Characterization of ultrashort femtosecond pulses

• Grant number: 21/02891-6
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: May 01, 2021
• End date: December 31, 2022
• Field of knowledge: Physical Sciences and Mathematics - Physics - Condensed Matter Physics
• Principal Investigator: Cleber Renato Mendonça
• Grantee: Nathan Barbola Marucci
• Host Institution: Instituto de Física de São Carlos (IFSC). Universidade de São Paulo (USP). São Carlos , SP, Brazil
• Associated research grant: 18/11283-7 - Nonlinear photonics: spectroscopy and advanced processing of materials, AP.TEM

Abstract

To measure the time interval of an event, it is necessary to use another event with a shorter duration than the one to be measured. In the case of ultrashort laser pulses, which are the shortest events ever created by man, the pulse itself is used to determine its duration, using a technique known as autocorrelation. However, this technique does not allow us to obtain much more information about the pulse, for example, its intensity profile or its phase. Bearing in mind that ultrashort pulses are fundamental for the study of phenomena that occur in this time scale, and that in many experiments the results depend on details of the pulse structure, the determination of these pulse characteristics becomes essential. The determination of these details of the pulse: temporal profile, spectral and temporal phase can be performed using the Frequency-Resolved Optical Gating (FROG) technique. It is based on the autocorrelation method, where the spectrum of the pulse resulting from the nonlinear interaction is determined as a function of the relative delay between the pulses (FROG trace). Using pulse reconstruction algorithms, based on the FROG traces, it is possible to determine the temporal and spectral intensities, as well as the phase. In this project we will use the FROG technique to characterize distinct ultrashort pulses in certain experimental situations.