Quantum dot comb-laser as efficient light source for silicon photonics
We report on edge-emitting InAs/GaAs quantum dot laser promising as multiple wavelength light source for dense wavelength-division-multiplexing systems in future generation of silicon photonic integrated circuits. Broad and flat gain spectrum of quantum dots as well as pronounced gain saturation effect facilitate simultaneous lasing via a very large number of longitudinal modes with uniform intensity distribution (comb spectrum). A very broad lasing spectrum of about 75 nm in the 1.2-1.28 m wavelength range with a total output power of 750 mW in single lateral mode regime is achieved by intentional inhomogeneous broadening of ground state transition peak and contribution of lasing via excited state transitions. Average spectral power density exceeds 10 mW/nm. A bit error rate less than 10-13 is demonstrated for ten spectrally filtered and externally modulated at 10 Gb/s Fabry-Perot modes owing to a low (<0.3% in the 0.001-10 GHz range) relatively intensity noise of e ach individual mode. This result shows aptitude of a multimode quantum dot laser for high bandwidth wavelength-division-multiplexing systems.