Contents
2023
Volume: 5 Issue 1
4 Article(s)

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Letters
Topological transformation and free-space transport of photonic hopfions
Yijie Shen, Bingshi Yu, Haijun Wu, Chunyu Li, Zhihan Zhu, and Anatoly V. Zayats
Structured light fields embody strong spatial variations of polarization, phase, and amplitude. Understanding, characterization, and exploitation of such fields can be achieved through their topological properties. Three-dimensional (3D) topological solitons, such as hopfions, are 3D localized continuous field configurations with nontrivial particle-like structures that exhibit a host of important topologically protected properties. Here, we propose and demonstrate photonic counterparts of hopfions with exact characteristics of Hopf fibration, Hopf index, and Hopf mapping from real-space vector beams to homotopic hyperspheres representing polarization states. We experimentally generate photonic hopfions with on-demand high-order Hopf indices and independently controlled topological textures, including Néel-, Bloch-, and antiskyrmionic types. We also demonstrate a robust free-space transport of photonic hopfions, thus showing the potential of hopfions for developing optical topological informatics and communications.
Advanced Photonics
  • Publication Date: Jan. 10, 2023
  • Vol. 5, Issue 1, 015001 (2023)
Research Articles
Rapid crystallization-driven high-efficiency phase-pure deep-blue Ruddlesden–Popper perovskite light-emitting diodes
Gyumin Jang, Hyowon Han, Sunihl Ma, Junwoo Lee, Chan Uk Lee, Wooyong Jeong, Jaehyun Son, Dongki Cho, Ji-Hee Kim, Cheolmin Park, and Jooho Moon
Perovskite light-emitting diodes (PeLEDs) are considered as promising candidates for next-generation solution-processed full-color displays. However, the external quantum efficiencies (EQEs) and operational stabilities of deep-blue (n values >3 is hampered completely, so that phase-pure 2D-RPP films with bandgaps suitable for deep-blue PeLEDs can be obtained successfully. The uniquely developed rapid crystallization method also enables formation of randomly oriented 2D-RPP crystals, thereby improving the transfer and transport kinetics of the charge carriers. Thus, high-performance deep-blue PeLEDs emitting at 437 nm with a peak EQE of 0.63% are successfully demonstrated. The color coordinates are confirmed to be (0.165, 0.044), which match well with the Rec.2020 standard blue gamut and have excellent spectral stability.
Advanced Photonics
  • Publication Date: Jan. 04, 2023
  • Vol. 5, Issue 1, 016001 (2023)
Rydberg state excitation in molecules manipulated by bicircular two-color laser pulses
Wenbin Zhang, Yongzhe Ma, Chenxu Lu, Fei Chen, Shengzhe Pan, Peifen Lu, Hongcheng Ni, and Jian Wu
Multiphoton resonant excitation and frustrated tunneling ionization, manifesting the photonic and optical nature of the driving light via direct excitation and electron recapture, respectively, are complementary mechanisms to access Rydberg state excitation (RSE) of atoms and molecules in an intense laser field. However, clear identification and manipulation of their individual contributions in the light-induced RSE process remain experimentally challenging. Here, we bridge this gap by exploring the dissociative and nondissociative RSE of H2 molecules using bicircular two-color laser pulses. Depending on the relative field strength and polarization helicity of the two colors, the RSE probability can be boosted by more than one order of magnitude by exploiting the laser waveform-dependent field effect. The role of the photon effect is readily strengthened with increasing relative strength of the second-harmonic field of the two colors regardless of the polarization helicity. As compared to the nondissociative RSE forming H2 * , the field effect in producing the dissociative RSE channel of ( H + , H * ) is moderately suppressed, which is primarily accessed via a three-step sequential process separated by molecular bond stretching. Our work paves the way toward a comprehensive understanding of the interplay of the underlying field and photon effects in the strong-field RSE process, as well as facilitating the generation of Rydberg states optimized with tailored characteristics.
Advanced Photonics
  • Publication Date: Jan. 10, 2023
  • Vol. 5, Issue 1, 016002 (2023)
Massively parallel universal linear transformations using a wavelength-multiplexed diffractive optical network
Jingxi Li, Tianyi Gan, Bijie Bai, Yi Luo, Mona Jarrahi, and Aydogan Ozcan
Large-scale linear operations are the cornerstone for performing complex computational tasks. Using optical computing to perform linear transformations offers potential advantages in terms of speed, parallelism, and scalability. Previously, the design of successive spatially engineered diffractive surfaces forming an optical network was demonstrated to perform statistical inference and compute an arbitrary complex-valued linear transformation using narrowband illumination. We report deep-learning-based design of a massively parallel broadband diffractive neural network for all-optically performing a large group of arbitrarily selected, complex-valued linear transformations between an input and output field of view, each with Ni and No pixels, respectively. This broadband diffractive processor is composed of Nw wavelength channels, each of which is uniquely assigned to a distinct target transformation; a large set of arbitrarily selected linear transformations can be individually performed through the same diffractive network at different illumination wavelengths, either simultaneously or sequentially (wavelength scanning). We demonstrate that such a broadband diffractive network, regardless of its material dispersion, can successfully approximate Nw unique complex-valued linear transforms with a negligible error when the number of diffractive neurons (N) in its design is ≥2NwNiNo. We further report that the spectral multiplexing capability can be increased by increasing N; our numerical analyses confirm these conclusions for Nw > 180 and indicate that it can further increase to Nw ∼ 2000, depending on the upper bound of the approximation error. Massively parallel, wavelength-multiplexed diffractive networks will be useful for designing high-throughput intelligent machine-vision systems and hyperspectral processors that can perform statistical inference and analyze objects/scenes with unique spectral properties.
Advanced Photonics
  • Publication Date: Jan. 09, 2023
  • Vol. 5, Issue 1, 016003 (2023)