Laser-pump-resistive-probe technique to study nanosecond-scale relaxation processes

TL;DR

This paper introduces a novel laser-pump-resistive-probe technique that enables time-resolved electrical measurements from nanoseconds to seconds, overcoming optical delay line limitations and expanding analysis capabilities for various physical and biochemical processes.

Contribution

The paper presents a new pump-probe method combining optical and electrical pulses for time-resolved measurements over a wide temporal range, enhancing the study of relaxation processes.

Findings

Successfully measured heat-induced changes in VO$_x$ films

Demonstrated carrier relaxation in CdS photoresistors

Extended temporal resolution from nanoseconds to seconds

Abstract

Standard optical pump-probe methods analyze a system's temporal response to a laser pulse within sub-femtoseconds to several nanoseconds, constrained by the optical delay line's length. While resistance is a sensitive detector in various fields, its measurements are typically slow (>microseconds) due to stabilization requirements. We suggest here a time-resolved pump-probe technique which combines an optical pump pulse and a rectangular electrical probe pulse through the sample, measuring transmission in a 50 Ohm matched circuit with a digital oscilloscope. This allows electrically-driven delays from nanoseconds to seconds. Demonstrations include studying heat-induced changes in a thin amorphous VO$_x$ film and carrier relaxation in a CdS photoresistor, showcasing potential applications in heat transfer, biochemical reactions, and gradual electronic transformations.