A code-free optical undersampling technique for broadband microwave spectrum measurement

TL;DR

This paper introduces a novel optical undersampling method for broadband microwave spectrum measurement that simplifies hardware requirements and improves detection of weak signals using homodyne detection, demonstrating effective performance over a 20 GHz range.

Contribution

The paper presents a code-free optical undersampling approach combined with homodyne detection, eliminating the need for high-speed coding sequences and enhancing weak signal detection in microwave spectrum measurement.

Findings

Successfully measured a 20 GHz spectral range with high SNR

Homodyne detection reduces analysis bandwidth and improves weak signal detection

The scheme shows good performance and potential for further optimization

Abstract

A novel broadband microwave (MW) spectrum measurement (BMSM) scheme based on code-free optical undersampling and homodyne detection is proposed. The fully analog generation of optical pulses with a far-less-than-Nyquist rate is only through modulating cascaded electrooptical modulators by a single RF tone instead of any high-speed coding sequence modulation. Homodyne detection will reduce the analysis bandwidth of BMSM and enhance the detection performance of weak signal. A multi-band signal with 20 GHz spectral range and SNR = 61 dB is used to investigate the BMSM performance of this scheme, and the results show good performance for BMSM. The potentials for further optimization in practice are also discussed.