Optics express最新文献

{"title":"Multi-parameter optimization of polarization gradient cooling for ⁸⁷Rb atoms based on reinforcement learning.","authors":"Changwen Liang, Shaojun Gao, Jixun Liu, Guochao Wang, Shuhua Yan, Jun Yang, Lingxiao Zhu, Xiaoxiao Ma","doi":"10.1364/OE.537239","DOIUrl":"https://doi.org/10.1364/OE.537239","url":null,"abstract":"<p><p>Polarization gradient cooling (PGC) plays an important role in many cold atom applications including the formation of Bose-Einstein condensates (BECs) and cooling of single atoms. Traditional parameter optimization of PGC usually relies on subjective expertise, faces challenges in fine manipulation, and exhibits low optimization efficiency. Here, we propose a segmented control method that differs from the traditional PGC process by expanding the experiment parameters from 3 to 30. Subsequently, the conventional timing optimization problem is reformulated as a Markov decision process (MDP), and the experiment parameters are optimized using a reinforcement learning model. With proper settings of hyperparameters, the learning process exhibits good convergence and powerful parameter exploration capabilities. Finally, we capture ∼4.3 × 10⁸ cold atoms, with a phase space density of ∼7.1 × 10^-4 at a temperature of ∼3.7 µK in ∼18.8 min. Our work paves the way for the intelligent preparation of degenerate quantum gas.</p>","PeriodicalId":19691,"journal":{"name":"Optics express","volume":"32 23","pages":"40364-40374"},"PeriodicalIF":3.2,"publicationDate":"2024-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142688147","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Flat double-layer metal-only metasurface with polarization-dependent operation in a C/X dual band.","authors":"Xiangshuai Meng, Haoyu Zhang, Yujie Wang, Tao Wu, Anxue Zhang, Xiaoming Chen","doi":"10.1364/OE.539420","DOIUrl":"https://doi.org/10.1364/OE.539420","url":null,"abstract":"<p><p>In this communication, a dual-band, orthogonal polarization transmission metasurface antenna operating at 6.5 GHz and 9.5 GHz is proposed. The element of this transmitarray is composed of only two identical layers of metal plates, with air medium filling the space between the upper and lower layers. Each layer has four sets of staggered I-slots, thus ensuring dual-frequency orthogonal polarization operation. Moreover the proposed element overcomes the challenge of achieving full 360-degree phase shift in dual-layer metal-only structures without any additional connecting elements. By altering the length of the slots, it can achieve a continuous full 360-degree phase shift while maintaining a transmission amplitude above -2 dB and exhibits co-polarized transmission in both bands. Then a prototype containing 16 × 16 elements is designed and fabricated to verify the feasibility of the design scheme. The measurement results, which are consistent with the simulation, demonstrate that the maximum gains of 24.85 and 27.64 dBi are obtained at 6.4 GHz and 9.4 GHz, with corresponding aperture efficiencies of 23.18% and 20.4% and a 3-dB gain bandwidth of 15.6% and 22.34%. The good transmission coefficients of the element and the dual-band capability make the design a competitive candidate for satellite and high-power applications.</p>","PeriodicalId":19691,"journal":{"name":"Optics express","volume":"32 23","pages":"40979-40989"},"PeriodicalIF":3.2,"publicationDate":"2024-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142688337","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Picometer-scale OAM interferometry using an adaptive polar transform algorithm.","authors":"Lanlin Ni, Haojie Xia, FeiFan Xu, Qiang Wu, Jin Zhang, Songtao Chang","doi":"10.1364/OE.539096","DOIUrl":"https://doi.org/10.1364/OE.539096","url":null,"abstract":"<p><p>A phase demodulation algorithm based on an adaptive polar transform is proposed that can achieve picometer-scale measurements in orbital angular momentum (OAM) interferometry. The proposed algorithm converts the rotational movement in a petal-shaped interference pattern into translational movement of the grayscale projection curves, so that can be easily measured using correlation operations to determine the pixel displacement in determining the rotation angle. Displacements ranging from -120 nm to 120 nm have been measured for various topological charges, with a minimum average deviation of 0.07 nm. Furthermore, we have studied the effects of piezoelectric transducer alignment, various binary threshold values, fringe occlusion, and charge-coupled device (CCD) camera resolutions on displacement measurement. Comparative experiments indicate that the proposed algorithm can effectively manage the local measurement challenges in traditional OAM interferometers, demonstrating better measurement accuracy and robustness than several existing phase demodulation algorithms.