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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 plus or minus 15 mW was realized and the devices showed maximum light output powers of over 550 mW at 25 degrees Celsius and complete thermal rollover characteristics measured at temperatures up to 150 degrees Celsius 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 plus 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 degrees Celsius. 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.