Low-threshold and high-efficiency operation of distributed reflector laser with wirelike active regions by reduced waveguide loss

Due to a reduction of waveguide loss achieved by doping-profile modification, low-power operation, i.e. threshold current of as low as 0.9 mA as well as differential quantum efficiency of around 50% from the front facet, was achieved with 1.55-µm wavelength distributed reflector lasers with wirelike active regions. Injection currents for 1-mW output power of 4.2 and 3.6-mA were obtained for uniform and phase-shifted grating structures, respectively.