Fabrication and basic characteristics of a new structure InGaAs/InGaAsP (MQW) electroabsorption modulator integrated with a distributed feedback (DFB) laser are presented. First, a fundamental study was performed on the applicability of the InGaAs/InGaAsP MQW structure to an electroabsorption-type modulator. We have experimentally demonstrated both the efficient attenuation, the small hole pileup and small chirp characteristics of a discrete modulator based on this MQW structure. We also made a study of the controllability of in-plane band-gap energy by the use of selective area metal-organic chemical vapor deposition aimed at one-step growth integration of modulators and lasers. We demonstrated a sufficient range for controllable quantum energy level and high quality of the selectively grown MQW layers. By using this technique, the modulator was monolithically integrated with a same-material MQW DFB laser. Using a low-capacitance semi-insulating buried-hetero structure, we achieved over 14-GHz modulation under high-light-output operations up to +10 dBm. Modulation at 10 Gb/s with a modulation voltage swing of only 1 Vpp demonstrates the potential value of this InGaAs/InGaAsP MQW system for laser-integrated electroabsorption modulators for 1.55 µm lightwave communications.
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