Optical nonlinearity in the terahertz (THz) range represents a key technology to access high frequency
spectral windows that are usually difficult to cover using conventional solid state laser technologies. Over the past decade, the non-linear optical properties of graphene have been extensively investigated, and a wide range of related applications demonstrated, ranging from optical modulators [1] to saturable absorbers [2]. High harmonic generation (HHG) – the frequency up-conversion of an optical signal – in materials systems is governed by symmetries. This effect has been exploited in graphene [3], where HHG has been demonstrated, albeit only at odd multiples of the driving frequency owing to its inherent centro-symmetry. In topological insulators (TIs), unconventional HHG has been predicted [4], supported by the bulk and topological surface states, which are usually difficult to distinguish, relying on the ultrafast intraband dynamics, and the inversion symmetry- breaking even order nonlinearity in the topological phase. Here, we exploit innovative technological approaches in large area topological insulator metametarials and heterostructures or multilayer graphene to device both high efficient non-linear micro-devices, optically pumped by quantum cascade lasers (QCLs) delivering 2W optical power, and electrically-driven integrated plasmonic lasers comprising integrated QCL heterostructures, targeting HHG in the technologically relevant Reststrahlen gap (6-12 THz) at both odd or even orders, via symmetry breaking [5], [6], [7]. This talk will provide future perspectives in the fascinating field of topological photonics and non-linear THz photonics.
References
[1]A. Di Gaspare et al., Electrically Tunable Nonlinearity at 3.2 Terahertz in Single-Layer Graphene, ACS Photonics,
10, 3171−3180 (2023)
[2]A. Di Gaspare et al., All in one-chip, electrolyte-gated graphene amplitude modulator, saturable absorber mirror and
metrological frequency-tuner in the 2-5 THz range, Adv. Optical Mater., 10, 2200819 (2024)
[3]H. A. Hafez et al., Extremely efficient terahertz high-harmonic generation in graphene by hot Dirac fermions,
Nature, vol. 561, no. 7724, pp. 507–511, (2018)
[4]J. Stensberg et al., Observation of terahertz second harmonic generation from Dirac surface states in the topological
insulator Bi2Se3, Phys. Rev. B, vol. 109, no. 24, p. 245112, (2024)
[5]A. Di Gaspare et al., Compact terahertz harmonic generation in the Reststrahlenband using a graphene-embedded
metallic split ring resonator array, Nature Commun., vol. 15, no. 1, p. 2312, (2024)
[6] A. Di Gaspare et al., Second and third harmonic generation in topological insulator-based van der Waals
metamaterials, Nature Light Science&Applications in press (2025)
[7] A. Di Gaspare et al. Electrically-driven heterostructured wire lasers with integrated graphene plasmons, Nature
Nanotechnology in press (2025)
Prof. Miriam Serena Vitiello obtained her PhD in physics at University of Bari in 2006. From 2006 to December 2009 she was a Post-Doctoral Research assistant at the University of Bari. Since July 2010, she is group leader at the National Enterprise of Nanoscience and Nanotechnology and at the Nanoscience Institute of the National Research Council (CNR). Since 2015 she is Adjunct Professor of Condensed Matter Physics at the Scuola Normale Superiore. Since 2017 she is Director of Research at CNR. The THz photonics and optoelectronics group of Prof. Vitiello focuses on the design, development and applications of THz quantum cascade lasers; the development of THz nanostructured detectors based on semiconductor nanowires, 2D materials and vdW heterosctructures; far-infrared metrology; graphene-based photonics; near-field THz miscroscopy. Prof. Vitiello is member of the Scientific council of the National Institute of Metrology, of the CNR Department of Physics and technology of the Matter, of the CEITEC center (Czech Republic) and Mercator Fellow at the University of Regensbug (Germany).
She was visiting scientist for short research stages at the Technical University of Delft (April 2004, December 2004), at the Universität of Munchen (July 2004) and at the University of Paris VII (2006).
Prof. Vitiello has received the starting grant FIRB “Future in Research” from the Italian ministry of education and research, the ERC Consolidator Grant from the European Research Council, three EU-FET open projects, an EU ITN project, the Balzan research projects, three national research grants, and she coordinates the THz working group in the graphene flagship.
For her research activity she was awarded with the Frederic Volterra Medal 2020 from the Italian Physical Society , the Sapio Research and Innovation award (2018), the International research award Guido Dorso (2016), the SPIE early career award (2015) optoelectronic and photonics prize “Sergio Panizza” of the Italian Physical Society (2012), an International Scientific Author Award (USA, 2005) and 2 National Young Author Awards (2004; 2005). She is member of the programme committee of more than 30 key international conferences in the field of photonic devices.
She is co-author of more than 250-refereed papers on international journals, holds 1 patent and delivered more than 100 invited talks (including plenary talks) at international conferences.