</p>","PeriodicalId":19691,"journal":{"name":"Optics express","volume":"32 23","pages":"40227-40243"},"PeriodicalIF":3.2,"publicationDate":"2024-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142688339","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Two-step Fourier single-pixel imaging for secure and efficient hidden information transmission.","authors":"Zihao Wang, Yongan Wen, Yu Ma, Yilin Tian, Yanzhao Cui, Wei Peng, Feifei Wang, Yang Lu","doi":"10.1364/OE.541427","DOIUrl":"https://doi.org/10.1364/OE.541427","url":null,"abstract":"<p><p>In the rapidly evolving field of optical information security, single-pixel imaging (SPI) has emerged as a promising technique for hidden information transmission. However, traditional SPI methods face significant challenges, including the need for excessive modulation patterns and the vulnerability of encrypted information during transmission. Furthermore, the field lacks efficient methods to reconstruct both plaintext and ciphertext images from the same set of single-pixel measurements. Here, we propose a novel and efficient encryption strategy for Fourier single-pixel imaging (FSPI) that addresses these critical challenges. Our approach integrates two key innovations: a two-step Fourier-total variation conjugate gradient descent (F-TVCGD) method and a dual-key decryption mechanism. The F-TVCGD method significantly reduces the number of modulation patterns required for image reconstruction, enhancing efficiency and minimizing data redundancy. Our dual-key mechanism enables the reconstruction of both plaintext and ciphertext images from a single set of single-pixel measurements using different decryption keys, significantly enhancing security without compromising efficiency. The incorporation of Fourier symmetric patterns improves the convergence robustness of the symmetric gradient descent (SGD) algorithm, leading to superior performance under challenging conditions such as sparse sampling and noise attacks. Numerical simulations and optical experiments validate our method's improvements in both accuracy and security compared to traditional approaches. Our findings demonstrate that the proposed F-TVCGD and SGD strategies effectively address the challenges of excessive modulation patterns and information vulnerability in FSPI.</p>","PeriodicalId":19691,"journal":{"name":"Optics express","volume":"32 23","pages":"41255-41269"},"PeriodicalIF":3.2,"publicationDate":"2024-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142687988","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Determination of zooplankton absorption spectra and their potential contribution to ocean color.","authors":"Cait L McCarry, Sünnje L Basedow, Emlyn J Davies, Kim S Last, David McKee","doi":"10.1364/OE.537062","DOIUrl":"https://doi.org/10.1364/OE.537062","url":null,"abstract":"<p><p>Zooplankton are keystone organisms that provide a critical link between primary production and higher-order predators in the marine food web, as well as facilitating the sequestration of carbon within the ocean. In this context, there is considerable interest in the detection of zooplankton swarms from satellite ocean color signals. However, for this to be possible, accurate inherent optical property characterization of key zooplankton groups is first required. In this study, spectral absorption properties of six epipelagic zooplankton groups have been measured using what we believe to be a novel serial addition technique carried out with a Point Source Integrating Cavity Absorption Meter. The measured absorption spectra were used to model the impact of each group on remote sensing reflectance signals and determine a concentration threshold that would generate a distinguishable signal from ocean color data. Results indicate that the spectral shape of absorption did not vary much between species, with most organisms showing a peak at around 480 nm, characteristic of the pigment astaxanthin. Conversely, the magnitude of absorption did vary considerably between species, with larger organisms typically producing stronger absorption signals than smaller species. Thus, detection thresholds also varied for each group measured and were additionally influenced by background constituents within the water column. The calculated concentration thresholds indicate the feasibility of identifying zooplankton from ocean color, but owing to the spectral similarity in absorption properties, knowledge of in situ populations would be required to determine species abundances from satellite signals.