Highly Reliable 1060nm Vertical Cavity Surface Emitting Lasers (VCSELs) For Optical Interconnect

Abstract

ABSTRACTHigh reliability, low power consumption and high speed laser diodes are required for optical interconnect. We developed 1060nm VCSELs with InGaAs/GaAs strained quantum wells, oxide-confined and double intra-cavity structures for that purpose. As for the power consumption, low power dissipation of 0.14 mW/Gbps at 10 Gbps operation has been achieved. Clear eye openings up to 20 Gbps were confirmed at a low bias current of 5 mA. In the reliability test, accelerated aging tests were performed up to 5,000 hours at 6 mA in three different temperatures, 70 oC, 90 oC and 120 oC. The total number of the VCSELs was 4,898 pcs (approximately 5,000). No failure was observed. Under the normal operating condition of 40 oC and 6 mA, the total device-hours was 7.75×107 hours assuming Ea = 0.35 eV according to Telcordia GR-468-CORE. The random failure rate of 30 FIT with the confidence level (C.L.) of 90 % and 12 FIT with the C.L. of 60 % were estimated. To estimate the wear-out lifetime and the number of FITs, high stressed aging tests with 170 oC and 6 mA were performed. With the acceleration factor of Ea = 0.7 eV in the wear-out failure, the median lifetime was 3,000 hours which was equivalent to 300 years in 40 oC ambient. The FIT numbers due to the wear-out were estimated as 0.3 FIT for 10 years. Compared with the random failure rate of 30 FIT, the wear-out failure rates are considered to be negligible. In the extremely long term aging test with 90 oC and 6 mA, no wear-out trend has been observed in both threshold current and optical power up to 20,000 hours operation. These results indicate that 1060 nm VCSEL is promising light source used in optical interconnect for high performance computers and data centers.