Letters|29 Article(s)
Letters
Observation of robust subwavelength phase singularity in chiral medium
Jun-Hee Park, Jeongho Ha, Liyi Hsu, Guang Yang... and Abdoulaye Ndao|Show fewer author(s)
Photonic devices that exhibit both sensitivity and robustness have long been sought; yet, these characteristics are thought to be mutually exclusive; through sensitivity, a sensor responds to external stimuli, whereas robustness embodies the inherent ability of a device to withstand weathering by these same stimuli. This challenge stems from the inherent contradiction between robustness and sensitivity in wave dynamics, which require the coexistence of noise-immune sensitive states and modulation-sensitive transitions between these states. We report and experimentally demonstrate a subwavelength phase singularity in a chiral medium that is resilient to fabrication imperfections and disorder while remaining highly responsive to external stimuli. The combination of subwavelength light confinement and its robustness lays the foundation for the development of hitherto unexplored chip-scale photonics devices, enabling a simultaneous development of high-sensitivity and robust devices in both quantum and classical realms. Photonic devices that exhibit both sensitivity and robustness have long been sought; yet, these characteristics are thought to be mutually exclusive; through sensitivity, a sensor responds to external stimuli, whereas robustness embodies the inherent ability of a device to withstand weathering by these same stimuli. This challenge stems from the inherent contradiction between robustness and sensitivity in wave dynamics, which require the coexistence of noise-immune sensitive states and modulation-sensitive transitions between these states. We report and experimentally demonstrate a subwavelength phase singularity in a chiral medium that is resilient to fabrication imperfections and disorder while remaining highly responsive to external stimuli. The combination of subwavelength light confinement and its robustness lays the foundation for the development of hitherto unexplored chip-scale photonics devices, enabling a simultaneous development of high-sensitivity and robust devices in both quantum and classical realms.
Advanced Photonics
- Publication Date: Mar. 17, 2025
- Vol. 7, Issue 3, 035001 (2025)
Optical analog of black and white gravitational holes
Eric Plum, Anton N. Vetlugin, Baurzhan Salimzhanov, Nikolay I. Zheludev, and Nina Vaidya
In general relativity, a gravitational “white hole” is a hypothetical region of space that cannot be entered from outside. It is the reverse of a “black hole” from which light and information cannot escape. We report an optical device exhibiting intriguing similarities to these objects. It will either totally absorb (optical black hole) or totally reject (optical white hole) light of any wavelength, depending on its polarization. The device’s functionality is based on the formation of a standing wave from the wavefront of spatially coherent incident radiation. Interaction of the standing wave with a thin absorber enables coherent perfect absorption and transmission, whereas polarization sensitivity arises from the geometrical phase of the interfering beams. We provide experimental proof-of-principle demonstrations and show that the device operates as a black and white hole for orthogonal polarizations of the incident light. From a remote point, it will look similar to a gravitational black or white hole depending on the polarization of light. In principle, the optical black and white hole device can operate as a deterministic absorber or rejector throughout the entire electromagnetic spectrum. Broadband absorbers and rejectors can be useful for energy harvesting, detection, stealth technologies, and redistribution of light. In general relativity, a gravitational “white hole” is a hypothetical region of space that cannot be entered from outside. It is the reverse of a “black hole” from which light and information cannot escape. We report an optical device exhibiting intriguing similarities to these objects. It will either totally absorb (optical black hole) or totally reject (optical white hole) light of any wavelength, depending on its polarization. The device’s functionality is based on the formation of a standing wave from the wavefront of spatially coherent incident radiation. Interaction of the standing wave with a thin absorber enables coherent perfect absorption and transmission, whereas polarization sensitivity arises from the geometrical phase of the interfering beams. We provide experimental proof-of-principle demonstrations and show that the device operates as a black and white hole for orthogonal polarizations of the incident light. From a remote point, it will look similar to a gravitational black or white hole depending on the polarization of light. In principle, the optical black and white hole device can operate as a deterministic absorber or rejector throughout the entire electromagnetic spectrum. Broadband absorbers and rejectors can be useful for energy harvesting, detection, stealth technologies, and redistribution of light.
