bluuebunny/crossref_metadata_2025 huggingface dataset:
New Device Concepts in Polymer Optical Fibers
Authors: Kuzyk M. G. , Li Q. , Welker D. J. , Young P. , Zhou S. , Dirk C. W.
Published: February 2023

The fact that light induces a refractive index change in a material is the basis of an all-optical switching or logic device - where one beam of light affects its own propagation or the propagation of a second beam of light. There are many mechanisms that result in such a light- induced refractive index change. The heating mechanisms, for example, results when the refractive index changes in response to the density change that accompanies thermal heating when light energy is absorbed by a material. By virtue of the conductive nature of heating, the thermal effects are slow (approximately ≈ Is time scale). The fast electronic mechanism, on the other hand, results in refractive index changes due to electronic cloud deformation. When the excitations are far off any material resonances, electron cloud distortion does not result in real excitations of the atoms or molecules and is thus a fast response (≈ 10-15s).
Side-chain liquid crystalline polyesters with unusual optical information storage properties
Authors: Ramanujam P.S. , Hvilsted S. , Andruzzi F. , Kulinna C. , Siesler H.W.
Published: February 2023

Side-chain liquid crystalline (SCLC) polymers containing the photo responsive azobenzene group constantly present exciting optical storage opportunities [1].
Dispersion of linear and nonlinear quadratic optical properties of electrooptic polymers by spectroscopic ellipsometry
Authors: Toussaere E. , Zyss J.
Published: February 2023

Spectroscopic ellipsometry is an optical technique which can provide the depolarization ratio between s or p polarized waves after reflection on a sample. This method is indirect but subsequent multilayer modelling and different techniques such as iterative calculations or nonlinear regressions1 allow to infer the thicknesses and the optical properties of the films. In the case of thick uniaxial films, the angle of incidence must be varied so as to provide a sufficient number of significative and independant data2. This technique has been used to characterize electrooptic polymeric films through the different processing steps3 and could be used for 'on-line' characterization of polymeric devices4.
High-Temperature Sierrulate Nonlinear Optical Polymers
Authors: Lindsay G. A. , Stenger-Smith J. D. , Henry R. A. , Nissan R. A. , Merwin L. H. , Chafin A. P. , Yee R. Y. , Herman W. N.
Published: February 2023

Second-order nonlinear optical polymers (NLOPs) are excellent thin film active optical waveguiding materials.1 Integration of NLOP films on silicon to form low cost photonic devices, using current manufacturing lines, requires optical stability to at least 250°C for several minutes, and more preferably to 350°C. One approach has been to dissolve stable chromophores in high temperature polyimides.2 However, the addition of chromophores (20 to 30 percent) considerably lowers the glass transition temperature, and diffusion of the fugitive chromophores will cause long term stability problems. A second approach has been to crosslink a chromophore-polymer matrix.3 This approach can lead to unacceptably large optical losses due to scattering from density fluctuations trapped in the matrix during the crosslinking process. A third approach is the synthesis of amorphous mainchain thermoplastic NLOPs that have a high glass transition temperature (Tg) and a high chromophore concentration.4
A Folded Mainchain NLO Polymer: Optical Properties and Poling Stability
Authors: Herman W.N. , Hayden L.M. , Brower S. , Lindsay G.A. , Stenger-Smith J.D. , Henry R.A.
Published: February 2023

Nonlinear optical (NLO) organic molecules (chromophores) incorporated into polymers have attracted considerable interest1 for photonics applications due to their fast NLO response time, low cost, ease of fabrication, and large nonlinear second-order electric susceptibility, χ(2). One focus of current research is the enhancement of the thermal and temporal stability of χ(2), which in NLO polymers is dependent on the stability of the Chromophore orientation. This orientation, necessary for the removal of inversion symmetry in order to obtain a nonzero χ(2), can be achieved by electric field poling.2,3 The field is applied at temperatures near or above the glass transition temperature to orient the chromophores and removed only after cooling down to near room temperature. The stability of the resulting order in the thermodynamic nonequilibrium glassy state varies from polymer to polymer. Chemical attachment of the Chromophore to the polymer — as a sidechain,4-6 as part of the main chain,7,8 or in a crosslinked structure8-10 — has been found to retard the relaxation of orientational order.
Isocyanate Cross-linked Polymers for Nonlinear Optics: Polymers Derived From 3-amino-5-[4'-(N-ethyl-N-2"-hydroxyethyl)aminobenzylidene]rhodanine
Authors: Francis Cecil V. , White Kenneth M. , Boyd Gary T. , Moshrefzadeh Robert S. , Cross Elisa M.
Published: February 2023

Recently we reported the incorporation of a novel difunctional nonlinear optical (NLO) molecule, 3-amino-5-[4′-(N-ethyl-N-2″-hydroxyethyl)aminobenzylidene]-rhodanine (I), into a poled, cross-linked polymer by the stepwise reaction of different functionalities with a trifunctional comonomer.1 The difference in reactivity between the two functional groups on the molecule allows a stepwise reaction; first, oligomers are formed which are processed into optical quality films, and second, reaction conditions are changed while applying the electric field to induce reaction of the second functionality and cross-link the oriented NLO- phores. Here we discuss the curing, poling, and stability of this material.
Organic Dye-Doped Polymer Optical Fiber Amplifier
Authors: Yamamoto Tsuyoshi , Teramoto Shigehiro , Tagaya Akihiro , Nihei Eisuke , Kinoshita Takeshi , Koike Yasuhiro , Sasaki Keisuke , Fujii Kazuhito
Published: February 2023

