Chen Li   Kumar Singh Rakesh   Dogariu Aristide   Chen Ziyang   Pu Jixiong  

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Encoding information using the topological charge of vortex beams has been proposed for optical communications. The conservation of the topological charge on propagation and the detection of the topological charge by a receiver are significant in these applications and have been well established in free-space. However, when vortex beams enter a diffuser, the wavefront is distorted, leading to a challenge in the conservation and detection of the topological charge. Here, we present a technique to measure the topological charge of a vortex beam obscured in the randomly scattered light. The results of the numerical simulations and experiments are presented and are in good agreement. In particular, only a single-shot measurement is required to detect the topological charge of vortex beams, indicating that the method is applicable to a dynamic diffuser.

       PDF全文 (下载：0)        Chinese Optics Letters ，2021年第19卷第2期 pp.02      

Wang Pengwei   Wang Chenglong   yu cuiping   yue shuai   Gong Wenlin   Han Shensheng  

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We propose a color ghost imaging approach where the object is illuminated by three-color non-orthogonal random patterns and the object's reflection/transmission information is received by only one single-pixel detector, and both the sparsity constraint and non-local self-similarity of the object are utilized in the image reconstruction process. Numerical simulated results demonstrate that the imaging quality can be obviously enhanced by ghost imaging via sparsity constraint and non-local self-similarity (GISCNL), compared with the reconstruction methods where only the object’s sparsity is used. Factors affecting the quality of GISCNL, such as the measurement number and the detection SNR, are also studied.

       PDF全文 (下载：0)        Chinese Optics Letters ，年第卷第期 pp.      

Pang Chi   Li Rang   Li Ziqi   Dong Ningning   Wang Jun   Ren Feng   Chen Feng  

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Copper nanoparticles (Cu NPs) are synthesized under the near-surface region of the Nd:YAG crystal by direct Cu+ ions implantation. Subsequently, monolithic ridge waveguide with embedded Cu NPs is fabricated by C4+ ions implantation and diamond saw dicing. Nonlinear optical response of the sample is investigated by Z-scan technique and pronounced saturable absorption is observed at 1030 nm femtosecond laser. Based on the obvious saturable absorption of Cu NPs embedded Nd:YAG crystal, 1 μm monolithic mode-locked pulsed waveguide laser is implemented by evanescent field interaction between NPs and waveguide modes, reaching the pulse duration of 24.8 ps and repetition rate of 7.8 GHz. The work combines waveguides with NPs, achieving pulsed laser devices based on monolithic waveguide chip.

       PDF全文 (下载：0)        Chinese Optics Letters ，2021年第19卷第2期 pp.02      

Zhukova Lia   Salimgareev Dmitrii   Lvov Alexandr   Lashova Anastasiya   Korsakov Alexandr   Belousov Dmitrii  

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The article is devoted to the technology for obtaining optical ceramics of AgBr – TlI and AgBr-TlBr0.46I0.54 systems and manufacture samples with different compositions. The new heterophase crystal ceramics is transparent without absorption windows in the spectral range from 1.0 to 60.0 microns. In the ceramics' transparency spectra based on the AgBr – TlI and AgBr – TlBr0.46I0.54 systems fusibility diagrams, with an increase in the thallium halides mass fraction, as well as the replacement of bromine ion with iodine, the maximum transparency shifts to a long infrared region.

       PDF全文 (下载：0)        Chinese Optics Letters ，2021年第19卷第2期 pp.02      

Zhu Jing   Xu Shiqing   Lei Lei   Huang feifei   Xiao Zhen  

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Up-converting(UC) perovskite Er3+-doped PbTiO3 (Er-PTO) nanoparticles with green and red emissions were synthesized via hydrothermal method. The UC properties were manipulated by adjusting the concentration of Er3+ ions dopant. The green emission intensity was decreased as the doping concentration increased from 1 mol% to 4 mol%, whereas the red emission intensity was increased. The influences of Er3+ ions on the temperature-sensing performance were further investigated. The results demonstrated that Er-PTO nanoparticles with doping 1 mol% concentration of Er3+ ions possessed a sensitivity of 3.1×10-3 K-1 at 475 K, presenting a high potential in optical heating devices.

