High Speed Electro-optic Switch Based On Poled Polymer Materials

Fiber network has become a fundamental system on information processing in many countries. Wavelength-division multiplexing (WDM) technique is considered as a promising solution to meet the demand of tremendous information transmission in the current telecommunications network because it expands the network's capacity and also offers flexibility for the construction of novel network architectures. The devises such as electro-optic (EO) modulators and switches are of great technique for wide band optical communication systems and wireless information networks. The frequency conversion, modulation, switch, deflection are basis devices in optical information processing, which put into effect depending on the optical signal (intensity, phase, polarization, etc.) of nonlinear optical materials along with the change of applied electric, sound, magnetic and optical field. In recent years, compared with LiNbO3 crystal, polymers and hybrid materials have many intrinsic advantages, such as their low dispersion in the index of refraction between infrared and millimeter-wave frequencies, fast electronic response and high EO coefficient. These merits make a firm fundamental for the research and development of high speed EO devices.The thesis is supported by the 973 project. The history and the latest developments in EO switches have been introduced briefly. The necessity of the research on the work is explained. Some poled polymers have been investigated and the strip-loading waveguide structure is also introduced. Finally the switch devices are fabricated and the EO response is obtained. The main results are concluded as follows:1. The fundamental research on the new pattern of optical waveguide materials.Monomers of F-PI are synthesized. Polyamides have good thermo oxidative stability, outstanding mechanical properties, fire resistance and so on. We successfully synthesize five materials based on monomer of TFDAS and hope them can keep the advantage of the famous polyimide, such as adhesion to the substrate and hygroscopic. The experiments prove the polymers exhibit excellent thermal stabilities, low optical loss and birefringence, have good solubility in many solvents, suitable for the fabrication of waveguide.2. The research on new EO materials: DR1/F-PI.DR1 and F-PI have a good solution in DMF, we successfully gain the EO coefficient of the DR1/F-PI after corona poling. To compare the doped EO materials, the DR1/F-PI can have a better stability on EO coefficient due to the valence bond effect between the DR1 and F-PI. Considering the characteristic of the EO materials and the design of device, a reverse rib waveguide structure is used. And the output near-field profile from 2-cm-length waveguide is obtained.3. The hybrid DR1/SiO2 film utilizing sol-gel technique has been prepared.The reaction process of sol-gel system has been discussed theoretically. The optimal preparation for the DR1/SiO2 film was given. The DR1 chromophores are firmed in the networks of the TiO2-SiO2. The best concentration of solution and the heating treatment condition has been obtained by experiments. The large EO coefficient and good stability (1000h at room temperature only 5% relax) are obtained.4. A strip-loading waveguide structure is proposed. The waveguide using organic/inorganic film was also fabricated successfully.The hybrid materials have a small dielectric constant because of the doped host material and the good thermal stability due to rigid and stable inorganic network. But the depth and mismatch between the EO film and polymer can not be ignored. This strip-loading structure eliminates the damage to the EO material by the dry etching process and also avoids the cracks for EO material caused by the mismatch of the thermal expansion constant. Furthermore, the induced guiding core reduces the coupling loss with optical fiber due to its thickness. The modulated efficiency can be also enhanced. The design of the device is optimized by the solution of these problems. We have successfully fabricated the EO switch. And the measurement of the CPW electro-optic switch proves the possibility of this fabrication. The performance parameters of the EO switch are also measured and discussed.5. The enhancing performance of the EO materials doped with polyvinyl alcohol (PVA).The PVA is of great adhesion and flexibility. The doped PVA have effects on the electro-optic performance. And we obtain a good uniformity and the raised thickness of EO film by the experiment. Considering the excellent thermal stabilities of the hybrid film and the simple processes for the device fabrication, this type of device has great potential for electro-optic devices applications.The researches above are totally innovative. The exploratory work established fundamental for the fabrication of high quality poled polymer electro-optic switches.