There has been great interest in development of polymer optical fibers (POFs) for local area networks (LANs), datalinks, applications for automobile and medical applications etc., because of virtues, such as easy processing, handling, low cost and large diameter, enabling high efficiencies of fiber coupling and beam insertion.(1) In those days, highly developed Er3+-doped optical fiber amplifier can obtain much more functional applications. On the other hand, until now, POF system has no amplifying element, so applications of POFs are positioned in hopeless situation. Our proposals and experiment presented in this paper concerning graded-index (GI) Rhodamine B doped POF-Amplifiers (POFA) could give a break-through on such situation. The POFA gave sufficient gain with extremely short length of fiber for its large cross sections. Also, high-power amplification was tried with large core diameter fiber.
Nonlinear Optical Properties of Phthalocyanine Copolymers
Authors: Shirk James S. , Flom Steven R. , Lindle J.R. , Bartoli F.J. , Boyle Michael E. , Adkins James D. , Snow Arthur W.
Published: February 2023

Systematic studies of the third-order nonlinear optical properties of organic materials have led to the identification of several which have a large χ(3). In many of these materials, nonlinear absorption, α2, makes a substantial contribution to the nonlinear response. Some also possess a figure of merit, α2/α0 which makes them appealing for optical limiter applications.1,2 Among these materials, a class of heavy metal substituted macrocycles, most notably PbPc(CP)4, exhibited a wide dynamic range and the lowest thresholds for the onset of optical limiting. These materials are robust and photochemically stable in the solution phase. In this work the synthesis of similar phthalocyanines incorporated into the backbone of a urethane copolymer is reported. The nonlinear optical (NLO) properties of these copolymers have been measured and compared to the analogous materials in solution.
High Temperature NLO Chromophores for Polymer Applications
Authors: Miller R. D. , Betterton K. M. , Burland D. M. , Lee V. Y. , Moylan C. R. , Twieg R. J. , Walsh C. A. , Volksen W.
Published: February 2023

The demands on organic polymeric nonlinear optical materials include large and stable bulk nonlinearities which are not significantly degraded during the processing involved in semiconductor integration and subsequent use of the device. Poled polymer, electro-optical applications such as modulation or switching, may involve continuous operating temperatures of 80-100°C and processing excursions up to 250°C or more for brief periods.1 At elevated temperatures, any device must maintain polar order and the NLO chromophore must be stable or the bulk nonlinearity will degrade.
Monte Carlo Simulations of Charge Transport in Polymers for Second Order Nonlinear Optics
Authors: Pasmore Tom A. , Harper J. Daniel , Talbot Julian , Lackritz Hilary S.
Published: February 2023

In order to obtain sufficient noncentrosymmetric Chromophore orientation to achieve second order nonlinear properties in a molecularly doped polymer, a very strong field must be applied during poling. The resultant charge transfer induced by the strong field behaves very differently from currents found in semiconductors or metals. A Monte Carlo simulation has been developed to model charge carriers moving through a poled polymer single layer film. The program consists of a lattice containing 36,000 hopping sites with a Gaussian distribution of site energies. The hopping behavior can be manipulated by changing input variables including the temperature, magnitude of the applied field, concentration of the chromophores, overlap parameter, and the Gaussian width of the distribution of site energies. We have also developed a simulation based a random distribution of sites instead of the lattice configuration, and are currently examining the relationship between energetic and positional disorder. We have constructed a preliminary charge transport model which can predict current as a function of the inputs, positional disorder and energetic disorder. Thus far, models available in the literature consider only charge migration in lattice based, semi-infinite crystals, which are not suitable for polymeric materials.
Nonlinear Optical Response of Fullerene-doped Polymethyl Methacrylate Films
Authors: Ji W. , Tang S. H. , Xu G. Q. , Chan H. S. O. , Ng S. C. , Ng W. W.
Published: February 2023

Recently fullerenes (a mixture of C60 and C70) have received considerable attention because these molecules possess strong nonlinear-optical behaviour. Both optical limiting response [1] and photorefractive properties [2] of C60-doped polymers have been observed. In this article, we report the observation of a large third-order nonlinear optical susceptibility in fullerene-doped polymer thin films with nanosecond laser pulses and discuss the mechanism responsible for the observed nonlinear susceptibility.
Composite Molecular Films From Cyanine Dye Single Crystals Grown On Lipid Monolayers
Authors: Tsukruk V.V. , Liebmann A. , Foster  , Reneker D.H. , Bliznyuk V.N. , Kirstein S. , Möhwald H.
Published: February 2023

Cyanine dyes can be used for formation of composite molecular Langmuir- Blodgett (LB) films with interesting photosensitive properties and prospects of non-linear optical applications1. For water-soluble cyanine dye molecules the possibility of epitaxial single crystal growth by adsorption of dye molecules onto the surface of oppositely charged lipid monolayers was demonstrated recently2. X-ray analysis, electron diffraction and fluorescence microscopy give information about unit cell parameters, average thickness of these composite LB films, and their morphology on a micron scale2,3 Data about surface morphology and roughness on a submicron scale and details of the molecular packing in these films have not yet been obtained. Here we discuss the results of atomic force microscopy (AFM) and quantitative X-ray reflectivity studies of the molecular structures of these composite molecular films.
Application of a Poled Electro-Optic Organic Thin Film in an Evanescent Coupler
Authors: Mackenzie J. M. , Morgan R.E. , Ehlers S. L. , Jones K. J.
Published: February 2023