       PDF全文 (下载：0)        Chinese Optics Letters ，2021年第19卷第2期 pp.02      

Wang Guanxue   Miao Yu   Li Yang   Shan Xinzhi   Gao Xiumin  

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The unevenly distributed Lorentz-Gaussian beams are difficult to reproduce in practice, (R2-Q1) because it requires modulation in both amplitude and phase terms. Here a new linearly polarized Lorentz-Gauss beam modulated by a helical axicon (LGB-HA) is calculated and the two various experimental generation methods of this beam, (R2-2-Q1) Fourier Transform Method (FTM) and Complex-Amplitude Modulation (CAM) method are depicted. Compared with Fourier Transform Method, Complex-Amplitude Modulation method can modulate the phase and amplitude simultaneously by only one reflection-type phase-only liquid crystal spatial light modulator. Both the two methods are coincident with the numerical results. (R1-Q6) (R2-Q2) Yet the Complex-Amplitude Modulation is more simple, efficient and has a higher degree of conformance through data comparison. (R1-Q6) (R2-Q2) In addition, considering some barriers existed in shaping and reappearing the complicated Lorentz-Gauss beam with heterogeneous distribution, the evolution regularities of the beams with different parameters (B, n, m) were also implemented.

       PDF全文 (下载：0)        Chinese Optics Letters ，2021年第19卷第2期 pp.02      

Pang Xiaoyan   Feng Chen   Zhao Xinying  

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The evolution of the spin density vectors (SDVs) is studied in a strongly focused composite field. It is found that the SDVs can be spiral along the propagation axis and they are perpendicular to ys direction on the ys axis. This behavior is governed by the Gouy phase difference between the field polarization components. The 60° rotation of the spatial distribution of the transverse SDVs is also generated, which is found to be controlled by the Gouy phase difference between the field orbital angular momentum modes. Additionally, the spin density singularities are observed in the evolution of the SDVs.

       PDF全文 (下载：7)        Chinese Optics Letters ，2021年第19卷第2期 pp.02      

Fang Wei   Yang Kui   Li Haiyuan  

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To balance the accuracy and efficiency in multiple-view triangulation with sequential images, a high-efficiency propagation-based incremental triangulation (INT) method, carving 3D scene point by updating the incoming feature track one-by-one without iterations is proposed. Based on the INT method, a more accurate iteration-limited incremental triangulation (ININT) method is also established with few iterations to bound the propagated errors, ensuring the accuracy of subsequent 3D reconstruction. Finally, experimental results demonstrate that the proposed methods can balance the efficiency and accuracy in different multiple-view incremental triangulation situations.

       PDF全文 (下载：1)        Chinese Optics Letters ，2021年第19卷第2期 pp.02      

Deng Ming   Ren Tangxuan   Wang Jian   Chen Lin  

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Retroreflector that reflects light along its incident direction has found numerous applications in photonics, but the available metasurface schemes suffer from the issue of narrow bandwidth and/or a single angle of incidence. Here a retroreflector using double layers of achromatic gradient metasurfaces is reported, which can realize retroreflection over a continuous range of incidence angles within a wide spectral band. The first metasurface serves as a transmissive achromatic lens that performs a broadband spatial Fourier transform and its inverse, while the second metasurface works as a reflective achromatic lens that undergoes a wavelength- and position-dependent phase dispersions. Using this design strategy, a near-infrared retroreflector comprised of silicon nanopillars with the cross-sections of square pillars and square holes is numerically demonstrated, providing a high-performance retroreflection for polarization-independent incident light waves over a continuous range of incidence angles from 0 to 16° within an extremely broad wavelength range between 1.35 and 1.95 μm. The scheme herein can offer a design strategy of broadband retroreflectors, and impact numerous photonics applications.

