Fig. 1. Schematic diagram of femtosecond laser processing system

Fig. 2. Trend of microcavity length, width, and depth changing with laser power ( Insert: 0.9, 9.1, and 16.5 mW results)

Fig. 3. Trend of microcavity length, width, and depth changing with laser scanning speed ( Insert: 20, 100, and 600 μm/s results)

Fig. 4. Trend of microcavity length, width, and depth changing with laser scanning interval (Insert: 3, 6, and 9 μm results)

Fig. 5. Trend of microcavity length, width, and depth changing with the number of laser scanning times (Insert: 1, 3, and 5 times results)

Fig. 6. Trend of microcavity depth and sidewall inclination changing with the number of scans (Insert: results of 1 scan without feeding, 3 scans with 2 feedings, and 5 scans with 4 feedings)

Fig. 7. (a) Schematic diagram of scanning path change; (b)-(f) Top and side views of microgrooves with cavity lengths of 40, 80, 120, 160, and 200 μm

Fig. 8. Schematic diagram of side wall roughness measurement

Fig. 9. Overall and partial magnification of the response spectrum of (a)-(c) 40 μm cavity length sensor; (d)-(f) 80 μm cavity length sensor; (g)-(i) 120 μm cavity length sensor; (j)-(l) 160 μm cavity length sensor; (m)-(o) 200 μm cavity length sensor and numerical fitting diagram of characteristic wavelengths at different temperatures

Fig. 10. Overall and partial magnification of the sensor response spectrum of (a)-(c) stainless steel tube package; (d)-(f) Copper tube package; (g)-(i) Aluminum tube package and numerical fitting diagram of characteristic wavelengths at different temperatures

Fig. 11. (a) Stainless steel tube packaging; (b) Copper tube packaging; (c) Aluminum tube packaging