Measuring anisotropic refractive indices and film thicknesses of thin organic crystals using the prism coupling method

A DNA and Self-Doped Conjugated Polyelectrolyte Assembled for Organic Optoelectronics and Bioelectronics

Deoxyribonucleic acid (DNA) and a self-doped conjugated polyelectrolyte, poly(4-(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl-methoxy)-1-butanesulfonic acid (PEDOT-S), are assembled for organic optoelectronics and bioelectronics. The DNA's helix-coil phase transition in water is studied as a function of composition by thermo-optical analysis. DNA and PEDOT-S are functionalized by using a surfactant, cetyltrimethylammonium chloride (CTMA), and DNA:CTMA, PEDOT-S:CTMA, and DNA:CTMA:PEDOT-S:CTMA complexes were characterized regarding thermal, optical, morphological, and structural properties. Finally, DNA and DNA:PEDOT-S mixtures are processed in water for fabricating organized films through brushing. The electrical properties of these films are characterized using an interdigitated electrode. The films show an electronic conductivity of ∼10^-6-10^-5 S/cm in a range of semiconductors.

Toward parametric amplification in plasmonic systems: second harmonic generation enhanced by surface plasmon polaritons

Having in mind parametric amplification of surface plasmon polaritons (SPPs) as the final goal, we took the first step and studied in the Kretschmann geometry a simpler nonlinear optical process - second harmonic generation (SHG) enhanced by SPPs propagating at the interface between gold film and 2-methyl-4-nitroaniline (MNA). The experimentally demonstrated SHG efficiency was nearly 10(6) times larger than the one reported previously in the SPP system with different nonlinear optical material. The experimentally measured nonlinear conversion efficiency is estimated to be sufficient for parametric amplification of surface plasmon polaritons at ultra-short laser pumping.

Simultaneous measurement of thermo-optic and stress-optic coefficients of polymer thin films using prism coupler technique

We present a simple method for simultaneous measurement of thermo-optic and stress-optic coefficients of polymer thin films by measuring the film refractive indices as a function of temperature (dn/dT). Usually, such dn/dT value is considered as the thermo-optic coefficient. However, in the thin film systems, the measured dn/dT values result from both the thermo-optic and stress-optic effects. To demonstrate the stress-induced effects, the dn/dT values have been investigated for two different polymers: benzocyclobutene (high film stress) and epoxy 3505 (negligible film stress), using a prism coupler technique. The finite element method has been used so as to predict the stresses in the polymer film and, by combining them with the experimental dn/dT values, the individual thermo-optic and stress-optic coefficients have been determined. We found that the obtained thermo-optic coefficient is significantly different than the measured dn/dT values. The method is generic in nature and can thus be applied to a wide range of polymer waveguide materials.

Optical properties and microstructure of Ta2O5 biaxial film

This study investigates the optical properties and microstructure of Ta(2)O(5) film deposited with the glancing angle deposition technique. The tilted nanocolumn microstructure, examined with scanning electron microscopy, induces the optical anisotropy of thin film. The optical properties of thin film are characterized with an inverse synthesis method. Based on the Cauchy model, the dispersion equations of optical constants of film are determined from the transmittance spectra measured at normal and oblique incidence over 400-800 nm. The starting values derived with an envelope method quicken the optimization process greatly. The dispersion of the principal indices N(1), N(2), and N(3) and the thickness d of thin film are presented statistically. A good agreement between the measured optical properties and theoretical calculation is obtained, which validates the model established for thin film produced by glancing angle deposition.

A birefringent prism coupler in guided wave experiments

A rutile prism was used to excite guided waves in a CdS film. The wave vector matching condition was studied under the influence of prism's birefringence. Refractive indices and thickness of the film were determined.

Phase-matched second harmonic generation in poled dye/polymer waveguide

Poled film of 2-methyl-4-nitroaniline (MNA) and poly(methyl methacrylate) is prepared. Poling effects of MNA molecular alignments are observed by reducing the absorption spectrum and increasing the refractive index of the film. Phase-matched second harmonic generation (SHG) is achieved using the mode dispersion relation of the optical waveguide with an estimated SHG conversion efficiency of 7.4 x 10(-3) % in the waveguide.

Phase-matched second-harmonic generation in a four-layer 2-methyl-4-nitroaniline waveguide with grating couplers

A four-layer 2-methyl-4-nitroaniline (MNA) crystal waveguide device with grating couplers is fabricated. Second-harmonic generation is observed under phase-matching conditions using the mode dispersion curves of the optical waveguide. A second-harmonic generation conversion efficiency in the waveguide of 0.71% is obtained with a grating coupling efficiency of 11.4% and a decoupling efficiency of 43.2%. The MNA single crystal is never damaged mechanically, and it has been kept stable for nine months.

Cerenkov doubling of infrared radiation in a planar waveguide loaded by an organic thin film

Frequency doubling of infrared coherent radiation in a planar waveguide loaded by an organic thin film is described. By using a strongly nonlinear crystal, such as 2-methyl-4-nitroaniline, as the loading organic material, more secondharmonic radiation can be expected than that reported in a proton-exchanged or Ti-diffused LiNbO(3) waveguide. The electromagnetic field analysis shows that the selection of a cover material that bounds the surface of the organic film is important in fulfilling the Cerenkov condition.