Title :
Integration of an electrooptic polymer in an integrated optics circuit on silicon
Author :
Faderl, L. ; Labeye, P. ; Gidon, P. ; Mottier, P.
Author_Institution :
LETI CEA-Technol. Avancees, Grenoble, France
fDate :
10/1/1995 12:00:00 AM
Abstract :
This paper presents the joining of active nonlinear polymer waveguides with passive silicon nitride waveguides (SiO2-Si 3N4-SiO2) to form an integrated Mach-Zehnder modulator with a lateral electrode configuration on a silicon substrate. Passive and active waveguides are based on a silicon-nitride-strip guiding structure. In the active waveguide a nonlinear polymer layer is used to obtain an index modulation via the electrooptic effect. Despite the silicon nitride strip based guiding structure, 63% of the energy of the fundamental mode is guided in the nonlinear polymer (provided by Flamel Technology, Venissieux, France). Poling with field strengths up to 75 V/μm applied to the lateral electrodes has been employed to orient the chromophores. A half wave voltage of 35 V has been measured for an electrooptic coefficient of 5.8 pm/V at a wavelength of 1.3 μm. Optical loss measurements have been done on polymer and passive waveguides. The best results have been 1.8 dB/cm for the active and 0.78 dB/cm for the passive waveguides leading to a total loss of 6 dB for a modulator with an interaction length of 2.5 cm. The coupling loss between a laser diode and the passive waveguide structure was measured to be at least 4.6 dB using a microscope objective and piezo-electric displacement elements. Stability tests under atmospheric conditions have shown a decrease of the electrooptic coefficient which might be due to the hygroscopic behavior of the active polymer. The bandwidth of the modulator has been determined to be 4 MHz
Keywords :
dielectric polarisation; electro-optical modulation; electrodes; integrated optics; integrated optoelectronics; optical films; optical polymers; optical waveguides; piezoelectric devices; refractive index; substrates; 1.3 mum; 35 V; 4.6 dB; 6 dB; SiO2-Si3N4-SiO2; active nonlinear polymer waveguides; active waveguides; chromophore orientation; coupling loss; electrooptic effect; electrooptic polymer; field strengths; fundamental mode; guiding structure; index modulation; integrated Mach-Zehnder modulator; integrated optics circuit; lateral electrode configuration; lateral electrodes; nonlinear polymer layer; passive silicon nitride waveguides; passive waveguides; piezo-electric displacement elements; silicon; silicon substrate; silicon-nitride-strip guiding structure; Electrodes; Electrooptic modulators; Electrooptical waveguides; Integrated optics; Loss measurement; Optical losses; Optical polymers; Optical waveguides; Silicon; Wavelength measurement;
Journal_Title :
Lightwave Technology, Journal of