An essential component of any fiber optic network is a 2×2 crosspoint switch (1,2). Advanced organic thin film materials have shown great promise for potential applications for photonics (3). In particular, second order nonlinear polymers have demonstrated their utility in Mach-Zehnder modulators (4-7). This paper reports progress toward a 2×2 crosspoint switch using a poled electro-optic polymer to achieve switching in an active evanescent coupler. (8) This effort came as a result of a need to develop switching for composite-embedded fiber optic data links (9, 10, 11) in avionics. The active electro-optic evanescent coupler is depicted below in Figure 1.
Organotransition Metal Complexes as π Acceptors in Non-linear Optical Materials
Authors: Sheats John E. , Jones Andrew , Lang Albert , Bland Felicia , Hernandez Elizabeth
Published: February 2023

Previous investigators 1-4 have employed ferrocenyl derivatives as strong π-electron donors in the preparation of highly conjugated organic molecules such as Ia-c with high values of the second order hyperpolarizability, β.
Nonlocal Field Effects and Macroscopic Optical Properties of Self-Assembled Films
Authors: Ghiner A.V. , Surdutovich G.I.
Published: February 2023

Controlable thickness, surface uniformity and a high degree of orientational order of self-assembled organic films raise the problem of direct calculation of their macroscopic optical characteristics in terms of isolated molecule parameters. The two-dimensional character of the problem requires rethinking of the standard approach to the local field effects which in a three-dimensional case are given by the Lorentz-Lorenz formula.
Second Harmonic Generation and Optical Anisotropy of a Main Chain Polymer Film
Authors: Wang C. H. , Guan H. W.
Published: February 2023

Using both second harmonic generation (SHG) and optical waveguiding techniques, we have investigated the second order nonlinear optical response of a recently synthesized main chain accordion polymer, 1,2-benzyl-1 ,2-cyclohexyl-bridged syndioregic α-cyano cinnamamide1 (BCSC). The nonlinear optical active BCSC film was prepared by spin coating the polymer solution (in chloroform) on an indium tin oxide coated pyrex substrate (film thickness about 1.4 μm) The film was then poled slightly above Tg using the corona discharge during which time the intensity of second harmonic generation (SHG) was monitored. Shown in Fig. 1 is the SHG intensity of the BCSC film as it is heated from 190 to 250°C. The heating rate is 1.6°C/min.
Thermally Robust Electro-Optic Polymers
Authors: Moylan Christopher R. , Swanson Sally A. , Twieg Robert J. , Walsh C.A. , Thackara John I. , Miller Robert D. , Lee Victor Y.
Published: February 2023

Rational design of high-temperature stable electro-optical poled polymer materials requires custom synthesis of nonlinear chromophores, accurate measurement of their molecular hyperpolarizabilities and thermal stabilities, calculations to predict their nonlinearities at the desired wavelength, incorporation into thermally robust polymers, fabrication of test devices, and measurement of electro-optic coefficients. In this work, we describe the results of each step in this sequence for a variety of chromophores.
Studies of Polymer Optical Fibers
Authors: Chen W. D. , Shi R. F. , Garito A.F.
Published: February 2023

The growing demands in local area networks (LANs) for low cost broad band data communications are providing a major opportunity for further technology developments important to polymer optical materials and devices. Polymer optical fibers (POF) can satisfy requirements for high-bandwidth, quick-connect, fiber optics for short distance (100 m) data transmission in data links, multimedia, and multi-noded bus networks[1-4]. Figure 1 illustrates the variety of application areas together with their required transmission bandwidths.
Transparent Birefringence-free Copolymer and its Application
Authors: Iwata Shuichi , Tsukahara Hisashi , Nihei Eisuke , Koike Yasuhiro
Published: February 2023

The birefringence-free copolymer was prepared by randomly copolymerizing positive and negative birefringent monomers. The birefringence-free copolymer showed excellent transparency and no microscopic heterogeneous structures were observed. As a novel application of the birefringence-free copolymer, we propose the polarization preserving polymer optical fiber (POF).
Large Enhancement in the Third Order Response of Asymmetric β-Carotenoïds
Authors: Ricci Vincent , Torruellas William E. , Stegeman George I. , Gilmour Sandra , Marder Seth , Blanchard-Desce Mireille
Published: February 2023

Trans-β-Carotene shows one of the largest instantaneous off-resonant nonlinearities reported to date.1 Increasing the electron conjugation with longer back bones, polymers, has been the most common approach to enhance such a nonlinear optical response2. However it has been recognized that molecular asymmetrization represents another viable route for increasing the third order susceptibility without having to pay a price for smaller molecular densities, an increased molecular instability and poor solubility3. Here we report an enhancement of approximately a factor of 50.
Organic Thin-Films For Spatial Light Modulation
Authors: Nunzi Jean-Michel , Delysse Stephane , Pfeffer Nicola , Charra Fabrice
Published: February 2023

