A new interferometric sensor with ring-feedback MZI

An interferometric sensor configuration is proposed. This configuration is modified from a conventional Mach-Zehnder interferometer (MZI) with a provision of a feedback path. Such scheme possesses large transmission intensity change with a small phase unbalance between two arms of MZI. This property can greatly enhance the sensitivity by one to two order of magnitude compared with a traditional MZI-based sensor. The same configuration can be further enhanced in slope and detection range with introduction of small gain into the feedback path.