Research Progress of Two-Dimensional Nonlinear Optical Limiting Materials
Dong Ningning, Liu Qianghu, and Wang Jun
Significance With the rapid development of laser technologies, the number of laser weapon equipment is increasing. At the same time, human eyes, photoelectric detection equipment, and optical systems are being exposed to strong laser environment and are vulnerable to laser attacks. It is an urgent problem to ensure that these devices have anti-attack capability based on normal operation. Consequently, it is paramount to develop a laser protection technology.Based on the working principle, the laser protection technology can be divided into two types. One is based on the linear optical principle, such as absorption-type filter, reflection-type filter, and coherent filter. The other is based on the nonlinear optical (NLO) principle—also known as optical limiting (OL)—such as nonlinear absorption-, scattering-, and refraction-type optical limiters. In addition, there are thermally induced phase-change materials and liquid-crystal materials, etc. The OL technology can combine high transmittance to weak light and low transmittance to strong light at the same wavelength. In addition, it has obvious advantages in the protection against high-energy, continuous broadband laser spectra, and ultrafast response time. Moreover, it is one of the materials with high practical application value in the field of laser protection.Progress Various materials, such as graphene, transition metal dichalcogenide (TMDC), black phosphorus (BP), carbon nanotube, phthalocyanine, and porphyrin, can be used to fabricate optical limiters. This study focuses on the progress of two-dimensional (2D) nonlinear optical limiting materials, such as graphene, TMDC, and BP, applied in the aspect of laser protection.In 2009, Wang et al. first reported the OL characteristics of high-quality graphene (Fig. 3). By dispersing graphite in organic solvents, they have successfully produced large numbers of graphene mono- and multilayers. A significant NLO response of graphene dispersions to nanosecond laser pulses at 532 nm and 1064 nm was observed, thereby implying a potential broadband OL application. Nonlinear scattering arising from the formation of solvent bubbles and micro-plasmas is the principal mechanism for OL. The surface tension of solvents has a strong influence on the OL performance of graphene dispersions. The OL effect of N,N-dimethylacetamide (DMA) dispersions is better than those of N-methyl-2-pyrrolidone (NMP) and γ-butyrolactone (GBL) dispersions.Feng et al. investigated the NLO and OL properties of graphene families, including graphene oxide nanosheets, graphene nanosheets (GNSs), graphene oxide nanoribbons (GONRs), and graphene nanoribbons (GNRs), using 532 nm and 1064 nm nanosecond lasers (Fig. 4). GNSs, GONRs, and GNRs exhibit broadband NLO and OL properties. The reduced graphene samples exhibit stronger NLO and OL responses than their corresponding oxide precursors due to their increased crystallinity and conjugation. Nonlinear scattering and two-photon absorption are found to have strong effects on the NLO and OL responses of graphene nanostructures.Dong et al. reported the NLO properties of TMDC nanosheet dispersions, including MoS2, MoSe2, WS2, and WSe2, using nanosecond laser pulses at 1064 nm and 532 nm (Fig. 5). The results demonstrate that the TMDC dispersions exhibit a significant OL response at 1064 nm due to nonlinear scattering, contrary to the combined effect of both saturation absorption and nonlinear scattering at 532 nm. Selenium compounds exhibit a better OL performance than sulfides at near-infrared. A liquid dispersion system-based theoretical model is proposed to estimate the number density of nanosheet dispersions, the relationship between the incident laser fluence and the size of laser-generated microbubbles, and the Mie scattering-induced broadband OL behavior in the TMDC dispersions.Li et al. synthesized mono- and multilayer MoS2 triangular islands using a seeding method via chemical vapor deposition (Fig. 6). Distinct NLO responses demonstrate that multilayer MoS2 exhibits the SA effect. However, monolayer MoS2 exhibits a remarkable two-photon absorption effect for a femtosecond laser pulse at 1030 nm. Notably, they observed two-photon pumped upconverted luminescence in monolayer MoS2, another vital third-order NLO response in 2D semiconductors.Huang et al.investigated the wavelength- and pulse-duration-dependent SA properties of BP by a femtosecond laser pulse at 1030 nm/515 nm and a nanosecond laser pulse at 1064 nm/532 nm (Fig. 8). The results reveal that BP exhibits a better NLO response in the visible range than that in the near-infrared range and stronger SA ability in 6 ns-pulsed excitation than in 340-fs-pulsed excitation. Finally, they reported the SA-induced optical transparency and NLS induced optical limiting in BP dispersions.Conclusion and Prospect In this paper, we have introduced the basic concept of a laser protection technology, summarized several laser protection schemes, and illustrated the mechanism of laser protection technology based on the NLO principle. Moreover, we have introduced the research progress of three types of 2D NLO materials—graphene, TMDC, and BP—in term of laser protection. In summary, these materials exhibit OL characteristics in the range of visible to near-infrared bands. For ns-pulsed laser, laser protection is mainly induced by nonlinear scattering, while for fs-pulsed laser, it is dominated by two-photon absorption. Under the same experimental conditions, the OL properties of three materials from strong to weak orders are TMDC, graphene, and BP. In addition, the covalent modification can improve the dispersion of 2D nanomaterials as well as their OL and NLO properties. However, the development of laser protection devices based on these materials is still in the research stage, and they are yet to be practicalized. For 2D nanomaterials, many problems still remain, such as: 1) the materials have a strong aggregation effect, leading to poor dispersion; 2) the problem of realizing the precise control of the layer number and size of 2D materials makes it difficult to achieve low-cost and large-scale material fabrications. In the future, we need to focus on these materials to design and fabricate high-quality covalent chemically modified 2D nanomaterials as well as develop ideal OL devices with broad protective spectral bands, low input thresholds, high linear transmittance to weak radiation, fast responses, and large damage thresholds.
