@article{64978,
  abstract     = {{The degrees of freedom (DoFs) of light determine the maximum number of independent signal
channels an optical system can support. However, the polarization DoF is intrinsically limited to two by
orthogonality, which causes unavoidable crosstalk and often forces position multiplexing, where different
channels are assigned to distinct spatial locations to suppress crosstalk. This research introduces a multilayer
synchronous polarization projection method that fundamentally increases the DoF for polarization
multiplexing. The DoF equals twice the number of projection layers. We experimentally demonstrate six-
channel polarization multiplexing holography without position multiplexing. The six-channel multiplexing
results indicate that our approach exceeds the conventional polarization multiplexing method, yielding an
average 3.79 dB improvement in extinction ratio across the six channels. Compared with the theoretical
limit of traditional polarization multiplexing, our method reduces crosstalk by an average of 6.52 dB across
all channels in a seven-channel design. The polarization projection method breaks the DoF limitation
of polarization multiplexing, opening a path toward high-dimensional photonic information encoding for
communication, encryption, and imaging.}},
  author       = {{Jin, Xiao and Zentgraf, Thomas}},
  issn         = {{2577-5421}},
  journal      = {{Advanced Photonics}},
  number       = {{02}},
  publisher    = {{SPIE-Intl Soc Optical Eng}},
  title        = {{{Increasing the design degree of freedom for polarization through multilayer synchronous polarization projection}}},
  doi          = {{10.1117/1.ap.8.2.026010}},
  volume       = {{8}},
  year         = {{2026}},
}

@article{8797,
  abstract     = {{Free from phase-matching constraints, plasmonic metasurfaces have contributed significantly to the control of optical nonlinearity and enhancement of nonlinear generation efficiency by engineering subwavelength meta-atoms. However, high dissipative losses and inevitable thermal heating limit their applicability in nonlinear nanophotonics. All-dielectric metasurfaces, supporting both electric and magnetic Mie-type resonances in their nanostructures, have appeared as a promising alternative to nonlinear plasmonics. High-index dielectric nanostructures, allowing additional magnetic resonances, can induce magnetic nonlinear effects, which, along with electric nonlinearities, increase the nonlinear conversion efficiency. In addition, low dissipative losses and high damage thresholds provide an extra degree of freedom for operating at high pump intensities, resulting in a considerable enhancement of the nonlinear processes. We discuss the current state of the art in the intensely developing area of all-dielectric nonlinear nanostructures and metasurfaces, including the role of Mie modes, Fano resonances, and anapole moments for harmonic generation, wave mixing, and ultrafast optical switching. Furthermore, we review the recent progress in the nonlinear phase and wavefront control using all-dielectric metasurfaces. We discuss techniques to realize all-dielectric metasurfaces for multifunctional applications and generation of second-order nonlinear processes from complementary metal–oxide–semiconductor-compatible materials.}},
  author       = {{Sain, Basudeb and Meier, Cedrik and Zentgraf, Thomas}},
  issn         = {{2577-5421}},
  journal      = {{Advanced Photonics}},
  number       = {{2}},
  pages        = {{024002}},
  title        = {{{Nonlinear optics in all-dielectric nanoantennas and metasurfaces: a review}}},
  doi          = {{10.1117/1.ap.1.2.024002}},
  volume       = {{1}},
  year         = {{2019}},
}