Highly reliable high-power 1480-nm pump lasers for EDFAs and Raman amplifiers

Ultra high power 14XX (1400-1520) nm lasers are required for erbium doped fiber amplifiers (EDFAs) and Raman amplifiers in dense wavelength division multiplexing (DWDM) systems. To realize both high-power and high-reliability performances, we introduced a novel concept in laser diode (LD) chip design in terms of energy conversion efficiency. We also investigated the dependency of laser cavity length on LD characteristics to minimize the total power consumption of both the LD-chip and the LD-module with thermal electric cooler. Using this concept, we successfully reduced the total power consumption of the LD-module by 2Watts, comparing with an old-generation chip design. We have developed the next-generation chips for ultra high power LD-modules with over 300mW fiber-coupled-power in the range of 1400nm-1520nm lasing wavelength, which are suitable pumping sources for Raman amplifiers. The stable operation over 4000hrs in the reliability test under 60 degree C was obtained at 90% of maximum rollover power, indicating that the next-generation chip is robust enough to commercial use. In addition, the cavity length dependency on the reliability performances has been studied. We found that activation energy was 0.62eV, which is consistent with any cavity lengths, and that no degradation of reliability is observed as the facet optical power increases.