Twist-angle two-dimensional superlattices and their application in (opto)electronics
Twist-angle two-dimensional systems, such as twisted bilayer graphene, twisted bilayer transition metal dichalcogenides, twisted bilayer phosphorene and their multilayer van der Waals heterostructures, exhibit novel and tunable properties due to the formation of Moiré superlattice and modulated Moiré bands. The review presents a brief venation on the development of “twistronics” and subsequent applications based on band engineering by twisting. Theoretical predictions followed by experimental realization of magic-angle bilayer graphene ignited the flame of investigation on the new freedom degree, twist-angle, to adjust (opto)electrical behaviors. Then, the merging of Dirac cones and the presence of flat bands gave rise to enhanced light-matter interaction and gate-dependent electrical phases, respectively, leading to applications in photodetectors and superconductor electronic devices. At the same time, the increasing amount of theoretical simulation on extended twisted 2D materials like TMDs and BPs called for further experimental verification. Finally, recently discovered properties in twisted bilayer h-BN evidenced h-BN could be an ideal candidate for dielectric and ferroelectric devices. Hence, both the predictions and confirmed properties imply twist-angle two-dimensional superlattice is a group of promising candidates for next-generation (opto)electronics.
  • Jan. 17, 2022
  • Journal of Semiconductors
  • Vol.43 Issue, 1 011001 (2022)
  • DOI:10.1088/1674-4926/43/1/011001
White-light emission from organic aggregates: a review
Jianyu Zhang, Xueqian Zhao, Hanchen Shen, Jacky W. Y. Lam, Haoke Zhang, and Ben Zhong Tang
White light, which contains polychromic visible components, affects the rhythm of organisms and has the potential for advanced applications of lighting, display, and communication. Compared with traditional incandescent bulbs and inorganic diodes, pure organic materials are superior in terms of better compatibility, flexibility, structural diversity, and environmental friendliness. In the past few years, polychromic emission has been obtained based on organic aggregates, which provides a platform to achieve white-light emission. Several white-light emitters are sporadically reported, but the underlying mechanistic picture is still not fully established. Based on these considerations, we will focus on the single-component and multicomponent strategies to achieve efficient white-light emission from pure organic aggregates. Thereinto, single-component strategy is introduced from four parts: dual fluorescence, fluorescence and phosphorescence, dual phosphorescence with anti-Kasha’s behavior, and clusteroluminescence. Meanwhile, doping, supramolecular assembly, and cocrystallization are summarized as strategies for multicomponent systems. Beyond the construction strategies of white-light emitters, their advanced representative applications, such as organic light-emitting diodes, white luminescent dyes, circularly polarized luminescence, and encryption, are also prospected. It is expected that this review will draw a comprehensive picture of white-light emission from organic aggregates as well as their emerging applications.
  • Jan. 04, 2022
  • Advanced Photonics
  • Vol.4 Issue, 1 014001 (2022)
  • DOI:10.1117/1.AP.4.1.014001
Reconstruction Algorithms for Ghost Imaging and Single-Pixel Imaging
Sun Mingjie, Yan Songming, and Wang Siyuan
Ghost imaging and single-pixel imaging originate from different physical concepts. They have been closely integrated and developed together due to many similarities they share in the system schemes and image reconstruction algorithms. As typical computational imaging technologies, these two imaging schemes have received extensive attention in the fields of optics, imaging, and information acquisition. Different from traditional area array imaging, ghost imaging and single-pixel imaging obtain images by using the reconstruction algorithms, which is one important feature of computational imaging. In this paper, the history of ghost imaging and single-pixel imaging is briefly reviewed with a focus on typical image reconstruction algorithms. The principles of ghost imaging and single-pixel imaging using light field second-order correlation, sampling theory, compressed sensing, and machine learning are explained. Their application potential and prospects are discussed.
  • Dec. 29, 2021
  • Laser & Optoelectronics Progress
  • Vol.59 Issue, 2 0200001 (2022)
  • DOI:10.3788/LOP202259.0200001
Theory and Application of Edge States in Topological Photonic Crystals
Liu Chao, Guo Xiaowei, Li Shaorong, and Gao Yuan
In recent years, topological photonic crystals have attracted growing interest for their unique propagation characteristics. With the development of theoretical models in topological photonics, numerous novel applications have emerged. Topological edge states formed by topological photonic crystals can realize optical enhancement and unidirectional transmission in optoelectronic devices. Such optoelectronic devices can have distinct characteristics such as immunity to local defects and high transmission efficiency, offering enormous potential benefits to chip development, biosensor, military communication, and other applications. This study summarizes and analyzes a range of optical devices based on theoretical models of edge states formed by topological photonics in different dimensions: topological lasers, optical waveguides, unidirectional conduction devices, and optical modulators. The presented examples demonstrate the huge potential of topological photonic crystals in structural design and material selection. Finally, the current research progress of topological photonic crystals is clarified and the defects and optimization direction of topological photonic devices in the design process are evaluated and prospected.
