Sampled Grating DFB Laser Array by Periodic Injection Blocking

We present a novel multiwavelength laser array with a sampled grating formed by periodically loaded n-doped injection blocking layer on top of the uniform base grating. With an optimized design of the sampled grating as well as the laser operation conditions, all the even order, including the zeroth-order reflections, can be effectively suppressed, leaving only the first-order reflection wavelength to lase. Unlike in the conventional sampled grating where part of the base grating will have to be removed, the whole base grating is retained in the proposed structure; hence, the side-mode suppression ratio will not be jeopardized due to the weakened grating coupling strength. As an example, an array of 12 lasers has been designed to cover a wavelength range from 1542 to 1560 nm.