In the field of image and beam processing, there is great need for devices in which a spatial light-intensity profile such as an image can be recorded and transformed into a transmission or a phase retardation profile. A solution in order to process a still increasing volume of information issued from sensors and data banks is indeed to treat it in parallel. And as information is often available as optical images, a simple idea is to pre-process or to compress it prior to acquisition. This is performed using correlation or novelty filtering techniques [1]. A key device in this respect is the optically addressed spatial light modulator (SLM) [2]. It permits the achievement of input functions in optical image processors based on holographic and Fourier optics. The principle of the SLM process is the same as with the more classical silver-halide photography, except that SLM must perform real-time operations. The drawback of silver-halide photography is indeed the delay, larger than a minute, between exposure and processing. Different techniques, with commercially available devices, already permit the achievement of real-time spatial light modulation. They use a juxtaposition of photoconductor and liquid-crystal films in an artificial photorefractive-like sandwich [3]. However, operation with typical pixel densities of 1µm2, beam surfaces of 1cm2 and processing speeds larger than 100MHz is far from being realised with commercial SLMs. It is the reason for considering the performances offered by organic thin films in this respect [4].
Two-Photon Resonant Contributions to the Third-Order Susceptibility of C60 in the Solid State
Authors: Bartoli F. J. , Flom S. R. , Lindle J. R.
Published: February 2023

The role two-photon states play in the third-order optical response of
organic systems has received much recent attention.1 Third
harmonic generation (THG) measurements are especially useful since
they directly probe coherent electronic processes involving two- and
three-photon resonances.2,3 Degenerate four-wave
mixing (DWFM) and nonlinear transmission (NLT) are complementary
techniques which are also sensitive to two-photon states, but may also
contain contributions from incoherent excited-state processes. The
advantage of the latter experiments is that they yield information on
the third-order coefficient
χ(3)(-ω;ω,ω,-ω)
which is directly related to the nonlinear refractive index of
interest for device applications. A direct comparison of DFWM and NLT
results, when coherent electronic processes dominate, to
χ(3)(-3ω;ω,ω,ω)
determined by THG should yield useful information concerning the
origin of the nonlinear optical response.
Guest-Host Crosslinked Polyimides for Integrated Optics
Authors: Kowalczyk T.C. , Kosc T.Z. , Singer K.D. , Beuhler A. J. , Wargowski D.A. , Cahill P.A. , Seager C.H. , Meinhardt M.B.
Published: February 2023

We report on our approach to the development of device-quality electro-optic materials. We have sought to optimize the optical losses and processing properties first, and later to functionalize the materials having learned how to synthesize and process them for devices. [1,2] We started with perfluorinated, preimidized fully aromatic polyimides. Preimidization makes processing doped polymer systems more flexible, by making functionalizing easier (no harsh imidization process) while allowing spin coating of soluble fully-imidized polymers. Fluorination increases solubility while decreasing optical loss and refractive index. Fully aromatic polymers allow for the best high temperature properties. We found that by introducing alkylated crosslinking groups which can be photo- or thermally activated, optical losses were further reduced, so that high quality waveguides could be fabricated. [1] Another advantage of the crosslinking groups is that they open up new processing capabilities. [2] For example, cross-linking allows for simple multilayer formation, permits a liquid etch process to define waveguides, and provides a chemical hook to which chromophores may be covalently attached. We have uncovered a number of issues relating to functionalization, such as increased optical loss due to long absorption tails in the chromophore and enhanced mobility of small chromophores. We have also studied poling issues related to multilayer films. We believe that this approach, focused on the processing and operation of devices, has led to a flexible material system which shows exceptional promise for the development of electro-optic polymer devices.
Pyroelectric, dielectric and electro-optical investigation of cross-linking in Red Acid Magly
Authors: Bauer S. , Bauer-Gogonea S. , Yilmaz S. , Dinger C. , Wirges W. , Gerhard-Multhaupt R. , Michelotti F. , Toussaere E. , Levenson R. , Liang J. , Zyss J.
Published: February 2023

Cross-linking of nonlinear optical polymers during the poling process is an interesting way to increase the thermal stability of the dipole orientation [1]. For the optimization of the poling process in cross-linking polymers, experimental techniques for the in- situ characterization of the polar order are highly desirable. Recently, Aramaki et al. [2] introduced in-situ electro-optical measurements by the ellipsometric method in order to follow the cross-linking process by optical means. They also established a direct connection between dielectric and in-situ electro-optical measurements [3]. Here we report a comprehensive study of the cross-linking process of Red Acid Magly by means of dielectric, in-situ electro-optical and pyroelectrical measurements. In addition we extend the model in [3] for the interpretation of in-situ electro-optical measurements and their connection to the dielectric properties.
Optically Aligned Liquid Crystal Cells as Diffractive Optical Elements
Authors: Kosa T. , Palffy-Muhoray P.
Published: February 2023

Conventional diffractive elements, such as gratings and zone plates, may be regarded as surfaces which are transparent in some regions and opaque in others. Their usefulness stems from the constructive interference of the transmitted light in certain regions of space. Here we propose another way to produce such constructive interference, by allowing light to pass through the originally opaque regions of the diffractive surface but with its polarization rotated by 90°. An interference pattern similar to that of the original surface is obtained, since orthogonal polarizations do not interfere.
Nonlinear Optical Anisotropy of Highly Oriented Poly(p-Phenylene Benzobisthiazole)Langmuir-Blodgett Films
Authors: Wang Liming , Wada Tatsuo , Yuba Tomoyuki , Kakimoto Masaaki , Imai Yoshio , Sasabe Hiroyuki
Published: February 2023