Advanced Photonics
- Publication Date: Feb. 27, 2025
- Vol. 7, Issue 2, 025001 (2025)
Plasmon-assisted mode selection lasing in a lanthanide-based microcavity
Lei Guo, Min Ji, Bowen Kang, Min Zhang... and Zhenglong Zhang|Show fewer author(s)
Lanthanide-based microlasers have attracted considerable attention owing to their large anti-Stokes shifts, multiple emission bands, and narrow linewidths. Various applications of microlasers, such as optical communication, optical storage, and polarization imaging, require selecting the appropriate laser polarization mode and remote control of the laser properties. Here, we propose a unique plasmon-assisted method for the mode selection and remote control of microlasing using a lanthanide-based microcavity coupled with surface plasmon polaritons (SPPs) that propagate on a silver microplate. With this method, the transverse electrical (TE) mode of microlasers can be easily separated from the transverse magnetic (TM) mode. Because the SPPs excited on the silver microplate only support TM mode propagation, the reserved TE mode is resonance-enhanced in the microcavity and amplified by the local electromagnetic field. Meanwhile, lasing-mode splitting can be observed under the near-field excitation of SPPs due to the coherent coupling between the microcavity and mirror microcavity modes. Benefiting from the long-distance propagation characteristics of tens of micrometers of SPPs on a silver microplate, remote excitation and control of upconversion microlasing can also be realized. These plasmon-assisted polarization mode-optional and remote-controllable upconversion microlasers have promising prospects in on-chip optoelectronic devices, encrypted optical information transmission, and high-precision sensors. Lanthanide-based microlasers have attracted considerable attention owing to their large anti-Stokes shifts, multiple emission bands, and narrow linewidths. Various applications of microlasers, such as optical communication, optical storage, and polarization imaging, require selecting the appropriate laser polarization mode and remote control of the laser properties. Here, we propose a unique plasmon-assisted method for the mode selection and remote control of microlasing using a lanthanide-based microcavity coupled with surface plasmon polaritons (SPPs) that propagate on a silver microplate. With this method, the transverse electrical (TE) mode of microlasers can be easily separated from the transverse magnetic (TM) mode. Because the SPPs excited on the silver microplate only support TM mode propagation, the reserved TE mode is resonance-enhanced in the microcavity and amplified by the local electromagnetic field. Meanwhile, lasing-mode splitting can be observed under the near-field excitation of SPPs due to the coherent coupling between the microcavity and mirror microcavity modes. Benefiting from the long-distance propagation characteristics of tens of micrometers of SPPs on a silver microplate, remote excitation and control of upconversion microlasing can also be realized. These plasmon-assisted polarization mode-optional and remote-controllable upconversion microlasers have promising prospects in on-chip optoelectronic devices, encrypted optical information transmission, and high-precision sensors.
Advanced Photonics
- Publication Date: May. 08, 2024
- Vol. 6, Issue 3, 035001 (2024)
Perturbation-driven echo-like superfluorescence in perovskite superlattices
Qiangqiang Wang, Jiqing Tan, Qi Jie, Hongxing Dong... and Hongxing Xu|Show fewer author(s)
The collective response of macroscopic quantum states under perturbation is widely used to study quantum correlations and cooperative properties, such as defect-induced quantum vortices in Bose–Einstein condensates and the non-destructive scattering of impurities in superfluids. Superfluorescence (SF), as a collective effect rooted in dipole–dipole cooperation through virtual photon exchange, leads to the macroscopic dipole moment (MDM) in high-density dipole ensembles. However, the perturbation response of the MDM in SF systems remains unknown. Echo-like behavior is observed in a cooperative exciton ensemble under a controllable perturbation, corresponding to an initial collapse followed by a revival of the MDM. Such a dynamic response could refer to a phase transition between the macroscopic coherence regime and the incoherent classical state on a time scale of 10 ps. The echo-like behavior is absent above 100 K due to the instability of MDM in a strongly dephased exciton ensemble. Experimentally, the MDM response to perturbations is shown to be controlled by the amplitude and injection time of the perturbations. The collective response of macroscopic quantum states under perturbation is widely used to study quantum correlations and cooperative properties, such as defect-induced quantum vortices in Bose–Einstein condensates and the non-destructive scattering of impurities in superfluids. Superfluorescence (SF), as a collective effect rooted in dipole–dipole cooperation through virtual photon exchange, leads to the macroscopic dipole moment (MDM) in high-density dipole ensembles. However, the perturbation response of the MDM in SF systems remains unknown. Echo-like behavior is observed in a cooperative exciton ensemble under a controllable perturbation, corresponding to an initial collapse followed by a revival of the MDM. Such a dynamic response could refer to a phase transition between the macroscopic coherence regime and the incoherent classical state on a time scale of 10 ps. The echo-like behavior is absent above 100 K due to the instability of MDM in a strongly dephased exciton ensemble. Experimentally, the MDM response to perturbations is shown to be controlled by the amplitude and injection time of the perturbations.