  • Jun. 15, 2021
  • Chinese Journal of Lasers
  • Vol.48 Issue, 13 1300001 (2021)
  • DOI:10.3788/CJL202148.1300001
[in Chinese]
Wang Qingpu
  • Jun. 11, 2021
  • Chinese Journal of Lasers
  • Vol.48 Issue, 12 1200001 (2021)
  • DOI:
A review of silicon-based wafer bonding processes, an approach to realize the monolithic integration of Si-CMOS and III–V-on-Si wafers
Bao Shuyu, Wang Yue, Lina Khaw, Zhang Li, Wang Bing, Sasangka Wardhana Aji, Lee Kenneth Eng Kian, Chua Soo Jin, Michel Jurgen, Fitzgerald Eugene, Tan Chuan Seng, and Lee Kwang Hong
The heterogeneous integration of III–V devices with Si-CMOS on a common Si platform has shown great promise in the new generations of electrical and optical systems for novel applications, such as HEMT or LED with integrated control circuitry. For heterogeneous integration, direct wafer bonding (DWB) techniques can overcome the materials and thermal mismatch issues by directly bonding dissimilar materials systems and device structures together. In addition, DWB can perform at wafer-level, which eases the requirements for integration alignment and increases the scalability for volume production. In this paper, a brief review of the different bonding technologies is discussed. After that, three main DWB techniques of single-, double- and multi-bonding are presented with the demonstrations of various heterogeneous integration applications. Meanwhile, the integration challenges, such as micro-defects, surface roughness and bonding yield are discussed in detail.
  • Jun. 09, 2021
  • Journal of Semiconductors
  • Vol.42 Issue, 2 023106 (2021)
  • DOI:10.1088/1674-4926/42/2/023106
A review: Photonics devices, architectures, and algorithms for optical neural computing
Xiang Shuiying, Han Yanan, Song Ziwei, Guo Xingxing, Zhang Yahui, Ren Zhenxing, Wang Suhong, Ma Yuanting, Zou Weiwen, Ma Bowen, Xu Shaofu, Dong Jianji, Zhou Hailong, Ren Quansheng, Deng Tao, Liu Yan, Han Genquan, and Hao Yue
The explosive growth of data and information has motivated various emerging non-von Neumann computational approaches in the More-than-Moore era. Photonics neuromorphic computing has attracted lots of attention due to the fascinating advantages such as high speed, wide bandwidth, and massive parallelism. Here, we offer a review on the optical neural computing in our research groups at the device and system levels. The photonics neuron and photonics synapse plasticity are presented. In addition, we introduce several optical neural computing architectures and algorithms including photonic spiking neural network, photonic convolutional neural network, photonic matrix computation, photonic reservoir computing, and photonic reinforcement learning. Finally, we summarize the major challenges faced by photonic neuromorphic computing, and propose promising solutions and perspectives.
  • Jun. 09, 2021
  • Journal of Semiconductors
  • Vol.42 Issue, 2 023105 (2021)
  • DOI:10.1088/1674-4926/42/2/023105
Towards electronic-photonic-converged thermo-optic feedback tuning
Tan Min, Ye Kaixuan, Ming Da, Wang Yuhang, Wang Zhicheng, Jin Li, and Feng Junbo
As Moore’s law approaching its end, electronics is hitting its power, bandwidth, and capacity limits. Photonics is able to overcome the performance limits of electronics but lacks practical photonic register and flexible control. Combining electronics and photonics provides the best of both worlds and is widely regarded as an important post-Moore’s direction. For stability and dynamic operations considerations, feedback tuning of photonic devices is required. For silicon photonics, the thermo-optic effect is the most frequently used tuning mechanism due to the advantages of high efficiency and low loss. However, it brings new design requirements, creating new design challenges. Emerging applications, such as optical phased array, optical switches, and optical neural networks, employ a large number of photonic devices, making PCB tuning solutions no longer suitable. Electronic-photonic-converged solutions with compact footprints will play an important role in system scalability. In this paper, we present a unified model for thermo-optic feedback tuning that can be specialized to different applications, review its recent advances, and discuss its future trends.