</p>","PeriodicalId":19691,"journal":{"name":"Optics express","volume":"32 23","pages":"41314-41334"},"PeriodicalIF":3.2,"publicationDate":"2024-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142688212","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"3D coherent single shot lidar imaging beyond coherence length.","authors":"Ataberk Atalar, Christian Joseph Margison, Mustafa Mert Bayer, Xun Li, Ozan Berk Boyraz, Ozdal Boyraz","doi":"10.1364/OE.529563","DOIUrl":"https://doi.org/10.1364/OE.529563","url":null,"abstract":"<p><p>Advancements in remote sensing and autonomous vehicle technologies made lidars equally important for unmanned objects alongside cameras. Therefore, precise 3D lidar imaging and point cloud generation have become important subjects. Although existing coherent lidar technologies provide precise imaging results, the spectral linewidth of the laser sources becomes a key limitation over long distances as it defines the maximum detection range. Here, we present long-distance 3D lidar imaging which removes the coherence length limitations and therefore the necessity of high-coherence laser sources. Mainly, we generate optical sidebands, by modulating a continuous wave (CW) laser source with multiple radio-frequency (RF) tones. Then, using our own post-processing and triangulation methods, we use the relative phase changes between the sidebands which are free from laser phase noise to determine the target distance. We prove that the multi-tone coherent Lidar technique can perform precise 3D imaging and point cloud generation of various targets at sub-10pW optical power reception and distances up to ∼12× beyond the coherence length of the CW laser employed in the lidar architecture. Overall, it is demonstrated that coherence length restriction is removed by the suggested method, which makes precise long-distance 3D lidar imaging possible, particularly for applications such as spacecraft and aerial coherent lidars.</p>","PeriodicalId":19691,"journal":{"name":"Optics express","volume":"32 23","pages":"40783-40793"},"PeriodicalIF":3.2,"publicationDate":"2024-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142688338","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Real-time holographic 3D display using Split-Lohmann Fresnel computer-generated hologram (SL-FCGH).","authors":"Xian Ding, Chenliang Chang, Bo Dai, Qi Wang, Dawei Zhang, Songlin Zhuang","doi":"10.1364/OE.534359","DOIUrl":"https://doi.org/10.1364/OE.534359","url":null,"abstract":"<p><p>Real-time generation of computer-generated hologram (CGH) from three-dimensional (3D) objects has been a long-standing problem in holographic display. In this paper we report a fast CGH generation algorithm, which can rapidly synthesize a 3D Fresnel hologram in only one-step backward propagation calculation in a Split-Lohmann lens-based diffraction model. In such a calculation scheme, we utilize an image padding and cropping strategy to remove image artifacts and improve the display quality in a large depth range. The generated hologram, which is called Split-Lohmann Fresnel CGH (SL-FCGH), can reproduce 3D images through free-space Fresnel diffraction optics. The computation time of the proposed method is independent of the quantized layer numbers and, therefore, can achieve real-time computation speed with a very dense depth sampling. Both simulation and experimental results of full-color holographic display prove the validation of the proposed method.</p>","PeriodicalId":19691,"journal":{"name":"Optics express","volume":"32 23","pages":"40175-40189"},"PeriodicalIF":3.2,"publicationDate":"2024-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142688378","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reconfigurable binary diffractive optical neural network based on chalcogenide phase change material Ge₂Sb₂Se₄Te₁.","authors":"Ziwei Fu, Tingzhao Fu, Hao Wu, Zhihong Zhu, Jianfa Zhang","doi":"10.1364/OE.539235","DOIUrl":"https://doi.org/10.1364/OE.539235","url":null,"abstract":"<p><p>Diffractive optical neural networks (DONNs) possess unique advantages such as light-speed computing, low energy consumption, and parallel processing, which have obtained increasing attention in recent years. However, once conventional DONNs are fabricated, their function remains fixed, which greatly limits the applications of DONNs. Thus, we propose a reconfigurable DONN framework based on a repeatable and non-volatile phase change material Ge₂Sb₂Se₄Te₁(GSST). By utilizing phase modulation units made of GSST to form the network's neurons, we can flexibly switch the functions of the DONN. Meanwhile, we apply a binary training algorithm to train the DONN weights to binary values of 0 and π, which is beneficial for simplifying the design and fabrication of DONN while reducing errors during physical implementation. Furthermore, the reconfigurable binary DONN has been trained as a handwritten digit classifier and a fashion product classifier to validate the feasibility of the framework. This work provides an efficient and flexible control mechanism for reconfigurable DONNs, with potential applications in various complex tasks.