Advanced Photonics
- Publication Date: Oct. 06, 2023
- Vol. 5, Issue 5, 055001 (2023)
Topological transformation and free-space transport of photonic hopfions|On the Cover
Yijie Shen, Bingshi Yu, Haijun Wu, Chunyu Li... and Anatoly V. Zayats|Show fewer author(s)
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. 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)
Nonlinear thermal emission and visible thermometry
Zhihao Zhou, Wei Liu, Hengzhe Yan, Xianfeng Chen, and Wenjie Wan
The control of thermal emission is of great importance for emerging applications in energy conversion and thermometric sensing. Usually, thermal emission at ambient temperature is limited to the mid- to far-infrared, according to the linear theory of Planck’s law. We experimentally demonstrate a broadband nonlinear thermal emission in the visible-NIR spectrum within a quadradic nonlinear medium, which emits visible thermal radiation through a pump-driven nonlinear upconversion from its mid-IR components even at room temperature, unlike its linear counterpart which requires ultrahigh temperature. The broadband emission is enabled by the crucial random quasi-phase-matching condition in our nonlinear nanocrystal powders. Moreover, nonlinear thermal emission also permits visible thermometry using traditional optical cameras instead of thermal ones. This scheme paves the way to understand thermal radiation dynamics with nonlinearity in many fields, such as nonlinear heat transfer and nonlinear thermodynamics. The control of thermal emission is of great importance for emerging applications in energy conversion and thermometric sensing. Usually, thermal emission at ambient temperature is limited to the mid- to far-infrared, according to the linear theory of Planck’s law. We experimentally demonstrate a broadband nonlinear thermal emission in the visible-NIR spectrum within a quadradic nonlinear medium, which emits visible thermal radiation through a pump-driven nonlinear upconversion from its mid-IR components even at room temperature, unlike its linear counterpart which requires ultrahigh temperature. The broadband emission is enabled by the crucial random quasi-phase-matching condition in our nonlinear nanocrystal powders. Moreover, nonlinear thermal emission also permits visible thermometry using traditional optical cameras instead of thermal ones. This scheme paves the way to understand thermal radiation dynamics with nonlinearity in many fields, such as nonlinear heat transfer and nonlinear thermodynamics.
Advanced Photonics
- Publication Date: Jul. 06, 2022
- Vol. 4, Issue 4, 045001 (2022)
Experimental verification of ill-defined topologies and energy sinks in electromagnetic continua
David E. Fernandes, Ricardo A. M. Pereira, Sylvain Lannebère, Tiago A. Morgado, and Mário G. Silveirinha
It is experimentally verified that nonreciprocal photonic systems with continuous translation symmetry may have an ill-defined topology. The topological classification of such systems is only feasible when the material response is regularized with a spatial-frequency cutoff. We experimentally demonstrate that adjoining a small air layer to the relevant material interface may effectively imitate an idealized spatial cutoff that suppresses the nonreciprocal response for short wavelengths and regularizes the topology. Furthermore, it is experimentally verified that nonreciprocal systems with an ill-defined topology may be used to abruptly halt the energy flow in a unidirectional waveguide due to the violation of the bulk-edge correspondence. In particular, we report the formation of an energy sink that absorbs the incoming electromagnetic waves with a large field enhancement at the singularity. It is experimentally verified that nonreciprocal photonic systems with continuous translation symmetry may have an ill-defined topology. The topological classification of such systems is only feasible when the material response is regularized with a spatial-frequency cutoff. We experimentally demonstrate that adjoining a small air layer to the relevant material interface may effectively imitate an idealized spatial cutoff that suppresses the nonreciprocal response for short wavelengths and regularizes the topology. Furthermore, it is experimentally verified that nonreciprocal systems with an ill-defined topology may be used to abruptly halt the energy flow in a unidirectional waveguide due to the violation of the bulk-edge correspondence. In particular, we report the formation of an energy sink that absorbs the incoming electromagnetic waves with a large field enhancement at the singularity.