       PDF全文 (下载：0)        Chinese Optics Letters ，2021年第19卷第2期 pp.02      

Zhang ZeXin   Tian Jinrong   Xu Changxing   Xu Runqin   Cui Youshuo   Zhuang Bihui   Song Yanrong  

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Noise like pulses having pedestal of 690 fs and spike of 59.6 fs were generated in a nonlinear Yb-doped fiber amplification system. The seed source is a mode-locked Yb-doped fiber laser by nonlinear polarization rotation, and dissipative soliton pulses were obtained in it. Then the dissipative soliton pulses passed through a 7.6-m dispersive fiber to enhance the dispersion and nonlinearity. On further the dissipative soliton pulses were launched into an Yb-doped fiber nonlinear amplifier, and stable noise like pulses with a pedestal of 6.26 ps and spike of 227 fs were achieved. Finally, by a grating pair, the pedestal and spike of the noise like pulses were effectively compressed to 690 fs and 59.6 fs, respectively. To the best of our knowledge, this is the shortest pedestal demonstrated in noise like pulses operating at 1 µm.

       PDF全文 (下载：5)        Chinese Optics Letters ，2020年第18卷第12期 pp.12      

VIJAYAKUMAR   A.   Katkus Tomas   Ng Soon Hock   Juodkazis Saulius  

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Fresnel incoherent correlation holography (FINCH) is a well-established incoherent imaging technique. In FINCH, three self-interference holograms are recorded with calculated phase differences between the two interfering, differently modulated object waves and projected into a complex hologram. The object is reconstructed without the twin image and bias terms by a numerical Fresnel back propagation of the complex hologram. A modified approach to implement FINCH by a single camera shot by pre-calibrating the system involving recording of the point spread function library and reconstruction by a non-linear cross-correlation has been introduced recently. The expression of the imaging characteristics from the modulation functions in original FINCH and the modified approach by pre-calibration in spatial and polarization multiplexing schemes are reviewed. The study reveals that a reconstructing function completely independent of the function of the phase mask is required for the faithful expression of the characteristics of the modulating function in the image reconstruction. In polarization multiplexing method by cross-correlation, a partial expression was observed, while in spatial multiplexing method by cross-correlation, the imaging characteristics converged towards a uniform behavior.

       PDF全文 (下载：1)        Chinese Optics Letters ，2021年第19卷第2期 pp.02      

Liu Xu   TAN CHAOYONG   Cheng Yong   Wei Jingsong   Mengzhen Zhu   CHEN XIA   MI CHAOWEI  

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To obtain short pulse width and high peak power laser, 7 kHz sub-nanosecond microchip laser amplified by a grazing incidence double pass slab amplifier is experimentally demonstrated in this letter. We use a compact side-pumped Nd:YVO4 bounce amplifier with grazing incidence beam for achieving high gains and power extraction. Laser output power of 7.37 W at 7 kHz, 1.2 MW pulse peak power with 877 ps duration and 1.05 mJ energy, 25 pm spectral width, and near diffraction limited mode beam quality are achieved, the optical-to-optical efficiency is 18%. The laser is packaged in a volume of 356×226×84 mm3, may be used for applications such as laser altimeters and ladar systems.

       PDF全文 (下载：2)        Chinese Optics Letters ，2021年第19卷第2期 pp.02      

Kong Hui   Bian Tian   Yao Jiyong   Ye Qing   Sun Xiaoquan  

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The temperature tuning of BGSe was demonstrated for the first time. When the temperature of BGSe (56.3°，0°) rised from 30℃ to 140℃, the idle light under type I raised from 3637 nm to 3989 nm, the tunable range reached 352 nm, and the ∆λ_2/ΔT reached 3.20 nm/℃. We calculated the phase matching curve of BGSe when ∅ and T take different values. The relationship between θ and ∆λ_2/ΔT was obtained by fixing ∅ at 0°. The maximum ∆λ_2/ΔT and its corresponding (θ, ∅), phase matching type were reported under different fixed λ_2 (3μm,3.2μm,…5μm).