Poly(p-phenylene benzobisthiazole) (PBT) has received a strong attention as a nonlinear optical (NLO) material because of its large, ultrafast NLO response1 and inherently superior physical and chemical properties2. However, the material is difficult to process into thin film with good optical quality, which hindered the detailed and accurate NLO studies. In order to improve optical quality, the PBT Langmuir-Blodgett (LB) films were fabricated via a novel precursor route. The PBT LB films show not only improved optical quality but also highly in-plane oriented molecular packing. Because the π-electrons are delocalized along the polymer chain direction, the highly oriented packing of the polymer chains results in linear and NLO anisotropy properties. Therefore, in-plane anisotropy measurement of optical third-harmonic generation (THG) is one of the powerful tools to elucidate the packing arrangement in LB films of one-dimensional conjugated system.
Investigation of the Stability of Electro-Optic Dyes
Authors: Zhang Lixia , Calamegham Priya , Dirk Carl W. , Ermer Susan , Twieg R. J.
Published: February 2023

Recent progress in organic electro-optic materials has lead to organic polymer devices that can modulate broad band visible light at frequencies which will permit the simultaneous transmission of thousands of real-time television signals down a single optical fiber. The intent is to manufacture modulator device structures which are incorporated directly on the same semiconductor chip which supplies both the electronics and power for the modulation process. Doing this requires polymers and electro-optic dyes that can withstand the processing conditions typical for semiconductor devices. The lowest temperature conditions available are about 350°C. We are presently involved in a collaborative project in conjunction with IBM Almaden Research Laboratories and Lockheed Corporation, in attempting to discover the decomposition temperatures of existing electro-optic dyes and conducting the analysis of the relationship between the decomposition temperatures and the molecular structures.
Two Beam Coupling in a Photorefractive Polymer Waveguide
Authors: Kokron Dan , Evanko Stephen M. , Hayden L. Michael
Published: February 2023

Photorefractive polymers have attracted a great deal of attention since they were first reported1 in 1991. Since then, four wave mixing (FWM) diffraction efficiencies have increased from 10-5 to near unity2 in films on the order of 100 μm thick. Two beam coupling gains have also seen dramatic increases.3 These enhancements are mostly due to improvements in the materials and their processing. For example, it has been found that by substantially reducing the glass transition temperature of the polymer composite, a significant orientation of the nonlinear optical (NLO) chromophores in these composites can be achieved. The orientational enhancement4 gives rise to a large modulation of the linear birefringence which in turn gives a stronger photorefractive (PR) effect. In this work, we report on a new application for these PR polymer composites.
Growth of Thin Single Crystalline Films of m-Nitroaniline and their Nonlinear Optical Characterization
Authors: Leyderman A. , Espinosa M.
Published: February 2023

During the last decade, efforts have been focused on optimizing electro-optic coefficients as well as on search for a reliable configuration of electro-optic devices. There have been reported a few configurations of optical waveguides made from organic material.1-6 To our best knowledge, there was no indication that structures fabricated were suitable for device fabrication. In the following, we give description of a method used for fabrication of thin single crystalline organic films. We call it plate-guided (PG) method, and have applied it to grow thin films of numerous organic compounds. In this communication, we report fabrication of meta-nitroaniline (mNA) thin single crystalline films and their nonlinear optical properties. Data on other compounds will be published elsewhere.
Growth and Characterization of Vacuum Deposited Organic Thin Films
Authors: Seo Kang I. , Jones Isaac , Lowe Calvin W.
Published: February 2023

The properties of vacuum evaporated thin films are of current interest both from applied and fundamental standpoints, as they may lead to useful and unusual devices. While such thin films have traditionally been composed of inorganic materials, it has recently been known that organic thin films can also have potentially useful electrical and optical behavior related to their large nonlinear optical susceptibilities. Thin films of large stable organic molecules such as perylenetetracarboxylic dianhydride (PTCDA) on semiconductor surfaces were extensively studied by Forrest et al. [1-4].
Dependency of Sidechain Chromophore Orientations on Langmuir-Blodgett Polymer Structures
Authors: West D. , Williams D.L. , King T.A. , Ali-Adib Z. , Hodge P. , Dunne D.
Published: February 2023

The LB technique allows optical chromophores to be placed within a predetermined series of organic molecular layers. Moreover, the orientations of the chromophores can be controlled when they are positioned in the apolar tail sections of the amphiphiles that are used. The fragility, the tendency to reorganise and even the diffusion mobility of dyes included in an LB film may be greatly reduced if polymeric materials are used. In addition to thermal and mechanical stability, polymers offer an amorphous structure in the plane of the film layers with a reduction in optical scatter relative to monomer films of materials such as fatty acids[1].
Suppression of multi-photon fluorescence in hyper-Rayleigh scattering
Authors: Clays Koen , Vos Rita , Persoons André
Published: February 2023

We propose the suppression of the multi-photon fluorescence contribution to the hyper Rayleigh scattering signal at the second-harmonic wavelength by phase-sensitive detection.
Quadratic Electro-optical Measurements of Polythiophene Films by a Modified Mach-Zehnder Interferometer.
Authors: Jakobsen C. , Petersen J.C. , Geisler T. , Bjømholm T. , Greve D.R. , McCullough R.M.
Published: February 2023

