Highly reliable buried-stripe type 980 nm laser diodes for practical optical communications

We have developed high power and highly reliable single-mode 980 nm laser diodes (LDs) as an excitation light source for erbium doped fiber amplifiers (EDFAs) for practical communication usage. We designed buried-stripe type 980 nm LDs with a weakly index guided structure to maintain a stable single transverse mode even in high power output operation. Regarding the typical initial device characteristics, a kink level of 315±15 mW was realized and the devices showed maximum light output powers of over 550 mW at 25 °C and complete thermal rollover characteristics measured at temperatures up to 150 °C with 800 mA current injection. In electrostatic discharge (ESD) tests, no significant change of light output and/or voltage versus current characteristics after forward bias discharges typically up to about +12 kV and reverse up to -30 kV (equipment limitation) was found. Regarding the reliability, we carried out long-term aging tests at 120 mW light output power at 50 °C. In the tests, we confirmed no sudden failure and very stable spectral characteristics. In addition, we obtained similar degradation rates over different device groups. Furthermore, 150-250 mW light output aging tests also showed stable operation. The characteristics of these devices make them suitable for practical communication applications.