Spectral chirp in long wavelength multiquantum well semiconductor lasers subject to gain switching

The authors report the spectral performance of both multiquantum well (MQW) and bulk, distributed feedback long wavelength semiconductor lasers, subject to gain switching at gigahertz rates. Their performance is assessed under a variety of different bias and modulation conditions, and compared with that of Fabry Perot lasers. The linewidth enhancement factor is deduced using the Chirp Half Power method and shows a marked difference between MQW and bulk laser devices. Experimental results for bulk and MQW long wavelength laser devices are successfully simulated using two level and three level rate equation models