scispace - formally typeset

Journal ArticleDOI

Hyper-Rayleigh scattering in centrosymmetric systems

28 Sep 2015-Journal of Chemical Physics (AIP Publishing)-Vol. 143, Iss: 12, pp 124301-124301

TL;DR: The detailed derivation in this work leads to results which are summarized for perpendicular detection of polarization components both parallel and perpendicular to the pump radiation, leading to distinct polarization ratio results, as well as a reversal ratio for forward scattered circular polarizations.

AbstractHyper-Rayleigh scattering (HRS) is an incoherent mechanism for optical second harmonic generation. The frequency-doubled light that emerges from this mechanism is not emitted in a laser-like manner, in the forward direction; it is scattered in all directions. The underlying theory for this effect involves terms that are quadratic in the incident field and involves an even-order optical susceptibility (for a molecule, its associated hyperpolarizability). In consequence, HRS is often regarded as formally forbidden in centrosymmetric media. However, for the fundamental three-photon interaction, theory based on the standard electric dipole approximation, representable as E13, does not account for all experimental observations. The relevant results emerge upon extending the theory to include E12M1 and E12E2 contributions, incorporating one magnetic dipolar or electric quadrupolar interaction, respectively, to a consistent level of multipolar expansion. Both additional interactions require the deployment of higher orders in the multipole expansion, with the E12E2 interaction analogous in rank and parity to a four-wave susceptibility. To elicit the correct form of response from fluid or disordered media invites a tensor representation which does not oversimplify the molecular components, yet which can produce results to facilitate the interpretation of experimental observations. The detailed derivation in this work leads to results which are summarized for the following: perpendicular detection of polarization components both parallel and perpendicular to the pump radiation, leading to distinct polarization ratio results, as well as a reversal ratio for forward scattered circular polarizations. The results provide a route to handling data with direct physical interpretation, to enable the more sophisticated design of molecules with sought nonlinear optical properties.

Topics: Multipole expansion (55%), Rayleigh scattering (54%), Electric dipole moment (53%), Dipole (53%), Hyperpolarizability (52%)

...read more

Content maybe subject to copyright    Report

Citations
More filters

Journal ArticleDOI
Abstract: One of the key frameworks for developing the theory of light–matter interactions in modern optics and photonics is quantum electrodynamics (QED). Contrasting with semiclassical theory, which depicts electromagnetic radiation as a classical wave, QED representations of quantized light fully embrace the concept of the photon. This tutorial review is a broad guide to cutting-edge applications of QED, providing an outline of its underlying foundation and an examination of its role in photon science. Alongside the full quantum methods, it is shown how significant distinctions can be drawn when compared to semiclassical approaches. Clear advantages in outcome arise in the predictive capacity and physical insights afforded by QED methods, which favors its adoption over other formulations of radiation–matter interaction.

22 citations


Journal ArticleDOI
23 Jul 2018-Symmetry
TL;DR: In the wide realm of applications of quantum electrodynamics, a non-covariant formulation of theory is particularly well suited to describing the interactions of light with molecular matter, and a variety of symmetry principles are drawn out with reference to applications.
Abstract: In the wide realm of applications of quantum electrodynamics, a non-covariant formulation of theory is particularly well suited to describing the interactions of light with molecular matter The robust framework upon which this formulation is built, fully accounting for the intrinsically quantum nature of both light and the molecular states, enables powerful symmetry principles to be applied With their origins in the fundamental transformation properties of the electromagnetic field, the application of these principles can readily resolve issues concerning the validity of mechanisms, as well as facilitate the identification of conditions for widely ranging forms of linear and nonlinear optics Considerations of temporal, structural, and tensorial symmetry offer significant additional advantages in correctly registering chiral forms of interaction More generally, the implementation of symmetry principles can considerably simplify analysis by reducing the number of independent quantities necessary to relate to experimental results to a minimum In this account, a variety of such principles are drawn out with reference to applications, including recent advances Connections are established with parity, duality, angular momentum, continuity equations, conservation laws, chirality, and spectroscopic selection rules Particular attention is paid to the optical interactions of molecules as they are commonly studied, in fluids and randomly organised media

14 citations


Cites background from "Hyper-Rayleigh scattering in centro..."

  • ...The associated ‘J’ and ‘K’ tensors molecular tensors retain index permutational symmetry if the M1 or E2 interaction is involved in the output emission, but not if it is linked with one of the two input photon annihilation events [80,81]....

    [...]


