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The image on the cover for Chinese Optics Letters Volume 19, Issue 11, summarizes the PAI techniques, imaging systems, and their biomedical applications in microrobots tracking in vitro and in vivo. From a robotic tracking perspective, some insight into the future of PAI technology in clinical applications is also provided.The image is based on original research by Dengfeng Li et al. presented in their paper "Review of photoacoustic imaging for microrobots tracking in vivo [Invited]", Chinese Optics Letters 19 (11), 111701 (2021).

The image on the cover for Photonics Research Volume 9, Issue 11, proposes a device that could be used for both display and visible light communication (VLC) applications. The semipolar blue &mu;LED array fabricated in this study shows a negligible wavelength shift, indicating a significant reduction in the quantum confined Stark effect. The image is based on original research by Tingzhu Wu et al. presented in their paper "Highly stable full-color display device with VLC application potential using semipolar &mu;LEDs and all-inorganic encapsulated perovskite nanocrystal", Photonics Research 9 (11), 11002132 (2021).

The image on the cover for Advanced Photonics Volume 3 Issue 5 depicts a novel spintronic-metasurface terahertz emitter, developed by researchers from Fudan University. Composed of alternating magnetic heterostructures, the emitter allows efficient, flexible generation and manipulation of chiral terahertz waves. Terahertz radiation is generated by exciting the emitter with laser pulses under an oriented external magnetic field. Transverse anisotropic confinement of the laser-induced charge currents imposed by the metasurface structure leads to chiralterahertz-wave emission.The image is based on original research presented in the report by Changqin Liu, Shunjia Wang, Sheng Zhang, and Qingnan Cai, et al., “Active spintronic-metasurface terahertz emitters with tunable chirality,” Adv. Photonics 3(5), 056002 (2021), doi: 10.1117/1.AP.3.5.056002.

The image on the cover of High Power Laser Science and Engineering Volume 9, Issue 3, presents an all-optical scheme to generate a high-energy &gamma;-photon beam with large beam angular momentum (BAM), small divergence, and high brilliance.The image is based on original research by Hao Zhang et al. presented in their paper "Efficient bright &gamma;-ray vortex emission from a laser-illuminated light-fan-in-channel target", High Power Laser Science and Engineering 9 (3), 03000e43 (2021).

The image on the cover for Chinese Optics Letters Volume 19, Issue 10, reviews the important parameters including the refractive index detection range, resonance wavelength, and spectral sensitivity responsible for the sensing properties of PCF-SPR sensors.The image is based on original research by Chao Liu et al. presented in their paper "Overview of refractive index sensors comprising photonic crystal fibers based on the surface plasmon resonance effect [Invited]", Chinese Optics Letters 19 (10), 102202 (2021).

Editors' Picks
Optical tweezers (OTs) provide a powerful tool for trapping, guiding, and assembly of biological nanoparticles and cells, thus playing a unique role in biomedical and photonics areas. Particularly, OTs have been widely used to explore the structure, mechanism, and interaction of cells due to their ability of non-contact and high-resolution manipulation.
Photonics Research
• Jan. 20, 2022
• Vol. 10, Issue 1 (2022)
Editors' Picks
Topological states of matter are one of the most important research fields in condensed physics and have been deeply studied over the last 10 years. Before the discovery of topological states, researchers believed that almost all states of matter could be characterized by symmetry or local order parameters, and the phase transition of matters was accompanied by symmetry breaking.
• Jan. 19, 2022
• Vol. 10, Issue 1 (2022)
AP Highlights
Real-time, in-situ sensing and tracking of cell development and maturation is achieved using a label-free nano-optical device
• Jan. 19, 2022
• Vol. 4, Issue 1 (2022)
News
Original manuscripts are sought to the special issue on "Future Control Systems and Machine Learning at High Power Laser Facilities" of High Power Laser Science and Engineering (HPL),
High Power Laser Science and Engineering
• Jan. 18, 2022
• Vol. , Issue (2022)
Editors' Picks
Monolayered molybdenum disulfide (MoS2) has attracted much attention from researchers because of its direct bandgap electronic structure and unique excitonic properties. In particular, MoS2 in its monolayer form has broad applications in catalysis, nanoelectronics and optoelectronics and so forth. The performances of these devices are determined by the physical properties of MoS2 layered materials, which are, fundamentally, determined by the material characteristics, such as morphology and quality. So, it is essential to synthesize high-quality MoS2 films with the desired morphology and physical properties. So far, numerous fabrication methods have been developed to obtain monolayer or few-layer MoS2 such as exfoliation,physical vapor deposition, hydrothermal synthesis and so on.
Chinese Optics Letters
• Jan. 18, 2022
• Vol. 20, Issue 1 (2022)
Fabrication of micrometre-sized periodic gratings in free-standing metallic foils for laser–plasma experiments

