High power low divergence angle SSC integrated 1.3 μm InGaAlAs/InP MQW DFB laser

We report the design and fabrication of a novel, to the best of our knowledge, high power 1.3 μm InGaAlAs/InP multi-quantum well (MQW) distributed feedback (DFB) laser integrated with a laterally tapered spot size converter (SSC). In the device, a section having no ridge waveguide above the MQW active material layer is introduced after the SSC section, which helps to decrease divergence angle further. The measured far field divergence angles of the laser are smaller than 10° in both lateral and vertical directions. The side mode suppression ratio (SMSR) of the laser emission is larger than 50 dB. At 50°C, the optical power is larger than 50 mW at 250 mA injection current.