Fig. 1. (a) Schematic of the self-interference microring resonator. (b) Simulated transmission at resonance frequency with different ratios K=κex/κin varying with the phase difference, which is induced by the feedback waveguide.

Fig. 2. Schematic of the experiment setup of the self-interference microring sensor. The laser is coupled into and out of the microring using fiber lens. FPC, fiber polarization controller; DSO, digital oscilloscope. Inset shows an optical microscopy picture of the device.

Fig. 3. (a), (b) Transmission spectra of the SIMRR system at two different applied electrical powers of the microheater: P=0 (black lines), P=0.063  W (red lines). The green area highlights the change of transmission spectrum analyzed below. The insets show the expanded transmission spectra of the green area.

Fig. 4. (a), (b) Measured transmission spectra of different gaps with varying voltages applied to the microheater above the feedback waveguide: (a) gap ∼200  nm, (b) gap ∼100  nm. (c), (d) Effective external coupling rate and extinction ratio varying with applied power.