Search query: Resonantly enhanced SHG

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abstract: Nonlinear optical phenomena in nanostructured materials have been challenging our perceptions of nonlinear optical processes that have been explored since the invention of lasers. For example, the ability to control optical field confinement, enhancement, and scattering almost independently allows nonlinear frequency conversion efficiencies to be enhanced by many orders of magnitude compared to bulk materials. Also, the subwavelength length scale renders phase matching issues irrelevant. Compared with plasmonic nanostructures, dielectric resonator metamaterials show great promise for enhanced nonlinear optical processes due to their larger mode volumes. Here, we present, for the first time, resonantly enhanced second harmonic generation (SHG) using gallium arsenide (GaAs) based dielectric metasurfaces. Using arrays of cylindrical resonators we observe SHG enhancement factors as large as 10(4) relative to unpatterned GaAs. At the magnetic dipole resonance, we measure an absolute nonlinear conversion efficiency of ~2 x 10( 5) with ~3.4 GW/cm(2) pump intensity. The polarization properties of the SHG reveal that both bulk and surface nonlinearities play important roles in the observed nonlinear process.
author_names: Sheng Liu

Michael B Sinclair

Sina Saravi

Gordon Arthur Keeler

Yuanmu Yang

John Louis Reno

Gregory M Peake

Frank Setzpfandt

Isabelle Staude

Thomas Pertsch

Igal Brener
title: Resonantly Enhanced Second Harmonic Generation Using III V Semiconductor All Dielectric Metasurfaces.
venue: Nano letters
year: 2016

abstract: The immobilization of oligonucleotide sequences onto glass supports is central to the field of biodiagnostics and molecular biology with the widespread use of DNA microarrays. However, the influence of confinement on the behavior of DNA immobilized on silica is not well understood owing to the difficulties associated with monitoring this buried interface. Second harmonic generation (SHG) is an inherently surface specific technique making it well suited to observe processes at insulator interfaces like silica. Using a universal 3 nitropyrolle nucleotide as an SHG active label, we monitored the hybridization rate and thermal dissociation of a 15 mer of DNA immobilized at the silica/aqueous interface. The immobilized DNA exhibits hybridization rates on the minute time scale, which is much slower than hybridization kinetics in solution but on par with hybridization behavior observed at electrochemical interfaces. In contrast, the thermal dissociation temperature of the DNA immobilized on silica is on average 12 degC lower than the analogous duplex in solution, which is more significant than that observed on other surfaces like gold. We attribute the destabilizing affect of silica to its negatively charged surface at neutral pH that repels the hybridizing complementary DNA.
author_names: Md Shafiul Azam

Julianne M Gibbs-Davis
title: Monitoring DNA hybridization and thermal dissociation at the silica/water interface using resonantly enhanced second harmonic generation spectroscopy.
venue: Analytical chemistry
year: 2013

abstract: Due to their strong modal confinement, optical microfibres (OMs) provide an excellent opportunity for studying nonlinear effects and in particular intermodally phase matched second (SHG) and third (THG) harmonic generation with predicted efficiencies up to 10 1 over several cm in an ideal uniform silica OM for both cases. Experimentally however, fabricating the required phase matching diameter uniformly over such lengths remains challenging. A simple solution is to reconfigure the OM as a resonator, such that pump recirculation near resonance increases conversion without the need for higher power sources or OM lengths greater than a few mm. Here, we theoretically study surface SHG and THG in OM loop resonators by numerically solving the underlying coupled mode equations to determine the dependence of the enhancement on the resonance properties.
author_names: T Lee

Neil Broderick

Rand Ismaeel

Marcelo A Gouveia

Gilberto Brambilla
title: Resonantly enhanced second and third harmonic generation in microfibre loop resonators
venue: 2013 Conference on Lasers Electro Optics Europe International Quantum Electronics Conference CLEO EUROPE/IQEC
year: 2013

abstract: Abstract Based on the transient electric field migration directly probed by the time resolved microscopic optical second harmonic generation (TRM SHG) technique, we successfully detected the transient hole transport in the perovskite for the first time. From the spectroscopic point of view, SHG signal resonantly enhanced at the fundamental wavelength of around 1560 nm through the band transition under the voltage application. Square dependence of the SH intensity on the applied voltage at the wavelength of 1560 nm clearly indicated the electric field induced process of the SHG. We could visualize the carrier motion in the channel of perovskite field effect transistor (FET) with this wavelength. Carrier mobility was estimated as 0.02 cm2/V by analyzing the transient carrier motion. TRM SHG technique was also employed to investigate the effect of traps on the transient carrier motion. Based on the peak of the transient electric field distribution, trap density, and dynamic carrier mobility were separately estimated.
author_names: Lei Lei Yin Win

