As photonic integration continues to evolve, compact and low loss Mach–Zehnder interferometers (MZI) have been an area of significant research in recent years. Here, we propose a valley-Hall effect based topologically protected Mach–Zehnder interferometer (TPMZI). Our simulations show that the TPMZI is efficient and stable even in complex situations. Sharp waveguide bending and defects such as obstructions and epitaxial disorders, do not affect the propagation of photons along the interface, which guarantees the TPMZI high output power. In addition, the TPMZI yields excellent sensitivity, extinction ratio and modulation depths, making it advantageous over existing systems when applied to optical communication, biochemical sensing, spectrometer analysis and measurement systems, etc