       PDF全文 (下载：1)        Chinese Optics Letters ，2021年第19卷第2期 pp.02      

Li Shangyuan   Cao Haidong   Xiaoping Zheng  

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A photonic approach to concurrently measure the angle-of-arrival (AOA) and the chirp rate of a linear frequency modulated (LFM) signal is proposed and experimentally demonstrated. The measurement is achieved by estimating the differential frequency of a two-tone signal output by a dual-parallel Mach-Zehnder modulator and an additional asymmetry Mach-Zehnder interferometer. Experiments show that the AOA and the chirp rate are measured simultaneously, with an AOA measurement error of $\pm 0.1^\circ$ at an SNR of 9.6 dB. When SNR = -10.4 dB, the AOA error is $\pm 1.3^\circ$ and the chirp rate, measured as $210.2\pm1.5\ \rm{Hz/ps}$ has a standard deviation of $0.7\%$. The measured chirp rate agrees well with the real LFM signal.

       PDF全文 (下载：0)        Chinese Optics Letters ，2020年第18卷第12期 pp.12      

Wu Han   Han Bing   wang zinan   Liang Houkun  

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In this letter, we experimentally investigate fast temporal intensity dynamics and statistical properties of the cladding-pumped Er/Yb co-doped random Rayleigh feedback fiber laser (EYRFL) for the first time, to the best of our knowledge. By using the optical spectral filtering method, strong and fast intensity fluctuations with the generation of extreme events are revealed at the output of EYRFL. The statistics of the intensity fluctuations strongly depends on the wavelength of the filtered radiation, and the intensity probability density function (PDF) with heavy tail is observed in the far wings of the spectrum. We also find the PDF of the intensity in the central part of the spectrum deviates from the exponential distribution, and has the dependence on the laser operating regimes, which indicates some correlations among different frequency components exist in the EYRFL radiation and may play an important role in the random lasing spectrum stabilization process.

       PDF全文 (下载：9)        Chinese Optics Letters ，2021年第19卷第2期 pp.02      

Tang Kaifei   Liao Wenbin   Lin Da   Li Bingxuan   chen weidong   Zhang Ge  

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The behavior of self-polarization emission in Nd:YAG/Cr4+:YAG lasers has been proved in some cases, however, the degree and direction of polarization were often sensitive and unstable. We experimentally observed different beam profiles versus the angle of polarizer relative to the polarization direction of laser. In order to explore the polarization mechanism, the dynamics of intracavity polarized eigenmodes were analyzed theoretically. Simulative results were well consistent with our experimental observations. It indicated that the linearly self-polarization emission was a composite state rather than intrinsic state. This study contributed to the improvement of the polarization stability in Nd:YAG/Cr4+:YAG passively Q-switched lasers.

       PDF全文 (下载：0)        Chinese Optics Letters ，2021年第19卷第2期 pp.02      

Gao Chao   Lei Bing  

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We report a spatially modulated polarimetry scheme by using a zero-order vortex half-wave retarder (ZVHR) and spatial Fourier analysis method. A ZVHR is employed to analyze the input polarized light and convert it into a vectorial optical field, and an analyzer is set after the ZVHR to form an hourglass intensity pattern due to the spatial polarization modulation, and then the input light’s Stokes parameters can be calculated by spatial Fourier analysis of the hourglass pattern with a single shot. The working principle of the polarimeter has been analyzed by the Stokes-Mueller formalism, and some quantitative measuring experiments of different polarization states have been demonstrated, and the experimental results indicate that the proposed polarimeter is accurate, robust and simple to use.

