Slow-wave-enhanced on-chip loop-terminated Mach-Zehnder interferometer sensor

The device described in our earlier paper [ Opt. Lett. 48 , 5968 ( 2023 ) 10.1364/OL.500033 ] as a slow wave enhanced on-chip Michelson interferometer sensor is correctly designated as a slow wave enhanced on-chip loop terminated Mach-Zehnder interferometer sensor. In the earlier paper, we experimentally demonstrated slow wave enhanced phase and spectral sensitivity in asymmetric loop-terminated Mach-Zehnder interferometer (LT-MZI) sensors. Compared to Mach-Zehnder interferometers (MZI) that experimentally demonstrated a phase sensitivity 84,000 rad/RIU-cm, the reflected path enhancement of the optical path length coupled with slow light enhancement with photonic crystal waveguides in on-chip slow light loop-terminated Mach-Zehnder interferometer sensors resulted in experimentally demonstrated phase sensitivity 277,750 rad/RIU-cm with theoretical phase sensitivity as high as 461,810 rad/RIU-cm, at the same form factor as the MZI of identical interferometer arm lengths.