Properties of loss-coupled distributed feedback laser arrays for wavelength division multiplexing systems

The characteristics of loss-coupled distributed feedback (DFB) semiconductor laser arrays are investigated both theoretically and experimentally. Using simulations based on a transfer matrix method, the strong influence of the residual facet reflectivity on the singlemode yield and the statistical fluctuation of the emission wavelength for as-cleaved and AR/HR coated loss-coupled DFB lasers is pointed out and compared to purely index-coupled /spl lambda//4 phase-shifted devices. Experimental results and the fabrication techniques are given for loss-coupled 1.55 /spl mu/m InGaAs/InGaAlAs/InP DFB laser arrays with four channels and integrated striped thin-film heaters, which were successfully used for fine tuning the channel spacings.