Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2024 Jan 26;15(1):794.
doi: 10.1038/s41467-024-45054-z.

Thermo-optic epsilon-near-zero effects

Affiliations

Thermo-optic epsilon-near-zero effects

Jiaye Wu et al. Nat Commun. .

Abstract

Nonlinear epsilon-near-zero (ENZ) nanodevices featuring vanishing permittivity and CMOS-compatibility are attractive solutions for large-scale-integrated systems-on-chips. Such confined systems with unavoidable heat generation impose critical challenges for semiconductor-based ENZ performances. While their optical properties are temperature-sensitive, there is no systematic analysis on such crucial dependence. Here, we experimentally report the linear and nonlinear thermo-optic ENZ effects in indium tin oxide. We characterize its temperature-dependent optical properties with ENZ frequencies covering the telecommunication O-band, C-band, and 2-μm-band. Depending on the ENZ frequency, it exhibits an unprecedented 70-93-THz-broadband 660-955% enhancement over the conventional thermo-optic effect. The ENZ-induced fast-varying large group velocity dispersion up to 0.03-0.18 fs2nm-1 and its temperature dependence are also observed for the first time. Remarkably, the thermo-optic nonlinearity demonstrates a 1113-2866% enhancement, on par with its reported ENZ-enhanced Kerr nonlinearity. Our work provides references for packaged ENZ-enabled photonic integrated circuit designs, as well as a new platform for nonlinear photonic applications and emulations.

PubMed Disclaimer

Conflict of interest statement

The authors declare no competing interests.

Figures

Fig. 1
Fig. 1. Adapted grain-boundary barrier model in indium tin oxide at different temperature ranges.
a The energy levels of a degenerate semiconductor such as indium tin oxide. b Oxygen diffusion mechanism in the sub-annealing domain with increasing temperature. c Permanent structural change above the annealing threshold.
Fig. 2
Fig. 2. Samples and their epsilon-near-zero (ENZ) frequency response.
a Indium tin oxide samples with ENZ frequency at O-band, C-band, 2-μm-band, and without ENZ effects. b The variation of ENZ frequency with temperature at different thermal phases of O-band (top), C-band (middle), and 2-μm-band (bottom) samples.
Fig. 3
Fig. 3. Spectra of refractive index and the giant enhancement of thermo-optic effects in the epsilon-near-zero (ENZ) region.
a Full refractive index spectrum of the O-band, C-band, and 2-μm-band samples. IR stands for infrared, and UV is ultraviolet. NZI represents near-zero-index where n < 1. bd The variations of refractive indices with temperature for these three sets of samples near the ENZ frequency, respectively. e the TOCs in ENZ region. The top panel of the diagram shows the values of thermo-optic effects of the O-band, C-band, 2-μm, and non-ENZ samples. The bottom panel of the diagram is the ENZ-induced thermo-optic effect enhancement with respect to the non-ENZ sample. The colored rectangles denote the full-width-at-half-maximum (FWHM) bandwidth (BW) of the corresponding curve. The colored vertical lines in a and e denote the corresponding ENZ frequencies.
Fig. 4
Fig. 4. Spectra of group velocity dispersion (GVD) and absorption.
a Full GVD spectrum of the O-band, C-band, and 2-μm-band samples. bd The variations of GVD with temperature for these three sets of samples near the epsilon-near-zero (ENZ) frequency, respectively. e Full absorption spectrum of the three sets of samples. fh The corresponding absorption variations with temperature near the ENZ frequency. In a and e, the colored vertical lines indicate the exact ENZ frequencies of the corresponding curves.
Fig. 5
Fig. 5. Thermo-optic nonlinearity near epsilon-near-zero (ENZ) region.
a The thermo-optic nonlinear-index coefficients of the O-band, C-band, 2-μm-band ENZ and non-ENZ samples. b The ENZ-induced enhancement of the thermo-optic nonlinearity. The colored vertical lines indicate the exact ENZ frequencies of the corresponding curves.

References

    1. Reshef O, De Leon I, Alam MZ, Boyd RW. Nonlinear optical effects in epsilon-near-zero media. Nat. Rev. Mater. 2019;4:535–551. doi: 10.1038/s41578-019-0120-5. - DOI
    1. Kinsey N, DeVault C, Boltasseva A, Shalaev VM. Near-zero-index materials for photonics. Nat. Rev. Mater. 2019;4:742–760. doi: 10.1038/s41578-019-0133-0. - DOI
    1. Wu J, Xie ZT, Sha Y, Fu HY, et al. Epsilon-near-zero photonics: infinite potentials. Photonics Res. 2021;9:1616. doi: 10.1364/PRJ.427246. - DOI
    1. Niu X, Hu X, Chu S, Gong Q. Epsilon-near-zero photonics: a new platform for integrated devices. Adv. Opt. Mater. 2018;6:1701292. doi: 10.1002/adom.201701292. - DOI
    1. Silveirinha M, Engheta N. Tunneling of electromagnetic energy through subwavelength channels and bends using ϵ-near-zero materials. Phys. Rev. Lett. 2006;97:157403. doi: 10.1103/PhysRevLett.97.157403. - DOI - PubMed