Journal ArticleDOI
TL;DR: This work presents a rigorous quantum electrodynamical analysis of the scattering process, involving a partially index-symmetric construction of the fourth-rank γ tensor-dispensing with the Kleinman symmetry condition.
Abstract: Third-harmonic scattering is a nonlinear optical process that involves the molecular second-hyperpolarizability, γ. This work presents a rigorous quantum electrodynamical analysis of the scattering process, involving a partially index-symmetric construction of the fourth-rank γ tensor—dispensing with the Kleinman symmetry condition. To account for stochastic molecular rotation in fluids, methods of isotropic averaging must be employed to relate the molecular properties to accessible experimental quantities such as depolarization ratio. A complete eighth-rank tensor rotational average yields results for observable third-harmonic scattering rates, cast as a function of the natural-invariant γ components, and the polarization geometry of the experiment. Decomposing the tensor γ into irreducible weights allows specific predictions to be made for each molecular point group, allowing greater discrimination between the results for different molecular symmetries.

13 citations


Journal ArticleDOI
Abstract: The generation of correlated photon pairs is a key to the production of entangled quantum states, which have a variety of applications within the area of quantum information. In spontaneous parametric down-conversion—the primary method of generating correlated photon pairs—the associated photon annihilation and creation events are generally thought of as being colocated: The correlated pair of photons is localized with regards to the pump photon and its positional origin. A detailed quantum electrodynamical analysis highlights a mechanism exhibiting the possibility of a delocalized origin for paired output photons: The spatial extent of the region from which the pair is generated can be much larger than previously thought. The theory of both localized and nonlocalized degenerate down-conversion is presented, followed by a quantitative analysis using discrete-volume computational methods. The results may have significant implications for quantum information and imaging applications, and the design of nonlinear optical metamaterials.

6 citations


Cites background from "Hyper-Rayleigh scattering in centro..."

  • ...Higher-order couplings that occur outside the electric-dipole approximation become significant when studying chiral discriminatory effects in optical processes including forces [70] and nonlinear optics [71,72]....

    [...]


Journal ArticleDOI
Abstract: We extend the usual multipolar theory of linear Rayleigh and Raman scattering to include the second-order correction. These terms promise a wealth of information about the shape of a scatterer and yet are insensitive to the scatterer's chirality. Our extended theory might prove especially useful for analyzing samples in which the scatterers have nontrivial shapes but no chiral preference overall, as the zeroth-order theory offers little information about shape and the first-order correction is often quenched for such samples. A basic estimate suggests that our extended theory can be applied to a scatterer as large as ${k}_{0}d\ensuremath{\sim}1/10$ with less than $\ensuremath{\sim}0.1%$ error resulting from the neglect of the third- and higher-order corrections. Our results are entirely analytical.

6 citations


References
More filters

Journal ArticleDOI
TL;DR: The development of nonlinear optical materials has been driven by a multitude of important technological applications that can be realized if suitable materials are available, and future generations of optoelectronic devices for telecommunications, information storage, optical switching, and signal processing are predicted to a large degree on the development of materials with exceptional NLO responses.
Abstract: The development of nonlinear optical (NLO) materials has been driven by a multitude of important technological applications that can be realized if suitable materials are available 1–15. Future generations of optoelectronic devices for telecommunications, information storage, optical switching, and signal processing are predicted to a large degree on the development of materials with exceptional NLO responses 1–15. A large number of organic π-conjugated molecules have been investigated in the last thirty years for suitability to function as components in hypothetical NLO materials 1–19. Several books and reviews have appeared dealing with theory of nonlinear optics and the structural characteristics and applications of nonlinear optical molecules and materials 1–19. Truly, all-optical NLO effects were not discovered until the discovery of lasers. Second-harmonic generation (SHG) was first observed in a single crystal of quartz by Franken et.al. 20 in 1961. Parametric amplification was observed in lithium niobate (LiNbO3) by two-wave mixing in temperature-tuned single crystals 21. Rentzepis and Pao 22 made the first observation of SHG in an organic material, benzpyrene, in 1964. Heilmeir examined hexamethylenetetramine single crystal SHG in the same year 24. Two other organic materials followed rapidly: hippuric acid and benzil 25. Benzil was the first material that proved relatively easy to grow into large single crystals. Over the last two decades the study of nonlinear optical process in organic and polymer systems has enjoyed rapid and sustained growth 1–19, 25–39. One indication of the growth is the increase in the number of articles published in refereed society journals, as one can find from web of science 25, SCIFINDER 26 and Scopus 27 search. The four years period 1980–1983 saw the publication of 124 such articles. In the next four years period 1984–1987, the production of articles increased to 736 (nearly six times). From 1988–1992, the number of articles increased to more than 4000 25–27. In the last decade, academia, industry and government laboratories have been working in this field to replace electronics by photonics and as a result, the number of publications has reached more than 70,000 25–27. The rapid growth of the field is mainly due to the technological promise of these materials 1–19, 28–37. Traditionally, the materials used to measure second-order NLO behavior were inorganic crystals, such as lithium niobate (LiNbO3) and potassium dihydrogen phosphate (KDP). The optical nonlinearity in these materials is to a large extent caused by the nuclear displacement in an applied electric field, and to a smaller extent by the movement of the electrons 1–10. This limits the bandwidth of the modulator. Organic materials have a number of advantages over inorganic materials for NLO applications 28–35. The ease of modification of organic molecular structures makes it possible to synthesize tailor-made molecules and to fine-tune the properties for the desired application 28–35. Unfortunately, not all organic materials display second-order NLO properties. At the molecular level, they need to be non-centrosymmetric. A large number of organic π-conjugated molecules have been investigated 1–9, 28–35 in the last twenty years. The outcome of the results has helped to establish certain guidelines for molecular design to get good second order NLO materials. However, roughly more than 80% of all π-conjugated organic molecules crystallize in centro-symmetric space groups 1–19, therefore producing materials with no second order bulk susceptibility. To overcome this limitation, organic NLO material doped or covalently attached in polymers, have been introduced by Dalton et. al 5,6,16,38–39. A few of these chromophores have served as components of functioning polymer-based optoelectronic devices; the physical properties of all these prototype materials possess one or more critical deficiencies that render commercialization of these systems impractical 28–39. These facts suggest that new types of molecular design are necessary if significant advances are to be realized. From 1998 onwards, researchers started effort on developing various nanomaterials, with high second order NLO properties and seeking for their applications in photonics as well as chemical and biological detection 40–106. The surface-enhanced phenomenon is predicted to have a particularly important impact in nonlinear optical NLO applications, since the generally weak nonlinear effects can be significantly increased via strong electromagnetic fields at the surfaces of metallic nanostructures 60–129. NLO based sensing have provided great potentials and opportunities for detecting different environmental toxins that exhibit some specific advantages, compared to other conventional and nanomaterial based techniques. Aim of this review is mainly to summarize and evaluate the achievements in development of nanoparticle based second order NLO materials with different sizes and shapes and it will focus on the following three major issues: (i) design of novel NLO active materials using nanoparticles (ii) nonlinear optical properties of single nanoparticle, nanoparticle aggregates and self assembly, and (iii) applications in chemical and biological sensing.

