Laser Fusion Energy: Opportunities and Challenges

The National Ignition Facility (NIF), the world’s largest and most energetic laser system built for studying inertial confinement fusion (ICF) and high-energy-density (HED) science, is now operational at Lawrence Livermore National Laboratory (LLNL). NIF’s 192 beams are configured to create pressures as high as 100 GB, matter temperatures approaching 10^9 and densities over 1000 g/cmm^3. With these capabilities, the NIF will enable exploring scientific problems in strategic defense, basic science and fusion energy.

Modeling, Simulation and Analysis of Integrated Building Energy and Control Systems

The modeling, simulation and analysis of integrated building energy and control systems that significantly reduce energy consumption poses challenges that are not well addressed by standard building simulation pro- grams. This seminar discusses how modular system modeling based on the object-oriented equation-based Modelica language and on co-simulation can address these challenges. We demonstrate applications that are enabled by this new approach and that are outside the scope of standard building simulation programs.

Photonic Propulsion for Relativistic Flight: Enabling the First Interstellar Missions

Recent advances in photonics and directed energy systems now allow us to realize what was only a decade ago, simply science fiction. It is no longer. Spacecraft from fully-functional gram-level wafer-scale systems (“wafer sats”) capable of speeds greater than ¼ c  that could reach the nearest star in  20 years to spacecraft for large missions capable of supporting human life with masses more than 105 kg (100 tons) that could reach speeds of greater than 1000 km/s can be realized.

III-Nitride Quantum Dot and Dot-in-nanowire Light Sources: From Visible to Near-Infrared

Low threshold visible lasers are useful for a number of applications including full color mobile projectors, optical data storage, heads-up displays in automobiles, in medicine and plastic fiber communication. Lasers emitting in the blue and green are generally realized with GaN-based InGaN/GaN quantum wells (QWs) as the gain media. Self-organized quantum dots (QDs), which form by strain relaxation, offer distinct advantages over quantum wells and their emission can be extended to longer wavelengths (~ 630 nm).

From Mud to Electrode Catalysts and Conductive Nanomaterials

Dissimilatory metal-reducing bacteria (DMRB) are a class of microorganisms that inhabit many subsurface environments including marine sediments. They occupy a distinct metabolic niche wherein they can acquire energy by coupling oxidation of organic matter with reduction of insoluble oxidants such as mineral deposits. This capability requires that DMRB transfer electrons to their outer surface where electron-transfer can occur to an insoluble oxidant which is distinct from the dominant paradigm in which soluble oxidants are transported into cells for reduction during metabolism.

Integrated Photonic Technologies for On-Chip and Space Applications

Integrated photonics has the potential to greatly reduce the size, weight, and power (SWaP) while improving the performance and reliability of photonic systems. This technology has already impacted telecommunications and is expected to transform data center communications, high performance computing, microwave photonics, and sensing. This talk will describe examples of integrated photonic technologies being developed in our research group and also discuss a novel application for integrated photonics, namely, space optical communications.

Single-Step Low-Temperature Growth of High-Mobility Large-Area Graphene and the Potential Applications

Graphene, a monolayer of carbon atoms forming a two-dimensional honeycomb lattice structure, is considered a wonder material for both scientific research and technological applications since its successful isolation in 2004. As a flexible, transparent conductor with intrinsically very high electrical mobility and thermal conductivity, graphene is promising for large-area electronic devices such as touch screen displays, electrodes for photovoltaic cells, interconnects for electrical circuits, and panels for light emitting diodes.

Mixed-signal Circuit Techniques for High-linearity 50 GS/s Sampling and Pulsewidth Modulation for High-Speed Signaling

Capacity growth in communication and sensor networks suggests order of magnitude increases over the next decade. To satisfy this growth, wireless and optical network technologies will increase spectral efficiency through a combination of signal processing and device improvements. At millimeter-wave bands, high-order modulation such as quadrature-amplitude modulation (QAM) is critical for backhaul links at the expense of higher peak-to-average power ratios. Similarly, coherent optical detection techniques for QPSK in 40/100 GbE optical networks have gained industry acceptance.