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D. R. Solli

Publications and source records attributed to D. R. Solli.

13 recordsLinked to original sources
arXiv2013

Controlling and Streaking Nanotip Photoemission by Enhanced Single-cycle Terahertz Pulses

The active control of matter by strong electromagnetic fields is of growing importance, with applications all across the optical spectrum from the extreme-ultraviolet to the far-infrared. In recent years, phase-stable terahertz (THz) fields have shown tremendous potential in the observation and manipulation of elementary excitations in complex systems. The combination of concepts from attosecond science with advanced THz technology facilitates novel spectroscopic schemes, such as THz streaking. In general, driving charges at lower frequency enhances interaction energies and can promote drastically different dynamics. For example, mid-infrared excitation induces field-driven sub-cycle electron dynamics in nanostructure nearfields. Such frequency scalings will also impact nanostructure-based streaking, which has been theoretically proposed. Here, we experimentally demonstrate extensive control over nanostructure photoelectron emission using single-cycle THz transients. The locally enhanced THz near-field at a nanotip significantly amplifies or suppresses the detected photocurrent. We present field-driven streaking spectroscopy with spectral compression and expansion arising from electron propagation within the nanolocalized volume. THz near-field streaking produces rich spectrotemporal features and will yield unprecedented control over ultrashort electron pulses for imaging and spectroscopy.

physics.optics↗
arXiv2009

Rare frustration of optical supercontinuum generation

Extremely large, rare events arise in various systems, often representing a defining character of their behavior. Another class of extreme occurrences, unexpected failures, may appear less important, but in applications demanding stringent reliability, the rare absence of an intended effect can be significant. Here, we report the observation of rare gaps in supercontinuum pulse trains, events we term rogue voids. These pulses of unusually small spectral bandwidth follow a reverse-heavy-tailed statistical form. Previous analysis has shown that rogue waves, the opposite extremes in supercontinuum generation, arise by stochastic enhancement of nonlinearity. In contrast, rogue voids appear when spectral broadening is suppressed by competition between pre-solitonic features within the modulation-instability band. This suppression effect can also be externally induced with a weak control pulse.

physics.optics↗
arXiv2008

Inverse Raman Scattering in Silicon

Stimulated Raman scattering is a well-known nonlinear process that can be harnessed to produce optical gain in a wide variety of media. This effect has been used to produce the first silicon-based lasers and high-gain amplifiers. Interestingly, the Raman effect can also produce intensity-dependent nonlinear loss through a corollary process known as inverse Raman scattering (IRS). Here, we demonstrate IRS in silicon--a process that is substantially modified by the presence of optically-generated free carriers--achieving attenuation levels >15 dB with a pump intensity of 4 GW/cm^2. Ironically, we find that free-carrier absorption, the detrimental effect that suppresses other nonlinear effects in silicon, actually facilitates IRS by delaying the onset of contamination from coherent anti-Stokes Raman scattering. The carriers allow significant IRS attenuation over a wide intensity range. Silicon-based IRS could be used to produce chip-scale wavelength-division multiplexers, optical signal inverters, and fast optical switches.

physics.optics↗
arXiv2008

Real-time Spectroscopy with Sub-GHz Resolution using Amplified Dispersive Fourier Transformation

Dispersive Fourier transformation is a powerful technique in which spectral information is mapped into the time domain using chromatic dispersion. It replaces a spectrometer with an electronic digitizer, and enables real-time spectroscopy. The fundamental problem in this technique is the trade-off between the detection sensitivity and spectral resolution, a limitation set by the digitizer's bandwidth. This predicament is caused by the power loss associated with optical dispersion. We overcome this limitation using Raman amplified spectrum-to-time transformation. An extraordinary loss-less -11.76 ns/nm dispersive device is used to demonstrate single-shot gas absorption spectroscopy with 950 MHz resolution--a record in real-time spectroscopy.

physics.optics↗
arXiv2008

Demonstration of Stimulated Supercontinuum Generation - An Optical Tipping Point

Optical supercontinuum radiation, a special kind of white light, has found numerous applications in scientific research and technology. This bright, broadband radiation can be generated from nearly monochromatic light through the cooperative action of multiple nonlinear effects. Unfortunately, supercontinuum radiation is plagued by large spectral and temporal fluctuations owing to the spontaneous initiation of the generation process. While these fluctuations give rise to fascinating behavior in the form of optical rogue waves [1], they impede many critical applications of supercontinuum. Here, we introduce, and experimentally demonstrate, a powerful means of control over supercontinuum generation by stimulating the process with a very weak optical seed signal [2]. This minute addition significantly reduces the input power threshold for the process and dramatically increases the stability of the resulting radiation. This effect represents an optical tipping point, as the controlled addition of a specialized, but extraordinarily weak perturbation powerfully impacts a much stronger optical field, inducing a drastic transition in the optical system.

physics.optics↗
arXiv2003

Fast light, slow light, and phase singularities: a connection to generalized weak values

We demonstrate that Aharonov-Albert-Vaidman (AAV) weak values have a direct relationship with the response function of a system, and have a much wider range of applicability in both the classical and quantum domains than previously thought. Using this idea, we have built an optical system, based on a birefringent photonic crystal, with an infinite number of weak values. In this system, the propagation speed of a polarized light pulse displays both superluminal and slow light behavior with a sharp transition between the two regimes. We show that this system's response possesses two-dimensional, vortex-antivortex phase singularities. Important consequences for optical signal processing are discussed.

quant-ph↗
arXiv2003

Experimental demonstration of photonic crystal waveplates

We have constructed and experimentally tested a microwave half waveplate using the dispersive birefringent properties of a bulk two-dimensional photonic crystal away from its band gap. Our waveplate device exhibited a 200:1 polarization contrast, limited by our experimental resolution. We anticipate that photonic crystal waveplates will have important practical applications in several areas, including integrated photonic circuits.

cond-mat↗
arXiv2003

Photonic crystal polarizers and polarizing beam splitters

We have experimentally demonstrated polarizers and polarizing beam splitters based on microwave-scale two-dimensional photonic crystals. Using polarized microwaves within certain frequency bands, we have observed a squared-sinusoid (Malus) transmission law when using the photonic crystal as a polarizer. The photonic crystal also functions as a polarizing beamsplitter; in this configuration it can be engineered to split incident polarizations in either order, making it more versatile than conventional, Brewster-angle beamsplitters.

cond-mat↗
arXiv2003

Nonlinear absorption and refraction in near-detuned rubidium vapor

Using the z-scan technique, we have measured the self-induced absorptive and refractive nonlinear behavior of hot atomic rubidium vapor within the Doppler profile of the D2 line. We observe large nonlinear amplitude and phase effects with only tens of microwatts of incident power. Our results are in good agreement with numerical calculations based on an analytic model of a Doppler- broadened two-level system.

physics.atom-ph↗
arXiv2003

Demonstration of superluminal effects in an absorptionless, non-reflective system

We present an experimental and theoretical study of a simple, passive system consisting of a birefringent, two-dimensional photonic crystal and a polarizer in series, and show that superluminal dispersive effects can arise even though no incident radiation is absorbed or reflected. We demonstrate that a vector formulation of the Kramers-Kronig dispersion relations facilitates an understanding of these counter-intuitive effects.

quant-ph↗