Contents
2020
Volume: 18 Issue 5
17 Article(s)

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Reviews
Quantum Optics and Quantum Information
Research Articles
Biomedical Optics
Detection of breast cancer based on novel porous silicon Bragg reflector surface-enhanced Raman spectroscopy-active structure
Xiaorong Ma, Hong Cheng, Junwei Hou, Zhenhong Jia, Guohua Wu, Xiaoyi Lü, Hongyi Li, Xiangxiang Zheng, and Chen Chen
In this Letter, the surface-enhanced Raman scattering (SERS) signal of early breast cancer (BRC) patient serum is obtained by a composite silver nanoparticles (Ag NPs) PSi Bragg reflector SERS substrate. Based on these advantages, the serum SERS signals of 30 normal people and 30 early BRC patients were detected by this substrate. After a baseline correction of the experimental data, principal component analysis and linear discriminant analysis were used to complete the data processing. The results showed that the diagnostic accuracy, specificity, and sensitivity of the composite Ag NPs PSi Bragg reflector SERS substrate were 95%, 96.7%, and 93.3%, respectively. The results of this exploratory study prove that the detection of early BRC serum based on a composite Ag NPs PSi Bragg reflector SERS substrate is with a stable strong SERS signal, and an unmarked and noninvasive BRC diagnosis technology. In the future, this technology can serve as a noninvasive clinical tool to detect cancer diseases and have a considerable impact on clinical medical detection.
Chinese Optics Letters
  • Publication Date: May. 10, 2020
  • Vol. 18, Issue 5, 051701 (2020)
Fiber Optics and Optical Communications
Uniformly high-speed semi-open loop polarization control and PMD suppression | Editors' Pick
Bochen Wang, and Zhengyong Li
We propose and demonstrate a novel scheme of semi-open-loop polarization control (SOL-PC), which controls the state of polarization (SOP) with high accuracy and uniform high speed. For any desired SOP, we first adjust the initial SOP using open-loop control (OLC) based on the matrix model of a three-unit piezoelectric polarization controller, and quickly move it close to the objective one. Then closed-loop control (CLC) is performed to reduce the error and reach precisely the desired SOP. The response time is three orders faster than that of the present closed-loop polarization control, while the average deviation is on par with it. Finally, the SOL-PC system is successfully applied to realize the suppression of the polarization mode dispersion (PMD) effect and reduce the first-order PMD to near zero. Due to its perfect performance, the SOL-PC energizes the present polarization control to pursue an ideal product that can meet the future requirements in ultrafast optical transmission and quantum communication.
Chinese Optics Letters
  • Publication Date: May. 10, 2020
  • Vol. 18, Issue 5, 050601 (2020)
Deep learning for position fixing in the micron scale by using convolutional neural networks
Hongye Li, Hu Liang, Qihao Hu, Meng Wang, and Zefeng Wang
Chinese Optics Letters
  • Publication Date: May. 10, 2020
  • Vol. 18, Issue 5, 050602 (2020)
Integrated Optics
Experimental observation of topologically protected defect states in silicon waveguide arrays
Tianying Lin, Ze Chen, Xiaopei Zhang, He Li, Xiaoping Liu, and Haibin Lü
Photonic waveguide arrays provide a simple and versatile platform for simulating conventional topological systems. Here, we investigate a novel one-dimensional (1D) topological band structure, a dimer chain, consisting of silicon waveguides with alternating self-coupling and inter-coupling. Coupled mode theory is used to study topological features of such a model. It is found that topological invariants of our proposed model are described by the global Berry phase instead of the Berry phase of the upper or lower energy band, which is commonly used in the 1D topological models such as the Su–Schrieffer–Heeger model. Next, we design an array configuration composed of two dimer patterns with different global Berry phases to realize the topologically protected waveguiding. The topologically protected propagation feature is simulated based on the finite-difference time-domain method and then observed in the experiment. Our results provide an in-depth understanding of the dynamics of the topological defect state in a 1D silicon waveguide array, and may provide different routes for on-chip lightwave shaping and routing.
