Multi-waveguding type photonic functional devices for WDM systems

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For the application to advanced wavelength-division multiplexing systems, this project was carried out to propose and realize the novel multi-mode or multi-waveguide photonic devices, which were expected for new functions as well as compactness, through the analyses and experiments. The main results during the two-year term are as follows :1) Multi-mode interference (MMI) photonic switches (MIPS) were proposed. The analyses suggest that an MIPS is capable to show good characteristics for a low cross-talk of -20dB or less and so on with a device length of about 50mum. Actually the devices were fabricated, and fundamental photonic switching was demonstrated. It was also confirmed that the MIPS could operate in versatile functions such as switching and distributing of the light for the same device. 2) Multi-mode interference wavelength converters (MIWC) were proposed, which have the advantage of a simple device structure without additional components to separate a signal and a converted l … More ights. Fabrication process was investigated, and cross-gain modulation characteristics which was a necessary effect to show wavelength conversion was experimentally confirmed. These results shows the potential of the active MMI for effective wavelength converters. 3) As for the narrow-band optical add-drop multiplexer, the theoretical investigations clarified that low side-lob characteristics with about -30dB suppression ratio can be attained by introducing appropriate density-modulated grating. 4) Quite a compact arrayed waveguide with multiple reflection structure was invented, and fundamental theoretical and experimental investigations clarified its effectiveness. 5) Laser diodes integrated with a multi-mode interference waveguide (MILD) were proposed, and narrow beam characteristics suitable for easy coupling to a single mode fiber was demonstrated theoretically with as low as -4dB coupling loss.Through this project, multi-mode and multi-waveguide devices were shown to be quite effective for high-performance versatile photonic switching, and further research is planned to undergo for realization of practical devices and system evaluation. Less