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The image on the cover for Chinese Optics Letters Volume 20, Issue 5, reports reflective photon nanosieves that consist of metallic meta-mirrors sitting on a transparent quartz substrate. Upon illumination, these meta-mirrors offer the reflectance of &sim;50%, which is higher than the transmission of visible light through diameter-identical nanoholes.The image is based on original research by Samia Osman Hamid Mohammed et al. presented in their paper "Efficiency-enhanced reflective nanosieve holograms", Chinese Optics Letters 20 (5), 053602. (2022)

The image on the cover for Photonics Research Volume 10, Issue 4, reports the demonstration of an N-polar InGaN/GaN nanowire sub-microscale LED emitting in the red spectrum that can overcome the efficiency cliff of conventional red-emitting micro-LEDs. The image is based on original research by A. Pandey et al. presented in their paper "N-polar InGaN/GaN nanowires: overcoming the efficiency cliff of red-emitting micro-LEDs", Photonics Research 10 (4), 04001107 (2022).

The image on the cover for Advanced Photonics Volume 4 Issue 2 illustrates a schematic of a Mueller matrix measurement system and a conceptional Mueller matrix of the sample (4x4 matrix), as well as the related vectorial properties of the light beams.The image is based on original research presented in the article by Chao He, Jintao Chang, Patrick S. Salter, Yuanxing Shen, Ben Dai, Pengcheng Li, Yihan Jin, Samlan Chandran Thodika, Mengmeng Li, Tariq Aziz, Jingyu Wang, Jacopo Antonello, Yang Dong, Ji Qi, Jianyu Lin, Daniel S. Elson, Min Zhang, Honghui He, Hui Ma, and Martin J. Booth, “ Revealing complex optical phenomena through vectorial metrics,” Adv. Photon. 4(2), 026001 (2022), doi 10.1117/1.AP.4.2.026001.

The image on the cover for Chinese Optics Letters Volume 20, Issue 4, indicates that an InAs/GaAs quantum dot photonic crystal bandedge laser, which is directly grown on an on-axis Si (001) substrate, which provides a feasible route towards a low-cost and large-scale integration method for light sources on the Si platform was achieved under the pumping condition of a continuous-wave 632.8 nm He&ndash;Ne gas laser at room temperature.The image is based on original research by Yaoran Huang et al. presented in their paper "Highly integrated photonic crystal bandedge lasers monolithically grown on Si substrates", Chinese Optics Letters 20 (4), 041401 (2022).

Editors' Picks
Photonic topological insulators are special materials in whose structural topology fully disallows the energy transport into their interior. Instead, they keep energy circulating along their surfaces. In contrast to ordinary surface wave systems, the prominence of photonic topological insulators lies on the fact that the surface transport occurs in unidirectional fashion, irrespective of whether the system exhibits disorder or contains random imperfections.
Photonics Research
• Jun. 23, 2022
• Vol. 10, Issue 5 (2022)
News
Original manuscripts are sought to the special issue on "Relativistic Laser Plasma Interaction (RLPI) Diagnostics and Instrumentation" of High Power Laser Science and Engineering (HPL).
High Power Laser Science and Engineering
• Jun. 10, 2022
• Vol. 10, Issue (2022)
Editors' Picks
Almost all optical systems, including LiDAR for autonomous vehicles and robotic applications, medical imaging systems such as optical coherent tomography, and high-speed point-to-point optical communication links greatly benefit from a photonic beamforming and beam steering sub-system. This sub-system directs and concentrates the optical beam in the desired direction, improving the system's sensitivity and imaging resolution.
Photonics Research
• Jun. 09, 2022
• Vol. 10, Issue 5 (2022)
On the Cover
Vertical-cavity surface-emitting lasers (VCSELs) have many unique features like circular beam, low power consumption, high modulation speed, and easy fabrication of two-dimensional arrays. Now VCSELs have been widely used in optical interconnects, consumer electronics, 3D sensing, and automotive applications.
Photonics Research
• Jun. 08, 2022
• Vol. 10, Issue 5 (2022)
On the Cover
Photon sieves composed of etched holes on an opaque film have been proposed firstly, to the best of our knowledge, to reduce the focal spot size and alleviate high diffraction orders in soft X-ray and the optical spectrum. With the rapid development of nano-fabrication technology, photon sieves have been demonstrated at nanoscale and worked as binary-amplitude metasurfaces for optical focusing. The photon nanosieves have the advantages of polarization independence and more degrees of freedom in design than the concentric rings in zone plates, which therefore enable more complex manipulation of light, such as hologram, by arranging the locations of holes in a customized way. Due to the subwavelength feature of nanosieves, their related holograms usually support broadband operation. In addition, the non-resonating mechanism of amplitude modulation makes the nanosieve hologram have a wider spectrum than other metasurface devices with resonating nano-structures. The nanosieve hologram also enables a large field of view for holographic display when combined with tunable phase realized by a spatial light modulator. Beyond the circular shape, rectangle nanosieves have also been proposed to control the geometric phase of a circularly polarized light by rotating the orientations of the rectangular nanosieves, thus enabling full-color holography and the generation of optical vortices in various electromagnetic spectra such as X-ray and vacuum ultraviolet wavelengths.
Chinese Optics Letters
• Jun. 08, 2022
• Vol. 20, Issue 5 (2022)
Observation of flat-band and band transition in the synthetic space

