Alexandre MATIC : "Periodically poled resonators on oblique cuts of lithium niobate for radiofrequency filtering applications"

PhD works of Alexandre MATIC : "Periodically poled resonators on oblique cuts of lithium niobate for radiofrequency filtering applications"

Even if thesis defense is public, sanitary measures oblige me to limit the access of the amphitheater to invited persons only, with strict observance of social distancing rules. A videoconference solution will be offered for attendance, more information to come about this.

Abstract : Piezoelectric surface acoustic waves (SAW) and bulk acoustic waves (BAW) filters play a key role in development and performances of mobile telephony. As the mobile phone standards enters its 5^th generation (5G), acoustic wave filters must adapt to the expected increase of frequencies. In the 2000s, studies are carried out on piezoelectric components based on periodic poled structures, which allow, due to their architecture, an easier increase of operating frequency. However, these devices, initially made from Z-cut lithium niobate or tantalate, do not fulfill performance requirements for wideband filter applications. In this work, use of lithium niobate oblique cuts for the realization of periodically poled resonators is investigated. A theoretical study, based on finite element simulations, is performed to determine the contribution of the oblique cuts. Fabrication and feasibility of ferroelectric domains on these cuts is then presented. Finally, characterization of resonators made on different lithium niobate cuts is carried out. Increase in the performance of theses devices associated with the use of oblique cuts is demonstrated and paves the way for applications in radiofrequency filtering.

Jury composition: M. Thomas BARON, Ingénieur de Recherche, ENSMM, PhD Director

M. Thierry AUBERT, Professeur des Universités, Université de Lorraine, Reporter

M. Dominique CERTON, Professeur des Universités, Université de Tours, Reporter

Mme Thérèse LEBLOIS, Professeur des Universités, Université de Franche-Comté, Reviewer

M. Victor PLESSKY, Director of Engineering, Resonant Inc., Reviewer

M. Samuel MARGUERON, Maître de Conférences, ENSMM, Reviewer

M. Jean-Jacques BOY, Ingénieur de Recherche, ENSMM, PhD co-director

M. Florent BASSIGNOT, Ingénieur Recherche et Développement, Femto-Engineering, Invitee

Localization : Amphithéâtre J-J Gagnepain, Institut FEMTO-ST, 15 B, Avenue des Montboucons - Besançon