Polymer Electro-optic Modulator Design And Simulation

Electro-optic modulators are the key devices in the optical fiber communication system, which makes good use of the wide bandwidth of optical fiber. Because of the significant advantages such as: simple fabricating process, low production costs and easy to achieve high bandwidth modulation, the polymer electro-optic modulators had become a research focus both at home and abroad recently.In this dissertation, the doped CLD1/PMMA polymer were used, the waveguide structure of electro-optic polymer was designer and simulated. First, the rib waveguide structure was analyzed theoretical by effective index method, the single-mode structure was achieved. Combined with optiBPM software simulation, the optical field transmission in the rib waveguide and DC bias characteristics were analyzed. The results also showed that microstrip electrode by vertical polarization, refractive index change of TM mode was 3 times TE mode, better modulation performance can be achieved by TM mode incident, so the analysis was dominated by TM mode in our paper.Electrode optimiazation was another key technology, using HFSS software to simulate the structure of the gold electrode at modulation frequency of 10GHz.With impedance matching for the goal, under the given dimensions of rib waveguide, the electrode structure was designed optimized. The electrode parameters were obtained when impedance matching, and microwave characteristics of the electrode was analyzed. The results indicated that the signal transmission efficiency was very high at the impedance matching point. And the structure of the electrode parameters affects on all the microwave effective index, the characteristic impedance and the loss cofficient. Under electrodes optimization parameters, the relationship between microwave frequency and half-wave voltage was achieved, the results show that the impedance mismatch, the rate mismatch and conductor loss can increase the half-wave voltage. Combined with the frequency response, the results indicated that the increase of bandwidth at the cost of half-wave voltage, so when designing we should integrated consider the bandwidth and voltage. Finally, the time domain characteristics of electro-optic modulators was analyzed, because of the conductor loss, the output waveform results distortion.