Amplifying light-semiconductor optical amplifiers and integrated devices

We have developed a semiconductor optical amplifier (SOA) for "amplifying light." The SOA is small and inexpensive, facilitating monolithic integration with other functional devices. It can be used not only to amplify optical signals, but also to switch them and to convert their wavelengths. Functional devices can be devised by integrating SOAs with optical couplers, interferometers, and so on. We developed SOA gates having spot-size converters on both sides of the SOA for hybrid integration. High-performance characteristics for gate switching and optical coupling were achieved. We also developed a monolithic wavelength converter by integrating an SOA and an interferometer, and achieved filter-free wavelength conversion. Investigation of its reliability showed that the SOA has a lifetime of over 10⁵ hours.