Abstract

Nanostructures proved to be versatile platforms to control the electromagnetic field at subwavelength scale. Indeed, high-quality-factors nanocavities have been used to boost and control nonlinear frequency generation by increasing the light–matter interaction. However, nonlinear processes are triggered by high-intensities, which are provided by ultrashort laser pulses with large bandwidth, which cannot be fully exploited in such devices. Time-varying optical systems allow one to overcome the time-bandwidth limit by modulating the cavity external coupling. Here we present a general treatment, based on coupled mode theory, to describe second harmonic generation in a doubly resonant cavity for which the quality-factor at the fundamental frequency is modulated in time. We identify the initial quality factor maximizing second harmonic efficiency when performing Q-boosting and we predict a theoretical energy conversion efficiency close to unity. Our results have direct impact on the design of next generation time-dependent metasurfaces to boost nonlinear frequency conversion of ultrashort laser pulses.

Details

Title
Enhancing second harmonic generation by Q-boosting lossless cavities beyond the time bandwidth limit
Author
Franceschini, Paolo 1 ; Tognazzi, Andrea 2 ; Chernyak, Anna M 3 ; Musorin, Alexander I 3 ; Cino, Alfonso C 4 ; Fedyanin, Andrey A 3 ; De Angelis, Costantino 1 

 Department of Information Engineering, University of Brescia, Via Branze 38, 25123, Brescia, Italy; National Institute of Optics – National Research Council (INO-CNR), Via Branze 45, 25123, Brescia, Italy 
 National Institute of Optics – National Research Council (INO-CNR), Via Branze 45, 25123, Brescia, Italy; Department of Engineering, University of Palermo, Viale delle Scienze ed. 9, 90128, Palermo, Italy 
 Faculty of Physics, Lomonosov Moscow State University, Leninskie gory 1, 119991, Moscow, Russia 
 Department of Engineering, University of Palermo, Viale delle Scienze ed. 9, 90128, Palermo, Italy 
Pages
1-8
Publication year
2024
Publication date
2024
Publisher
Walter de Gruyter GmbH
ISSN
21928606
e-ISSN
21928614
Source type
Scholarly Journal
Language of publication
English
ProQuest document ID
2915107263
Copyright
© 2024. This work is published under http://creativecommons.org/licenses/by/4.0 (the “License”). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.