Repository logo

Ultra-strong nonlinear optical processes and trigonal warping in MoS2 layers

Published version



Change log


Saynatjoki, A 
Karvonen, L 
Rostami, H 
Autere, A 
Mehravar, S 


Nonlinear optical processes, such as harmonic generation, are of great interest for various applications, e.g., microscopy, therapy, and frequency conversion. However, high-order harmonic conversion is typically much less efficient than low-order, due to the weak intrinsic response of the higher-order nonlinear processes. Here we report ultra-strong optical nonlinearities in monolayer MoS2 (1L-MoS2): the third harmonic is 30 times stronger than the second, and the fourth is comparable to the second. The third harmonic generation efficiency for 1L-MoS2 is approximately three times higher than that for graphene, which was reported to have a large χ (3). We explain this by calculating the nonlinear response functions of 1L-MoS2 with a continuum-model Hamiltonian and quantum mechanical diagrammatic perturbation theory, highlighting the role of trigonal warping. A similar effect is expected in all other transition-metal dichalcogenides. Our results pave the way for efficient harmonic generation based on layered materials for applications such as microscopy and imaging.



cond-mat.mes-hall, cond-mat.mes-hall, cond-mat.mtrl-sci

Journal Title

Nature Communications

Conference Name

Journal ISSN


Volume Title



Nature Publishing Group
European Research Council (319277)
Engineering and Physical Sciences Research Council (EP/K01711X/1)
Engineering and Physical Sciences Research Council (EP/K017144/1)
European Commission (604391)
Engineering and Physical Sciences Research Council (EP/L016087/1)
European Commission Horizon 2020 (H2020) Future and Emerging Technologies (FET) (696656)
Engineering and Physical Sciences Research Council (EP/G042357/1)
The Royal Society (wm090070)
We acknowledge funding from the Academy of Finland (Nos: 276376, 284548, 295777, 298297, and 304666), TEKES (NP-Nano, OPEC), Royal Academy of Engineering (RAEng) Research Fellowships, Fondazione Istituto Italiano di Tecnologia, the Graphene Flagship, ERC grants Hetero2D, Nokia Foundation, EPSRC Grants EP/K01711X/1, EP/K017144/1, EP/L016087/1, AFOSR COMAS MURI (FA9550-10-1-0558), ONR NECom MURI, CIAN NSF ERC under Grant EEC-0812072, and TRIF Photonics funding from the state of Arizona and the Micronova, Nanofabrication Centre of Aalto University.