Semiconductor materials are suitable for monolithic photonic integrated circuits since they can realize almost all the necessary photonic functions such as light emission, light amplifications, light detection, light modulation/switching and optical waveguiding. Additionally, since the figure of merit of various physical effects used to realize the foregoing functions is large and since it is easy to arrange the spatial region to generate these effects into compact and convenient shape, it is advantageous for small size and high performance.
The research and development of photonic integrated circuits utilizing semiconductors has an accumulation of history, knowledge, and technology, already spanning a quarter of a century. Although it has required a longer time before it becomes practical than the electronic integrated circuits, it has shown rapid progress since the end of 1980's. This is attributed to the combination of the driving force from the needs point of view based on the advances in semiconductor laser technology, introduction, and spreading of quantum well structures and evolution of processing technology such as epitaxial growth methods and the strong demand from the needs point of view toward all optical telecommunication networks where not only trunk lines but also switching nodes and subscriber lines use an optical wave.
This paper reviews the present status of photonic devices and circuits obtained by monolithic integration of semiconductor element devices by classifying them into light emitters, optical switches, and combiners/splitters. Finally, the necessity of semiconductor integrated photonic systems is set forth toward the future.
