Amplitude independent instantaneous frequency measurement using all optical technique

A novel all-optical system which independently measures both the amplitude and frequency of an RF signal is proposed and demonstrated. A photonic Hilbert transformer provides two orthogonal measurements of an RF signal. These are compared using four wave mixing in a highly nonlinear fiber, producing two independent outputs enabling determination of both signal frequency and amplitude. This all optical approach requires only simple, low cost DC electronics at the receiver. The system is demonstrated up to 20 GHz but can be scaled to 40 GHz and beyond.