Reconfigurable Linear Optical FM Discriminator

Abstract — We present a reconfigurable optical discriminator filter for frequency modulated microwave-photonics link appli-cations. The filter is based on a simplified ring-assisted Mach– Zehnder interferometer configuration. It enables conversion of a highly linear frequency to amplitude modulation. Operations in a fixed bandwidth (BW) of 30 GHz and a tunable bandwidth from 10 to 30 GHz are achieved using third- and fifth-order filters. A balanced frequency discrimination architecture with electronically reconfigurable transfer characteristics is demon-strated. We measured a ∼7.8 dB output-third order intercept point (OIP3) linearity improvement over that of a dual-output Mach–Zehnder. Index Terms — Bandpass filter, high-index-contrast waveguide