Rapid Scan White Light Pump-Probe Spectroscopy with 100 kHz Shot-to-Shot Detection

TL;DR

This paper presents a femtosecond pump-probe spectrometer using white light supercontinuum and synchronized detection, enabling rapid, high-throughput spectroscopy with minimized sample exposure and improved noise performance.

Contribution

It introduces a synchronized shot-to-shot detection method for pump-probe spectroscopy that significantly increases data acquisition speed and reduces noise compared to traditional scanning techniques.

Findings

Achieved 100 kHz shot-to-shot detection rate.

Reduced data collection time by 30 times.

Demonstrated low RMS noise of ~0.33 mOD in scattering samples.

Abstract

We demonstrate a femtosecond pump-probe spectrometer which utilizes a white light supercontinuum as input, and relies on mutual synchronization of acousto-optical chopper, pump-probe delay stage and the CCD camera to record shot-to-shot pump-probe spectra while the pump-probe delay is scanned synchronously with the laser repetition rate. The unique combination of technologies implemented here allows for electronically controllable and repetition-rate scalable detection throughput that is only limited by the camera frame rate. Despite RMS white-light probe fluctuations of ~5.5%, fully leveraging the temporal correlations in white light and fine sampling of pump-probe delay along with 30x reduction in equivalent data collection time compared to stepwise scanning leads to reduction of RMS noise without multichannel referencing down to ~0.33 mOD for a scattering nanotube sample. This demonstration opens door for impulsive pump-probe micro-spectroscopy of scattering samples with broadband spectral coverage and minimized sample exposure.