Chinese Optics Letters
  • Publication Date: May. 10, 2020
  • Vol. 18, Issue 5, 051301 (2020)
Lasers and Laser Optics
Temperature measurement based on adaptive dual-comb absorption spectral detection
Kangwen Yang, Hai Li, Hang Gong, Xuling Shen, Qiang Hao, Ming Yan, Kun Huang, and Heping Zeng
Chinese Optics Letters
  • Publication Date: May. 10, 2020
  • Vol. 18, Issue 5, 051401 (2020)
Investigation of multispectral SF6 stimulated Raman scattering laser
Chencheng Shen, Xianglong Cai, Youbao Sang, Tiancheng Zheng, Zhonghui Li, Dong Liu, Wanfa Liu, and Jingwei Guo
Chinese Optics Letters
  • Publication Date: May. 10, 2020
  • Vol. 18, Issue 5, 051402 (2020)
Experimental investigation of spontaneous emission characteristics of InGaAs-based indium-rich cluster-induced special quantum structure | Editors' Pick
Ming Zheng, Qingnan Yu, Hanxu Tai, Jianwei Zhang, Yongqiang Ning, and Jian Wu
The unamplified spontaneous emission (SE) is one of the important physical processes of the light–matter interaction in a diode laser in terms of Einstein’s theory. The recent research on a kind of new indium-rich cluster (IRC) laser structure did not reveal SE characteristics of the IRC structure, as its unusual quantum confined structure made it difficult to acquire correctly the SE spectra through theoretical simulation or previous experimental techniques. Thus, in this Letter, we firstly established a convenient and effective experimental approach to acquire SE spectra of the IRC structure by the measurement of amplified SEs from dual facets of a single edge-emitting chip with little sample processing. With the proposed method, the special SE spectra due to the IRC effect were observed. Then, the SE formation mechanism and characteristics in the IRC structure were analyzed by comparing the experimental data with theoretical SE spectra using a standard InGaAs/GaAs quantum well with similar material composition. This research provides a useful tool to investigate the SE characteristics of any non-standard diode laser structure and is very meaningful to develop a new type of IRC lasers.
Chinese Optics Letters
  • Publication Date: May. 10, 2020
  • Vol. 18, Issue 5, 051403 (2020)
Ultimate capacity analysis of cladding-pumped 10/130 Tm:fiber laser
Encai Ji, Jie Shi, Congwen Zha, Jing Zeng, Xinwu Zhou, Zhengdi He, Yong Yao, and Qitao Lü
The ultimate capacity of a cladding-pumped 10/130 Tm:fiber is experimentally investigated with a 793 nm laser diode bidirectionally pumped amplifier. The laser system works stably at the output powers of 52 W, 65 W, and 87 W. Eventually, the damage of the amplifier occurs when the output power reaches about 103.5 W with a total incident pump power of 176.8 W. Considering the incident seed power of 12.3 W, the amplifier conversion efficiency is estimated to be about 51.6% before it is damaged. With valuable exploration, we achieve the first air-cooling 60 W Tm:fiber laser at 1945.845 nm with a spectral linewidth of 0.4 nm. The laser power stability reaches 1.24% during a continuous test time of >65 h. The beam quality is measured as Mx2=1.16 and My2=1.14.
Chinese Optics Letters
  • Publication Date: May. 10, 2020
  • Vol. 18, Issue 5, 051404 (2020)
Laser-induced liquid tin discharge plasma and its EUV spectra
Junwu Wang, Xinbing Wang, Duluo Zuo, and Vassily Zakharov
Laser-induced discharge plasmas (LDPs) have the potential to be inspection and metrology sources in extreme ultraviolet (EUV) lithography. An LDP EUV source was developed to avoid tin electrode erosion in which a tin pool was used as a cathode. A CO2 pulse laser was focused on the liquid tin target surface, and then a breakdown occurred in a very short time. The voltage-current characteristics of the discharge oscillated, lasting for several microseconds, and an RLC fitting model was used to obtain the inductance and resistance. An intensified charge-coupled device (ICCD) camera was used to investigate the dynamics of LDP, which can explain the formation of a discharge channel. The EUV spectra of laser-induced liquid tin discharge plasma were detected by a grazing incident ultraviolet spectrometer, compared with a laser-produced tin droplet plasma EUV spectrum. To explain the EUV spectrum difference of laser-induced liquid tin discharge plasma and laser-produced tin droplet plasma, the collision radiation (CR) model combined with COWAN code was used to fit the experimental EUV spectrum, which can estimate the electron temperature and density of the plasma.
