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  • Optica Publishing Group  (26)
  • 2020-2024  (26)
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  • Optica Publishing Group  (26)
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Language
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  • 2020-2024  (26)
Year
  • 1
    Online Resource
    Online Resource
    A versatile multi-tone laser system for manipulating atomic qubits based on a fiber Mach–Zehnder modulator and second harmonic generation
    Optica Publishing Group ; 2022
    In:  Optics Express Vol. 30, No. 17 ( 2022-08-15), p. 30098-
    Details
    In: Optics Express, Optica Publishing Group, Vol. 30, No. 17 ( 2022-08-15), p. 30098-
    Abstract: Stimulated Raman transition is a fundamental method to coherently manipulate quantum states in different physical systems. Phase-coherent dichromatic radiation fields matching the energy level splitting are the key to realizing stimulated Raman transition. Here we demonstrate a flexible-tuning, spectrum-clean and fiber-compatible method to generate a highly phase-coherent and high-power multi-tone laser. This method features the utilization of a broadband fiber Mach–Zehnder modulator working at carrier suppression condition and second harmonic generation. We generate a multi-tone continuous-wave 532 nm laser with a power of 1.5 Watts and utilize it to manipulate the spin and motional states of a trapped 171 Yb + ion via stimulated Raman transition. For spin state manipulation, we acquire an effective Rabi frequency of 2π × 662.3 kHz. Due to the broad bandwidth of the fiber modulator and nonlinear crystal, the frequency gap between tones can be flexibly tuned. Benefiting from the features above, this method can manipulate 171 Yb + and 137 Ba + simultaneously in the multi-species ion trap and has potential to be widely applied in atomic, molecular and optical physics.
    Type of Medium: Online Resource
    ISSN: 1094-4087
    URL: Article
    DOI: 10.1364/OE.462737
    Language: English
    Publisher: Optica Publishing Group
    Publication Date: 2022
    detail.hit.zdb_id: 1491859-6
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  • 2
    Online Resource
    Online Resource
    Heterodyne detection of backscattering for whispering-gallery-mode sensors
    Optica Publishing Group ; 2022
    In:  Optics Letters Vol. 47, No. 15 ( 2022-08-01), p. 3944-
    Details
    In: Optics Letters, Optica Publishing Group, Vol. 47, No. 15 ( 2022-08-01), p. 3944-
    Abstract: Whispering-gallery-mode (WGM) microcavities have shown significant applications in nanoparticle sensing for environmental monitoring and biological analysis. However, the enhancement of detection resolution often calls for active cavities or elaborate structural designs, leading to an increase of fabrication complexity and cost. Herein, heterodyne amplification is implemented in WGM microsensors based on backscattering detection mechanism. By interfering with an exotic reference laser, the reflecting light backscattered by perturbation targets can be strongly enlarged, yielding an easy-to-resolve and consequently sensitive microsensor. The dependence of detection laser frequency has also been characterized with the assistance of optothermal dynamics. We show that exploiting heterodyne interferometry boosts the detection of weak signals in microresonator systems and provides a fertile ground for optical microsensor development.
    Type of Medium: Online Resource
    ISSN: 0146-9592 , 1539-4794
    URL: Article
    DOI: 10.1364/OL.468937
    Language: English
    Publisher: Optica Publishing Group
    Publication Date: 2022
    detail.hit.zdb_id: 243290-0
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  • 3
    Online Resource
    Online Resource
    Concise fractional Fourier transform based on a non-uniform order searching method for estimating physical parameters from Newton’s rings
    Optica Publishing Group ; 2022
    In:  Applied Optics Vol. 61, No. 15 ( 2022-05-20), p. 4478-
    Details
    In: Applied Optics, Optica Publishing Group, Vol. 61, No. 15 ( 2022-05-20), p. 4478-
    Abstract: Newton’s ring pattern is very common in interferometry. By analyzing it, the physical parameters can be estimated, such as the curvature radius and the rings’ center. However, parameter estimation from large images using fractional Fourier transform (FRFT) consumes considerable time. A concise FRFT based on a non-uniform order searching method is proposed to reduce the computational time without decreasing the accuracy. Experimental results show that the time of the proposed method is about 2.7 s, which is about 1/600 of that of the traditional FRFT-based method and 1/5 of that of the Fast FRFT-based method when processing 960 × 960 pixel images.
    Type of Medium: Online Resource
    ISSN: 1559-128X , 2155-3165
    URL: Article
    DOI: 10.1364/AO.457830
    Language: English
    Publisher: Optica Publishing Group
    Publication Date: 2022
    detail.hit.zdb_id: 207387-0
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    Online Resource
  • 4
    Online Resource
    Online Resource
    Convolutional neural network for estimating physical parameters from Newton’s rings
    Optica Publishing Group ; 2021
    In:  Applied Optics Vol. 60, No. 13 ( 2021-05-01), p. 3964-
    Details
    In: Applied Optics, Optica Publishing Group, Vol. 60, No. 13 ( 2021-05-01), p. 3964-
    Abstract: By analyzing Newton’s rings, often encountered in interferometry, the parameters of spherical surfaces such as the rings’ center and the curvature radius can be estimated. First, the classical convolutional neural networks,  visual geometry group (VGG) network and U-Net, are applied to parameter estimation of Newton’s rings. After these models are trained, the rings’ center and curvature radius can be obtained simultaneously. Compared with previous analysis methods of Newton’s rings, it is shown that the proposed method has higher precision, better immunity to noise, and lower time consumption. For a Newton’s rings pattern of 640 × 480 pixels comprising − 5 d B Gaussian noise or 60% salt-and-pepper noise, the parameters can be estimated by the VGG model in 0.01 s, the error of the rings’ center is less than one pixel, and the error of curvature radius is lower than 0.5%.
