Experimental demonstration of fixed wavelength slow-light interferometric sensor with phase change material tuning

We demonstrate phase change material (PCM) based active tuning in a loop-terminated Mach-Zehnder interferometer (LT-MZI) to correct fabrication induced fringe wavelength shifts, enabling sensor chip matching with fixed-wavelength lasers. Slow light PC waveguide and loop-terminated mirror enhance the compactness and phase sensitivity of the sensor. Non-volatile PCM switching permanently aligns interference fringes without continuous power consumption, avoiding thermal analyte perturbation during sensing measurements. We compare the fringe tuning efficiency for PCMs integrated on different sections of the interferometer.