Low-Threshold and High-Efficiency Operation of Distributed Reflector Laser With Wirelike Active Regions

A high differential quantum efficiency of about 50% from the front facet and low threshold current operation have been achieved. By modifying the doping profile in 1.55-mum distributed reflector lasers, waveguide loss was reduced from 6-7 to 4 cm
^-1
. Injection currents of 4.2 and 3.6 mA were obtained to achieve a 1-mW output power for lasers with uniform and phase-shifted grating structures, respectively.