Optical properties of azo (EO) chromophore (DR1) doped in poly amic acid (PAM)
In this work, we studied the effects of annealing on the structural and optical properties of an azo electro optic (EO) polymer, Disperse Red1 (DR1), doped in Poly Amic Acid (PAM). Thin films were deposited on glass substrates by spin coating technique. The films were annealed at 195°C. The Structural and optical properties of the doped films were investigated by using UV-VIS spectra, Atomic Force Microscopy (AFM) and Prism Coupling technique. The number of modes, angles of coupling, thickness and refractive index were compared before and after annealing. The experimental results, showed 24nm blue shift in the photon absorption peak and number of modes and surface roughness of thin films decreased after annealing. Thickness was reduced about 1um and refractive index was increased by 0.03.
Thermal stability of electro‐optic response in poled polyimide systems
Using polyimide as host in a guest‐host thin film we demonstrate the first poled‐polymer electro‐optic response stable at temperatures up to 150 °C (samples poled and cured at 250 °C). A coplanar‐electrode poling geometry is used so that the molecular alignment of the guest dye between the electrodes is coincident with the free volume of the host. We hypothesize that ‘‘high’’ temperature poling during the imidization process, when the polyimide forms rings and densifies, accounts for the excellent poled response stability.
Optical to microwave conversion in a traveling wave electro-optic polymer based device
This paper describes the design of an optical to microwave converter. The physical effect used for the conversion is based on the non-linear behavior of an electro-optic polymer material. The microwave frequency is generated by the way of an optical waves mixing process, which means by the frequency difference of two optical waves propagating simultaneously inside an optical waveguide. If one of these optical waves is modulated by an informative signal, the microwave signal will infer the modulation. The converter is designed for working at the 1.55 μm optical telecommunication wavelength. The active waveguide is built with the crosslinked PMMA-DR1 electro-optic copolymer, and the cladding layers are made of NOA material. For the first characterizations there is no need of a master-slave configuration for the sources, and the two optical waves are produced by highly stable and fine tunable lasers. The microwave signal is collected on a strip line which characteristic impedance has to be adapted to the conversion process. Simulations have been conducted showing the feasibility of the method and by matching the velocities of the microwave signal and of the optical signal it is possible to create constructive microwave photonic mixing at more than 60 GHz. To achieve the conversion it is necessary to work with a traveling-wave configuration. Some special test devices have been built for the determination of the NOA material permittivity leading to a precise adjustment of the effective index of both optical and microwave waveguide. From all these measurements it has been possible to design completely the device, which is now under test.