Dai Taguchi

Takaaki Manaka
title: Transient carrier visualization of organic inorganic hybrid perovskite thin films by using time resolved microscopic second harmonic generation (TRM SHG)
year: 2019

abstract: We report the first use of resonantly enhanced second harmonic generation (SHG) to study uranyl adsorption at a buried mineral oxide/water interface. Uranyl adsorption is studied in real time, under flow conditions, and in the presence of environmentally relevant screening electrolyte concentrations. The in situ SHG spectrum of surface bound uranyl reveals a well defined resonance at 306 nm. By monitoring the SHG response at 306 nm, adsorption isotherms were collected for uranyl species at the fused silica/water interface at pH 7, and in the presence of aqueous carbonate. The measured adsorption free energies determined by the Langmuir isotherm are consistent with physisorption via hydrogen bonding. The speciation of the surface active uranyl species at pH 7 was elucidated via a free energy versus interfacial potential analysis, which reveals that the uranyl adsorbates are either neutral or univalent cationic species. Complementary surface charge density data, obtained using the Eisenthal chi(3) technique, reveal that the charge on the ionic uranyl species adsorbing under the experimental conditions are positive. It is proposed that a mixture of neutral and univalent, cationic uranyl species is surface active at pH 7 and in the presence of carbonate ions. Insofar as the experimental conditions model those found in natural groundwater systems, the results of this work are valuable to the prediction and assessment of uranium pollution transport in groundwater and soils. Our thermodynamic results can also serve as important benchmarks for computer simulations of U(VI) transport in heterogeneous geochemical environments.
author_names: Jessica N Malin

Franz M Geiger
title: Uranyl adsorption and speciation at the fused silica/water interface studied by resonantly enhanced second harmonic generation and the chi(3) method.
venue: The journal of physical chemistry. A
year: 2010

abstract: Nanostructured materials offer many advantages over bulk materials in nonlinear optical phenomena. For example, the subwavelength scale allows the neglect of phase matching issues. The ability to control tight confinement and large resonant enhancement of electromagnetic fields also results in higher nonlinear frequency conversion efficiencies than bulk materials. Compared with plasmonic nanostructures, high index dielectric nanostructures render larger mode volumes and show great promise for enhanced nonlinear optical processes. In this work, we present resonantly enhanced second harmonic generation from L shaped AlGaAs nanoantennas. By tuning the nanostructure thickness, arm length, and width, the overlap of resonances at fundamental and second harmonic wavelengths can be achieved using any pump wavelength in a broad near infrared spectral region. We predict SHG efficiency exceeding {4} \times {10} 3}$4x10 3 with a pump intensity of {1}\rm GW/cm}^2}$1GW/cm2 at two representative pump wavelengths of 1675 and 1800 nm. Our findings are valuable for applications involving all dielectric nanoantennas, such as efficient sensing and single biomolecule tracking microscopy.
author_names: Tao Zeng

Lingwei Guo

Long Xu

Tiancheng Han
title: Enhanced second harmonic generation from L shaped AlGaAs nanoantennas
year: 2020

abstract: At room temperature, by using a tunable broadband femtosecond laser as excitation source we observed second harmonic generation (SHG) and nonlinear photoluminescence (NPL) in GaN film grown on sapphire simultaneously or individually. In addition to the observation of the resonance effect of the nonlinear response when the SHG is tuned to coincide with the near band edge emission, we carefully measured dependence of the SHG and NPL signals on polarization of the excitation light. The results reveal that the reabsorption of the SHG photons with energies higher than the fundamental gap of GaN significantly contributes to generation of the efficient NPL signal.
author_names: Hui Yang

Shijie Xu

Q L Li

Jie Zhang
title: Resonantly enhanced femtosecond second harmonic generation and nonlinear luminescence in GaN film grown on sapphire
year: 2006

abstract: Using a variety of fixed frequency and tunable laser sources, we investigated optical second harmonic generation (SHG) of wavelengths near and inside the charge transfer absorption band of the organic crystal DAN [4 (N,N dimethylamino) 3 acetamidonitrobenzene] This represents the first study of second harmonic generation in the absorption band of an organic nonlinear crystal, we believe.
author_names: Herbert Looser

William P Risk

Robert J Twieg

Gary C Bjorklund
title: Resonantly enhanced second harmonic generation in the charge transfer band of DAN
year: 1989

abstract: Nearly perfectly unidirectional second harmonic generation of light is realized in a magnetoelectric material. Mirror symmetries are of particular importance because they are connected to fundamental properties and conservation laws. Spatial inversion and time reversal are typically associated to charge and spin phenomena, respectively. When both are broken, magnetoelectric cross coupling can arise. In the optical regime, a difference between forward and backward propagation of light may result. Usually, this nonreciprocal response is small. We show that a giant nonreciprocal optical response can occur when transferring from linear to nonlinear optics, specifically second harmonic generation (SHG) CuB2O4 exhibits SHG transmission changes by almost 100% upon reversal of a magnetic field of just 10 mT. The observed nonreciprocity results from an interference between magnetic dipole and electric dipole SHG. Although the former is inherently weaker than the latter, a resonantly enhanced magnetic dipole transition has a comparable amplitude as a nonresonant electric dipole transition, thus maximizing the nonreciprocity. Multiferroics and magnetoelectrics are an obvious materials platform to exhibit nonreciprocal nonlinear optical functionalities.
author_names: Shingo Toyoda

Manfred Fiebig

Taka-hisa Arima

Yoshinori Tokura

Naoki Ogawa
title: Nonreciprocal second harmonic generation in a magnetoelectric material
venue: Science Advances
year: 2021

abstract: Leveraging the resonantly enhanced parametric excitation of amorphous silicon metasurface, we achieved second harmonic generation (SHG) with ultra high ON/OFF ratio of 15000. It provides a compact and electrically tunable approach to boosting and dynamically controlling SHG.
author_names: Xuexue Guo

Yimin Ding

Xingjie Ni
title: Electrically Tunable Second Harmonic Generation Enhancement on a Parametrically Excited Metasurface
venue: 2020 Conference on Lasers and Electro Optics (CLEO)
year: 2020