Fig. 1. Chip structure and tuning principle of MG-Y laser. (a) Diagram of structure; (b) additive vernier effect

Fig. 2. Wavelength tuning curves with increasing and decreasing phase region currents. (a) Switching of current combination at same feature point; (b) switching of current combination between different feature points

Fig. 3. Flowchart of tuning method of MG-Y laser

Fig. 4. Locating tuning path based on arc-shaped test frame. (a) Scanning result based on test frame; (b) smooth wavelength tuning paths

Fig. 5. Target wavelength retrieval based on increasing and decreasing phase currents. (a) Scanning result of path 5; (b) fine wavelength splicing and interpolation of path 5; (c) fine wavelength tuning curves of path 5

Fig. 6. Closed-loop calibration model

Fig. 7. C-band tuning curves of I_LR, I_RR, I_PH, I_GN, and I_SOA. (a) C-band wavelength current tuning curves; (b) C-band power current tuning curves

Fig. 8. Experimental system of MG-Y laser

Fig. 9. Arbitrary wavelength switching test results. (a) Wavelength bias when tuning in 0.1 nm step; (b) wavelength bias when tuning in 4 nm step; (c) three sets of spectra when tuning in 0.1 nm step; (d) three sets of spectra when tuning in 4 nm step

Fig. 10. Long-term stability test of output wavelength

Fig. 11. Linear scan test results in full wavelength range. (a) Tuning wavelength bias; (b) output power fluctuation