       PDF全文 (下载：8)        Chinese Optics Letters ，2021年第19卷第2期 pp.02      

Chen Shuaidong   Liu Bo   Mao Yaya   Ren Jianxin   Song Xiumin   Ullah Rahat   Zhao Delin   Jiang Lei   Han Shun   Zhao Jianye   Shen Jiajia   Liu Xueyang  

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A novel physical layer data encryption using two-level constellation masking in three-dimension carrier-less amplitude and phase modulation passive optical network (3D-CAP-PON) is proposed in this letter. The chaotic sequence generated by the Chua's circuit model realizes two-level encryption of displacement masking and constellation rotation for 3D constellation. We successfully conduct an experiment demonstrating 8.7 Gb/s 3D-CAP-8 data transmission over 25 km standard single-mode fiber (SSMF). With two-level constellation masking, a key space size of 2.1×10⁸⁵is achieved to bring about high security and good encryption performance, suggesting broad application prospects in future short-range secure communications.

       PDF全文 (下载：3)        Chinese Optics Letters ，2021年第19卷第1期 pp.01      

Dai Haitao   Mohamed Zolkefl A.Y.   Xiao Aixiang   Xue Yongxiang   Guo Ziyang   Zhang Yu   Zhang Xiaodong   Liu Changlong  

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In this letter, we report on an Airy-like beam of magnetostatic surface spin wave (AiBMSSW) supported on the ferromagnetic film, which is transferred from optical field. The propagation properties of AiBMSSW were verified with micromagnetic simulation. From simulation results, the typical parabolic trajectory of Airy-type beam was observed by encoding 3/2 phase pattern into excitation sources. The simulation results are coincident well with design parameters. Furthermore, simulated results showed that the trajectories of AiBMSSW beam could be tuned readily with varied external magnetic field. This work can extend the application scenario of SWs.

       PDF全文 (下载：3)        Chinese Optics Letters ，2021年第19卷第1期 pp.01      

Zhang Wending   Zhang Lu   Meng Chao   Gao Feng  

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We present the generation of the nanosecond cylindrical vector beams (CVBs) in two-mode fiber (TMF) and its applications of stimulated Raman scattering. The nanosecond (1064 nm, 10 ns, 10 Hz) CVBs has been directly produced with mode conversion efficiency of ~18 dB (98.4%) via an acoustically-induced fiber grating (AIFG), and then the stimulated Raman scattering signal is generated based on the transmission of the nanosecond CVBs in a 100-meters length TMF. The transverse mode intensity and polarization distributions of the 1st-order Stokes shift component (1116.8 nm) is consistent with the nanosecond CVBs pump pulse.

       PDF全文 (下载：8)        Chinese Optics Letters ，2021年第19卷第1期 pp.01      

Pan Yue   Gao Xu-Zhen   Ma Rende   Tu Chenghou   Li Yongnan   Wang Huitian  

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Orbital angular momentum (OAM), as a fundamental parameter of photon, has attracted great attention in recent years. Although various properties and applications have been developed by modulating the OAM of photons, there is rare research about the non-uniform OAM. We propose and generate a new kind of continuously tunable azimuthally non-uniform OAM for the first time, which is carried by hybridly polarized vector optical field with cylindrically symmetric intensity profile and a complex polarization singularity. We also present the perfect vector optical field carrying non-uniform OAM with fixed radius independent of topological charges, which can propagate steadily without radial separation, solving the problem of the unsteady propagation due to the broaden OAM spectrum of the non-uniform OAM. This new kind of tunable non-uniform OAM with cylindrical symmetric intensity profile, complex polarization singularity and propagation stability enriches the family of OAM, and can be widely used in many regions such as optical manipulation, quantum optics, optical communications and so on.

       PDF全文 (下载：1)        Chinese Optics Letters ，2020年第18卷第12期 pp.12      

Wang Ju   JIA Ting   Wang Shuaishuai   Li Tianyu   Ma Chuang   Xie Tianyuan   Yu Yang   Yu Jinlong  

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We propose a concept of wavelength synchronization to ensure the stability of ultra-dense channels in ultra dense wavelength division multiplexing passive optical network (UDWDM-PON) transmitter. A mode-locked laser (MLL) is used to provide wavelength references for users. By injection locking semiconductor laser, the separation of wavelength reference is realized in optical line terminal (OLT). The downlink and uplink wavelength references are interlaced distributed to facilitate the synchronization of uplink carriers. In optical network unit (ONU), the uplink optical carriers are filtered by injection locking semiconductor lasers, which achieve wavelength synchronization for the uplink users. In this paper, an adaptive wavelength synchronization transmitter for UDWDM-PON is realized with a channel spacing of 5 GHz.

