1.54‐μm phase‐adjusted InGaAsP/InP distributed feedback lasers with mass‐transported windows

1.54‐μm wavelength phase‐adjusted InGaAsP/InP distributed feedback lasers with low threshold and almost symmetrical subthreshold spectra are demonstrated. Antireflecting window structures were formed by a novel mass transport technique over a length of 25 μm. The phase adjustment was accomplished by a groove in the substrate. Asymmetric output characteristics due to displacement of the groove from the cavity center were observed in agreement with theory.