Constructions of synthetic lattices in modulated ring resonators attract growing attention to interesting physics beyond the geometric dimensionality, whe

Constructions of synthetic lattices in modulated ring resonators attract growing attention to interesting physics beyond the geometric dimensionality, where complicated connectivities between resonant frequency modes are explored in many theoretical proposals. We implement experimental demonstration of generating a stub lattice along the frequency axis of light, in two coupled ring resonators of different lengths, with the longer one dynamically modulated. Such a synthetic photonic structure intrinsically exhibits the physics of flat band. We show that the time-resolved band structure read-out from the drop-port output of the excited ring is the intensity projection of the band structure onto a specific resonant mode in the synthetic momentum space, where gapped flat band, mode localization effect, and flat-to-nonflat band transition are observed in experiments and verified by simulations. This work provides evidence for constructing a synthetic stub lattice using two different rings, which, hence, makes a solid step toward experimentally constructing complicated lattices in multiple rings associated with synthetic frequency dimensions.

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• Jun.25，2022
• Article Video
• Advanced Photonics,Vol. 4, Issue 3
• 036002 (2022)
Loss-tolerant measurement device independent quantum key distribution with reference frame misalignment

Reference frame independent and measurement device independent quantum key distribution (RFI-MDI-QKD) has the advantages of being immune to detector side

Reference frame independent and measurement device independent quantum key distribution (RFI-MDI-QKD) has the advantages of being immune to detector side loopholes and misalignment of the reference frame. However, several former related research works are based on the unrealistic assumption of perfect source preparation. In this paper, we merge a loss-tolerant method into RFI-MDI-QKD to consider source flaws into key rate estimation and compare it with quantum coin method. Based on a reliable experimental scheme, the joint influence of both source flaws and reference frame misalignment is discussed with consideration of the finite-key effect. The results show that the loss-tolerant RFI-MDI-QKD protocol can reach longer key rate performance while considering the existence of source flaws in a real-world implementation.show less

• Jun.25，2022
• Chinese Optics Letters,Vol. 20, Issue 9
• 092701 (2022)
Colloidal quantum-dot light emitting diodes with bias-tunable color

Although the performance of quantum-dot-based light emitting diodes (QLEDs) has been significantly enhanced over the past years, conventional full-color Q

Although the performance of quantum-dot-based light emitting diodes (QLEDs) has been significantly enhanced over the past years, conventional full-color QLED displays still rely on the side-by-side pattern techniques of red (R)/green (G)/blue (B) quantum dots (QDs). Such lateral integration of multi-color pixels imposes technological difficulty in the development of high-resolution displays due to limited pixel density and fill factors. Herein, we demonstrate the development of full-color QLEDs with bias-tunable emission spectra by engineering mixed R/G/B QDs as light emitting layers. In Commission Internationale de l’Eclairage (CIE) chromaticity coordinates, QLEDs with bias-tunable color exhibit wide color variation ranging from red (0.649, 0.330) to green (0.283, 0.305) to blue (0.255, 0.264) upon increasing voltages and can be tuned to emit white light (0.316, 0.325). More importantly, the fabricated multi-color QLEDs show high luminance approaching $103 cd m-2$ and superior external quantum efficiency of 13.3%. Benefitting from the wide spectral tunability and light emitting efficiency, we believe the proposed multi-color QLEDs have great application prospects for both displays and lighting.show less

• Jun.25，2022
• Photonics Research,Vol. 10, Issue 7
• 07001633 (2022)
Synthetic aperture ptychography: coded sensor translation for joint spatial-Fourier bandwidth expansion

Conventional ptychography translates an object through a localized probe beam to widen the field of view in real space. Fourier ptychography translates th

Conventional ptychography translates an object through a localized probe beam to widen the field of view in real space. Fourier ptychography translates the object spectrum through a pupil aperture to expand the Fourier bandwidth in reciprocal space. Here we report an imaging modality, termed synthetic aperture ptychography (SAP), to get the best of both techniques. In SAP, we illuminate a stationary object using an extended plane wave and translate a coded image sensor at the far field for data acquisition. The coded layer attached on the sensor modulates the object exit waves and serves as an effective ptychographic probe for phase retrieval. The sensor translation process in SAP synthesizes a large complex-valued wavefront at the intermediate aperture plane. By propagating this wavefront back to the object plane, we can widen the field of view in real space and expand the Fourier bandwidth in reciprocal space simultaneously. We validate the SAP approach with transmission targets and reflection silicon microchips. A 20-mm aperture was synthesized using a 5-mm sensor, achieving a fourfold gain in resolution and 16-fold gain in field of view for object recovery. In addition, the thin sample requirement in ptychography is no longer required in SAP. One can digitally propagate the recovered exit wave to any axial position for post-acquisition refocusing. The SAP scheme offers a solution for far-field sub-diffraction imaging without using lenses. It can be adopted in coherent diffraction imaging setups with radiation sources from visible light, extreme ultraviolet, and X-ray, to electron.show less