We report the measurement of quadratic electro-optical coefficients of head-to-tail poly(3-dodecylthiophene) using a modified Mach-Zehnder interferometer at 633 nm. We find s1133 = 3.7×10-20 m2/V2 and s3333 = 4. 1×10-20 m2/V2.
Third Harmonic Dispersion Studies of Centrosymmetric and Noncentrosymmetric Squaraines
Authors: Andrews James H. , Khaydarov John D. V. , Singer Kenneth D. , Hull Diana L. , Chuang Kathy C.
Published: February 2023

Third harmonic dispersion was measured in centrosymmetric and noncentrosymmetric squaraine molecular solutions. A large contribution to the third order nonlinearity from the 1Bu to 2Ag state was revealed. Contributions from ground and excited state dipole moments in ostensibly centrosymmetric and noncentrosymmetric dyes were observed.
Spatial and Temporal Orientational Correlations Between Nonlinear Optical Chromophores Probed by Femtosecond Hyper-Rayleigh Scattering
Authors: Clays Koen , Wu Marvin , Persoons André
Published: February 2023

After designing and synthesizing a new candidate molecule for nonlinear optical (NLO) applications, the molecular hyperpolarizability of this molecule has to be experimentally determined. This measurement at the microscopic level can be performed in an isotropic solution using hyper-Raleigh scattering (HRS).1 For a second-order NLO application, the individual molecules have to be assembled in a macroscopically non-centrosymmetric fashion. The efficiency of a phase-matched second-order NLO process is highly dependent on the length over which the coherent nonlinear interaction can be maintained. In artificially ordered systems, such as poled polymers and Langmuir- Blodgett films, this length is much more determined by the length over which the local order is constant than by the coherence length, calculated from the bulk refractive indices at fundamental and second-harmonic wavelength. A measurement scheme to determine the degree of spatial correlation between the chromophores would therefore be instrumental in the development of reliable and reproducible devices.
Evanescent Wave Surface Enhanced Raman Scattering from Organic Molecules Bonded to “Optical Chemical Benches”
Authors: Xu Wenbo , Andrews Mark P.
Published: February 2023

Our interest is in using molecular self-assembly (MSA) techniques to develop hybrid functional organic/inorganic thin film materials for applications in spectroscopy, optics and photonics.1,2,3 MSA can be seen as a convergent methodology for combining the "bottom up" techniques of molecular chemistry with the "top down" techniques of nanoscale device fabrication.
Linearly and Circularly Polarized Probes of Second-Order Optical Activity of Chiral Surfaces
Authors: Verbiest Thierry , Kauranen Martti , Maki Jeffery J. , Teerenstra M.N. , Schouten A. J. , Nolte R.J.M. , Persoons André
Published: February 2023

It was recently observed experimentally that second-harmonic generation (SHG) from chiral surfaces is sensitive to the handedness of the incoming fundamental light. This phenomena is called nonlinear optical activity1,2. We have subsequently developed a theory of SHG from chiral surfaces that includes contributions of electric- and magnetic-dipole transitions to the surface nonlinearity. The theory can be used to explain the experimental results very well3-5.
Bulk-type phase-matched SHG devices of poled polymer
Authors: Tao X. T. , Watanabe T. , Ukuda H. , Mivata S.
Published: February 2023

Bulk phase-matched second-harmonic generation has been realized from a drawn and poled polymer by prism and end-fire coupling at 1.064 μm.
High Efficiency White and Colored Organic Electroluminescence
Authors: Jordan R. H. , Dodabalapur A. , Strukelj M. , Rothberg L. J. , Slusher R. E. , Miller T. M.
Published: February 2023

The need for light weight, low power multicolor displays and backlights has spurred interest in thin-film, organic electroluminescent (EL) devices. A typical organic EL device consists of an indium-tin oxide anode (ITO) layer on a glass substrate, and sequential layers of bis(triphenyl)diamine (TAD, hole transporter), tris(8-hydroxyquinoline)aluminum (A1Q, electron transporter and green light-emitter), and a low work function metal cathode (e.g., Al or Mg:Ag).1 Device efficiency, stability, and spectral output can be tailored by incorporating intermediate layers of organic hole-blockers2 or blue-emitters,3 or doping A1Q with narrow spectral linewidth organic dyes.4 Cavity resonance effects have been employed in lithographically patterned optical microcavities to select single5or multiple6 colors out of broad spectrum organic emitters like A1Q. Device efficiency is a critical parameter, especially for liquid crystal display backlight applications. We will describe an approach for white light EL and an approach for enhancing device efficiency.
Polymer Light-Emitting Electrochemical Cells
Authors: Pei Qibing , Yu Gang , Zhang Chi , Yang Yang , Heeger Alan J.
Published: February 2023

Electrochemistry provides a convenient means of reversibly doping conjugated polymers n-type (electron carriers) or p-type (hole carriers). When such charge carriers are introduced by electrochemical doping, they are compensated by counter-ions from the electrolyte. At high doping levels, the material becomes metallic, leading to low resistance contacts and easy charge injection (both n-type and p-type, respectively).1-5
Optical Second Harmonic Generations of the Thermotropic Liquid Crystalline Main-Chain Polymer (Aromatic Polyesters)
Authors: Asada Tadahiro
Published: February 2023