Advanced Photonics
- Publication Date: May. 23, 2022
- Vol. 4, Issue 3, 035003 (2022)
Organic room-temperature phosphorescent polymers for efficient X-ray scintillation and imaging|Article Video
Juan Wei, Yangyang Jiang, Chenyuan Liu, Jiayu Duan... and Qiang Zhao|Show fewer author(s)
Materials that exhibit visible luminescence upon X-ray irradiation show great potential in the medical and industrial fields. Pure organic materials have recently emerged as promising scintillators for X-ray detection and radiography, due to their diversified design, low cost, and facile preparation. However, recent progress in efficient radioluminescence has mainly focused on small molecules, which are inevitably associated with processability and repeatability issues. Here, a concise strategy is proposed to prepare radioluminescent polymers that exhibit multiple emission colors from blue to yellow with high brightness in an amorphous state by the radical copolymerization of negatively charged polyacrylic acid and different positively charged quaternary phosphonium salts. One of the obtained polymers exhibits excellent photostability under a high X-ray irradiation dosage of 27.35 Gy and has a detection limit of 149 nGy s - 1. This performance is superior to that of conventional anthracene-based scintillators. Furthermore, by simply drop-casting a polymer methanol solution on a quartz plate, a transparent scintillator screen was successfully fabricated for X-ray imaging with a resolution of 8.7 line pairs mm - 1. The pure organic phosphorescent polymers with a highly efficient radioluminescence were demonstrated for the first time, and the strategy reported herein offers a promising pathway to expand the application range of amorphous organic scintillators. Materials that exhibit visible luminescence upon X-ray irradiation show great potential in the medical and industrial fields. Pure organic materials have recently emerged as promising scintillators for X-ray detection and radiography, due to their diversified design, low cost, and facile preparation. However, recent progress in efficient radioluminescence has mainly focused on small molecules, which are inevitably associated with processability and repeatability issues. Here, a concise strategy is proposed to prepare radioluminescent polymers that exhibit multiple emission colors from blue to yellow with high brightness in an amorphous state by the radical copolymerization of negatively charged polyacrylic acid and different positively charged quaternary phosphonium salts. One of the obtained polymers exhibits excellent photostability under a high X-ray irradiation dosage of 27.35 Gy and has a detection limit of 149 nGy s - 1. This performance is superior to that of conventional anthracene-based scintillators. Furthermore, by simply drop-casting a polymer methanol solution on a quartz plate, a transparent scintillator screen was successfully fabricated for X-ray imaging with a resolution of 8.7 line pairs mm - 1. The pure organic phosphorescent polymers with a highly efficient radioluminescence were demonstrated for the first time, and the strategy reported herein offers a promising pathway to expand the application range of amorphous organic scintillators.
