Synthesis of secondary amines

We present a new formulation of Maker fringes in parallel-surface films, using self-consistent boundary conditions for reflections and allowing for any degree of refractive-index dispersion. This treatment of the second-harmonic reflections and dispersion, unlike a number of previous derivations, leads correctly to the expected form for the effective second-harmonic d coefficients. Complete expressions with physically meaningful factors are given for the generated second-harmonic power for either absorbing or birefringent films including reflections for the case of no pump depletion. A comparison with the isotropic approximation is given, and practical considerations in the use of these expressions for the fitting of experimental data are discussed.

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Maker fringes revisited: second-harmonic generation from birefringent or absorbing materials

Recent progress in second-order nonlinear optical polymers and dendrimers

A brief survey of the electrical and optical properties of poled polymer electrets for sensors and photonic applications is given Semicrystalline ferroelectric polymers are highly suitable for piezo‐ and pyroelectric applications, while amorphous polymers containing molecular dipoles with acceptor and donor groups linked by delocalized π electrons (A‐π‐D) are interesting for photonic applications The large variety of poling techniques, such as electrode, corona, electron‐beam, and photothermal poling, is discussed in detail together with specifically developed poling techniques for ferroelectric or amorphous polymers Methods for the experimental investigation of the polar order are based on the piezo‐, and pyroelectric effect, birefringence, the electro‐optical effect and second‐harmonic generation Newly developed thermal analysis techniques and dipole relaxation spectroscopies complement traditional techniques, such as thermally stimulated depolarization and broadband linear and nonlinear dielectric relaxation spectroscopy The compatibility of polymers with semiconductor technology is illustrated with selected applications in hybrid integrated thermal and acoustical imaging devices, electro‐optical modulators and second‐harmonic generators

Poled polymers for sensors and photonic applications

Interference pigment flakes and foils are provided which have luminescent and color-shifting properties. A luminescent material coating structure is provided which partially covers or encapsulates a color-shifting pigment flake, or covers the outer surface of a foil. The pigment flakes can have a symmetrical coating structure on opposing sides of a core layer, can have an asymmetrical coating structure with all of the layers on one side of the core layer, or can be formed with encapsulating coatings around the core layer. The coating structure of the flakes and foils includes a core layer, a dielectric layer overlying the core layer, and an absorber layer overlying the dielectric layer. The luminescent pigment flakes and foils exhibit a discrete color shift so as to have a first color at a first angle of incident light or viewing and a second color different from the first color at a second angle of incident light or viewing. The luminescent pigment flakes can be interspersed into liquid media such as paints or inks to produce colorant materials for subsequent application to objects or papers. The luminescent foils can be laminated to various objects or can be formed on a carrier substrate.

Color-shifting pigments and foils with luminescent coatings

The second harmonic generation (SHG) coefficients dij of several corona‐poled guest‐host and side‐chain polymers have been measured and studied over time using a new Maker Fringe analysis. The electro‐optic coefficient r33 and scattering losses have also been measured in thin‐film waveguides, on silicon and glass substrates, made from some of the polymers. Kleinman symmetry (d15=d31) was not valid for near‐resonant SHG in these materials and d15/d31 was determined. Stable values of d33, for a fundamental of 1.064 μm, were as high as 40 pm/V for one of the side‐chain polymers. Optical waveguide losses determined from scattering measurements were as low as 0.4 dB/cm at 1.06 μm.

Second‐order nonlinear optical measurements in guest‐host and side‐chain polymers

The accordion polymer [CH 2 N(C 16 H 33 )PhCH=C(CN)CONHCH 2 CHOHCH 2 NHCOC(CN)=CHPhN(C 16 H 33 )CH 2 ] n is prepared by a Knoevenagel polycondensation The Y-type multilayer of this polymer gave no second harmonic generation, which was not unexpected, because the dipole in adjacnet layers should be pointing in opposite direction

Main-chain accordion polymers for nonlinear optics

The complete synthesis and characterization of a poly(methyl methacrylate-co-couma-romethacrylate) is described. Thin films of this polymer were corona-poled and aged under various conditions. The intensity of second harmonic light, generated by passing a laser beam through the polarized films, indicated the average degree of dipole alignment in the films as a function of time and temperature. The long-term aging data were fit with biexponential and stretched exponential equations. A model based on diffusion of defects (holes) in a locally heterogeneous glassy matrix is discussed

Sub-Tg relaxation behavior of corona-poled nonlinear optical polymer films and views on physical aging

Coumarin dyes such as alkylaminocoumarincarboxamides which have functional hydroxyl groups or which are chemically attached to vinyl monomers such as methacrylic acid. The dyes which are chemically attached to vinyl monomers can be copolymerized, e.g. with acrylic monomers to produce a coumarin dye-containing polymer. The dyes which have functional hydroxyl groups can be reacted with an existing polymer or copolymer, e.g. a copolymer of styrene and acrylic acid to esterify the acid groups of the polymer to form a coumarin dye-containing polymer. Such coumarin dye-containing polymers are formed into films and fibers which when poled in an electric field yield a film or fiber with nonlinear optical properties.

Coumarin dyes and side-chain coumarin dye-substituted polymers which exhibit nonlinear optical properties

Second-order nonlinear optical properties of newly designed and synthesized coumaromethacrylate side-chain polymers are reported. The optimum poling conditions were determined experimentally. The optimum poling temperature for these side-chain polymers is well above the glass transition temperature. The second harmonic coefficient of films poled by coronaonset at elevated temperature and the linear electro-optic coefficient of films poled by contact electrodes were measured. The stabilized value of the second harmonic coefficient, d33, at 1064nm fundamental wavelength was found to be 13 pm/V. The linear electro-optic coefficient, r33, exhibits strong dispersion ranging from 2 to 12pm/V in the wavelength range 477 to 1115 nm.

James M. Hoover

Papers

Second‐order nonlinear optical measurements in guest‐host and side‐chain polymers

Main-chain accordion polymers for nonlinear optics

Sub-Tg relaxation behavior of corona-poled nonlinear optical polymer films and views on physical aging

Coumarin dyes and side-chain coumarin dye-substituted polymers which exhibit nonlinear optical properties

Second-order nonlinear optical properties of poled coumaromethacrylate copolymers