    Type of Medium: Online Resource
    ISSN: 1559-128X , 2155-3165
    URL: Article
    DOI: 10.1364/AO.422012
    Language: English
    Publisher: Optica Publishing Group
    Publication Date: 2021
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  • 5
    Online Resource
    Online Resource
    Quantum frequency conversion from ultraviolet to visible band through waveguides in a period-poled MgO:LiTaO 3 crystal
    Optica Publishing Group ; 2021
    In:  Optics Express Vol. 29, No. 23 ( 2021-11-08), p. 38488-
    Details
    In: Optics Express, Optica Publishing Group, Vol. 29, No. 23 ( 2021-11-08), p. 38488-
    Abstract: In research on hybrid quantum networks, visible or near-infrared frequency conversion has been realized. However, technical limitations mean that there have been few studies involving the ultraviolet band, and unfortunately the wavelengths of the rare-earth or alkaline-earth metal atoms or ions that are used widely in research on quantum information are often in the UV band. Therefore, frequency conversion of the ultraviolet band is very important. In this paper, we demonstrate a quantum frequency conversion between ultraviolet and visible wavelengths by fabricating waveguides in a period-poled MgO:LiTaO 3 crystal with a laser writing system, which will be used to connect the wavelength of the dipole transition of 171 Yb + at 369.5 nm and the absorption wavelength of Eu 3+ at 580 nm in a solid-state quantum memory system. An external conversion efficiency of 0.85% and a signal-to-noise ratio of greater than 500 are realized with a pumping power of 3.28 W at 1018 nm. Furthermore, we complete frequency conversion of the classical polarization state by means of a symmetric optical setup based on the fabricated waveguide, and the process fidelity of the conversion is (96.13 ± 0.021)%. This converter paves the way for constructing a hybrid quantum network and realizing a quantum router in the ultraviolet band in the future.
    Type of Medium: Online Resource
    ISSN: 1094-4087
    URL: Article
    DOI: 10.1364/OE.439513
    Language: English
    Publisher: Optica Publishing Group
    Publication Date: 2021
    detail.hit.zdb_id: 1491859-6
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  • 6
    Online Resource
    Online Resource
    Chaotic physical layer encryption scheme based on phase ambiguity for a DMT system
    Optica Publishing Group ; 2022
    In:  Optics Express Vol. 30, No. 9 ( 2022-04-25), p. 14782-
    Details
    In: Optics Express, Optica Publishing Group, Vol. 30, No. 9 ( 2022-04-25), p. 14782-
    Abstract: Chaotic encryption is a promising scheme for physical layer security. By solving the multi-dimensional chaotic equations and transforming the obtained results, both bit-level and symbol-level encryption can be realized. One of the mainstream symbol-level encryption solutions is the constellation shifting (CS) scheme, which treats the chaotic sequence as artificial noise and adds it to the QAM signal sequence to achieve encryption. However, this scheme has several technical flaws in practical application, in terms of computational complexity and coexistence with blind equalization algorithm and the probabilistic shaping (PS) technique. In this paper, we propose a novel symbol-level encryption scheme based on phase ambiguity (PA), which converts the two sequences originally used to generate artificial noise into a set of phase rotation keys and complex conjugate keys, so that the encrypted symbols are still on the ideal constellation point coordinates. Simulation verification is carried out in a discrete multi-tone (DMT) system with 64QAM modulation. Results show that the proposed scheme can fully retain the shaping gain brought by the PS technique and avoid the error convergence of the blind equalizer. Moreover, the time required to solve the chaotic equations is only 38% of the CS scheme. Experimental verification is carried out, and the obtained results once again prove the superiority of the proposed encryption algorithm, which is a practical alternative for future physical layer secure optical communications.