  • Jun. 09, 2021
  • Journal of Semiconductors
  • Vol.42 Issue, 2 023104 (2021)
  • DOI:10.1088/1674-4926/42/2/023104
Photoic crystal nanobeam cavity devices for on-chip integrated silicon photonics
Yang Daquan, Liu Xiao, Li Xiaogang, Duan Bing, Wang Aiqiang, and Xiao Yunfeng
Integrated circuit (IC) industry has fully considered the fact that the Moore’s Law is slowing down or ending. Alternative solutions are highly and urgently desired to break the physical size limits in the More-than-Moore era. Integrated silicon photonics technology exhibits distinguished potential to achieve faster operation speed, less power dissipation, and lower cost in IC industry, because their COMS compatibility, fast response, and high monolithic integration capability. Particularly, compared with other on-chip resonators (e.g. microrings, 2D photonic crystal cavities) silicon-on-insulator (SOI)-based photonic crystal nanobeam cavity (PCNC) has emerged as a promising platform for on-chip integration, due to their attractive properties of ultra-high Q/V, ultra-compact footprints and convenient integration with silicon bus-waveguides. In this paper, we present a comprehensive review on recent progress of on-chip PCNC devices for lasing, modulation, switching/filting and label-free sensing, etc.
  • Jun. 09, 2021
  • Journal of Semiconductors
  • Vol.42 Issue, 2 023103 (2021)
  • DOI:10.1088/1674-4926/42/2/023103
The past and future of multi-gate field-effect transistors: Process challenges and reliability issues
Sun Ying, Yu Xiao, Zhang Rui, Chen Bing, and Cheng Ran
This work reviews the state-of-the art multi-gate field-effect transistor (MuGFET) process technologies and compares the device performance and reliability characteristics of the MuGFETs with the planar Si CMOS devices. Owing to the 3D wrapped gate structure, MuGFETs can suppress the SCEs and improve the ON-current performance due to the volume inversion of the channel region. As the Si CMOS technology pioneers to sub-10 nm nodes, the process challenges in terms of lithography capability, process integration controversies, performance variability etc. were also discussed in this work. Due to the severe self-heating effect in the MuGFETs, the ballistic transport and reliability characteristics were investigated. Future alternatives for the current Si MuGFET technology were discussed at the end of the paper. More work needs to be done to realize novel high mobility channel MuGFETs with better performance and reliability.
  • Jun. 09, 2021
  • Journal of Semiconductors
  • Vol.42 Issue, 2 023102 (2021)
  • DOI:10.1088/1674-4926/42/2/023102
Mobility enhancement techniques for Ge and GeSn MOSFETs
Cheng Ran, Chen Zhuo, Yuan Sicong, Takenaka Mitsuru, Takagi Shinichi, Han Genquan, and Zhang Rui
  • Jun. 09, 2021
  • Journal of Semiconductors
  • Vol.42 Issue, 2 023101 (2021)
  • DOI:10.1088/1674-4926/42/2/023101
Research Status of Laser Processing Technology of Broken Connecting Rod Cracking Groove
Su Peilin, Cheng Yan, Wang Guan, Zhang Chuanyou, Lin Xiaoping, and Zou Xin
Connecting rod cracking processing is a key technology for connecting rod processing, which contains many advantages, such as fewer processing procedures, which can minimize equipment investment; the material loss is low, which can achieve the effect of energy saving and material saving; and the products have higher quality and improve the carrying capacity of connecting rods. Its core technologies include three types, the first is connecting rod cracking groove processing, the second is the directional splitting connecting rod, and the last is fixed torque assembly bolts. The main processing method of connecting rod cracking groove processing is laser processing. This article mainly introduces the principle and characteristics of laser processing connecting rod cracking tank and the development status, and characteristics and prospects of laser processing connecting rod cracking tank equipment at home and abroad. The characteristics of laser processing connecting rod cracking tank are mainly high precision and high efficiency. At present, domestic and foreign laser processing connecting rod cracking tank equipment is developing in the direction of improving processing efficiency and reducing costs.
  • Jun. 07, 2021
  • Laser & Optoelectronics Progress
  • Vol.58 Issue, 11 1100005 (2021)
  • DOI:10.3788/LOP202158.1100005
Laser-Induced Liquid Micro-Jet Effect and Its Application in Medical Field
Mingxuan Lü, Shi Xiaowei, Xue Jianwei, Wu Lingjin, and Zhang Xianzeng
  • Jun. 07, 2021
  • Laser & Optoelectronics Progress
  • Vol.58 Issue, 11 1100004 (2021)
  • DOI:10.3788/LOP202158.1100004