Abstract
Recently people are trying to demonstrate zero index material (ZIM) by utilizing metamaterials and photonic crystal structures to realize really specific functions: super coupling and bending, cloaking effect in ZIM. But still there are no devices which provide the platform to develop novel functional devices in telecom regime.
In the presentation, the speaker will introduce the ZIM based on the accidental degeneracy of photonic band structure at the Gamma point. The ZIM consists of Si pillar array embedded in a polymer, and it is also sandwiched by gold mirrors to reduce the scattering loss at the Gamma point and assume the infinite high pillars to the normal direction. By carefully tuning the pitch and diameter of the pillar structure, the research group could obtain the Dirac-cone shape band structure which realizes double zero index (both real and imaginary parts becomes simultaneously zero) and it gives them finite impedance to have a good light coupling efficiency by using conventional Si waveguide structures. Based on the simulation results, the research group actually fabricated the ZIM through the standard clean room process, and evaluated that effective index by observing the refraction angles output from the ZIM prism. Finally the research group obtained the index of around -0.1 at the telecom regime. This ZIM would give them further variation of on-chip photonic devices to realize a novel functions.
About the speaker
Prof Yoshiyuki Kawazoe is a Professor Emeritus at Tohoku University, Japan, and the founder of the Asian Consortium on Computational Materials Science (ACCMS) to establish communication among research groups in Asian region on computational materials science, and has been the President of Nano-science and technology Society, Japan. He is currently working in the New Industry Creation Hatchery Center, Tohoku University and Siberian Branch, Russian Academy of Sciences, continuously studying his original program, and collaborating with a number of researchers in Japan and overseas.
Prof Kawazoe has been working for 22 years in the Institute for Materials Research (IMR), Tohoku University as a full professor on computational materials design developing his original software, TOMBO, introducing the dedicated supercomputer in IMR and working as a committee member in the K supercomputer project.
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