Fig. 1. Schematic diagram of the fabrication process of the DOT

Fig. 2. Schematic diagram of DST based on MZI

Fig. 3. Mode interference analysis based on DOT structure

Fig. 4. Microscope images of DOT structure and corresponding transmission spectrum

Fig. 5. Comparative analysis of DOT structure and DDT structure

Fig. 6. The strain sensing experiment set up

Fig. 7. The strain response of DOT structure

Fig. 8. The temperature response of DOT structure