Engineered targets are expected to play a key role in future high-power laser experiments calling for joined, extensive knowledge in materials properties,

Engineered targets are expected to play a key role in future high-power laser experiments calling for joined, extensive knowledge in materials properties, engineering techniques and plasma physics. In this work, we propose a novel patterning procedure of self-supported 10 μm thick Au and Cu foils for obtaining micrometre-sized periodic gratings as targets for high-power laser applications. Accessible techniques were considered, by using cold rolling, electron-beam lithography and the Ar-ion milling process. The developed patterning procedure allows efficient control of the grating and foil surface on large area. Targets consisting of patterned regions of 450 μm × 450 μm, with 2 μm periodic gratings, were prepared on 25 mm × 25 mm Au and Cu free-standing foils, and preliminary investigations of the micro-targets interacting with an ultrashort, relativistic laser pulse were performed. These test experiments demonstrated that, in certain conditions, the micro-gratings show enhanced laser energy absorption and higher efficiency in accelerating charge particle beams compared with planar thin foils of similar thickness.show less

• Jan.20，2022
• High Power Laser Science and Engineering,Vol. 10, Issue 1
• 010000e3 (2022)
Matching-based two-color X-ray free-electron laser generation utilizing laser–plasma accelerated electron beam

Laser–plasma accelerators (LPAs) have great potential to realize a compact X-ray free-electron laser (FEL), which is limited by the beam properties curren

Laser–plasma accelerators (LPAs) have great potential to realize a compact X-ray free-electron laser (FEL), which is limited by the beam properties currently. Two-color high-intensity X-ray FEL provides a powerful tool for probing ultrafast dynamic systems. In this paper, we present a simple and feasible method to generate a two-color X-ray FEL pulse based on an LPA beam. In this scheme, time-dependent mismatch along the bunch is generated and manipulated by the designed lattice system, enabling FEL lasing at different wavelength within two undulator sections. The time separation between the two pulses can be precisely adjusted by varying the time-delay chicane. Numerical simulations show that two-color soft X-ray FELs with gigawatt-level peak power and femtosecond duration can be generated, which confirm the validity and feasibility of the scheme.show less

• Jan.20，2022
• High Power Laser Science and Engineering,Vol. 10, Issue 1
• 010000e1 (2022)
Mapping non-laminar proton acceleration in laser-driven target normal sheath field

We report on experimental observation of non-laminar proton acceleration modulated by a strong magnetic field in laser irradiating micrometer aluminum tar

We report on experimental observation of non-laminar proton acceleration modulated by a strong magnetic field in laser irradiating micrometer aluminum targets. The results illustrate the coexistence of ring-like and filamentation structures. We implement the knife edge method into the radiochromic film detector to map the accelerated beams, measuring a source size of 30–110 μm for protons of more than 5 MeV. The diagnosis reveals that the ring-like profile originates from low-energy protons far off the axis whereas the filamentation is from the near-axis high-energy protons, exhibiting non-laminar features. Particle-in-cell simulations reproduced the experimental results, showing that the short-term magnetic turbulence via Weibel instability and the long-term quasi-static annular magnetic field by the streaming electric current account for the measured beam profile. Our work provides direct mapping of laser-driven proton sources in the space-energy domain and reveals the non-laminar beam evolution at featured time scales.show less

• Jan.20，2022
• High Power Laser Science and Engineering,Vol. 10, Issue 1
• 010000e2 (2022)
Third-order nonlinear phenomenon generated on the inner surface of bulk lithium niobate crystals with magnesium doping

When two synchronized laser beams illuminate the inner surface of bulk lithium niobate crystals with magnesium doping (5%/mol MgO:LiNbO3) under the condit

When two synchronized laser beams illuminate the inner surface of bulk lithium niobate crystals with magnesium doping (5%/mol $MgO:LiNbO3$) under the condition of total reflection, semi-degenerate four-wave mixing (FWM) is generated. On this basis, a more sophisticated frequency conversion process on the interface of nonlinear crystal has been researched. The generation mechanism of FWM is associated with the fundamental waves reflected on the inner surface of the nonlinear crystal. Analysis of the phase-matching mechanism confirms that the FWM is radiated by the third-order nonlinear polarized waves, which are stimulated by the third-order nonlinear susceptibility coefficient of the nonlinear crystal. Theoretically calculated and experimentally measured corresponding data have been presented in this article. These results are expected to provide new inspiration for further experimental and theoretical research on frequency conversion in nonlinear crystals.show less

• Jan.20，2022
• Chinese Optics Letters,Vol. 20, Issue 3
• 031901 (2022)

Light field imaging has shown significance in research fields for its high-temporal-resolution 3D imaging ability. However, in scenes of light field imaging through scattering, such as

