2020/09/08 by Durga Prasad Khatua, Khatua, Durga Prasad, Sabina Gurung +9
Chemical Engineering · Engineering · Physics and Astronomy · #Advanced Fiber Laser Technologies #Analytical Chemistry and Sensors #FOS: Physical sciences #Instrumentation and Detectors (physics.ins-det) #Materials Science (cond-mat.mtrl-sci) #Optics (physics.optics) #Photonic and Optical Devices
paper · pdf · doi:10.48550/arxiv.2009.03639
openalex publication_date 2020/09/08 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Optical pump-probe spectroscopy is a powerful tool to directly probe the carrier dynamics in materials down to sub-femtosecond resolution. To perform such measurement, while keeping the pump induced perturbation to the sample as small as possible, it is essential to have a detection scheme with high signal to noise ratio. Achieving such high signal to noise ratio is easy with phase sensitive detection based on lock-in-amplifier when a high repetition rate laser is used as the optical pulse source. However such a lock-in-amplifier based method does not work well when a low repetition rate laser is used for the measurement. In this article, a sensitive detection scheme which combines the advantages of boxcar which rejects noise in time domain and lock-in-amplifier which isolates signal in frequency domain for performing pump-probe measurements using low-repetition rate laser system is proposed and experimentally demonstrated. A theoretical model to explain the process of signal detection and a method to reduce the pulse to pulse energy fluctuation in probe pulses is presented. By performing pump-probe measurements at various detection conditions the optimum condition required for obtaining transient absorption signal with low noise is presented. The reported technique is not limited to pump-probe measurements and can be easily modified to suite for other sensitive measurements at low-repetition rates.