High-frequency, low-crosstalk modulator arrays based on FTC polymer systems

Abstract

A novel electro-optic polymer, Furan TetraCyano Indane (FTC), has been utilised in the fabrication of low Vπ, high-speed, travelling-wave Mach-Zehnder modulator arrays. The modulators were realised with microstrip transmission lines that were optimised resulting in a line loss of 3.64 dB/cm at 40 GHz. Mach-Zehnder modulators based on this design with 1.62 cm interaction length resulted in devices with Vπ < 5 V and a reasonably flat frequency response up to 40 GHz. Electrical crosstalk measurements were also conducted on adjacent modulators separated by 400 µm in a modulator array. Without the implementation of any crosstalk reduction techniques, the measurement results indicated a crosstalk level of < –40 dB in the frequency band between 0 and 40 GHz. These impressive results were a consequence of the low dielectric constant of the polymer material at microwave frequencies and of the small lateral dimensions of the microstrip lines.