Advanced Photonics
- Publication Date: May. 17, 2022
- Vol. 4, Issue 3, 035002 (2022)
Ultrafast and real-time physical random bit extraction with all-optical quantization
Ya Guo, Qiang Cai, Pu Li, Ruonan Zhang... and Yuncai Wang|Show fewer author(s)
Optical chaos generated by perturbing semiconductor lasers has been viewed, over recent decades, as an excellent entropy source for fast physical random bit generation (RBG) owing to its high bandwidth and large random fluctuations. However, most optical-chaos-based random bit generators perform their quantization process in the electrical domain using electrical analog-to-digital converters, so their real-time rates in a single channel are severely limited at the level of Gb/s due to the electronic bottleneck. Here, we propose and experimentally demonstrate an all-optical method for RBG where chaotic pulses are quantized into a physical random bit stream in the all-optical domain by means of a length of highly nonlinear fiber. In our proof-of-concept experiment, a 10-Gb/s random bit stream is successfully generated on-line using our method. Note that the single-channel real-time rate is limited only by the chaos bandwidth. Considering that the Kerr nonlinearity of silica fiber with an ultrafast response of few femtoseconds is exploited for composing the key part of quantizing laser chaos, this scheme thus may operate potentially at much higher real-time rates than 100 Gb/s provided that a chaotic entropy source of sufficient bandwidth is available. Optical chaos generated by perturbing semiconductor lasers has been viewed, over recent decades, as an excellent entropy source for fast physical random bit generation (RBG) owing to its high bandwidth and large random fluctuations. However, most optical-chaos-based random bit generators perform their quantization process in the electrical domain using electrical analog-to-digital converters, so their real-time rates in a single channel are severely limited at the level of Gb/s due to the electronic bottleneck. Here, we propose and experimentally demonstrate an all-optical method for RBG where chaotic pulses are quantized into a physical random bit stream in the all-optical domain by means of a length of highly nonlinear fiber. In our proof-of-concept experiment, a 10-Gb/s random bit stream is successfully generated on-line using our method. Note that the single-channel real-time rate is limited only by the chaos bandwidth. Considering that the Kerr nonlinearity of silica fiber with an ultrafast response of few femtoseconds is exploited for composing the key part of quantizing laser chaos, this scheme thus may operate potentially at much higher real-time rates than 100 Gb/s provided that a chaotic entropy source of sufficient bandwidth is available.
Advanced Photonics
- Publication Date: May. 02, 2022
- Vol. 4, Issue 3, 035001 (2022)
Light-controllable time-domain digital coding metasurfaces|Article Video
Xin Ge Zhang, Ya Lun Sun, Bingcheng Zhu, Wei Xiang Jiang... and Tie Jun Cui|Show fewer author(s)
Programmable metasurfaces enable real-time control of electromagnetic waves in a digital coding manner, which are suitable for implementing time-domain metasurfaces with strong harmonic manipulation capabilities. However, the time-domain metasurfaces are usually realized by adopting the wired electrical control method, which is effective and robust, but there are still some limitations. Here, we propose a light-controllable time-domain digital coding metasurface consisting of a full-polarization dynamic metasurface and a high-speed photoelectric detection circuit, from which the microwave reflection spectra are manipulated by time-varying light signals with periodic phase modulations. As demonstrated, the light-controllable time-domain digital coding metasurface is illuminated by the light signals with two designed time-coding sequences. The measured results show that the metasurface can well generate symmetrical harmonics and white-noise-like spectra, respectively, under such cases in the reflected wave. The proposed light-controllable time-varying metasurface offers a planar interface to tailor and link microwaves with lights in the time domain, which could promote the development of photoelectric hybrid metasurfaces and related multiphysics applications. Programmable metasurfaces enable real-time control of electromagnetic waves in a digital coding manner, which are suitable for implementing time-domain metasurfaces with strong harmonic manipulation capabilities. However, the time-domain metasurfaces are usually realized by adopting the wired electrical control method, which is effective and robust, but there are still some limitations. Here, we propose a light-controllable time-domain digital coding metasurface consisting of a full-polarization dynamic metasurface and a high-speed photoelectric detection circuit, from which the microwave reflection spectra are manipulated by time-varying light signals with periodic phase modulations. As demonstrated, the light-controllable time-domain digital coding metasurface is illuminated by the light signals with two designed time-coding sequences. The measured results show that the metasurface can well generate symmetrical harmonics and white-noise-like spectra, respectively, under such cases in the reflected wave. The proposed light-controllable time-varying metasurface offers a planar interface to tailor and link microwaves with lights in the time domain, which could promote the development of photoelectric hybrid metasurfaces and related multiphysics applications.
Advanced Photonics
- Publication Date: Apr. 18, 2022
- Vol. 4, Issue 2, 025001 (2022)
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