  • Dec. 23, 2021
  • Laser & Optoelectronics Progress
  • Vol.59 Issue, 1 0100001 (2022)
  • DOI:10.3788/LOP202259.0100001
Experimental Research Progress in Squeezed Light of Continuous Variable Higher-Order Mode
Ma Long, Yan Manjun, Guo Changyuan, and Fan Hongjin
Continuous variable squeezed light plays an important role in quantum information processing, and the most effective generation tool known is the optical parametric oscillator. At present, most research focus on the fundamental mode, however, the intensity and phase distribution of higher-order mode are more complicated. In addition, based on the characteristics of different order modes and their orthogonal characteristics, high-order mode squeezed light brings more choices and applications for quantum communication and quantum precision measurement. This review introduces the experimental research progress of the continuous variable higher-order mode squeezed light based on the optical parametric oscillator, and expounds two common methods for generating high-order mode squeezed light field, including operation in high-order mode OPO and fundamental mode squeezed light combined mode shaping device.
  • Dec. 23, 2021
  • Laser & Optoelectronics Progress
  • Vol.59 Issue, 1 0100005 (2022)
  • DOI:10.3788/LOP202259.0100005
Application of Thulium-Doped Laser in the Biomedicine Field
Zhang Anjun, Duan Jialin, Xing Yingbin, and Li Jinyan
Thulium-doped lasers are an ideal choice for biological tissue ablation and lithotripsy applications due to the advantage of efficient absorption by water molecules. They have great application prospects in the field of biomedicine. This paper briefly describes the principle of thulium-doped lasers and biological action, introduces the latest research results for thulium-doped lasers at home and abroad and their application in tissue ablation and lithotripsy surgery, and summarizes different laser parameters, including working mode and power. The effects of the irradiation time, spot area, and pulse frequency, among others, on tissue ablation and lithotripsy surgery reveal that the thulium-doped fiber lasers are an important development direction for medical lasers in the future. In addition, suggestions are made for the development of domestic thulium-doped lasers in the biomedical field.
  • Dec. 23, 2021
  • Laser & Optoelectronics Progress
  • Vol.59 Issue, 1 0100004 (2022)
  • DOI:10.3788/LOP202259.0100004
Improved U-Net Models and Its Applications in Medical Image Segmentation: A Review
Zhang Huan, Qiu Dawei, Feng Yibo, and Liu Jing
Recently, with the developments of deep learning technology, deep neural networks have been widely applied in the field of medical image segmentation. Due to its good segmentation performance, U-Net has gradually become a research focus in the field of image segmentation. First, the improved works of U-Net are summarized from two perspectives: structural and non-structural improvements. Then, four medical images of retinal vessels, pulmonary nodules, liver and liver tumors, and brain tumors are used as examples to demonstrate the characteristics and segmentation difficulties of various images and to summarize the application of U-Net and its improved networks in relevant images. Finally, the problems encountered in the improvement of U-Net are discussed, and future developments are forecasted.
  • Dec. 23, 2021
  • Laser & Optoelectronics Progress
  • Vol.59 Issue, 2 0200005 (2022)
  • DOI:10.3788/LOP202259.0200005
Recent Advances of Binary Computed Holography in High-Speed Wavefront Modulation
Fang Zhaoxiang, Zhao Juan, Xiao Zhenzhong, Shi Shaoguang, Sun Rui, and Zhu Liyan
The wavefront modulation system, which swiftly and flexibly performed the wavefront measuring and shaping in a coherent time, is vital in biomedical and optical communications. This high-speed wavefront modulation system, in particular, sets the basis for the effective application of coherent beams in the rapidly-changing scattering media, and digital micromirror devices combined with computed holography are an efficient method for the implementation of this technology. In this study, first, the importance, research advancement, and the application of high-speed wavefront modulation at coherent optical areas were introduced; thereafter, various binary computed holographic methods used in the current wavefront modulation technique were reviewed. The principles and the features of the holographic methods were specifically discussed, existing challenges in the holographic algorithm were summarized, and the trend of the binary computed holography was forecasted.
  • Dec. 23, 2021
  • Laser & Optoelectronics Progress
  • Vol.59 Issue, 2 0200004 (2022)
  • DOI:10.3788/LOP202259.0200004
Research Progress in Ultrasonic Imaging Detection Technology
Zhang Penghui, Zhao Yang, Li Peng, Zhou Zhiquan, Bai Xue, and Ma Jian
Ultrasonic imaging detection (UID) technology has the advantages of intuitive test results, and is one of the main development directions in the field of nondestructive testing in the future. Compared to traditional ultrasonic testing methods, laser ultrasonic detection has gained popularity due to its non-contact characteristics. The time reversal imaging method has a potential application in locating and detecting targets in inhomogeneous media due to its ability of acoustic beam self-focusing in time and space domains. This study primarily reviews the time reversal method and other conventional ultrasonic imaging methods. The results of different imaging algorithms used in the data post-processing are compared and analyzed. Moreover, the professional simulation softwares available for use in the ultrasonic imaging field are briefly summarized. Starting from laser ultrasound and compared to conventional ultrasound, the general situation of the modern ultrasonic testing technology and the advanced industrial ultrasonic imaging testing instruments and equipment at home and abroad are discussed. Further, the future imaging testing technology is briefly analyzed.
  • Dec. 23, 2021
  • Laser & Optoelectronics Progress
  • Vol.59 Issue, 2 0200003 (2022)
  • DOI:10.3788/LOP202259.0200003