Wide tuning with narrow linewidth in DFB lasers with superstructure grating (SSG)

A DFB laser with superstructure grating (SSG) is reported. This laser consists of two SSG reflectors with slightly different designs and a phase control region, and it operates at high power at ∼ 1.55μm. A wide tuning range of 86 nm was obtained by tuning the SSGs in combination. Linewidth characteristics of less than 5 MHz were demonstrated over a tuning range as wide as 50 nm.