High reliability demonstrated on high-power and high-brightness diode lasers

Abstract

In this paper we present nLIGHT's most recent reliability assessment of both the released and newly developed high power, high brightness single emitter laser diodes for fiber laser pumps and material processing applications. We report on the latest updates of lifetests performed on released 18W-rated diode lasers which have been successfully incorporated into nLIGHT's 210W 200μm/0.18NA element^TM pump module. A total of 371 units of 18W-rated single emitters at 915 nm, were assessed at 22A and 2 A at a junction temperature, Tj~70ºC. Cumulatively, these devices have accrued ~ 6.0 million equivalent device hours at module use conditions. The initial reliability analysis based on these lifetest results support <99% module reliability for 2-year of continuous operation. Industry leading dollars-per-watt element_TM e06, e12 and e18 packages based on these diode lasers are also presented. Two element_TM e18 packages have been lifetested for <5400 hours with only one device failure so far. We also report on the initial lifetest of the newly developed high brightness REM-diodes (Reduced Mode diodes) for new element_TM configuration. Preliminary highly accelerated lifetest on ~15 W REM-diodes show very low failure rate compared to the control diode lasers under the same conditions. The more optimized <15W REM-diodes have been lifetested for almost 4000h with no failures observed so far. Superior performance has already been demonstrated on the initialelement_TMe06, e12 and e18 packages with these new REM designs, supporting a 25% increase in power with a minimal degradation in NA. Module level reliability assessment is underway.