Bandpass filter and frequency–time mapping method for pulse measurement with optical delay

Abstract

The pulse signal’s transients and low duty cycle characteristics lead to excessive omission and erroneous amplitude measurement in signal capture. We offer a combined microwave photonics frequency–time mapping and optical delay electrical pulse measurement system. Beneficial from the true delay of a long fiber with several paths, the pulse is extended to have a more significant duty cycle so as to boost the capturing possibility. We adopt the bandpass filter to avoid sampling the low-frequency range, prevent phase noise from affecting the signal measurement, and improve the signal-to-noise ratio (SNR). This solves the phase noise issue induced by multiple optical delay paths. The proof-of-concept experiments conduct that a 25 μs pulse with a 50 μs period is stretched to a continuous wave, and the SNR is improved by 7 dB.