R. Rokitski

Excitation and direct imaging of surface plasmon polariton modes in a two-dimensional grating

We describe the simultaneous excitation and direct far-field imaging of the scattering from surface plasmon polariton modes in a two-dimensional metallic hole array grating. Conditions for the coupling and imaging are discussed, where the coupling is shown to be consistent with both measured and calculated dispersion relations. Excitation is accomplished at several different wavelengths (from 1.31 to 1.57μm), incidence angles, and grating periods, enabling the observation of a number of distinct modes with various in-plane wave vectors.

Time reversal of ultrafast waveforms by wave mixing of spectrally decomposed waves.

Two different realizations of time-reversal experiments of ultrafast waveforms are carried out in real time by use of four-wave mixing arrangements of spectrally decomposed waves. The first, conventional, method is based on phase conjugation of the waveforms spectrum and achieves time reversal of real amplitude waveforms. The second arrangement of the spectrally decomposed waves spatially inverts the waveforms spectrum with respect to the optical axis of the processor and achieves true time reversal for complex-amplitude ultrafast waveforms. We compare and contrast these two real-time techniques.

Study of spatial–temporal characteristics of optical fiber based on ultrashort-pulse interferometry

We demonstrate a method for reconstruction of the modal intensity distribution of light at the output of an optical fiber. Spatial modes of the optical fiber are separated in time as a result of differences in group velocity and are detected experimentally by observation of the interference of the modal field distribution with the time-gating reference field. The detected interference patterns of the modal fields are analyzed, providing the spatial impulse response of the fiber. We also use interferometric correlation to determine the spatiotemporal characteristics of the fiber modes, such as pulse width, linear chirp, and group velocity, for each mode.

Propagation of ultrashort pulses in multimode fiber in space and time

We perform 3D cross-correlation measurements of the optical field distribution resulting from an ultrashort pulse propagating in 6 meters of multimode fiber. Spatial amplitude and phase distributions of the optical field at the output of the fiber are measured using a time-gated spatial heterodyne interferometer as a function of time delay between the signal and the reference optical fields. We show that the measured signal represents an approximation to the optical impulse response of the multimode fiber.

Dynamic diffractive optical elements displayed on spatial light modulators

We present the optical implementation of dynamic diffractive optical elements on different types of commercially available spatial light modulators; one using twisted-nematic liquid crystals, one using analog ferro-electric liquid crystals and one using a matrix of micromirrors. Experimental results are shown and the various implementations are compared.

Surface plasmonic fields in nanophotonics

This article explores the ultrafast electrodynamics of surface plasmon-polariton fields on nanostructured metal-dielectric boundaries, and describes how to make a sensor to measure chemical reactions at a surface by generating spatially resolved, reaction-dependent, spatial and spectral frequency information.

Sequence estimation with run-length coding for VCSEL-based multimode fiber links

We demonstrate an electronic equalization technique using sequence estimation that can compensate severe intersymbol interference for run-length coded multimode VCSEL-based links.

High-speed, electronic arbitrary waveform generation using time-domain processing of ultrashort optical pulses

Ultra wideband (UWB) microwave signals are receiving much attention for their potential use in both radar systems and high-speed data links. The currently available arbitrary waveform generation (AWG) devices operates up to only a few gigahertz. The desire to create UWB signals with carrier frequencies in the 10s of GHz and fractional bandwidths approaching 100% suggests investigating microwave-photonic approaches. In this paper, the authors demonstrate a method for electrical AWG with independent envelope and carrier control though the manipulation of wide bandwidth optical pulses in a time-domain processor.

Reply to "Comment on 'Time reversal of ultrafast waveforms by wave mixing spectrally decomposed waves'".

In response to a comment on our Letter [Opt. Lett. 25, 132 (2000)], we reiterate the distinction between the spectral inversion and the spectral phase conjugation processing techniques. The former achieves time reversal of the complex amplitude waveform, whereas the latter performs time reversal of the real electric field.

Nanophotonics for Information Systems

Optical technology plays an increasingly important role in numerous applications areas, including communications, information processing, and data storage. However, as optical technology develops, it is evident that there is a growing need to develop reliable photonic integration technologies. This will include the development of passive as well as active optical components that can be integrated into functional optical circuits and systems, including filters, switching fabrics that can be controlled either electrically or optically, optical sources, detectors, amplifiers, etc. We explore the unique capabilities and advantages of nanotechnology in developing next generation integrated photonic chips. Our long-range goal is to develop a range of photonic nanostructures including artificially birefringent and resonant devices, photonic crystals, and photonic crystals with defects to tailor spectral filters, and nanostructures for spatial field localization to enhance optical nonlinearities, to facilitate on-chip system integration through compatible materials and fabrication processes. The design of artificial nanostructured materials, PCs and integrated photonic systems is one of the most challenging tasks as it not only involves the accurate solution of electromagnetic optics equations, but also the need to incorporate the material and quantum physics equations. Near-field interactions in artificial nanostructured materials provide a variety of functionalities useful for optical systems integration. Recently, the inclusion of surface plasmon photonics in this area has opened up a host of new possibilities Finally and most importantly, nanophotonics may enable easier integration with other nanotechnologies: electronics, magnetics, mechanics, chemistry, and biology. We will address some of these areas in this paper.