Liquid crystals and polymer glasses can be formed into orientationally ordered materials by raising the temperature of material to a at which molecular motion is greatly enhanced, applying an external aligning field, then cooling with field applied. The resulting exhibits second-order nonlinear-optical effects. In this paper, relationship between hyperpolarizability macroscopic susceptibility presented. seen depend on microscopic order parameters commonly associated liquid discussed in...

Electro-optic phase modulation was measured along with optical second-harmonic generation in thin films of a new copolymer containing dicyanovinyl-terminated azo dye side chain. Orientational order imparted to these by poling corona discharge. Details the electro-optic measurement technique, which real part coefficient can be determined directly, are presented. Taking advantage increased orientation and hindered motion nonlinear moiety chain polymer leads substantial improvements both...

We apply sum rules to answer the question: What is largest off-resonance electronic nonlinear susceptibility allowed by quantum mechanics? The sum-rule-restricted three-level model shows that two-level limit yields absolute maximum susceptibility, which found depend only on first excited state transition energy and number of electrons-in agreement with a large set second- third-order data from literature. As such, provide target for possible off-resonant susceptibilities.

Abstract A simplified three‐level model for γ, the molecular third‐order nonlinear optical susceptibility, is presented and discussed. The perturbation theory‐based approach suggests that there are three primary avenues to optimizing four‐wave mixing susceptibilities with each of these associated a particular class electronic structures. structure classes consist (1) conjugated donor–acceptor dipolar molecules large secondorder β; (2) even‐member chains such as ‐enes, ‐ynes, ene–ynes...

Our approach to the problem of understanding nonlinear-optical response a material focuses on fundamental concepts, which are exact and lead broad results that encompass all systems. For example, one can calculate precisely without approximation limit efficiency any optical phenomenon. Such limits, in turn, when built into scale-invariant figure merit be used determine what makes optimal for maximizing desired property, such as its response. However, since general (for guidelines making...

The incorporation of gold nanoparticles within thermally responsive poly( N ‐isopropyl acrylamide) hydrogels provides a simple means to define photothermally addressable materials. Relying on such composite gels, it is established here that micropatterned bilayer photoactuators demonstrate rapid and highly reversible bending unbending behavior in response illumination with visible light. In addition actuation by free space light, as most previous research nanocomposite hydrogels, light from...

We apply sum rules to calculate the maximum limit of resonant two-photon absorption cross section. Comparison theory with experimental data from literature shows that no molecule ever measured exceeds this limit. Molecules more π electrons have larger sections; but, sections fall further below fundamental as number increases—implying additional are not participating efficiently. The can aid in developing structure property relationships by providing metrics lead a deeper understanding available data.

By the use of sum rules, largest third-order molecular nonlinear-optical susceptibilities allowed by quantum mechanics are determined. The theoretical upper limit is found to depend only on first excited-state transition energy and number electrons, in agreement with experimental data.

The off-resonant electronic third-order optical susceptibility is derived in the dipole approximation using method of averages. These results are studied detail for two-, three-, and N-level model to determine origin with symmetry considerations. If matrix elements independent, shown be maximized centrosymmetric structures two-level while, general system, weak coupling between excited states also required. To address interdependence elements, a two- three-level system perturbed make...

We present the experimental and theoretical considerations needed to determine mechanisms of quadratic electro-optic modulation in dye-doped polymer systems. The is observed thin films Kerr coefficient determined by using a modified Mach–Zehnder interferometric technique. theory several nonlinear developed applied representative systems various contributions. fast, virtual electronic mechanism shown be largest contribution, as inferred from measured frequency dispersion effect. This quick...

The orientational distribution function of a poled, doped polymer film under stress is measured using polarized second-harmonic generation. four interface nonlinear boundary conditions are solved, and both the magnitude second-order susceptibility ratio tensor components susceptibility, χ113(2)/χ333(2)(≡a), shown to vary with poling field stress. Further, sign order parameter ratio, 〈P3〉/〈P1〉, as directly by generation these materials, shows that materials fall into regime unlike other...

A new strategy for optimizing the first hyperpolarizability based on concept of a modulated conjugated path in linear molecules is investigated. series seven novel chromophores with different types paths were synthesized and characterized. Hyper-Rayleigh scattering experiments confirmed that conjugation include benzene, thiophene, and/or thiazole rings combination azo ethenyl linkages between dihydroxyethylamino donor groups various acceptor result enhanced intrinsic hyperpolarizabilities...

This work aims to determine the mechanism of photomechanical response poly(Methyl methacrylate) polymer doped with photo-isomerizable dye Disperse Red 1 using non-isomerizable Orange 11 as a control isolate photoisomerization. Samples are free-standing thin films thickness that is small compared optical skin depth assure uniform illumination and throughout their volume, which differentiates these studies from most others. Polarization-dependent measurements stress used deconvolute...

Quantum sum rules impose limits on the hyperpolarizability, beta. A survey of largest second-order molecular susceptibilities finds what appears to be a universal gap between experimental results and fundamental limits. In this work, we use theory, linear spectroscopy, Raman measured values beta (using hyper-Rayleigh scattering Stark Spectroscopy) show that is due an unfavorable arrangement excited state energies. The question whether result property quantum system or matter present...

The purpose of this article is to study the materials physics behind dye-doped polymethyl metharcylate (PMMA) that important for optical fiber drawing process. We report effects fabrication process on mechanical properties final fiber. qualitative degree polymer chain alignment found increase with force, which in turn decreases temperature and increases ratio. relaxes when fibers are annealed at 95 °C a commensurate decrease length diameter. has higher ductility but lower strength than...

We report on the fabrication of poly(methyl methacrylate) (PMMA) nonlinear optical fibers with dye-doped cores. The cores have an elevated refractive index that defines a waveguiding region large third-order susceptibility and single-mode dimensions. measured squarylium-doped PMMA film material loss fiber core results in figure merit is suitable for all-optical device applications at λ=1.3 μm. impact further improvements chromophore nonlinearity are also discussed.

Using sum rules, the dipolar terms can be eliminated from commonly-used sum-over-states (SOS) expression for nonlinear susceptibilities. This new dipole-free is more compact, converges to same results as common SOS equation, and appropriate analyzing certain systems such octupolar molecules. The theory used a tool uncertainties in quantum calculations of susceptibilities, applied broader set three-level model where standard fails, naturally leads fundamental limits

We report on a series of chromophores that have been synthesized with modulated conjugation path between donor and acceptor. Hyper-Rayleigh scattering measurements the best molecule show an enhanced intrinsic hyperpolarizability breaches apparent limit all previously studied molecules.

We rigorously apply the sum rules to sum-over-states expression calculate fundamental limits of dispersion two-photon absorption cross-section. A comparison theory with data suggests that truncated in three-level model give a reasonable limit. Our ansatz two photon cross-section near limit must have only three dominant statesis is supported by rigorous analytical calculation resonant term gets smaller as more states are added. also find contributions non-explicitly terms can not be neglected...

Applying the three-level ansatz and sum rules to new dipole-free sum-over-states expression, we develop a rigorous method for calculating fundamental limits of dispersion real imaginary parts second-order electronic nonlinear-optical susceptibilities. These results can be applied all orders nonlinearity, hence used study any phenomena at wavelength. The theory understand how strongly light interacts with matter optimizing material’s properties applications. In particular, find that resonant...