Fig. 1. Schematic diagram of semiconductor laser structure

Fig. 2. Driving current-time curves of the semiconductor laser in the three different degradation forms

Fig. 3. DLD and DSD observed by transmission electron microscope^[9]. (a) DLD; (b) DSD

Fig. 4. Formation of catastrophic optical damage

Fig. 5. Defects observed by photoluminescence. (a) Top-view image of DLD on the n-AlGaInP layer; (b) top-view image of DLD on the p-AlGaInP layer; (c) DLDs obtained by FIB analysis^[15]; (d) defect in InGaN-based laser with unoptimized process; (e) defect in InGaN-based laser with optimized process^[16]

Fig. 6. DLD observed in the experiment^[17].(a)‒(d) COMD, DLD at the front facet; (e)(f) COMD, DLD at the rear facet; (g)(h) COBD, DLD at the front facet; (i)(j) COBD, DLD at the rear facet; (k)(l) COBD, DLD in the middle of the active region

Fig. 7. DLD observed by cathodoluminescence technology. (a) DLDs diffuse along V-type defects^[18]; (b) DLDs near the melting spots at cavity surface^[19]; (c) halo formed by DLDs^[20]

Fig. 8. Thermal imaging analysis of laser degradation. (a) Schematic of the sample by thermal imaging analysis; (b) thermal imaging of COMD^[21]; (c) thermal imaging of COMD in the SWIR and MWIR^[22]

Fig. 9. Defects analysis by EMMI. (a) Micro-image of laser facet before aging under reverse 8-V bias voltage; (b) micro-image of laser facet after aging under reverse 8-V bias voltage^[23]; (c) micro-image of laser COMD after aging under reverse 10-V bias voltage^[24]; (d) micro-image of defect emission of laser with leakage current under reverse 9-V bias voltage