Fig. 1. AFMI device. (a) Scheme of our AFMI. The interferometer combines an FA for photon coupling, a DC with the splitting ratio of 50:50, a 200 ps delay line, and two FMs; (b) photograph of our AFMI. The size of the chip is about 27.8  mm×23.1  mm, and the length of the FM is about 17.5 mm. A copper heat sink with a TEC and a thermistor is attached to the back of the chip. The entire system is packaged in an aluminum box with temperature isolation (not shown in this figure).

Fig. 2. Experimental setup to evaluate the characteristics of our AFMIs. Laser, gain-switch laser source; TEC, temperature controller; ATT, light attenuator; PC, polarization controller; Cir, circulator; SPD1 and SPD2, single-photon detectors.

Fig. 3. Interference results with temperature scanning of AFMI1. The black dots are measured data points, and the red line is the corresponding curve fitting.

Fig. 4. Interference results for fixed polarization states.

Fig. 5. Results of continuous polarization scramble test. (a) Diagram of interference visibility with and without continuous polarization scramble; insets, the diagram of normalized Stokes parameters and interference visibility during test; (b) visibilities in the range of 10°C–35°C with and without polarization scramble. The 3σ error bar is selected as the confidence interval using 10 min testing data.

Fig. 6. Results of long-term phase stability test. Shadow areas represent the 1σ error bar.

Fig. 7. Results of delay difference calculation. (a) Variations of the visibilities for temporal and amplitude mismatch. The red triangle is where our AFMIs stand. (b) Normalized light intensity after propagating through two AFMIs, detected by an SPD. The ΔT represents relative delay time.