cross section, i.e. several microns in transversal dimension, possesses high coupling efficiency with standard single-mode glass fibers, and has the potential for integration with optical fiber communication systems and opto-electronic systems [13]. This article proposes an MZI biochemical sensor based on an SOI rib waveguide with a large cross section. The configuration of the MZI-based sensing platform is proposed in Section 5, and the discussion and results of this research are given in the last two sections
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