PhD Defense: "Reconfigurable Optical Metasurfaces : PhD Defense Talk"

Prasad P Iyer

February 9th (Friday), 10:00am
Elings Hall (CNSI) Room 1601

Dynamic control of propagating electromagnetic waves has been a principal challenge in the field of optics. The emergence of dielectric nano-antennas has revolutionized the field of nano-photonics by enabling optical phase control at subwavelength dimensions. These components underlie the nascent field of artificial surfaces, or ‘metasurfaces,’ which has already shown tremendous potential for the miniaturization of bulky refractive and diffractive optical elements. To reach their ultimate potential, however, metasurfaces must also become dynamic. In this presentation, I will discuss design principles and experimental results detailing the free-carrier refraction based reconfigurability of infrared optical metasurfaces using low-loss, high-index semiconductors resonators. We demonstrate a new class of high-Q dielectric optical antennas leveraging low-loss zero-index phononic (AlN and SiO2) and tunable plasmonic (InSb) cavities. A novel thermal refractive index tuning is demonstrated in n-InSb based on the electron effective mass modulation. This leads to a large refractive index change (δn>1.7), an order of magnitude increase in the thermo-optic co-efficient and multiple linewidth tunability of dielectric antennas. Reconfigurable meta-gratings and metalenses which operate without any spatial thermal gradients are conceptualized based on these experimental results. Furthermore, I will present the design and experimental results of electrically reconfigurable InAs/AlGaSb heterojunction (p-i-n) optical metasurfaces for achieving low-loss 2π phase shifts and unidirectional beam-steering in the mid-infrared wavelength regime. Such electrically tunable metasurfaces, which can arbitrarily control the spatial phase profile at the subwavelength scale, can form the device platform enabling unprecedented control over the electromagnetic wavefront.

About Prasad P Iyer:

Prasad P Iyer received his B.Tech degree from the Materials and Metallurgical Engineering department in Indian Institute of Technology Kanpur (India) in 2008. Since then he has been working in field of nano-optics with Prof. Jon Schuller in Electrical and Computer Engineering department of the University of California Santa Barbara.

Hosted by: Prof. Jon Schuller