Photonic Integrated Circuits for High Speed Photonic Networks-Challenges for Large Scale Photonic Integration-

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A large scale photonic integrated circuit (Photonic IC) is a key device for use in future ultrahigh capacity photonic networks including metro-area networks, high speed photonic LANs and optical interconnects. The purpose of this project is to establish the device science and technology on massively integrated photonic devices including multiple wavelength laser arrays, ultra-compact microring resonators and so on.We realized 100 channel multi-wavelength VCSEL arrays emitting in 1100nm wavelength band. We also proposed and demonstrated an "athermal VCSEL" with avoiding temperature controllers for uncooled WDM applications. The temperature dependence of the lasing wavelength of VCSELs could be reduced by a factor of 50 with a novel thermally-actuated membrane mirror. We achieved athermal and tunable operations for the first time based on this concept.In addition, new functions on VCSELs for optical signal processing are realized. We demonstrated an optical nonlinear phase shifter based … More on a VCSEL saturable absorber. A large nonlinear phase shift could be observed in both modeling and experiments. The proposed device would be useful for mitigating fiber nonlinearities in optical domain and for optically manipulating the phase of light. Slow light can be obtained in Bragg reflector waveguides with their large waveguide dispersion. The basic structure is the same as that used in VCSELs. We demonstrated a slow light modulator with a Bragg waveguide, which shows a possibility of low modulation voltage even for ultra-compact waveguide modulators. Our recent work exhibited a possibility of ultra-compact optical waveguide switches with slowing light.We also demonstrated a tunable hollow optical waveguide with a variable air core toward a new class of photonic integrated circuits. We presented various unique features in hollow waveguides and thecombinationwith microelectro-mechanical system (MEMS) will gives us widely tunable waveguide devices. The result shows a possibility of a large change of over 10% in propagation constant with a variable air core. We exhibited a wide variety of device applications based on hollow waveguides, which include tunable Bragg reflectors, tunable dispersion compensators and tunable lasers. The device structure can be formed by fully planar fabrication processes based on lithography and etching. The proposed concept may open up a new class of various tunable optical devices, which give us unique features of wide tunability, compact size and temperature insensitivity.Utilizing high index contrast optical waveguides, ultra-compact optical devices such as waveguide branch, Mach-Zehnder interferometer, arrayed waveguide grating filter, microring resonator filter, and so on could be realized. We have proposed and demonstrated a vertically coupled microring resonator as an Add/Drop filter, and a hitless wavelength channel selective switch using Thermo-Optic effect of double series coupled dielectric microring resonator. The tuning range of wavelength selective switch was expanded to over 10nm using the Vernier effect, and a large extinction ratio of more than 20dB was realized. Less