New photonic device integration by selective‐area MOVPE and its application to optical modulator/laser integration (invited paper)

This article describes a novel fabrication technology for photonic integrated circuits (PICs) that easily produces a smooth and high‐quality waveguide coupling between interconnected guided‐wave elements. This technique is based on the in‐plane quantum energy control selective area metal‐organic vapor‐phase epitaxy of multiple‐quantum‐well (MQW) structures. Good local quantum energy control over a very wide range is shown for simultaneously grown MQW crystals. Moreover, the crystal quality, well/barrier heterointerface, and flatness and uniformity of these selectively grown MQW crystals are bound to be as good as those of normally grown crystals. This technique is applied to an electroabsorption modulator/distributed feedback laser integrated device. Superior device performance, including a low threshold and high‐efficiency lasing properties, as well as high‐speed, low‐drive‐voltage, and low‐chirp modulator characteristics are attained due to improved optical coupling, easy fabrication, and sufficient crystal quality of selectively grown MQW structures. 2.5 Gbit/s penalty‐free data transmission is demonstrated over an 80‐km normal single‐mode fiber, which, combined with long‐term device reliability, makes this integration technique more attractive for practical fabrication of semiconductor PICs.