A concave tapered DFB semiconductor laser based on reconstruction-equivalent-chirp technology

A concave tapered DFB semiconductor laser based on reconstruction-equivalent-chirp (REC) technology was designed and experimentally demonstrated for the first time to the best of our knowledge. As predicted theoretically, the concave tapered DFB laser with a π phase shift can suppress the spatial hole burning effectively. But the realization of such lasers has not been reported up to now to our knowledge for its hard fabrication. In this paper, this kind of laser has been successfully fabricated with the combination of the equivalent apodization and equivalent phase shift. Because the seeding grating of the sampling structure keeps uniform, such structures with different taper profiles s can be fabricated on the same wafer simultaneously by the standard holographic exposure easily. Experimental results show that the laser maintains good single longitudinal mode operation with side mode suppression ratio (SMSR) nearly 50 dB under high injection current of 100mA.