In the project “Ultrafast time-resolved spectroscopy characterization of perovskites thin films” (UTRSCofPTF) we propose a new approach that offers the possibility of characterizing perovskite oxide thin films properties by ultrafast time resolved spectroscopy using pump-probe ultrashort laser pulses, thus combining two important research domains, as follows: ultrafast laser engineering and thin films properties characterization. This approach offers unique insides of the fast-dynamic processes that happen on a fs-ps time scale, by combining the capability of optical spectroscopy with ultrafast lasers and spatial and temporal imaging, making this a means for the diagnosis of a wide range of phenomenon associated with the carrier transport and relaxation dynamics in nanoscale materials. The purpose of the project is to develop for the first time in Romania at National Institute for Lasers, Plasma and Radiation Physics (INFLPR) an Ultrafast time resolved spectroscopy experimental setup based on ultrashort laser pulses generated by Ti:Saphir CPA laser systems, namely 15 TW laser system TEWALAS and at the front-end of the CETAL 1PW laser system. In proposed project we will characterize the transient absorption spectroscopy for different perovskite oxide thin films obtained by laser deposition techniques with different structural strain. Transient absorption spectroscopy characterization of complex oxide thin films will provide major insides in revealing the changes of optical properties as a result of optical excitation at fs-ps time scale.

1. developing an ultrafast time-resolved spectroscopy set-up -  that will be used for characterizing fast dynamic processes that appear when a short optical pump pulse interacts with matter. This experimental set-up will be made for the first time at national level, to our knowledge;
2. revealing the transient optical properties changes during ultrafast light irradiation - in strain engineered epitaxial thin films of perovskite materials.

 Development of time resolved spectroscopy optical setup

•  Desing and implementation of ultrafast time-resolved spectroscopy optical setup
•  Generation and characterization of large bandwidth laser pulses that will be used as probe beams 

Temporal and spatial synchronization of the pump and probe pulses at the target level, real- time detection and experimental data acquisition

•   Temporal and spatial synchronization of the pump and probe pulses at the target level;
•   Development and implementation of a real-time detection and characterization system for transitory absorbtion in perovskite this films
•   Automatization in LabVIEW of the experimental setup and data acquisition
•   Management, data analysis, disemination

In proiectul “Spectroscopie ultra-rapida rezolvata temporal pentru caracterizarea filmelor subtiri perovskitice” (UTRSCofPTF) este propusa o noua abordare care ofera posibilitatea caracterizarii proprietatilor filmelor subtiri din materiale oxidice perovskitice prin metoda spectroscopiei ultra-rapide rezolvate temporal, folosind pulsuri laser ultra-scurte intr-o configuratie de tip pump-probe. Aceasta metoda combina doua domenii importante ale cercetarii, si anume: ingineria laserilor cu pulsuri ultra-scurte si caracterizarea proprietatilor filmelor subtiri. Aceasta abordare ofera o perspectiva unica asupra proceselor dinamice rapide, cu durate in domeniul fs-ps, ca urmare a imbinarii rezultatelor spectroscopiei optice cu imagistica spatio-temporala obtinuta cu ajutorul pulsurilor laser ultra-scurte, facand din aceasta metoda o modalitate de a diagnostica o varietate de fenomene associate cu dinamica de transport si relaxare a purtatorilor de sarcina din structura nanomaterialelor. Scopul acestui proiect este de a dezvolta pentru prima data in Romania, in cadrul Institutului National de Fizica Laserilor, Plasmei si Radiatiei (INFLPR) un montaj experimental de spectroscopie optica rezolvata temporal bazata pe utilizarea pulsurilor laser ultrascurte generate de doua sisteme laser, bazate pe tehnologia de amplificare a pulsurilor laser cu deriva de frecventa (CPA), si anume: sistemul laser TEWALAS, a carui putere maxima este mai mare de 15 TW si etajul de amplificare incipent al sistemului laser CETAL-PW. In cadrul proiectului propus se urmareste caracterizarea absortiei tranzitorii a filmelor oxidice perovskitice cu diferite grade de deformare structurala, obtinute prin tehnici de depunere asistata cu laserul, ceea ce va oferi informatii importante asupra modificarii proprietatilor optice in domeniul fs-ps, ca urmare excitarii optice.

1. Dezvoltarea unui montaj optic pentru spectroscopie ultrarapida rezolvata temporal. Acest montaj este utilizat in cadrul proiectului pentru caracterizarea proceselor dinamice ultrarapide care apar atunci cand un puls scurt de pompaj optic interactioneaza cu filmele subtiri. Aceasta configuratie experimentala este realizata pentru prima data la nivel national, dupa cunostintele noastre.
  2. revealing the transient optical properties changes during ultrafast light irradiation in strain engineered epitaxial thin films of perovskite materials.

Dezvoltarea montajului optic, pentru spectroscopie ultra-rapida, bazat pe pulsuri ultra-scurte

•   Proiectarea si implementarea montajului experimental utilizat pentru spectroscopie ultra-rapida

 

Montajul experimental pentru spectroscopie utra-rapida rezolvata temporal. M-oglinzi metalice, L1-L5 lentile, DM- oglinzi dicroice 400/800, BS-divizor de fascicul, BBO-cristal dublor, T-tinta, a) spectrul fasciculului de proba, b) imagine a tintei obtinuta cu ajutorul microscopului optic.

 

•   Generarea si caracterizarea pulsurilor de banda larga utilizate ca pulsuri de proba

Spectrul de banda larga al pulsului de proba obtinut la facilitatea laser TEWALAS

Sincronizarea spatio-temporala a pulsurilor la nivelul tintei, detectia si achizitia datelor experimentale in timp real.

•   Sincronizarea spatio-temporala a pulsurilor laser la nivelul tintei

In partea din stanga sunt prezentate fasciculelel laser atunci cand nu sunt suprapuse spatial si in partea din dreapta sunt prezentate fasciculele laser atunci cand sunt suprapuse spatial.

Semnalul armonicii a doua (400nm) se afla in mijlocul celor doua fascicule a caror lungime de unda este de 800nm

•   Automatizarea montajului experimental prin dezvoltarea de  aplicatii software in programul LabVIEW

Echipa de cercetare
- Dr. Victor-Gabriel COJOCARU (Director de proiect)
- Prof. Dr. Maria DINESCU (Mentor)

REZULTATE

Rapoarte stiintifice

Raport stiintific 1 - Download

Raport stiintific 2 - Download

Raport stiintific final - Download 

1) J. Wheeler  , P.-G. Bleotu A. Naziru, R. Fabbri , M. Masruri, R. Secareanu, D.M. Farinella,
G. Cojocaru, R. Ungureanu , E. Baynard, J. Demailly, M. Pittman, R. Dabu, I. Dancus, D. Ursescu, D. Ros, T. Tajima, and G. Mourou
"Compressing High Energy Lasers through Optical Polymer Films", Photonics (2022)

Acknowledgment: G. Cojocaru acknowledges the support by a grant of the Ministry of Education 257
and Research, CNCS-UEFISCDI (project no. PN-III-P1-1.1-PD-2019- contract no. 84/2020