Rapid scan white light pump�probe spectroscopy with 100 kHz shot-to-shot detection

Bhat, VN and Thomas, AS and Bhattacharyya, A and Tiwari, V (2023) Rapid scan white light pump�probe spectroscopy with 100 kHz shot-to-shot detection. In: OSA Continuum, 2 (9). pp. 1981-1995.

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Abstract

We demonstrate a femtosecond pump�probe spectrometer that utilizes a white light supercontinuum as input and relies on mutual synchronization of the laser repetition rate, 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 high probe RMS fluctuations due to sample scatter (from �1.8 with solvent to 7.9 with sample scatter), a combination of fast and slow averaging with a fine sampling of pump�probe delay leads to reduction of RMS noise without multichannel referencing down to �0.4 mOD for a scattering nanotube sample. Throughput and limitations of the rapid versus stepwise scanning approaches are analyzed. Experimental comparison with stepwise scan shows �1.9x noise reduction in a significantly faster experiment, suggesting an additional suppression of 1/f noise enabled by rapid scan data collection. The particular combination of technologies implemented here makes our approach especially suitable for high throughput impulsive pump�probe micro-spectroscopy of highly scattering samples, without added cost and complexity of light sources, multichannel detection, or long sample exposure. © 2023 OSA - The Optical Society. All rights reserved.

Item Type:	Journal Article
Publication:	OSA Continuum
Publisher:	Optica Publishing Group (formerly OSA)
Additional Information:	The copyright for this article belongs to author.
Keywords:	Noise abatement; Probes; Pumping (laser); Spectrometers, Femtosecond pump probes; Laser repetition rate; Mutual synchronization; Optical chopper; Pump-probe delays; Pump/probe spectroscopy; Rapid scan; Shot detection; White light; White-light supercontinuum, CCD cameras
Department/Centre:	Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Date Deposited:	04 Mar 2024 09:10
Last Modified:	04 Mar 2024 09:10
URI:	https://eprints.iisc.ac.in/id/eprint/84312

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