Light field imaging has shown significance in research fields for its high-temporal-resolution 3D imaging ability. However, in scenes of light field imaging through scattering, such as biological imaging in vivo and imaging in fog, the quality of 3D reconstruction will be severely reduced due to the scattering of the light field information. In this paper, we propose a deep learning-based method of scattering removal of light field imaging. In this method, a neural network, trained by simulation samples which are generated by light field imaging forward models with and without scattering, is utilized to remove the effect of scattering on light field captured experimentally. With the deblurred light field and the scattering-free forward model, 3D reconstruction with high resolution and high contrast can be realized. We demonstrate the proposed method by using it to realize high-quality 3D reconstruction through a single scattering layer experimentally.show less

• Jan.20，2022
• Chinese Optics Letters,Vol. 20, Issue 4
• (2022)

A single-frequency 1645 nm pulsed laser with frequency stability close to 100 kHz was demonstrated. The laser oscillator is injection-seeded by a single-frequency narrow linewidth Er:YA

A single-frequency 1645 nm pulsed laser with frequency stability close to 100 kHz was demonstrated. The laser oscillator is injection-seeded by a single-frequency narrow linewidth Er:YAG nonplanar ring oscillator and frequency stabilized by modified Pound–Drever–Hall method. The pulse repetition rate can be set from 100 to 500 Hz with the frequency stability from 82.72 kHz to 134.44 kHz and pulse energy from 9.84 mJ to 19.55 mJ. To our knowledge this is the best frequency stability of single-frequency pulsed laser with injection-seeded. show less

• Jan.20，2022
• Chinese Optics Letters,Vol. 20, Issue 4
• (2022)

We demonstrate a novel approach to achieve wavelength-tunable ultrashort pulses from an all-fiber mode-locked laser with a saturable absorber based on nonlinear Kerr beam clean-up effec

We demonstrate a novel approach to achieve wavelength-tunable ultrashort pulses from an all-fiber mode-locked laser with a saturable absorber based on nonlinear Kerr beam clean-up effect. This saturable absorber was formed by a single-mode fiber spliced to a graded-index multimode fiber, and its tunable band-pass filter effect is described by a numerical model. By adjusting the bending condition of graded-index multimode fiber, the laser could produce dissipative soliton pulses with their central wavelength tunable from1040 nm to 1063 nm. The pulse duration of output laser could be compressed externally to 791 fs, and the signal to noise ratio of its radio frequency spectrum was measured to be 75.5 dB. show less

• Jan.20，2022
• Chinese Optics Letters,Vol. 20, Issue 4
• (2022)

The linewidth of BaGa4Se7 optical parametric oscillator (BGSe OPO) was narrowed for the first time by inserting a Fabry-Perot (FP) etalon into an L-shaped cavity. When a 15 mm long BGSe

The linewidth of BaGa4Se7 optical parametric oscillator (BGSe OPO) was narrowed for the first time by inserting a Fabry-Perot (FP) etalon into an L-shaped cavity. When a 15 mm long BGSe(56.3°, 0°) was pumped by a 1064 nm laser, the peak wavelength was ~3529 nm and the linewidth was 4.53 nm (3.64 cm-1) under type I phase matching. After inserting a 350 µm thick FP etalon, the linewidth was decreased to 1.27-2.05 nm. When the tilt angle of the etalon was 2.34°, the linewidth was 2.05 nm (1.65 cm-1) and the peak wavelength was still ~3529 nm. When the tilt angle of the etalon was 3.90°, the peak wavelength was 3534.9 nm and the linewidth was 1.27 nm (1.02 cm-1), which was the narrowest linewidth of BGSe OPO, to the best of our knowledge. The beam quality was improved after inserting the FP etalon, too.show less

• Jan.20，2022
• Chinese Optics Letters,Vol. 20, Issue 4
• (2022)
Xi'an, ChinaAug 7-10, 2022
Hangzhou, ChinaJuly 14-16, 2022
The image on the cover for Chinese Optics Letters Volume 19, Issue 11, summarizes the PAI techniques, imaging systems, and their biomedical applications in microrobots tracking in vitro and in vivo. From a robotic tracking perspective, some insight into the future of PAI technology in clinical applications is also provided.The image is based on original research by Dengfeng Li et al. presented in their paper "Review of photoacoustic imaging for microrobots tracking in vivo [Invited]", Chinese Optics Letters 19 (11), 111701 (2021).
• Journal
• 19th Nov，2021
The image on the cover for Photonics Research Volume 9, Issue 11, proposes a device that could be used for both display and visible light communication (VLC) applications. The semipolar blue &mu;LED array fabricated in this study shows a negligible wavelength shift, indicating a significant reduction in the quantum confined Stark effect. The image is based on original research by Tingzhu Wu et al. presented in their paper "Highly stable full-color display device with VLC application potential using semipolar &mu;LEDs and all-inorganic encapsulated perovskite nanocrystal", Photonics Research 9 (11), 11002132 (2021).
• Journal
• 19th Nov，2021