• Jun.25，2022
• Photonics Research,Vol. 10, Issue 7
• 07001624 (2022)

The resolution of the Spatial Light Modulators (SLMs) screen and the encoding algorithm of the computer-generated hologram are the primary limiting factors in the generation of large t

The resolution of the Spatial Light Modulators (SLMs) screen and the encoding algorithm of the computer-generated hologram are the primary limiting factors in the generation of large topological charge vortex beams. This paper attempts to solve these problems by improving both the hardware and the algorithm. Theoretically, to overcome the limitations of beam waist radius, the amplitude profile function of large topological charge LG beam is properly improved. Then an experimental system employing a 4K phase-only SLM is set up, and the LG beams with topological charge up to 1200 are successfully generated. Furthermore, we discuss the effect of different beam waist radii on the generation of LG beams. Additionally, the function of the LG beam is further improved to generate a LG beam with a topological charge as high as 1400. Our results set a new benchmark for generating large topological charge vortex beams, which can be widely used in precise measurement, sensing, and communication.show less

• Jun.25，2022
• Chinese Optics Letters,Vol. 20, Issue 12
• (2022)

Four single crystals (Yb<sub>0.15</sub>Lu<sub>0.85x</sub>Y<sub>0.85-0.85x</sub>)<sub>3</sub>Al<sub>5</sub>O<sub>12<

Four single crystals (Yb<sub>0.15</sub>Lu<sub>0.85x</sub>Y<sub>0.85-0.85x</sub>)<sub>3</sub>Al<sub>5</sub>O<sub>12</sub> (x=0, 0.25, 0.5, 1) were grown by the Czochralski method. The correlation of the host atom Lu:Y ratios with the density and the luminescence properties were revealed. The density increases linearly with increasing of Lu<sup>3+</sup> content, which will improve the gamma ray cut-off ability. The integrated intensity of the XEL spectrum increases exponentially with increasing the Y:Lu ratio. While the decay time becomes even shorter with increasing the Lu<sup>3+</sup> content. These results will provide a basis to balance the comprehensive properties to match different application requirements.show less

• Jun.25，2022
• Chinese Optics Letters,Vol. 20, Issue 12
• (2022)

Understanding light-matter interaction lays at the core of our ability to harness novel physical effects and to translate them into new capabilities realized in modern integrated photon

Understanding light-matter interaction lays at the core of our ability to harness novel physical effects and to translate them into new capabilities realized in modern integrated photonics platforms. Here, we present the design and characterization of optofluidic components in integrated photonics platform, and numerically predict a series of novel physical effects which rely on thermocapillary-driven interaction between waveguide modes to topography changes of optically thin liquid dielectric film. Our results indicate that this coupling introduces substantial self-induced phase change in a single channel waveguide, transmittance through Bragg grating waveguide and nonlocal interaction between adjacent waveguides. We then employ the self-induced effects together with the inherent built-in finite relaxation time of the liquid film, to demonstrate that its light-driven deformation can serve as a reservoir computer capable to perform digital and analog tasks, where the gas-liquid interface operates both as a nonlinear actuator and as an optical memory element.show less

• Jun.25，2022

Controlling energy flow in waveguides has attractive potential in integrated devices from radio frequencies to optical bands. Due to the spin-orbit coupling, the mirror symmetry will be

Controlling energy flow in waveguides has attractive potential in integrated devices from radio frequencies to optical bands. Due to the spin-orbit coupling, the mirror symmetry will be broken, and the handedness of the near-field source will determine the direction of energy transport. Compared with well-established theories about spin-momentum locking, experimental visualization of unidirectional coupling is usually challenging due to the lack of generic chiral sources and the strict environmental requirement. In this work, we design a broadband near-field chiral source in the microwave band and discuss experimental details to visualize spin-momentum locking in three different metamaterial waveguides, including spoof surface plasmon polaritons, line waves, and valley topological insulators. The similarity of these edge waves relies on the abrupt sign change of intrinsic characteristics of two media across the interface, leading to universal spin-momentum locking. Besides the development of experimental technology, the advantages and research status of spin-sorting waveguides are summarized, and perspectives on future research are presented to explore an avenue for designing controllable spin-sorting devices in the microwave band. show less

• Jun.25，2022