Optimization of DFB lasers integrated with Franz-Keldysh absorption modulators

The influence of the residual facet reflectance on electroabsorption modulators monolithically integrated with DFB lasers is analyzed, for both index- and partly loss-coupled lasers. The optimum laser design is discussed from the standpoint of system requirements in long-distance 10 Gb/s transmission systems, requiring a minimum of chirp. The integrated device's performance will depend as much on the laser design as on the modulator. The DFB laser should be long (L>500 /spl mu/m) with a coupling strength of about /spl kappaspl middot/L=2-3 and should have a high relaxation oscillation frequency. The residual reflectance should be less than 1/spl middot/10/sup -4/.<
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