Simplified photonic approach for high-coding-efficiency, digitalized microwave frequency measurement using multiple optical filter arrays with different FSRs

Abstract

A simplified photonic approach to microwave frequency measurement with digital outputs based on multiple parallel optical filter arrays, is proposed and experimentally demonstrated. In the proposed approach, multiple optical phase-shifted filter arrays in parallel with different free spectral ranges (FSRs) are designed to obtain digitalized results in the form of binary code with high-coding efficiency and fine measurement resolution. In particular, compared with previous approaches, larger tolerances on the phase shifts of optical filter arrays are provided in the proposed approach having the same coding efficiency and resolution. Therefore, the proposed system is greatly simplified and robust to noise. A proof-of-concept experiment is performed when two optical filter arrays are used. 8-bit binary digitalized results with a 5-bit effective number and a 2-GHz measurement resolution are obtained in the range from 10 to 40GHz.