Fundamental Research On Microwave Electrode Of Poled Polymer Electro-optic Switches

It has put forward higher requirements for the information processing speed, transmitting speed and storage capacity with the development of information science. But the traditional electricity network is unable to satisfy this requirement because of its "electronic bottleneck". Meanwhile, there has urgent need of optical integrated devices of large capacity, easy connectivity, and resistance to electromagnetic and wireless in the fields of computer, telecommunications, and optical information processing. As a result, the optical network becomes the main way to solution this problem. And as it precisely conforms to this demand, the polymer E-O (electro-optic) devices has gradually developed into a focus in recent years.Besides a logic operation device, optical switch is also able to do the conversion to optical transmission line and integrated optical signal. It has one or a number of selected transmission ports. As important optoelectronics and integrated optical devices, optical switch and its arrays are one of the main factors that affect performance of the optical network, because of their core position. It completely depend on optical switches, optical filter, erbium-doped fiber amplifier (EDFA) of new generation, dense wavelength division multiplexing (DWDM) technology, and progress of other technology.The poled polymer electro-optic switch discussed in this paper is a member of the optical switch family. With its favorable performance of high switching speed (speed of response in the order of picoseconds or femtoseconds), it shows wide applications in the new generation of all-optical network and system of RoF, and has become one of the international focus of many hot research. In order to achieve the goals and good performance, a detailed study of the microwave electrode system should be done. This paper mainly covers the following aspects:1. By analyzing many kinds of configurations of the micro-wave electrode system of poled polymer electro-optic switches, we selected CPW traveling -wave electrode.2. We got the analytical expression of the characteristic impedance Z 0, microwave equivalent refractive index n m, ohmic lossαc, dielectric lossαd, and other parameters of CPW traveling-wave electrode system according to conformal mapping theory. And all of this work provided a theoretical basis for designing the microwave electrode.3. We analyzed the effective field distribution of CPW traveling-wave electrodes in detail. Additionally, by combining software (ADS2005a) simulation and theoretical calculations (the errors in the calculation are in the scope of the license), we discussed the relationship of parameters of electrode system such as Z 0,n m,α0,Vπ,Δf 3dB and its performance parameters such as W,G,t,εr,L and so on. Then the CPW traveling-wave electrode of poled polymer electro-optic modulator is designed finally with Vπ=12.4V,Δf 3 dB =22.8GHz(Si substrate); Vπ=13.1V,Δf 3 dB =156.5GHz(SiO2 substrate); and Vπ=13.4V,Δf 3 dB =35.4GHz(Glass substrate).4. We analyzed the effect of multiple electrodes structure to the performance of the directional coupler electro-optical switch based on coupled mode theory, got the optical field dispersion of E0y0 mode by single-mode transmission condition, and optimized parameters of electrodes and waveguides. And finally, the directional coupler electro-optic switches with switching voltage of 21.7V,9.59V,6.47V,4.47V were designed.5. After introducing the preparation process of CPW traveling-wave electrodes in detail, we prepared several CPW traveling-wave electrodes with different substrate materials and dielectric layers.6. A microwave probe used for high-frequency test is designed and fabricated. And then we built a testing system for electrodes by using microwave vector network analyzer (Anritsu37269C), the six-axes stage, high-frequency microwave probe, infrared CCD camera, monitor, pneumatic vibration isolation platform, DC and AC sources.7. We tested various of CPW traveling-wave electrode, illustrated the phenomenon of larger losses of CPW traveling-wave electrode based on Si substrate than other substrates. Besides that, poled polymer electro-optic modulator and the directional coupler electro-optical switches are tested preliminarily. Testing results showed that transmission loss was 31dB, return loss was 12dB, half-wave voltage was about 8V, and modulation bandwidth was 3.2GHz. In the end of the paper, we summarized the main problems of the current, and identified the future direction.