Chinese Optics Letters
  • Publication Date: May. 10, 2020
  • Vol. 18, Issue 5, 051405 (2020)
Materials
Blue–green color-tunable emissions in novel transparent Sr2LuF7:Eu/Tb glass-ceramics for WLEDs
Xiaoman Li, Shaoshuai Zhou, Rongfei Wei, Xueyun Liu, Bingqiang Cao, and Hai Guo
To introduce ordered nano-structures inside a transparent amorphous matrix with superior optical and mechanical properties bears scientific and technological importance, yet limited success has been achieved. Here, via simple melting-quenching and subsequent thermal activation, we report the successful preparation of transparent nano-structured glass-ceramics embedded in Sr2LuF7 nano-crystals (~26 nm), as evidenced by X-ray diffraction, transmission electron microscopy (TEM), and high resolution TEM. The successful incorporation of dopants into formed Sr2LuF7 nano-crystals with low phonon energy results in highly tunable blue–green photoemission, which depends on excitation wavelength, dopant type, and temperature. We found that Eu3+ and Eu2+ ions co-exist in this hybrid optical material, accompanied by the broadband blue emission of Eu2+ and sharp red emissions of Eu3+. A series of optical characterizations are summoned, including emission/excitation spectrum and decay curve measurement, to reveal the reduction mechanism of Eu3+ to Eu2+. Furthermore, near green–white photoemission is achieved via the enrichment of Tb3+/Eu3+ into crystallized Sr2LuF7 nano-crystals. The temperature-dependent visible photoemission reveals thermal activation energy increases with the precipitation of Sr2LuF7 nano-crystals in a glass matrix, suggesting better thermal stability of glass-ceramics than precursor glasses. These results could not only deepen the understanding of glass-ceramics but also indicate the promising potential of Eu3+/Tb3+-ions-doped Sr2LuF7 glass-ceramics for UV pumped white light emitting diodes (WLEDs) with good thermal stability.
Chinese Optics Letters
  • Publication Date: May. 10, 2020
  • Vol. 18, Issue 5, 051601 (2020)
Nonlinear Optics
Optical Sensing, Measurements, and Metrology
Displacement measurement method based on laser self-mixing interference in the presence of speckle
Yan Zhao, and Haiwei Zhang
In order to achieve the accurate measurement of displacement, this Letter presents a self-mixing interference displacement measurement method suitable for the speckle effect. Because of the speckle effect, the amplitude of the self-mixing interference signal fluctuates greatly, which will affect the measurement accuracy of displacement. The ensemble empirical mode decomposition is used to process the interference signal, which can filter out high-frequency noise and low-frequency noise at the same time. The envelope of the self-mixing interference signal is extracted by Hilbert transform, and it is used to realize the normalization of the signal. Through a series of signal processing, the influence of speckle can be effectively reduced, and the self-mixing interference signal can be transformed into standard form. The displacement can be reconstructed by fringe counting and the interpolation method. The experimental results show that the method is successfully applied to the displacement measurement in the presence of speckle, which verifies the effectiveness and feasibility of the method.
Chinese Optics Letters
  • Publication Date: May. 10, 2020
  • Vol. 18, Issue 5, 051201 (2020)
Optoelectronics
Physical Optics
Broadband NIR absorber based on square lattice arrangement in metallic and dielectric state VO2
Rong Tian, Yi Li, Zhimin Liu, Jianzhong Zhou, Jin Liu, Lina Fan, Wenqing Zhao, Junxian Li, Xin Zhang, Chuang Peng, Yuda Wu, Xiaohua Wang, and Baoying Fang
Chinese Optics Letters
  • Publication Date: May. 10, 2020
  • Vol. 18, Issue 5, 052601 (2020)
Plasmonics and Metamaterials
Wide range bilayer aluminum nanowire grating sensors with robust reflective peaks
Zhicheng Ye, and Jun Zheng
Chinese Optics Letters
  • Publication Date: May. 10, 2020
  • Vol. 18, Issue 5, 052401 (2020)
A polarization-insensitive fishnet/spacer/mirror plasmonic absorber for hot electron photodetection application
Zhiqiang Yang, Kang Du, Wending Zhang, Soojin Chua, and Ting Mei
Chinese Optics Letters
  • Publication Date: May. 10, 2020
  • Vol. 18, Issue 5, 052402 (2020)