       PDF全文 (下载：0)        Chinese Optics Letters ，2021年第19卷第1期 pp.01      

Zhang Jian   Tu Rui   Huang Chao   Yao Xiaoli   Hu Xin   Ge Haixiong   Zhang Xuefeng  

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Nanogap plasmonic structures with strong coupling between separated components have different responses to orthogonal polarized light, giving rise to giant optical chirality. Here, we proposed a 3D nanostructure consists of two vertically and twistedly aligned nanogaps, showing the hybridized charge distribution within 3D structures. It is discovered that the structure twisted with 60^o performs plasmonic coupling behaviour with/without gap mode for different circular-polarized plane waves, showing giant chiral response (ΔT) of 60% at the wavelength of 1550 nm. By controlling the disk radius and the insulator layer, the CD signal can be further tuned between 1538~1626 nm.

       PDF全文 (下载：1)        Chinese Optics Letters ，2021年第19卷第1期 pp.01      

Wang Yanyi   WANG KAIHUI   Zhou Wen   Yu Jianjun  

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A novel and simple scheme of photonic aided vector millimeter-wave (mm-wave) signal generation without a digital to analog converter (DAC) is proposed. Based on our scheme, 20Gb/s 4-ary quadrature amplitude modulation (4-QAM) mm-wave signal is generated without using a DAC. The experiment results demonstrate that the bit error rate (BER) of 20Gb/s 4-QAM mm-wave signal can reach below hard-decision forward-error-correction (HD-FEC) threshold of 3.8x10-3 after a delivery over 1-m wireless distance. Because the DAC is not required, it can reduce the system cost. Besides, by using photonic technology, the system is easily integrated to create large-scale production and application in high- speed optical communication

       PDF全文 (下载：0)        Chinese Optics Letters ，2021年第19卷第1期 pp.01      

Zhou Yuewen   Zhang Fangzheng   Pan Shilong  

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We propose a photonics-assisted equivalent frequency sampling (EFS) method to analyze the instantaneous frequency of broadband linearly frequency modulated (LFM) microwave signals. The proposed EFS method is implemented by a photonic scanning receiver which is operated with a frequency scanning rate slightly different from the repetition rate of the LFM signals. Compared with the broadband LFM signal analysis based on temporal sampling, the proposed method avoids the use of high-speed analog to digital converters and the instantaneous frequency acquisition realized by frequency-to-time mapping is also simplified since real-time Fourier transformation is not required. Feasibility of the proposed method is verified through an experiment, in which frequency analysis of Ka-band LFM signals with a bandwidth up to 3 GHz is demonstrated with a moderate sampling rate of 100 MSa/s. The proposed method is highly demanded for analyzing the instantaneous frequency of broadband LFM signals used in radar and electronic warfare systems.

       PDF全文 (下载：5)        Chinese Optics Letters ，2021年第19卷第1期 pp.01      

Sun Hao   Yang Jie   Liu Hengzhu   Zheng Xin   Wu Dan  

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Recently reported plasmon-induced transparency (PIT) in metamaterials endows the optical structures in classical system with quantum optical effects. In particular, nonreconfigurable nature in metamaterials makes multifunctional applications of PIT effect in terahertz communications and optical networks remain a great challenge. Here we present an ultrafast process-selectable modulation of PIT effect. By incorporating silicon islands into diatomic metamaterials, the PIT effect is modulated reversely, depending on the vertical and horizontal configurations, with giant modulation depth as high as 129% and 109%. Accompanied by the enormous switching of transparent window, remarkable slow light effect occurs.

