Free space millimeter wave-coupled electro-optic high speed nonlinear polymer phase modulator with in-plane slotted patch antennas.

We report in-plane slotted patch antenna-coupled electro-optic phase modulators with a carrier-to-sideband ratio (CSR) of 22 dB under an RF power density of 120 W/m(2) and a figure of merit of 2.0 W(-1/2) at the millimeter wave frequencies of 36-37 GHz based on guest-host type of second-order nonlinear polymer SEO125. CSR was improved more than 20 dB by using a SiO(2) protection layer. We demonstrate detection of 3 GHz modulation of the RF carrier. We also derive closed-form expressions for the modulated phase of optical wave and carrier-to-sideband ratio. Design, simulation, fabrication, and experimental results are discussed.

Unprecedented highest electro-optic coefficient of 226 pm/V for electro-optic polymer/TiO2 multilayer slot waveguide modulators.

We investigated the electrical properties and optical quality of two layers a titanium dioxide (TiO2) selective layer and a sol-gel silica cladding layer for use as coating layers for nonlinear optic (NLO) polymers in electro-optic (EO) polymer/TiO2 multilayer slot waveguide modulators. We used a simple ellipsometric reflective technique developed by Teng and Man to measure the electro-optic (EO) coefficients of poled thin films of an EO polymer in an EO multilayer device. The Pockels coefficient was enhanced up to 226 and 198 pm/V at wavelengths of 1.31 and 1.55 µm, respectively, when optimally poled with TiO2 and a sol-gel silica cladding.

Electro-optic polymer spatial light modulator based on a Fabry-Perot interferometer configuration.

A spatial light modulator (SLM) based on a Fabry-Perot interferometer configuration has been fabricated and tested. The Fabry-Perot spacer layer is a thin film of the SEO100 electro-optic polymer which serves as the nonlinear medium. Measurement results demonstrate the modulation of multiple pixels operating simultaneously at frequencies ranging from 300 kHz to 800 kHz which is significantly faster than SLMs based on liquid crystal and digital micromirror device technology. An average modulation contrast of 50% for all pixels is achieved with a drive voltage of 70 V(rms) at 100 kHz. Microwave speeds and CMOS compatibility are feasible with improved transmission line and cavity design.

Alignment-free fabrication of a hybrid electro-optic polymer/ion-exchange glass coplanar modulator.

A hybrid electro-optic (EO) polymer phase modulator with a 6 µm coplanar electrode gap was realized on ion exchange glass substrates. The critical alignment steps which may be required for hybrid optoelectronic devices were eliminated with a simple alignment-free fabrication technique. The low loss adiabatic transition from glass to EO polymer waveguide was enabled by gray scale patterning of novel EO polymer, AJLY. Total insertion loss of 5 dB and electrode gap of 8 µm was obtained for an optimized device design. EO polymer poling at 135 °C and 75 V/µm was demonstrated for the first time on a phosphate glass substrate and was enabled by the sol-gel buffer layer.

High Deltan strip-loaded electro-optic polymer waveguide modulator with low insertion loss.

We demonstrate a novel electro-optic polymer modulator design which shows a record low optical insertion loss of 5.7 dB at 1550 nm. The modulator consists of a high numerical aperture passive waveguide which is converted to a strip-loaded electro-optic polymer waveguide through refractive index tapers. The device is fabricated using all wet-etch techniques which results in low excess loss from roughness created during fabrication and, employs new low loss passive sol-gel materials. The fabricated device also shows a low half-wave voltage of 2.8 V.

Atomic force microcopy study of the mechanical and electrical properties of monolayer films of molecules with aromatic end groups.

The effect of intermolecular pi-pi stacking on the electrical and mechanical properties of monolayer film molecules containing aromatic groups was studied using atomic force microscopy. Two types of aromatic molecules, (4-mercaptophenyl) anthrylacetylene (MPAA) and (4-mercaptophenyl)-phenylacetylene (MPPA), were used as model systems with different pi-pi stacking strength. Monolayer films of these molecules on Au(111) surfaces exhibited conductivities differing by more than 1 order of magnitude, with MPAA being the most conductive and MPPA being the least conductive. The response to compressive loads by the AFM tip was also found to be very different for both molecules. In MPAA films, distinct molecular conductivity changes are observed upon mechanical perturbation. This effect, however, was not observed on the MPPA film, where intermolecular pi-pi interactions are likely weaker.

Quantum-chemical investigation of second-order nonlinear optical chromophores: comparison of strong nitrile-based acceptor end groups and role of auxiliary donors and acceptors.

We report a detailed quantum-chemical investigation of donor-acceptor substituted dipolar nonlinear optical chromophores incorporating the 4-(dimethylamino)phenyl donor end group and a variety of strong heterocyclic acceptor end groups, including tricyanofurans and tricyanopyrroles. In particular, we study the variation of the molecular second-order polarizability (beta) with the acceptor end group and when inserting auxiliary donors (thiophene) and acceptors (thiazole) into the pi bridge. Both finite-field calculations (in the context of local contributions) and sum-over-states calculations were carried out in order to probe the relationship between beta and the chemical structure of the various chromophores. The trends obtained with these two methods are fully consistent. The large beta values (up to 700 x 10(-30) esu) as well as the observed tunability of the optical absorption maximum (lambda(max)) make the chromophores investigated here interesting candidates for use in electro-optic applications at telecommunications wavelengths.