In this work, we present a novel refractive index (RI) sensing system that is capable of suppressing optical phase errors (noise). Phase errors, for instance, due to process and temperature variations, limit the detection accuracy and the limit of detection (LoD) of the sensor. The proposed system uses four loop-terminated Mach-Zehnder Interferometers (LT-MZI) to achieve wavelength splitting. LT-MZI allows us to tune the output spectrum using its directional couplers coefficients. Wavelength splitting occurs with accordance to RI change using two LT-MZIs with opposite wavelength sensitivity. By determining two independent parameters, namely the wavelength splitting and the average wavelength, the system is capable to differentiate between phase changes due to medium index change and phase changes due to any other effects (noise), which maximizes the detection accuracy. For interferometers with the same waveguide structure in both of the arms, this system can totally eliminate any optical phase errors. This wavelength splitting cannot be achieved using the conventional MZI. Another two LT-MZIs with a quarter of the length are used to double the detection range. This sensing system can be used for various chemical and biological detections using any platform and operating wavelength. Using this system, a liquid sensor based on the widespread CMOS compatible silicon-on-insulator (SOI) technology and operating in the near-infrared is designed. While the SOI platform can achieve high sensitivity to medium index change and compact devices due to the high index contrast, it is also very sensitive to optical phase errors. However, our proposed system can eliminate these errors. Finite difference eigenmode (FDE) and finite difference time domain (FDTD) solvers are used to design and optimize the sensor’s performance. The sensor achieves a figure of merit (FOM) of 1233 RIU-1, corresponding to an intrinsic LoD of 8e-4, and a sensitivity as high as 7890 nm/RIU with a sensing arm length of only 500 µm, which are 3 and 2 times higher than single MZI, respectively. Finally, this sensor has a much higher detection range, 6.3 times higher than a single MZI and is able to suppress optical noise.