594 citations


Journal ArticleDOI
Abstract: A general class of multipolar molecules is introduced in the context of quadratic nonlinear optics by way of extension of the more specific cases of dipolar and octupolar molecules. An adequate irreducible tensor formalism permits us to define rotationally invariant molecular features that couple to corresponding field tensor components, thereby enabling us to account for a variety of coherent and noncoherent processes such as harmonic light (hyper-Rayleigh) scattering, coherent second-harmonic generation in electrically poled media, and the recently proposed optical poling scheme. Experiments in both harmonic light scattering in solution (for some multipolar molecules) and optical poling (in Disperse Red 1–methyl methacrylate thin films) are analyzed in light of this model. A general tensorial permutation lemma of broad validity allows nonlinear light–matter interactions to be condensed in a statistical medium in compact rotationally invariant expressions: The main tensorial symmetry features for both molecular susceptibility and read–write field polarization tensors that jointly drive these interactions are clearly revealed.

242 citations



Journal ArticleDOI
TL;DR: Recent developments of nonlinear light scattering techniques have resulted in a deeper insight of the underlying light-matter interactions and shed new light on the molecular mechanism of surface kinetics in solution, properties of interfacial water in contact with hydrophilic and hydrophobic particles and droplets, and vesicle structure and transport properties.
Abstract: Nano- and microparticles have optical, structural, and chemical properties that differ from both their building blocks and the bulk materials themselves. These different physical and chemical properties are induced by the high surface-to-volume ratio. As a logical consequence, to understand the properties of nano- and microparticles, it is of fundamental importance to characterize the particle surfaces and their interactions with the surrounding medium. Recent developments of nonlinear light scattering techniques have resulted in a deeper insight of the underlying light-matter interactions. They have shed new light on the molecular mechanism of surface kinetics in solution, properties of interfacial water in contact with hydrophilic and hydrophobic particles and droplets, molecular orientation distribution of molecules at particle surfaces in solution, interfacial structure of surfactants at droplet interfaces, acid-base chemistry on particles in solution, and vesicle structure and transport properties.

194 citations


Journal ArticleDOI
Abstract: We have established analytical structure/(hyper)polarizability relationships for donor-acceptor conjugated molecules, within the framework of the two-state approximation. In this two-form model, a molecule is described as a mixture between neutral and charge-separated resonance forms. We defined a parameter MIX, characterizing the mixing between the limiting-resonance forms, that is measurable in solution. MIX is proportional to the change in dipole between the ground and excited states. We studied analytically the variation of (hyper)polarizabilities with MIX. Finally, we showed how this model can account for external perturbation, such as the solvent electric reaction field.

117 citations