Save the dates: 25 - 30 January 2025
Plenary Event
OPTO Plenary
30 January 2023 • 8:00 AM - 10:00 AM PST | Moscone Center, Room 207/215 (Level 2 South) 
8:00 AM - 8:05 AM: Welcome and Opening Remarks
Sonia García-Blanco, Univ. Twente (Netherlands) and Bernd Witzigmann, Friedrich-Alexander-Univ. Erlangen-Nürnberg (Germany)

8:05 AM - 8:15 AM: Announcement of the OPTO AI/ML and Net Zero Best Paper Awards

8:15 AM - 8:50 AM: High-performance electronic-photonic interfaces: from AI to quantum

Rajeev Ram, Massachusetts Institute of Technology (United States)

The last 36 years has seen a steady increase in the deployment of photonic integrated components. Over most of this history, the development of integrated photonic systems in both III-V and Group IV materials has been driven by the needs of fibre optic systems – driven primarily by the properties of the transmission media (single-mode vs multi-mode fibre, fibre gain, etc). Today, photonic integration is increasingly driven by the unique properties of high-performance electronic-photonic interfaces. The low-capacitance, low-energy, high-bandwidth density of photonic integrated systems is now driving optical interconnection into board-scale, chip-scale, and intra-chip photonic systems.

Here, we consider new applications ranging from (1) deep learning systems and other data intensive classical compute applications, (2) optically addressed quantum computing fabrics – with tremendous progress being made today in the area of trapped-ion quantum computing, and (3) next-generation brain-computer interfaces where photonics may play an important role in massively parallel signal detection.

Rajeev J. Ram works in the areas of physical optics and electronics. He developed the III-V wafer bonding technology that led to record brightness light emitting devices at Hewlett-Packard Laboratory and the first long-wavelength VCSELs at UCSB. Since 1997, Ram has been on the faculty at MIT. His group developed energy-efficient CMOS photonics for microprocessor systems, microfluidic systems for the control of cellular metabolism, and record-efficiency light sources. He has served as a Program Director at the newly founded Advanced Research Project Agency-Energy and co-founded AyarLabs and Erbi Biosystems. He is a Fellow of OSA and IEEE.

8:50 AM - 9:25 AM: Tandem photovoltaic devices: more than one way to make a solar cell

Emily Warren, National Renewable Energy Laboratory (United States)

Tandem or multijunction photovoltaic devices cells offer the clearest path to high efficiency and high areal energy density solar energy conversion. Theoretically and at the laboratory scale, increasing the number of junctions is a simple way to maximize the amount of electricity that can be produced from a small-area device. However, there are multiple approaches to electrically and optically interconnecting the sub-cells in a tandem stack that have different trade-offs in terms of efficiency, cost, and manufacturability.

Three terminal (3T) tandems have attracted a great deal of interest at the laboratory scale for their high potential efficiencies and polarity-changing interconnections. However, the coupled nature of 3T devices adds a degree of complexity to the devices themselves and the ways that their performance can be measured and reported. In this talk, I will discuss the recent progress in the field of 3T tandems, including our recently proposed taxonomy for naming 3T devices, experimental demonstrations, robust measurement approaches, and interconnecting 3T cells into strings.

Emily Warren is a staff scientist at the National Renewable Energy Laboratory where she leads a core program on the development of high efficiency tandem solar cells. Her research interests include optoelectronic modeling of tandem solar cells, heteroepitaxy of III-Vs on Si, and the photoelectrochemical production of solar fuels. She received her PhD from the California Institute of Technology and an MPhil from the University of Cambridge in Engineering for Sustainable Development. Beyond her technical research interests, Emily is dedicated to improving energy justice and diversity, equity, and inclusion in STEM fields.

9:25 AM - 10:00 AM: Are III-nitride semiconductors also suitable for red emission?

Nicolas Grandjean, Ecole Polytechnique Fédérale de Lausanne (Switzerland)

III-nitride semiconductors (GaN and related alloys) triggered the 21st century lighting revolution thanks to the achievement of blue LEDs exhibiting remarkable performance, e.g., a wall-plug efficiency of 80%. Another striking feature of those compound semiconductors is their capability of covering the whole visible spectrum when alloying GaN with indium. De facto, a single material platform could be used to make RGB displays based on direct light emission. In addition, InGaN alloy - which is behind all blue and green LEDs- exhibits strong alloy disorder, which is highly beneficial for micron-size LEDs thanks to reduced carrier diffusion length.

In this talk, I will first present the current understanding of the physics of blue LEDs. This will bring me to the question of the “green-gap” and its relevance in light of recent results reported on InGaN red LEDs. Eventually, I will discuss challenges and opportunities offered by III-nitrides for RGB microLED displays.

Nicolas Grandjean works on the physics and technology of III-nitride wide bandgap semiconductors. His main research activities are centered on GaN based photonic devices and nanostructures. His group pioneered microcavities that gave rise to room-temperature polariton lasing and monolithic blue VCSELs. He is currently involved in several projects aimed at developing InGaN microlasers and microLEDs for AR/VR applications. He received a PhD degree in Physics in 1994 and then joined the CNRS. He is Professor at EPFL since 2004. He was visiting professor at UCSB and received the “Nakamura Lecturer” Award in 2010.