High Speed Pump-Probe Apparatus for Observation of Transitional Effects in Ultrafast Laser Micromachining Processes

Ilya Alexeev,Michael Schmidt,Konstantin Nagulin,Kristian Cvecek,Johannes Heberle

doi:10.3390/mi6121462

Ilya Alexeev, Michael Schmidt + Show 3 more

Open Access

https://doi.org/10.3390/mi6121462

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Journal: Micromachines	Publication Date: Dec 7, 2015
Citations: 23	License type: CC BY 4.0

Affiliation: University of Erlangen-Nuremberg

Abstract

A pump-probe experimental approach has been shown to be a very efficient tool for the observation and analysis of various laser matter interaction effects. In those setups, synchronized laser pulses are used to create an event (pump) and to simultaneously observe it (probe). In general, the physical effects that can be investigated with such an apparatus are restricted by the temporal resolution of the probe pulse and the observation window. The latter can be greatly extended by adjusting the pump-probe time delay under the assumption that the interaction process remains fairly reproducible. Unfortunately, this assumption becomes invalid in the case of high-repetition-rate ultrafast laser material processing, where the irradiation history strongly affects the ongoing interaction process. In this contribution, the authors present an extension of the pump-probe setup that allows to investigate transitional and dynamic effects present during ultrafast laser machining performed at high pulse repetition frequencies.

Highlights

Within the last several years, ultrafast lasers have established themselves as an indispensable micromachining tool, especially for the processing of transparent media such as glass or polymers
It occurs at the expense of reduced precision in the temporal synchronization due to the electronic jitter that can significantly exceed the temporal resolution of the probe [7]
The temporal resolution is defined by the probe pulse duration, the observation window is limited by the available delay, and an assumption of process reproducibility and independence of subsequent events has to be made

Summary

Introduction

Within the last several years, ultrafast lasers have established themselves as an indispensable micromachining tool, especially for the processing of transparent media such as glass or polymers. The pump and the probe pulses are temporarily synchronized either optically or electronically [7] In the former case, the pump and probe beams are split using a fixed optical element, such as a beamsplitter, that allows achieving very precise temporal synchronization; the observation window becomes limited to tens of nanoseconds due to the finite length of optical delay lines. Some modifications of the pump-probe apparatus allow data acquisition over a single shot [9,11], permitting it not to rely on the reproducibility of the interaction process They have severe limitations on the duration of the observation window and provide reduced spatial information

Methods

Results

Conclusion