Optical trimming of electro-optical polymer devices using photo-bleaching

This thesis details the effects of photobleaching on electro-optic polymers. A different aspect of view on this traditional weakness is to use it for optical trimming of finished devices. This work involves the characterization of newly developed electro-optical (EO) polymer, the design and fabrication of polymer waveguide devices, understanding the cause of photobleaching, and exploring the application for optical trimming.;Different EO polymers were studied to exploit the potentials of nonlinear polymer and to overcome some practical issues. A modulator made of cross-linkable PSDA-AJL4, which employs Diels-Alder reaction to overcome nonlinearity-stability tradeoff, has demonstrated great thermal stability at 85°C. New poling scheme was developed for AJL8/APC, a high r33 guest-host polymer, to improve the poling efficiency up to 30% in a low Vpi modulator. CLD1/APC was used for the study of photobleaching.;The relation between oxygen and photobleaching was further studied in this work. Photo-oxidation appears to be the dominant cause for bleaching even at exposure wavelength away from resonance. While most bleaching process is under low exposure intensity, we demonstrated that a focused laser beam with wavelength at absorption peak can cause oxygen depletion and introduce saturated bleaching. This technique allowed us to have accurate control of index change at order of 10-4 so as precise positioning of the bleached area.;Wavelength-insensitive biasing of a polymer Mach-Zehnder modulator was demonstrated using photobleaching to adjust the optical path mismatch. The resulted modulator shows a reduction by a factor of 17 in bias dispersion, which can significantly increase the usable wavelength range of a MZ modulator before the second order distortion effects start to limit the SFDR.;Coupling tuning using photobleaching on polymer ring modulators was studied with different configurations of coupling and bleaching positions. The primitive results show at least 7dB improvement for extinction of transmission at resonance. A ring modulator with -22dB extinction was obtained after optical trimming.