       PDF全文 (下载：1)        Chinese Optics Letters ，2021年第19卷第1期 pp.01      

Yuan Qizhang   Feng Xunli  

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Recently the nested Mach-Zehnder interferometer [Phys. Rev. Lett.111, 240402 (2013)] was modified by adding Dove prisms in a paper [Quantum Stud.: Math. Found. 2, 255 (2015)], and an interesting result is that, after the Dove prisms being inserted, a signal at the first mirror of the nested interferometer was obtained. But according to the former original paper, the photons have never been present near that mirror. In this work we interpret this result naturally by resorting to the three path interference method. Moreover, we find that even the photons have been somewhere, they can hide the trace of being there.

       PDF全文 (下载：3)        Chinese Optics Letters ，2021年第19卷第1期 pp.01      

Li Wentao   Zhou Jian  

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In order to solve the shortcomings of the traditional contact and non-contact rotational speed measurement methods, and further improve the accuracy and universality of the rotational speed measurement, an instantaneous rotational speed measurement method based on laser Doppler technology is proposed. The principle of laser Doppler velocimeter is expounded, and the composition and working principle of the new system are discussed in detail. Theoretical and experimental results show that: the new rotational speed measurement system belongs to the non-contact measurement method, which greatly improves the applicability and accuracy. Compared to the commonly used speed measurement method, the measurement accuracy of the new speed measurement system will not be affected by the system’s installation angle deviation, and it does not need to measure the radius of the rotating body, so the influence of the radius fluctuation of the rotating body on the measurement accuracy can be avoided while outputting the rotational speed in real time. The relative error of the rotational speed measurement is less than 0.06% (1σ).

       PDF全文 (下载：2)        Chinese Optics Letters ，2021年第19卷第1期 pp.01      

Shen Danyang   Qian Jing   Wang Chengwei   Wang Guande   Wang Xuehui   Zhao Quanzhong  

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One-step precipitation of Ag nanoparticles in Ag+-doped silicate glasses was achieved through a focused picosecond laser with a high-repetition rate. Absorption spectra and transmission electron microscopy (TEM) confirmed that metallic Ag nanoparticles were precipitated within glass samples in the laser-written domain. The surface plasmon absorbance fits well with the experimental absorption spectrum. The nonlinear absorption coefficient β is determined to be 2.47 × 10−14 m/W by fitting the open aperture Z-scan curve, which originating from the intraband transition in the s-p Ag band. The formation mechanism of Ag-glass nanocomposites is discussed as well.

       PDF全文 (下载：5)        Chinese Optics Letters ，2021年第19卷第1期 pp.01      

Lu Cuicui   Ma Lifeng   Li Jing   Liu Zhouhui   Zhang Yuxuan   Zhang Nianen   Zheng Shuqiao  

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The research on nanophotonic devices has made great progress during the past decades. It is the unremitting pursuit of researchers that realize various device functions to meet practical applications. However, most of the traditional methods rely on human experience and physical inspiration for structural design and parameter optimization, which usually require a lot of resources, and the performance of the designed device is limited. Intelligent algorithms, which are composed of rich optimized algorithms, show a vigorous development trend in the field of nanophotonic devices in recent years. The design of nanophotonic devices by intelligent algorithms can break the restrictions of traditional methods and predict novel configurations, which is universal and efficient for different materials, different structures, different modes and different wavelengths, etc. In this review, intelligent algorithms for designing nanophotonic devices are introduced from their concepts to their applications, including deep learning methods, the gradient-based inverse design method, swarm intelligence algorithms, individual inspired algorithms and some other algorithms. The design principle based on intelligent algorithms and the design of typical new nanophotonic devices are reviewed. Intelligent algorithms can play an important role in designing complex functions and improving the performances of nanophotonic devices, which provide new avenues for the realization of photonic chip.

       PDF全文 (下载：2)        Chinese Optics Letters ，2021年第19卷第1期 pp.01