Ultrafast insulator-to-metal phase transition as a switch to measure the spectrogram of a supercontinuum light pulse

TL;DR

This paper introduces a method to measure the detailed temporal and spectral structure of complex light pulses using the ultrafast insulator-to-metal phase transition in VO2, enabling new broadband spectroscopic techniques.

Contribution

It demonstrates a novel approach to determine the spectrogram of supercontinuum pulses via ultrafast phase transition in VO2, simplifying pulse characterization.

Findings

Successful in-situ spectrogram measurement of supercontinuum pulses

Utilizes ultrafast phase transition to achieve broad spectral range analysis

Enables development of advanced broadband pump-probe experiments

Abstract

In this letter we demonstrate the possibility to determine the temporal and spectral structure (spectrogram) of a complex light pulse exploiting the ultrafast switching character of a non-thermal photo-induced phase transition. As a proof, we use a VO2 multi-film, undergoing an ultrafast insulator-to-metal phase transition when excited by femtosecond near-infrared laser pulses. The abrupt variation of the multi-film optical properties, over a broad infrared/visible frequency range, is exploited to determine, in-situ and in a simple way, the spectrogram of a supercontinuum pulse produced by a photonic crystal fiber. The determination of the structure of the pulse is mandatory to develop new pump-probe experiments with frequency resolution over a broad spectral range (700-1100 nm).