To improve the stabilities and processabilities, blend or graft polymerization of nonlinear optical organic materials with polymers has been intensively studied by many researchers (1-3). However, it was pointed out that there remain problems in the durability (4). To the contrary, the main-chain type nonlinear optical polymers are expected to be durable and good nonlinear optical materials for various applications, because these materials have been developed to be high performance materials.
Electroluminescence from Organometallic Thin Films
Authors: Campos R. A. , Kovalev I. , Wakili N. , Guo Y. , Skotheim T.
Published: February 2023

Efficient electrical conversion into a wide range of optical wavelengths as well as low fabrication costs are some of the attractions of organic thin films which drive the use of these materials for flat-panel display applications [1]. Since the pioneering work of Tang and VanSlyke in 1987 [2], the organometallic material tris-(8-hydroxyquinoline)-aluminum (ALQ) has been the focus of intense research. This compound electroluminesces in the green region of the spectrum over a broad spectrum peaked near 520 nm. Although ALQ microcavity architectures can provide narrowband emissions at select wavelengths [3], the resulting brightnesses in the blue and red regions are limited by the decreasing spectral content in the tails of the ALQ emission spectrum.
Progress Toward Practical Polymer Electro-Optic Devices
Authors: Ermer Susan , Anderson William W. , Van Eck Timothy E. , Girton Dexter G. , Marley James A. , Harwit Alex , Lovejoy Steven M. , Leung Doris S.
Published: February 2023

High speed analog and digital switching has been demonstrated in a polymer Mach-Zehnder modulator with a voltage-length product of 13 V-cm. Materials and process optimization will enhance this performance. Anisotropic V-groove etching for fiber attachment provides a path to low-cost packaging of these improved devices.
Incorporation of Thermally Stable Nonlinear Optical Polymers into Electrooptic Devices
Authors: Burland D.M. , Devoe R.G. , Jurich M.C. , Lee V. Y. , Miller R. D. , Moylan C.R. , Thackara J. I. , Twieg R. J. , Verbiest T. , Volksen W.
Published: February 2023

In order to be useful in practical nonlinear optical(NLO) devices such as high speed optical switches and modulators, several key properties of electrooptic(EO) polymers must be optimized: the polymer's electrooptic response must be sufficiently large, the response must be stable at all temperatures that the polymer will experience in processing and in operation and the attenuation of light in the polymer by scattering and by absorption must be low. For the specific applications of on-chip and chip-to-chip active optical interconnects, the thermal stability requirements are particularly severe. During the processes of microprocessor die attachment and hermetic packaging, the EO polymer will experience temperatures of >300°C for several minutes[1]. We have investigated the potential and limitations of electrooptic polymers under these severe thermal conditions, proceeding from the identification of NLO chromophores with high intrinsic molecular hyperpolarizabilities[2], incorporation into thermally stable polymers[3][4], and fabrication into electrooptic switches and devices[5].
Integration of Nonlinear Optical (NLO) Polymer Waveguides with Indium Gallium Arsenide p-i-n Photodiodes
Authors: Cites Jeffrey S. , Ashley Paul R. , Leavitt Richard P.
Published: February 2023

The integration of optoelectronic functions on a common substrate can offer significant advantages in terms of size, weight, cost, and performance over traditional hybrid approaches. Given the advantages of NLO polymers over other material systems for integrated photonics applications (flexible fabrication, low dielectric constant, etc.)1,2, it is advantageous to develop a processing technology for the integration of polymer waveguide devices on an active semiconductor substrate. The approach reported here allows for optimization of the semiconductor for source, detector, and electronic circuit functions, while relying on a flexible, multilayered spin-cast fabrication technology for passive waveguide and electro-optic modulator functions. Among those applications which may benefit from this integration are sensors such as the fiber optic gyroscope3. Reported here is the integration of NLO polymer waveguides with InGaAs p-i-n photodiodes on an InP substrate for operation at 1.3 μm, with special emphasis placed on the use of existing low-cost, low-risk fabrication processes.
Miniature Integrated Optical Wavelength Analyzer Chip
Authors: Kunz R. E. , Dübendorfer J.
Published: February 2023

Measuring or monitoring the spectrum of narrow-band light sources such as lasers is an important application of spectrometers. The conventional spectrometer types are typically based on converting the angular light distribution emerging from wavelength-dispersive elements such as prisms or diffraction gratings into a spatially varying intensity distribution either in a free-space [1] or planar [2] arrangement.
Photorefractive Polymers for Holographic Optical Storage
Authors: Moerner W. E. , Poga C. , Jia Y. , Twieg R. J.
Published: February 2023

In the past few years, a new class of polymeric materials for photonic applications has appeared called photorefractive (PR) polymers. Photorefractivity is defined as modulation of the index of refraction in an electro-optic material by internal electric fields produced by optical redistribution of charge carriers; hence it must not be confused with the more standard local mechanisms of index change such as photochromism, excited state population, heating, etc. When a material shows the required properties of charge generation, transport, trapping, and dependence of the index of refraction upon the internal electric field, it can be tested for photorefractivity by observation of asymmetric energy transfer (two-beam coupling) between two laser beams in the material.
Photochromic Azo-Polymer Structures for Photonic Applications
Authors: Sekkat Z. , Wood J. , Geerts Y. , Büchel M. , Aust E. F. , Miller R. D. , Knoll. W.
Published: February 2023

