A novel DFB structure to improve the single-longitudinal-mode property based on reconstruction-equivalent-chirp technology using bent waveguides

We propose a new DFB structure using bent waveguides, which can divide the seed grating into two sections with different period. Also, we design the sampled Bragg grating configuration according to the bent waveguides. Meanwhile, an equivalent λ/4 phase shift based on reconstruction-equivalent-chirp (REC) technology is introduced, this novel structure can suppress the lasing in its 0^th channel, and then ensure the single longitudinal mode (SLM) operation. This structure is very promising for fabrication of multiwavelength DFB semiconductor laser array (MLA) because of its low cost.