Fig. 1. Preparation process scheme of DFB semiconductor laser based on buried metal mask

Fig. 2. Top view of etched grating

Fig. 3. View of BM-DFB

Fig. 4. Spectra of BM-DFB and PM-DFB

Fig. 5. P-I-V curves of BM-DFB and PM-DFB

Fig. 6. Far field spot pattern of BM-DFB and PM-DFB