Monolithically Integrated Narrow Linewidth Semiconductor Laser With a Narrow Band Reflector

We proposed a monolithically integrated narrow linewidth semiconductor laser composing of an active section and a passive narrow band reflector (NBR) based on waveguide Bragg gratings. The π phase shifted Bragg grating is used in the active section to obtain single longitudinal mode output. The NBR is consist of a taper waveguide, π phase shifted antisymmetric Bragg grating (π-PS-ASBG) and uniform Bragg grating. Two sections are integrated on an identical InP wafer and share one continuous waveguide. Because of the hybrid mode resonance in the passive section, it has a relatively long effective length to narrow the linewidth of laser. Narrow linewidth about 16 kHz is obtained when the laser's length is 800 µm and the coupling coefficient of the π-PS-ASBG is 180 cm−1.