    Type of Medium: Online Resource
    ISSN: 1094-4087
    URL: Article
    DOI: 10.1364/OE.454432
    Language: English
    Publisher: Optica Publishing Group
    Publication Date: 2022
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  • 7
    Online Resource
    Online Resource
    Data rate measurement method with selectable range in linear optical sampling
    Optica Publishing Group ; 2023
    In:  Optics Express Vol. 31, No. 6 ( 2023-03-13), p. 9362-
    Details
    In: Optics Express, Optica Publishing Group, Vol. 31, No. 6 ( 2023-03-13), p. 9362-
    Abstract: Linear optical sampling (LOS) is one of the most powerful techniques for high-speed signal monitoring. To measure the data-rate of signal under test (SUT) in optical sampling, multi-frequency sampling (MFS) was proposed. However, the measurable data-rate range of the existing method based on MFS is limited, which makes it very difficult to measure the data-rate of high-speed signals. To solve the above problem, a range selectable data-rate measurement method based on MFS in LOS is proposed in this paper. Through this method, the measurable data-rate range can be selected to match the data-rate range of SUT and the data-rate of SUT can be measured precisely, independently of the modulation format. What’s more, the sampling order can be judged using the discriminant in the proposed method, which is key for plotting eye diagrams with correct time information. We experimentally measure the baud-rates of PDM-QPSK signal from 800 MBaud to 40.8 GBaud in different ranges and judge the sampling orders. The relative error of measured baud-rate is less than 0.17% while the error vector magnitude (EVM) is less than 0.38. Compared with the existing method, under the same sampling cost, our proposed method realizes the selectivity of the measurable data-rate range and the judgment of sampling order, greatly extends the measurable data-rate range of SUT. Hence, the data-rate measurement method with selectable range has great potential for high-speed signal data-rate monitoring.
    Type of Medium: Online Resource
    ISSN: 1094-4087
    URL: Article
    DOI: 10.1364/OE.484562
    Language: English
    Publisher: Optica Publishing Group
    Publication Date: 2023
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  • 8
    Online Resource
    Online Resource
    Mitigating the ambiguity problem in the CNN-based wavefront correction
    Optica Publishing Group ; 2022
    In:  Optics Letters Vol. 47, No. 13 ( 2022-07-01), p. 3251-
    Details
    In: Optics Letters, Optica Publishing Group, Vol. 47, No. 13 ( 2022-07-01), p. 3251-
    Abstract: In this work, we propose an attention-based adaptive optics method that uses a non-local block to integrate phase diversity with a convolutional neural network (CNN). The simulation results showcase the effectiveness of the proposed method to mitigate the ambiguity problem of phase retrieval and better performance than traditional CNN-based wavefront correction.
    Type of Medium: Online Resource
    ISSN: 0146-9592 , 1539-4794
    URL: Article
    DOI: 10.1364/OL.459799
    Language: English
    Publisher: Optica Publishing Group
    Publication Date: 2022
    detail.hit.zdb_id: 243290-0
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  • 9
    Online Resource
    Online Resource
    Probabilistic shaping and forward error correction scheme employing uneven segmentation mapping for data center optical communication
    Optica Publishing Group ; 2021
    In:  Optics Express Vol. 29, No. 4 ( 2021-02-15), p. 6209-
    Details
    In: Optics Express, Optica Publishing Group, Vol. 29, No. 4 ( 2021-02-15), p. 6209-
    Abstract: The combination of probabilistic shaping (PS) technology and forward error correction (FEC) technology can significantly boost the performance of a transmission system. In this paper, we propose a probabilistic shaping distribution matching algorithm employing uneven segmentation for data center optical networks, while keeping extremely low computational complexity for both encoding and decoding. Based on the proposed probabilistic shaping distribution matching algorithm, we develop a novel integrated scheme of PS and FEC coding that lifts the restrictions on the use of FEC technology and increases the use of interleaver. An experiment used to evaluate the probabilistically shaped data transmission is successfully conducted over a 25 km standard single-mode fiber (SSMF) with 16 quadrature amplitude modulation (16-QAM). Simultaneously, we use a simulation software to analyze the bit error rate performance at higher resolution. The results show that the joint coding scheme can achieve a 0.4dB performance improvement compared with the single FEC system.
    Type of Medium: Online Resource
    ISSN: 1094-4087
    URL: Article
    DOI: 10.1364/OE.416175
    Language: English
    Publisher: Optica Publishing Group
    Publication Date: 2021
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  • 10
    Online Resource
    Online Resource
    Displacement and strain mapping for osteocytes under fluid shear stress using digital holographic microscopy and digital image correlation
    Optica Publishing Group ; 2021
    In:  Biomedical Optics Express Vol. 12, No. 4 ( 2021-04-01), p. 1922-
    Details
    In: Biomedical Optics Express, Optica Publishing Group, Vol. 12, No. 4 ( 2021-04-01), p. 1922-
    Abstract: Osteocytes, as the mechano-sensors in bone, are always subjected to fluid shear stress (FSS) from the surrounding matrix. Quantification of FSS-induced cellular deformation is significant for clarifying the “perceive and transmit” process of cellular mechanotransduction. In this research, a label-free displacement and strain mapping method based on digital holographic microscopy (DHM) and digital image correlation (DIC) is introduced. The method, which is termed DHM-DIC, innovatively utilizes surface features extracted from holographic phase images instead of speckles as the metric for DIC searching. Simulation results on a hemisphere validate the feasibility of DHM-DIC. Displacement and strain maps of living osteocytes under 1.5 Pa FSS are evaluated from DHM-DIC and present good agreement with our previous finite element modeling results.
    Type of Medium: Online Resource
    ISSN: 2156-7085 , 2156-7085
    URL: Article
    DOI: 10.1364/BOE.418418
    Language: English
    Publisher: Optica Publishing Group
    Publication Date: 2021
    detail.hit.zdb_id: 2572216-5
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