Monolithic integration of laser and spot size converter using selective area MOCVD growth

Laser diodes with a narrow radiation beam is necessary to reduce the package cost in access networks. However, it is difficult to achieve both a narrow divergence angle of output beam and low threshold current and high quantum efficiency of the laser because the broadening of the mode profile, which is required to get a narrow beam, increase cavity loss and threshold current. To meet these requirements, spot size converted laser diodes (SSC-LD) integrated with a tapered passive waveguide, which is fabricated using a selective area MOCVD growth, have been proposed by many groups. This SSC-LD allows high direct coupling efficiency to the single mode optical fiber and extended alignment. Therefore, the number of packages can be reduced, and the passive alignment between the LD and fiber is realized.