Performance of 1.5 mu m DFB lasers with a narrow stripe region

The performance of distributed feedback (DFB) lasers with a narrow region in the middle of the waveguiding strip and antireflective(AR)-coated facet ends is presented. The narrow region is designed to act as a three-quarter wavelength phase shift. Single longitudinal mode (SLM) capability is discussed both theoretically and experimentally. Calculated results predict the shift region is effective in relaxing axial hole burning because of a dip at the center of the axial field profile and a smaller optical confinement factor in the region. Experimentally, stable SLM operation up to more than 50 mW, a sidemode suppression ratio of more than 40 dB, and 3 dB modulation bandwidth over 10 GHz are achieved.<
>