Short optical pulse generation at 40GHz and 1540nm wavelength is achieved using fully packaged bulk quaternary electro-absorption modulator modules. Experimental results obtained with broadband and narrowband optimized packaged modules are presented and compared against empirical model predictions. Pulse duty cycle, extinction ratio and chirp are studied as a function of sinusoidal drive voltage and detuning between operating wavelength and modulator absorption band edge. Design rules and performance trade-offs are discussed. Low-chirp pulses with a FWHM of ~12ps and sub-4ps at a rate of 40GHz are demonstrated. Optical time-domain demultiplexing of a 40GHz to a 10GHz pulse train is also demonstrated with better than 20dB extinction ratio.
We have fabricated 1.55 micrometers ridge waveguide DFB lasers consisting of p-doped, 1.5% compressive strained-layer all quaternary MQW active region by two-step MOCVD with a first-order grating located in the upper GRINSCH region. By optimizing the p-doped carrier concentration in the barrier layers, kL and detuning, the measured -3 dB bandwidth was 13 GHz with flat frequency response and very little RC roll-off in this structure. From RIN measurements, the intrinsic bandwidth was calculated to be 18 GHz. Furthermore, by changing the position of the grating to the MQW active region, partly gain-coupled DFB lasers were formed; these devices exhibit very stable single mode operation and narrow spectral linewidths. The -3 dB electrical bandwidth was measured around 22 GHz and the intrinsic bandwidth was estimated to be 28 - 30 GHz. Experimental results show that the devices have small wavelength chirps and clear eye patterns under 10 Gbit/s NRZ direct modulation.