Fig. 1. Flow chart of signal processing

Fig. 2. Schematic diagram of lock-in amplifier

Fig. 3. Schematic diagram of the detection optical path based on the common-path interferometer

Fig. 4. Schematic diagram of equivalent Michelson interferometer

Fig. 5. Slope curve graph of equation （7）

Fig. 6. Schematic diagram of the electro-optical probing setup based on lock-in amplifier

Fig. 7. Real picture of the electro-optical probing setup based on lock-in amplifier

Fig. 8. Chip function test circuit board （the red area is the silicon substrate on the backside of the chip）

Fig. 9. Position of the focused laser on the device under test

Fig. 10. Experimental results without lock-in amplifier

Fig. 11. Experimental results with lock-in amplifier