Selective-Area Growth for Novel 1.3 µm Distributed Feedback Laser Diodes with Graded Grating

We demonstrate a new approach to realizing graded grating, which is effective for improving the modulation characteristics of distributed feedback (DFB) laser diodes (LDs) for analog optical transmission, by using the selective-area-growth (SAG) technique. An ideal parabolic thickness profile and a thickness enhancement ratio as high as 4.6 in the grating layer have been realized by optimizing the mask shape using the simulation technique for SAG. We also successfully realized high light-current linearity in 1.3 µm DFB-LDs with a graded grating for the first time. It has been shown that the LDs have excellent distortion characteristics.