Two-Segment Gain-Coupled Distributed Feedback Laser

A two-segment regrowth-free gain-coupled distributed feedback (DFB) laser monolithically integrated different gain contrast segments was proposed, realizing both wavelength-tunable (5 nm) and wavelength stabilization characteristics, controlled by a single electrode only. At current larger than 320 mA, side mode suppression ratio reached >30 dB with 3 dB linewidth <80 pm. The CW power reached up to 159 mW/facet at single-mode operation. Considering both uncoated facets all together, it is at the same power level as index-coupled DFB lasers. Periodic surface grooves and 4-
μ
m-width ridge were patterned merely by one-step i-line lithography. It provides a novel method for low-cost practical gain-coupled DFB laser fabrication, which can be used in either/both wavelength-tunable applications such as sensing and detection, or/and wavelength stabilization fields such as pumping fiber lasers.