Customizable Optical Pressure Sensor Based on Optimized Asymmetric Mach–Zehnder Interferometer: A Review

In this paper, we verify the feasibility of our proposed design scheme for customizable optical pressure sensor based on the photo-elastic effect of SiO
₂
waveguide in asymmetric Mach-Zehnder interferometer (a-MZI) structure. The curve lengths and minimum radii of curvature of several common types of a-MZI arm curves are calculated theoretically. By analyzing the relationship between the radius of curvature of the long arm curve, the length of the long arm curve and the arm length difference of the a-MZI sensor under different types of arm curves, the design scheme for an a-MZI pressure sensor with a specific arm length difference is obtained. By selecting a rationalized arm design scheme, customization of the sensing range can be achieved. No special processing (such as etching) is required for the waveguide, which improves the pressure tolerance of the sensor. When using the SiO
₂
waveguide with a refractive index difference of 2%, the a-MZI pressure sensor based on sine type arm with arm length difference of 5 mm has a sensing range of 4.83 MPa and a sensitivity of 1.24 mW/MPa. The a-MZI pressure sensor with the ease of fabrication can be used to monitor various scenarios, such as marine and building monitoring.