Cost-effective partially corrugated waveguide laser diodes for use in optical access networks

摘要

A high-yield and high-performance single longitudinal mode laser diode (LD) is essential for implementing a low-cost optical module for high capacity access networks. We have realized novel partially corrugated waveguide (PC) LDs and shown that they are cost-effective. Because of a unique resonance feature in a mirror loss profile, the PC-LD has higher yield in single longitudinal mode operation than that of a conventional distributed feedback (DFB) LD. The yield of the PC-LD with single-mode stability ($Delta$alpha@L $GRT 0.3) was theoretically predicted to be as high as $GRT 65%, which is 1.5 to 2 times higher than that of a conventional DFB-LD. Side-mode suppression ratio was experimentally as high as 40 to 50 dB. Uncooled high-efficiency characteristics have been realized for a cavity with asymmetrical reflectivity facets. The threshold current and slope efficiency were 16 mA and 0.26 W/A at 85$DGR@C. By introducing a spot-size converted waveguide with chirped corrugation, butt-coupling efficiency was improved by 3 dB higher than that of the conventional straight waveguide. Furthermore, excellent optical feedback resistant 622 Mb/s operation has been demonstrated over a wide temperature range of $MIN@40 to 85$DGR@C. The power penalty was as low as 1 dB under the optical feedback level of $MIN@8.5 dB. Isolator-free 2.5 Gb/s-70 km transmission was also demonstrated. The PC-LDs with this performance are very promising for realizing cost-effective optical modules for use in high capacity optical access networks.