</p>","PeriodicalId":19691,"journal":{"name":"Optics express","volume":"32 23","pages":"41433-41444"},"PeriodicalIF":3.2,"publicationDate":"2024-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142688404","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Adaptive generation of optical single-sideband signal with dually modulated EML.","authors":"Shuhua Zhao, Tianwai Bo, Zhongwei Tan, Yi Dong","doi":"10.1364/OE.539989","DOIUrl":"https://doi.org/10.1364/OE.539989","url":null,"abstract":"<p><p>The optical single sideband (SSB) transmitter based on dual modulation of an electro-absorption modulation laser (D-EML) has attracted considerable attention for its capability of monolithic integration and high output power. A model-based modulation method has been developed recently for generating high-quality optical SSB signals with this D-EML scheme. However, this method requires accurate characterization of the EML's chirps and pre-compensation for frequency responses of all-optical/electrical components, as well as the path difference between two driving signals. This imposes notable requirements on the transmitter characterization in practical applications. In this paper, we propose an adaptive method to approach the required responses of the pre-compensation filters for this optical SSB transmitter. This method avoids cumbersome device characterization and shows great resilience to the variation of system parameters. By using the proposed adaptive method, we generate a 56 Gb/s optical SSB orthogonal frequency-division multiplexed signal with the sideband suppression power ratio exceeding 21 dB. It is convenient with this method to switch the devices, i.e., directly modulated laser (DML) or electro-absorption modulator (EAM), to be pre-compensated for the optical SSB signal generation. Moreover, this method exhibits good tolerance to the path delay (±15 ps) between DML and EAM, as well as modulation depth. We also successfully transmit this signal over 80 km long standard single-mode fiber.</p>","PeriodicalId":19691,"journal":{"name":"Optics express","volume":"32 23","pages":"41500-41510"},"PeriodicalIF":3.2,"publicationDate":"2024-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142686574","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Optical turbulence simulations over the Tibetan Plateau based on a single-column model with high-order closure.","authors":"Kaixuan Yang, Tao Luo, Xuebin Li, Shengcheng Cui, Xiaoqing Wu, Kun Zhang","doi":"10.1364/OE.539239","DOIUrl":"https://doi.org/10.1364/OE.539239","url":null,"abstract":"<p><p>Optical turbulence limits the maximum resolution of ground-based telescopes and leads to image degradation. The use of atmospheric numerical techniques to forecast optical turbulence is crucial for observation scheduling and optimization of adaptive optic systems. Current research methods for forecasting optical turbulence are primarily based on mesoscale models with turbulence closure techniques to parameterize the key terms required for <i>C</i> <i>n</i>2 calculations under the assumption of atmospheric quasi-steady-state balance, and then the integrated astroclimatic parameters related to <i>C</i> <i>n</i>2 profile can be obtained. In this study, we propose what we believe to be a novel approach to forecast <i>C</i> <i>n</i>2 using a boundary layer parameterization based on higher-order turbulence closure in the single-column framework of the CLUBB model. Compared to mesoscale models, the CLUBB model serves as a single-column model, which simplifies modifications and reduces compilation time, and is more conducive to testing the performance of <i>C</i> <i>n</i>2 parameterization scheme. In the design of <i>C</i> <i>n</i>2 parameterization scheme, we consider a more complete physical process rather than omitting certain terms to obtain a steady-state solution. The performance of the model is evaluated using measurements obtained during a field campaign conducted at Da Qaidam site above the Tibetan Plateau. The results show that the model is able to capture typical features of the <i>C</i> <i>n</i>2 profile evolution under convective conditions. Comparison of the model with contemporaneous sounding measurements and quantification of the model's performance using statistical operators demonstrate the statistical agreement between simulations and measurements. In terms of atmospheric seeing, we can observe a bias of 0.01 and a root-mean-square error (RMSE) of 0.31 without any model calibration, which outperforms the results of previous mesoscale modeling studies. In addition, the new parameterization scheme is also compared with two representative <i>C</i> <i>n</i>2 algorithms previously used in the mesoscale models, with some improvements observed. The potential demonstrated by this approach is expected to bring greater value and advancement to the research of three-dimensional forecasting of optical turbulence in the future by coupling with the mesoscale model.</p>","PeriodicalId":19691,"journal":{"name":"Optics express","volume":"32 23","pages":"40640-40665"},"PeriodicalIF":3.2,"publicationDate":"2024-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142688234","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}