nterest in a first-principles understanding of interfacial structure and dynamics of organic semiconductors has increased dramatically, driven, e.g., by vigorous efforts to develop platforms for efficient solar energy conversion. Understanding the effects of these interfaces remains, however, a formidable challenge, since interactions between chemically different molecules or molecules and surfaces may alter the molecular electronic structure in important ways. This is particularly true for...

Subwavelength-scale semiconductor nanolasers have received wide attention recently for their applications in optical interconnect, bio/chemical sensing, data storage and imaging. We are particularly interested in using nanolasers to reduce the energy consumption in on-chip interconnect. Though many optical sources have been demonstrated on Si, most of them are significantly larger than transistors, making them unattractive for integration with electronic circuits. At Berkeley, we have been...

Researchers at the Oak Ridge National Laboratory have developed a series of superhydrophobic (extremely water-repellent) materials and surfaces. This research and development effort began over five years ago with a goal of making a nanostructured material that would be the most water-repellent material theoretically possible — a material with a water contact angle very close to the theoretical limit of 180 degrees. The idea was to create an ideal nanostructured surface pattern that greatly...

Multiplexed Föster resonant energy transfer imaging provides a systematic way to study signal networks that govern complex cellular processes. At present, real-time studying of these processes is limited by our inability to imaging the FRET network among four or more fluorescent labels simultaneously. The difficulty in multiplexed FRET rises from the complex photon pathway network in a multilabel FRET complex. To apply multiplexed FRET in live imaging, all photon pathways need to be imaged in...

Over 30 years ago, researchers investigating the ultimate limits of mechanical detection of gravitational waves understood theoretically how quantum mechanics should limit these ultrasensitive mechanical measurements. In the past 10 years, the tools to prepare micron-scale mechanical structures in fundamental quantum states have been rapidly developed, using both optical and electrical techniques. In this lecture, I will give an overview of the state of the art from experiments in my group...

Optical coherence tomography is one of the most rapidly developing biomedical imaging modalities. In this technique, the structural information is derived from the light backscattered or backreflected at the interfaces between the regions of different optical properties within the object. OCT technique enables two- or three-dimensional cross-sectional imaging with micrometer resolution. Recently, ultrahigh speed and ultrahigh resolution Spectral OCT imaging using CMOS and swept-source OCT...

Antennas are at the heart of modern radio and microwave frequency communications technologies. Because of their efficient coupling to light propagating in free space, antennas form the basis for transmitting and receiving electromagnetic radiation. Using metallic nanostructures, researchers have extended antenna concepts to the optical frequency domain and realized many advancements in nanophotonics [1]. However, recent research has begun to exploit the scattering resonances of...

Professor of Optometry and Vision Science and Affiliate Professor of Psychology and Engineering at the University of California, Berkeley Stereoscopic displays present different images to the two eyes and thereby create a compelling three-dimensional (3-D) sensation. They are being developed for numerous applications including cinema, television, virtual prototyping and medical imaging. However, stereoscopic displays cause perceptual distortions, performance decrements and visual fatigue....

The Multiangle Imaging SpectroRadiometer (MISR) instrument has been collecting global Earth data from NASA’s Terra satellite for more than a decade. With nine separate cameras, four visible/near-infrared spectral bands, and moderately high spatial resolution, MISR has demonstrated how multiangle intensity imaging offers unique tools for remote sensing of aerosol, cloud and surface properties. MISR observations of scattered light as a function of view angle and wavelength are used to retrieve...

I will describe recent experimental results, where we realize an asymmetric optical potential barrier for ultracold Rb 87 atoms using laser light tuned near the D2 optical transition. Such a one-way barrier, where atoms impinging on one side are transmitted but reflected from the other, is a realization of Maxwell's demon and has potential implications for cooling atoms and molecules not amenable to standard laser-cooling techniques. In our experiment, atoms are confined to a far-detuned...

Please enjoy Jim's unique insight into the history of — and the opportunities open to — our venerable institution.

We explore nonlinear optical phenomena at the nanoscale by launching femtosecond laser pulses into long silica nanowires. Using evanescent coupling between wires we demonstrate a number of nanophotonic devices. At high intensity, the nanowires produce a strong supercontinuum over short interaction lengths (less than 20 mm) and at a very low energy threshold (about 1 nJ), making them ideal sources of coherent white light for nanophotonic applications. The spectral broadening reveals an optimal...

Everyone knew it was coming because the microwave maser had proved the principle 10 years previous. But how to do it in the visible, at wavelengths 10,000 times shorter than microwaves? Ted Maiman got the glory with the ruby laser and Gordon Gould got the money for patents on optically pumped and gas discharge pumped lasers, as well as Brewster's angle laser windows.

The Shack-Hartmann wavefront sensor (SHWFS) has seen an increasing number of applications over the last 15 years. Originally used for high-energy laser adaptive optics, and then later applied to astronomy, more recently the numerous applications have been developed. The Shack-Hartmann wavefront sensor is used to measure the irradiance and phase distributions of an incident light beam by dissecting the income light with a lenslet array, and then detecting the direction of propagation by...

The concept of optical refrigeration (also known as laser cooling of solids) was described shortly after the birth of quantum mechanics. Interestingly, it was first rejected by many as unphysical and in violation of the laws of thermodynamics. The underlying mechanism is simple and based on anti-Stokes fluorescence where incident light from a coherent (low-entropy) source such as a laser is upconverted into high-entropy fluorescence via absorption or removal of vibrational energy (phonons)....

Multiterawatt femtosecond duration laser pulses, when launched in the atmosphere, undergo extreme self-focusing to produce dramatic spectral superbroadening and breakdown the molecular constituents of air to produce extended electron-ion plasma channels. The dramatic nonlinear events occurring in the interaction zone while only qualitatively understood, have prompted a flurry of activity over the past decade into exploiting these phenomena in real-life applications. Some applications include...