Optical nonlinearity in the terahertz (THz) range represents a key technology to access high frequency
spectral windows that are usually difficult to cover using conventional solid state laser technologies. Over the past decade, the non-linear optical properties of graphene have been extensively investigated, and a wide range of related applications demonstrated, ranging from optical modulators [1] to saturable absorbers [2]. High harmonic generation (HHG) – the frequency up-conversion of an optical signal – in materials systems is governed by symmetries. This effect has been exploited in graphene [3], where HHG has been demonstrated, albeit only at odd multiples of the driving frequency owing to its inherent centro-symmetry. In topological insulators (TIs), unconventional HHG has been predicted [4], supported by the bulk and topological surface states, which are usually difficult to distinguish, relying on the ultrafast intraband dynamics, and the inversion symmetry- breaking even order nonlinearity in the topological phase. Here, we exploit innovative technological approaches in large area topological insulator metametarials and heterostructures or multilayer graphene to device both high efficient non-linear micro-devices, optically pumped by quantum cascade lasers (QCLs) delivering 2W optical power, and electrically-driven integrated plasmonic lasers comprising integrated QCL heterostructures, targeting HHG in the technologically relevant Reststrahlen gap (6-12 THz) at both odd or even orders, via symmetry breaking [5], [6], [7]. This talk will provide future perspectives in the fascinating field of topological photonics and non-linear THz photonics.
References
[1]A. Di Gaspare et al., Electrically Tunable Nonlinearity at 3.2 Terahertz in Single-Layer Graphene, ACS Photonics,
10, 3171−3180 (2023)
[2]A. Di Gaspare et al., All in one-chip, electrolyte-gated graphene amplitude modulator, saturable absorber mirror and
metrological frequency-tuner in the 2-5 THz range, Adv. Optical Mater., 10, 2200819 (2024)
[3]H. A. Hafez et al., Extremely efficient terahertz high-harmonic generation in graphene by hot Dirac fermions,
Nature, vol. 561, no. 7724, pp. 507–511, (2018)
[4]J. Stensberg et al., Observation of terahertz second harmonic generation from Dirac surface states in the topological
insulator Bi2Se3, Phys. Rev. B, vol. 109, no. 24, p. 245112, (2024)
[5]A. Di Gaspare et al., Compact terahertz harmonic generation in the Reststrahlenband using a graphene-embedded
metallic split ring resonator array, Nature Commun., vol. 15, no. 1, p. 2312, (2024)
[6] A. Di Gaspare et al., Second and third harmonic generation in topological insulator-based van der Waals
metamaterials, Nature Light Science&Applications in press (2025)
[7] A. Di Gaspare et al. Electrically-driven heterostructured wire lasers with integrated graphene plasmons, Nature
Nanotechnology in press (2025)
Prof. Miriam Serena Vitiello obtained her PhD in physics at University of Bari in 2006. From 2006 to December 2009 she was a Post-Doctoral Research assistant at the University of Bari. Since July 2010, she is group leader at the National Enterprise of Nanoscience and Nanotechnology and at the Nanoscience Institute of the National Research Council (CNR). Since 2015 she is Adjunct Professor of Condensed Matter Physics at the Scuola Normale Superiore. Since 2017 she is Director of Research at CNR. The THz photonics and optoelectronics group of Prof. Vitiello focuses on the design, development and applications of THz quantum cascade lasers; the development of THz nanostructured detectors based on semiconductor nanowires, 2D materials and vdW heterosctructures; far-infrared metrology; graphene-based photonics; near-field THz miscroscopy. Prof. Vitiello is member of the Scientific council of the National Institute of Metrology, of the CNR Department of Physics and technology of the Matter, of the CEITEC center (Czech Republic) and Mercator Fellow at the University of Regensbug (Germany).
She was visiting scientist for short research stages at the Technical University of Delft (April 2004, December 2004), at the Universität of Munchen (July 2004) and at the University of Paris VII (2006).
Prof. Vitiello has received the starting grant FIRB “Future in Research” from the Italian ministry of education and research, the ERC Consolidator Grant from the European Research Council, three EU-FET open projects, an EU ITN project, the Balzan research projects, three national research grants, and she coordinates the THz working group in the graphene flagship.
For her research activity she was awarded with the Frederic Volterra Medal 2020 from the Italian Physical Society , the Sapio Research and Innovation award (2018), the International research award Guido Dorso (2016), the SPIE early career award (2015) optoelectronic and photonics prize “Sergio Panizza” of the Italian Physical Society (2012), an International Scientific Author Award (USA, 2005) and 2 National Young Author Awards (2004; 2005). She is member of the programme committee of more than 30 key international conferences in the field of photonic devices.
She is co-author of more than 250-refereed papers on international journals, holds 1 patent and delivered more than 100 invited talks (including plenary talks) at international conferences.
