Breaking the accuracy and resolution limitation of filter- and frequency-to-time mapping-based time and frequency acquisition methods by broadening the filter bandwidth

TL;DR

This paper enhances the accuracy and resolution of filter- and frequency-to-time mapping-based photonic time and frequency measurement methods by broadening filter bandwidth, especially effective at high sweep speeds, demonstrated through SBS effect experiments.

Contribution

It introduces a method to improve measurement accuracy and resolution in FTTM-based techniques by broadening filter bandwidth, overcoming previous limitations at fast sweep speeds.

Findings

Frequency measurement accuracy improved by ~25 times.

Frequency resolution of STFT significantly enhanced.

Broadening filter bandwidth reduces pulse width at high sweep speeds.

Abstract

In this paper, the filter- and frequency-to-time mapping (FTTM)-based photonics-assisted time and frequency acquisition methods are comprehensively analyzed and the accuracy and resolution limitation in the fast sweep scenario is broken by broadening the filter bandwidth. It is found that when the sweep speed is very fast, the width of the generated pulse via FTTM is mainly determined by the impulse response of the filter. In this case, appropriately increasing the filter bandwidth can significantly reduce the pulse width, so as to improve the measurement accuracy and resolution. FTTM-based short-time Fourier transform (STFT) and microwave frequency measurement using the stimulated Brillouin scattering (SBS) effect is demonstrated by comparing the results with and without SBS gain spectrum broadening and the improvement of measurement accuracy and frequency resolution is well confirmed. The frequency measurement accuracy of the system is improved by around 25 times compared with the former work using a similar sweep speed, while the frequency resolution of the STFT is also much improved compared with our former results.