Enhanced Nonlinear Optical Mixing in Photonic Structures

Strategic Insights -

Researchers at Hefei University of Technology, Anhui, People's Republic of China, have proposed a design strategy to enhance third-harmonic generation (THG) and four-wave mixing (FWM) by exciting two quasi-bound states in the continuum (Q-BICs) and an intrinsic leaky mode (LM) in a one-dimensional grating. This innovative approach has significant implications for applications in quantum computing, imaging technologies, and other photonic fields.

Key Takeaways:

  • The research proposes a design strategy to enhance THG and FWM by simultaneously exciting two Q-BICs and an intrinsic LM in a one-dimensional grating.
  • Eigenvalue calculations reveal that periodic perturbations induce band folding, bringing guided-mode resonances into the radiative continuum, forming a symmetry-protected BIC.
  • Under oblique incidence, the Brillouin zone-folding-induced BIC evolves into a Q-BIC, and the Q-BIC undergoes a spectral splitting into two resolvable resonant modes.
  • Finite-element simulations suggest that the LM yields the THG with a conversion efficiency of 10^(-4) - three orders of magnitude higher than that of the Q-BICs.
  • The cooperation between two Q-BICs and a LM enables the degenerate and non-degenerate FWM processes, yielding output powers of 4.07 and 1.55 W/m, respectively.
  • The FWM efficiencies exhibit remarkable robustness against variations in the incidence angle.
  • The research provides a novel theoretical platform for nonlinear frequency conversion and advances the application of optical mixers in quantum nanophotonics and photonic circuitry.
  • The study has been peer-reviewed and published in the Journal of Applied Physics.

Statistics:

  • The conversion efficiency of THG achieved by the LM is 10^(-4) - three orders of magnitude higher than that of the Q-BICs.
  • The output powers of FWM processes are 4.07 and 1.55 W/m, respectively.
  • The research provides a novel theoretical platform for nonlinear frequency conversion.
  • The study advances the application of optical mixers in quantum nanophotonics and photonic circuitry.

Sources:

  • Journal of Applied Physics, 2025;138(12).
  • Aip Publishing, 1305 Walt Whitman Rd, Ste 300, Melville, NY 11747-4501, USA.
  • American Institute of Physics - www.aip.org.
  • Journal of Applied Physics - jap.aip.org
  • Hefei University of Technology, School of Physics, Hefei 230009, Anhui, People's Republic of China.
  • Meng Qin, Hefei University of Technology, School of Physics, Hefei 230009, Anhui, People's Republic of China.