Large optical nonlinearity of nanoantennas coupled to an epsilon-near-zero material

M. Zahirul Alam, Sebastian Andreas Schulz, Jeremy Upham, Israel De Leon, Robert W. Boyd

Research output: Contribution to journalArticlepeer-review

300 Citations (Scopus)


The size and operating energy of a nonlinear optical device are fundamentally constrained by the weakness of the nonlinear optical response of common materials1. Here, we report that a 50-nm-thick optical metasurface made of optical dipole antennas coupled to an epsilon-near-zero material exhibits a broadband (∼400 nm bandwidth) and ultrafast (recovery time less than 1 ps) intensity-dependent refractive index n2 as large as −3.73 ± 0.56 cm2 GW−1. Furthermore, the metasurface exhibits a maximum optically induced refractive index change of ±2.5 over a spectral range of ∼200 nm. The inclusion of low-Q nanoantennas on an epsilon-near-zero thin film not only allows the design of a metasurface with an unprecedentedly large nonlinear optical response, but also offers the flexibility to tailor the sign of the response. Our technique removes a longstanding obstacle in nonlinear optics: the lack of materials with an ultrafast nonlinear contribution to refractive index on the order of unity. It consequently offers the possibility to design low-power nonlinear nano-optical devices with orders-of-magnitude smaller footprints.
Original languageEnglish
Pages (from-to)79-83
Number of pages6
JournalNature Photonics
Issue number2
Early online date26 Jan 2018
Publication statusPublished - Feb 2018


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