Friday April 26th | 12:00 pm | Elings 1605
Two-dimensional Van der Waals materials have emerged as a very attractive class of optoelectronic material due to the unprecedented strength in its interaction with light. In this talk I will discuss approaches to realize quantum photonic devices by integrating these 2D materials with microcavities, and metamaterials. I will first discuss the formation of strongly coupled half-light half-matter quasiparticles (microcavity polaritons) and their optical and electrical control in the 2D transition metal dichacogenide (TMD) systems. Prospects of realizing condensation and few photon nonlinear switches using Rydberg states in TMDs will also be discussed. Following this, I will discuss the broadband enhancement of light-matter interaction in these 2D materials using photonic hypercrystals and chiral metasurfaces. Finally, I will talk about room temperature single photon emission from hexagonal boron nitride and the prospects of developing deterministic quantum emitters using them through strain engineering. The realization of room temperature single photon emitters and few photon
nonlinear switches using 2D materials presents an attractive direction for robust next generation quantum photonic technologies.
Tuesday, April 23rd | 12:00 pm | Elings 1601
Today zettabytes of data are generated and nearly doubled every two years. The conventional microprocessor is reaching its physical limitation and cannot keep up with the exponential growth in rich data. This leads to the increased demands on memory systems due to their frequent access patterns between microprocessors and memories. High speed, low energy and high sensitive optical data links are desirable for data transmission between multicores, microprocessors and memories in the new data center and high performance computer architectures. I am going to talk about the silicon photonics efforts in developing low energy high speed optical links in Hewlett Packard Labs, including the development of low voltage SiGe avalanche photodiodes, as well as photonic links.
Monday, April 15 | 12:00pm | Elings 1605
Think small: developing color centers in crystals for nanoscale optical sensors of fields and forces
Friday, April 12 | 12:00pm | Elings 1605
From mapping inter-cellular mechanical interactions in the immune system to imaging magnetic phenomena in condensed matter systems, there is a growing need for noninvasive sensors with high spatial resolution. Color centers in crystals such as alkaline-earth upconverting nanoparticles (UCNPs) and the nitrogenvacancy (NV) center in diamond are an exciting class of sensors for highresolution imaging because of their optical readout, nanoscale size, and robust hosts. The first part of this talk will discuss UCNPs for mechanical force sensing in biological applications. UCNPs consist of a ceramic host doped with lanthanides (Yb3+ and Er3+). They operate by absorbing low energy infrared photons and emitting higher energy visible photons. Mechanical forces cause a change in the crystal symmetry and spacing of the dopant atoms, which results in a change of emission intensity and color. We have recently detected 27 nN forces with our UCNPs, a requisite for detecting inter-cellular forces in the immune system. The second half of this talk will discuss using the NV center in diamond as a magnetic force sensor. Through careful materials science studies in the Jayich lab, we created NV ensembles approaching the NV dipolar interaction limit of sensitivity. Using these NV ensembles, we imaged magnetic structure in CoTiSb.