Fig. 1. Local and global structure diagram of proposed sensor. (a) Schematic diagram of fabricated micro-ring resonator structure; (b) physical figure of sensor; (c) schematic diagram of overall structure of temperature and salinity sensor of micro-ring resonator

Fig. 2. Simulation results of proposed sensor. (a) Transmission spectra when coupling gap is 200, 150, 100, 50 and 0 nm;

Fig. 3. Schematic diagram of sensor preparation process. (a) Dropping photoresist (IP-Dip2) on a silicon substrate; (b) laser direct writing using an oil-immersion objective

Fig. 4. Schematic diagram of local scaling and parameter optimization based on Describe software. (a) High magnification of coupling region; (b) scanning array model with different laser intensities and writing speeds; (c) scanning array physical figure

Fig. 5. Sensor packaging process and experimental results. (a) Experimental setup for sensor packaging; (b) transmission spectrum of encapsulated on-chip micro-ring resonator

Fig. 6. Experimental setup for temperature sensitivity of on-chip micro-ring resonator

Fig. 7. Transmission spectra and linear fitting results of on-chip micro-ring resonator temperature sensor at different temperatures

Fig. 8. Long-term temperature monitoring results for on-chip micro-ring resonator

Fig. 9. Transmission spectra and linear fitting results of on-chip micro-ring resonator salinity sensor in standard seawater of different salinities