[Show abstract][Hide abstract] ABSTRACT: 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/m2 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 SiO2 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.
[Show abstract][Hide abstract] ABSTRACT: We report antenna-coupled electro-optic phase modulators operating at Ka-band based on in-plane polymeric waveguides using the nonlinear guest-host polymer SEO125. Design, simulation, fabrication, and experimental results are discussed.
[Show abstract][Hide abstract] ABSTRACT: Using a simple optical setup to detect and characterize transmission gratings in the far field, we demonstrate that going beyond the diffraction limit is not possible using linear interaction of nonclassical illumination with the target grating. We also confirm that nonlinear optical interactions with the target grating, or with the optical medium around it, do allow improvement in resolution.
[Show abstract][Hide abstract] ABSTRACT: We report on factors affecting the performance of a broadband, mid-IR absorber based on multiple, alternating dielectric / metal layers. In particular, we investigate the effect of interface roughness. Atomic layer deposition produces both a dramatic suppression of the interface roughness and a significant increase in the optical absorption as compared to devices fabricated using a conventional thermal evaporation source. Absorption characteristics greater than 80% across a 300 K black body spectrum are achieved. We demonstrate a further increase in this absorption via the inclusion of a patterned, porous anti-reflection layer.
[Show abstract][Hide abstract] ABSTRACT: MAP was used to fabricate polymer DRRs as its high resolution allows precise control on the coupling/transmission coefficients. Pedestal acrylic DRRs with 34nm 33nm FSR and -15dB isolation were fabricated and showed good qualitative agreement with simulation results.
[Show abstract][Hide abstract] ABSTRACT: Improvement of resolution beyond the Rayleigh limit is obtained by monitoring non-resonant four wave mixing generated by the target in a confocal scanning microscope configuration.
[Show abstract][Hide abstract] ABSTRACT: Multiphoton absorption polymerization (MAP) allows for rapid prototyping of microscale optical devices. We have created high-performance, single-mode optical waveguides and have demonstrated the coupling of these structures to optical fibers for use as in-line devices.
[Show abstract][Hide abstract] ABSTRACT: We consider the Mach-Zehnder interferometer (MZI) method that specifically uses a poled organic thin film as one of the reflective mirrors in order to characterize the two independent electro-optic tensor elements r<sub>13</sub> and r<sub>33</sub>. We discuss both a simple analysis based on a three-layer structure and a rigorous method including multiple reflection effects in a multilayer structure. In doing so, we find that the simple analysis of the reflective MZI method yields identical results to the reflection ellipsometric method (simple Teng-Man method), first introduced by Teng and Man as well as Shildkraut in 1990, when the ratio of r<sub>13</sub> to r<sub>33</sub> obtained from the MZI method is used in the analysis of the simple Teng-Man method. Error introduced by ignoring the multilayer nature of the sample structures in the MZI method is discussed and corrections are given for previous expressions in the literature for the simple analysis.
[Show abstract][Hide abstract] ABSTRACT: We propose a periodic multilayer structure of dielectric and metal interlayers to achieve a near-perfect broadband absorber of mid-infrared radiation. We examine the influence of four factors on its performance: (1) the interlayer metal conductance, (2) the number of dielectric layers, (3) a nanopatterned antireflective layer, and (4) a reflective metallic bottom layer for backreflection. Absorption characteristics greater than 99% of the 300 K and 500 K blackbody spectra are found for the optimized structures. Incident angle and polarization dependence of the absorption spectra are examined. We also investigate the possibility of fabricating a nanopatterned antireflective layer to maximize absorption.
[Show abstract][Hide abstract] ABSTRACT: We present results from measurements on periodic multilayer structure of
alternating dielectric and thin metal layers to achieve a broadband
absorber of mid-infrared radiation. We examine the effect on performance
of a back-reflective metallic bottom layer, surface roughness at
interfaces, the metal conductance, the thickness of dielectric layers,
and a patterned anti-reflective layer. We determine optimum structure
parameters for absorption of a 500 K-black body spectrum, and find that
the numerical results agree well with the measured absorption spectra.
We also investigate the possibility of fabricating a patterned
anti-reflective layer to further increase the absorption.
[Show abstract][Hide abstract] ABSTRACT: We report new closed-form expressions for Maker fringes of anisotropic and absorbing poled polymer thin films in multilayer structures that include back reflections of both fundamental and second-harmonic waves. The expressions, based on boundary conditions at each interface, can be applied to multilayer structures containing a buffer and a transparent conducting oxide layer, which might enhance multiple reflections of fundamental and second-harmonic waves inside a nonlinear thin film layer. This formulation facilitates Maker fringe analysis for a sample containing additional multilayer structures on either side of a poled polymer thin film. Experimental data and numerical simulations are given to indicate the importance of inclusion of such a reflective layer in analyses for reliable characterization of second-harmonic tensor elements.
[Show abstract][Hide abstract] ABSTRACT: Micro-ring resonators with good performance were fabricated using multi-photon absorption polymerization (MAP) on PDMS and directly pressed against SPF producing variable resonances in the optical output spectrum depending on positioning and pressure.
