Our group research focuses on the fundamental study of light-matter interaction and its applications in information processing, optical sensing, and energy conversion. Three main research directions are:
engineering of thermal radiation
quantum plasmonics and nanophotonics
time modulation and nonlinear optics
Thermal radiation is a ubiquitous and fundamental process by which all objects at non-zero temperatures radiate energy in the form of electromagnetic waves. Even though thermal radiation has been well known since the century-old Planck’s law, its applications in energy harvesting, radiative cooling, and sensing have led to recently renewed research interest on this topic (see our review article: "Nanophotonic engineering of far-field thermal emitters." Nat. Materials (2019)). We are interested in exploring the physics of thermal radiation from nanostructured objects and developing new thermal-radiation-based technologies for advanced sensing, material characterization, and mid-infrared light sources.
Related publication:
D. Shymkiv, et al, “Transient Depth Thermography for Probing Heat Transport”, arXiv. 2607.13262
D. Shymkiv, et al, “Accurate Depth-Resolved Temperature Profiling via Thermal-Radiation Spectroscopy: Numerical Methods vs Machine Learning”, Optics Express 33, 18, 39117 (2025) (Editor’s Pick)
Y. Xiao, et al., “Super-Planckian emission can’t really be “thermal””, Nat. Photonics 16, 397-401 (2022)
Y. Xiao, et al., “Planck spectroscopy”, Laser Photonics Rev. 15 (10) 2170051 (2021) (cover article)
Y. Xiao, et al., “Precision measurements of temperature-dependent and nonequilibrium thermal emitters”, Laser Photonics Rev. 14 (8) 1900443 (2020)
Y. Xiao, et al., “Depth thermography: non-invasive 3D temperature profiling using infrared thermal emission”, ACS Photonics 7, 853 (2020) (covered by Optics & Photonics News; Phys.org; Science Daily)
D. G. Baranov*, Y. Xiao*, et al., “Nanophotonic engineering of far-field thermal emitters", Nat. Mater. 18, 920 (2019) (*equal contribution)
Y. Xiao, et al., “Nanosecond mid-infrared pulse generation via modulated emissivity”, Light: Sci. Appl. 8, 51 (2019) (cover article)
Y. Xiao, et al., “Measuring thermal emission near room temperature using Fourier-transform infrared spectroscopy”, Phys. Rev. Appl. 11, 014026 (2019)
The field of plasmonics studies the interaction of light with free electrons inside metals or doped semiconductors. As the dimensions of plasmonic devices have shrunk into the sub-10 nm scale, quantum confinement effects become important: the free electrons are no longer "free" anymore and the classical Drude model cannot provide an accurate picture of the physics of these quantum-confined electrons. In particular, quantum confinement may lead to large nonlinear optical responses. We are interested in studying the impact of quantum effects on the optical properties of nanophotonic materials and developing quantum-engineered nanophotonic devices for applications in nonlinear light-matter interactions.
Related publication:
Y. Xiao, et al., “Efficient generation of optical bottle beams”, Nanophotonics 10 (11), 2893 (2021)
Y. Xiao, et al., “Nonlinear metasurface based on giant optical Kerr response of gold quantum wells”, ACS Photonics 5(5), 1654 (2018)
H. Qian*, Y. Xiao*, Z. Liu, “Giant Kerr nonlinearity from ultrathin gold films from quantum size effect”, Nat. Commun. 7, 13153 (2016) (*equal contribution)
H. Qian*, Y. Xiao*, D. Lepage*, et al., “Quantum electrostatic model for optical properties of nanoscale gold films”, Nanophotonics 4.1, 413 (2015) (*equal contribution)
Interaction of light with optical media with a time-dependent refractive index profile (i.e., time modulation) leads to many interesting phenomena, such as adiabatic wavelength conversion, time lens, and temporal waveguide. In addition to making spatially-varying optical media (such as multilayer thin films or photonic crystals), introducing temporally-varying optical media provides an additional degree of freedom to manipulate the properties of light, which could lead to frequency shift, pulse shape deformation, and time reflection. Nonlinear light-matter interaction is one approach to induce time modulation. We are interested in exploring new physics and applications of time modulation via nonlinear optical systems.
Related publication:
L. C. Herrera, et al, “Temporal Evolution of Blackbody Radiation in a One-Dimensional Photonic Time-Crystal”, arXiv. 2607.10577
Y. Xiao, et al., “Reflection and transmission of electromagnetic fields from a temporal boundary”, Opt. Lett. 39, 574 (2014)
Y. Xiao, et al., “Time-transformation approach to pulse propagation in nonlinear dispersive media: Inclusion of delayed Raman nonlinearity”, Phy. Rev. A 87, 063816 (2013)
Y. Xiao, et al., “Propagation of few-cycle pulses in nonlinear Kerr media: harmonic generation”, Opt. Lett. 38, 724 (2013)
Y. Xiao, et al., “New approach to pulse propagation in nonlinear dispersive optical media”, J. Opt. Soc. Am. B 29, 2958 (2012) (highlighted in Spotlight on Optics , top-downloaded article)
Y. Xiao, et al., “Nonlinear pulse propagation: a time transformation approach”, Opt. Lett. 37, 1271 (2012)
Y. Xiao, et al., “Optical pulse propagation in dynamic Fabry-Perot resonators”, J. Opt. Soc. Am. B 28, 1685 (2011)
Y. Xiao, et al., “Spectral and temporal changes of optical pulses propagating through time-varying linear media”, Opt. Lett. 36, 505 (2011)
We thank the support from the following funding agencies