Accuracy on emitted wavelengths in DFB laser arrays resulting from the longitudinal mode selection mechanism

We compare the merit of various longitudinal mode selection mechanism in distributed feedback laser for application as arrayed sources in the wavelength-division multiplexing context. Phase-shifted and complex-coupled laser arrays have been fabricated and characterized. We propose that the dispersion on the emitted wavelengths is strongly correlated to the field localization along the cavity. By comparison of the dispersion values measured within the laser arrays, we can conclude that the complex grating with gain is the best suitable mechanism for high wavelength accuracy and stability, due to the strong and distributed localization of the field in the gain sections of each period of the grating.