Active tuning of slow light in electro-optic polymer-filled photonic crystal for application to optical modulator

초록

We report on the active tuning of slow light in an optical modulator made of electro-optic(EO) polymer-filled photonic crystal (PhC) Mach-Zehnder interferometer (MZI). To reduce the length of the device, we investigate the characteristics of the slow light on the silicon PhC waveguide. The group index of the PhC waveguide can be changed by altering the refractive index of the PhC air holes, and the index of the air holes is changed by filling in the air holes with EO polymer materials. The higher the group index of the PhC waveguide is, the slower the light propagation is. We find that the change of the refractive index of the EO polymer in the hole by 0.005 induces the change of the group index of the PhC waveguide by up to 0.2. The group index also depends on the wavelength, the radius of the EO polymer hole, and the device length. Use of all of these findings led us to obtain even higher EO effect. When we apply voltage on the electrode, we can change the phase difference by due to the EO effect of the polymer. Our calculation shows the extinction ratio up to 43 dB.