Polymer-based directional coupler modulator with high linearity

A generalized novel two-section directional coupler modulator with a linear transfer function is presented. This scheme introduces different coupling coefficients for each of the sections. We show that this configuration effectively suppresses the third-order intermodulation distortion compared to a conventional Mach-Zehnder modulator. It can be easily implemented by the photobleaching technique in polymer technology and demonstrates a simple and promising design for high-performance analog optical links without a complicated structure or electrical control.