InP-Based Comb Generator for Optical OFDM.

We describe in more detail a novel InP-based comb generator for optical orthogonal frequency division multiplexed (OFDM) transmission. The device integrates a Mach-Zehnder interferometer inside an amplified ring. In order to maximize the number of lines in the spectrum, the phase modulators were designed with a 3-step asymmetric quantum well structure to maximize the index change with voltage change. We demonstrate a 6-line frequency comb which is tunable over 80 nm. The linewidth of the comb is limited by only the input laser, which makes this device especially suitable for coherent optical OFDM applications. [ABSTRACT FROM PUBLISHER]