Joint Seiminar - Department of Electronic and Computer Engineering, IEEE Photonics Society (Hong Kong Chapter)
On-chip double zero index platform for planar device applications in telecom regime

by Dr. Shota Kita,  Harvard University

 :  19 May 2014 (Mon)
 :  * 4:00 - 5:00pm
Venue  :  * Rm 4475, 4/F (Lift 25, 26), Academic Complex, HKUST


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 this presentation, we introduce our ZIM based on the accidental degeneracy of photonic band structure at the Gamma point. Our ZIM consist 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, we could obtain the Dirac-cone shape band structure which realizes double zero index (both real and imaginary parts becomes simultaneously zero) and it gives us finite impedance to have a good light coupling efficiency by using conventional Si waveguide structures. Based on the simulation results, we 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 we obtained the index of around -0.1 at the telecom regime. This ZIM would give us further variation of ! on-chip photonic devices to realize a novel functions.


Shota Kita - he was born in Kanazawa, Japan in 1984. He has graduated and got his PhD degree (Engineering) from Baba's group in Yokohama National University on Mar. 2012. After that, he got a fellowship from Japanese government (JSPS research fellowship for postdoctral research fellow) and joined to Loncar's group from Sep. 2012 until Mar. 2014 owing to that fellowship. For now, he is still one of the postdocs in Loncar's group. In his PhD course, he was doing the research relating photonic crystal nanolasers for biosensing applications. Currently, he is interested in 1) Optomechanical nanobeam trasducers for mass spec application, 2) On-chip zero index platform and its critical applications, 3) Crystal regrowth onto Si nano/microstructures for novel devices, and 4) Establishing Novel nanofabrication techniques. He really likes swimming, biking, taking pictures (including SEM images) doing research, and having whiskies & bourbons after his work.