In the past few years azo-dye containing polymeric films have been the subject of intensive investigations because of their possible application in the areas of optoelectronics, photonics and optical signal processing1-3. The trans ⟺cis isomerization of azobenzene derivatives in bulk polymer films has been used for producing polarization hologramms1a, optical channel waveguides1b, writing-erazing optical memories1c, and second order nonlinear-optical effects2. Langmuir-Blodgett-Khun (LBK) multilayer assemblies of azobenzene containing polymeric materials have been used for all-optical modulation3a, optical image recording3b, and molecular switching3c. However, despite this activity, the Weigert effect that is the induction of photochemical birefrengence or dichroism in certain materials, on irradiation with polarized light, has rarely been reported for organized molecular structures, or in azobenzene containing polymeric films. Here, we report on dichroism that has been induced in a monomolecular layer of azo-silane molecules self assembled on a quartz glass substrate. The Weigert effect is studied in an azo-polyglutamate polymer for spun-cast polymer films and for LBK multilayer assemblies. It will be particularly emphisized that in contrast to the LBK structures, efficient photoselection can be achieved in the spun-cast films. Finally, photoisomerization of the push-pull azo-dye Disperse Red 1 (DR1) molecule, will be shown to create an appreciable alignment of DR1 chromophores chemically attached to the side chains of a high Tg (about 210 °C) rigid main chains polyimide polymer. This may be used to help poling this kind of polymers for second order nonlinear-optical effects.
Thermooptic switches using fluorinated polyimide waveguides
Authors: Kobavashi Junva , Maruno Tohru , Hida Yasuhiro , Matsuura Tohru , Sasaki Shigekuni
Published: February 2023

Thermooptic (TO) switches using polymer optical waveguides have attracted much attention because the TO effect of polymers is ten times that of silica. Therefore, using polymers instead of silica [1-2] significantly reduces the required switching power. Moreover, fabricating polymer optical waveguides is easier than fabricating silica-based ones, so large optical devices can be made more easily.
High performance photorefractive polymers and their applications
Authors: Kippelen B. , Volodin B. L. , Hendrickx E. , Steele D. D. , Sandalphon  , Enami Y. , Wang J. F. , Röckel H. , Meyers F. , Marder S.R. , Peyghambarian N.
Published: February 2023

Within the past years, photorefractive polymers have gained in maturity and are emerging as a promising new class of materials for photonic applications.1,2 Several applications ranging from holographic storage to real-time optical processing3 have been demonstrated with highly efficient photorefractive polymers. In polymers with a low glass transition temperature, orientational effects were identified4 and were found to have the strongest contribution to the overall refractive index modulation amplitude.5 Due to these orientational effects, the design criteria or figure of merit of chromophores for photorefractive applications differ from those of purely electro-optic applications.
Organic photorefractive composite dynamics
Authors: Shakos JD , Cox AM , West DP , West KS , King TA , Blackburn RD
Published: February 2023

Several devices such as holographic memory elements and adaptive optical components benefit from a rapid rate of recording of diffraction gratings. In reorientationally-enhanced photorefractive materials1'1, the total electro-optic response is due to a combination of the electronic electro-optic effect (or Pockels effect) and the reorientation of polar birefringent molecules in the presence of the local electric field. This reorientational effect can be significantly larger than the Pockels effect in these materials, but may be slow due to the characteristic reorientation times of these polar molecules. This effect depends largely on the reorientational mobility of the molecules, which correlates with the material viscosity.
Plastic Optical Fibers; Yesterday, Today, and Tomorrow
Authors: Kaino Toshikuni
Published: February 2023

Plastic optical fibers (POF for short) is one of the attractive optical information transmission medium because of their handling ease with their good ductility, splicing ease to each other and to light sources with their large fiber diameter and high numerical aperture. In this paper, the potential of POFs for practical applications will be discussed.
Noncentrosymmetric Ionically Self-Assembled Thin Films for Second Order Nonlinear Optics
Authors: Heflin J.R. , Liu Y. , Figura C. , Marciu D. , Claus R.O.
Published: February 2023

Ionic self-assembled monolayers (ISAMs) are a recently developed [1], revolutionary class of materials that allows detailed structural control at the molecular level combined with ease of manufacturing and low cost. The ISAM method involves the alternate dipping of a charged substrate into an aqueous solution of a cation followed by dipping in an aqueous solution of an anion at room temperature. Since the adsorption is based on the electrostatic attraction of interlayer charges, each layer is self-limiting in thickness and uniform at the molecular level. We have recently demonstrated through second harmonic generation (SHG) measurements with fundamental wavelengths of 1064 and 1200 nm that the ISAM technique can produce a noncentrosymmetric arrangement of NLO chromophores to yield thin films with χ(2) values comparable to that of quartz. The development of ISAM χ(2) thin films provides significant advantages over the production of organic χ(2) thin films by alternative methods. For example, ISAM films can exhibit long-term stability of χ(2) in contrast to electric field poling of glassy polymers[2], can provide thicker films (upwards of 10 μm) than the Langmuir-Blodgett technique, and can be fabricated much more rapidly than covalent self-assembly[3] methods.