Lasers and Electro-Optics (CLEO), 2012 Conference on; 01/2012
[Show abstract][Hide abstract] ABSTRACT: Resolution of an optical system for grating detection was improved by a factor of two beyond the Abbe diffraction limit using nonlinear optics. Use of non-classical illumination did not provide any improvement.
Lasers and Electro-Optics (CLEO), 2012 Conference on; 01/2012
[Show abstract][Hide abstract] ABSTRACT: We report a simplified reflection mode Fabry-Perot interferometry method for determination of electro-optic (EO) coefficients of poled polymer thin films. Rather than fitting the detailed shape of the Fabry-Perot resonance curve, our simplification involves a technique to experimentally determine the voltage-induced shift in the angular position of the resonance minimum. Rigorous analysis based on optical properties of individual layers of the multilayer structure is not necessary in the data analysis. Although angle scans are involved, the experimental setup does not require a θ-2θ rotation stage and the simplified analysis is an advantage for polymer synthetic efforts requiring quick and reliable screening of new materials. Numerical and experimental results show that our proposed method can determine EO coefficients to within an error of ~8% if poled values for the refractive indices are used.
[Show abstract][Hide abstract] ABSTRACT: Molecular first hyperpolarizabilities and dipole moments of new benzo-fused dyes were calculated using quantum–mechanical density functional theory (DFT). Two new infrared dyes were synthesized: each one was terminated with 6-diethylaminobenzo[b]furan on one end, and with CF3-tricyanodihydrofuran on the other end. The midsection of the π-electron framework for one dye contained a morpholino-substituted cyclohexenylene unit, and the other dye contained an ethoxysiloxane-substituted cyclohexenylene unit. Guest–host films were deposited on ITO-glass and contact poled. Electro-optic coefficients (r33) were measured at a wavelength of 1550nm by the attenuated total reflection method and by a modified simple Teng-Man reflection method. The measured values of r33 were compared with values estimated from a well-known model that employs the molecular properties of the dyes and the film poling parameters. Thermal stability and electronic absorption spectra of the dyes were measured.
[Show abstract][Hide abstract] ABSTRACT: We describe for the first time the fabrication and poling of a 700 μm thick bulk piece of polymethylmethacrylate (PMMA) doped with various concentrations of Disperse Red 1 (DR1). Maker fringe analysis demonstrates that poling fields of 57 V/μm to 71 V/μm induce substantial ordering of the DR1 chromophores, resulting in birefringence and significant d 33 and r 33 values. The poling of thick sections of guest-host polymers will have applications for a range of electro-optic applications, including modulators and terahertz generation and detection.
[Show abstract][Hide abstract] ABSTRACT: In this paper, we report on progress in the fabrication of a high speed optical phase modulator based on a nonlinear electro-optic (EO) polymer with an in-plane slotline radio frequency (RF) electrode structure. Compared to microstrip, a slotline RF electrode design has several potential advantages such as easy fabrication, high poling efficiency, low Vpi, and suppression of current drift. The guest-host nonlinear polymer system AJL49/APC was used in the device. Design, fabrication, and characterization are presented.
Proceedings of SPIE - The International Society for Optical Engineering 02/2011; DOI:10.1117/12.876239 · 0.20 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We report on the effect of arrays of Au nanopillars of controlled size and spacing on the spectral response of a P3HT: PCBM bulk heterojunction solar cell. Prototype nanopillar-patterned devices have nearly the same overall power conversion efficiency as those without nanopillars. The patterned devices do show higher external quantum efficiency and calculated absorption in the wavelength range from approximately 640 nm to 720 nm, where the active layer is not very absorbing. The peak enhancement was approximately 60% at 675 nm. We find evidence that the corresponding resonance involves both localized particle plasmon excitation and multiple reflections/diffraction within the cavity formed by the electrodes. We explore the role of the attenuation coefficient of the active layer on the optical absorption of such an organic photovoltaic device.
[Show abstract][Hide abstract] ABSTRACT: We report a second-order electro-optic coefficient r33 of 155±5 pm/V at a telecommunication wavelength of 1550 nm from nonlinear poled polymer thin films at a cryogenic temperature of ~4.2 Kelvin using a reflection ellipsometry technique.
[Show abstract][Hide abstract] ABSTRACT: Easily processed electro-optic films are reported with potential for >100 GHz switching speeds. Dyes of the general chemical structure 1-(4-[N-ethyl-N-(2-hydroxyethyl)-amino]-phenylethynyl)-4-(4-cyanophenylethynyl)-2,5-disubstituted benzene were attached as side groups to a polyimide backbone. Substituents on the central ring of the three-ring dye prevented aggregation at high concentrations of dye. These amorphous films exhibited absorption maxima in the range of 375–395 nm. A film containing 25% dye attached to polyimide was poled to give an electro-optic coefficient (r33) of 12 ± 2 pm/V at 532 nm. Its properties were compared with the measured linear and nonlinear optical properties of several previously published dyes that have transparency in the blue-green part of the visible spectrum.