JournalTOCs

Journal of Optics
Number of Followers: 14

Hybrid journal (It can contain Open Access articles)
ISSN (Print) 2040-8978 - ISSN (Online) 2040-8986
Published by IOP

[40 journals]

Partial nonseparability of spin-orbit modes
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  Authors: V S Lamego; D G Braga, L S Oliveira, W F Balthazar J A O Huguenin
  First page: 034001
  Abstract: Structured light plays an essential role in several quantum information protocols by using the degrees of freedom of light to encode qubits. For exploring different correlations, especially in mixed states, such as discord, it is necessary to prepare partially entangled states. In this work, we present a theoretical and experimental study of a partial nonseparable spin-orbit modes. By exploring classical-quantum analogy, we perform the measurement of the concurrence of partially separable modes directly from projective measurement of polarization. The results show a clear agreement with predictions of quantum theory for partially entangled states. We also perform a study of Clauser, Horn, Shimony, and Holt (CHSH) inequality and show that partial violation is observed in entire agreement with the expected by quantum theory. For the maximally nonseparable mode, we achieve a violation of , one of the higher ones observed for spin-orbit modes based on our best knowledge.
  Citation: Journal of Optics
  PubDate: 2023-02-01T00:00:00Z
  DOI: 10.1088/2040-8986/acb36c
  Issue No: Vol. 25, No. 3 (2023)
Wavelength selection for spectrally combined laser beams propagating in
free space and the atmosphere
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  Authors: Xiaoqing Li; Hong Yu, Zhoulin Ding, Xiaoling Ji Ari T Friberg
  First page: 035601
  Abstract: Wavelength selection has a major impact on spectral beam combining (SBC) of laser beams that propagate in free space and in the atmosphere. We derive analytical expressions for the intensity and four characteristic quality parameters of free-space SBC beams. We show that the peak intensity, the mean-square beam width, and the M2 factor of an SBC beam at the target are all larger than those of one single laser beam of the same power and average wavelength. The peak intensity can be made higher by increasing the wavelength spacing but reducing the mean wavelength. However, when an SBC laser beam propagates in the atmosphere, the beam quality depends on the absorption coefficient of the multi-wavelength field due to thermal blooming. A thermal distortion number is introduced for an SBC beam and its validity is confirmed. We show that the power proportion of a high-absorption element within an SBC beam should be as low as possible to reduce the thermal blooming effect.
  Citation: Journal of Optics
  PubDate: 2023-01-25T00:00:00Z
  DOI: 10.1088/2040-8986/acb1c4
  Issue No: Vol. 25, No. 3 (2023)
High-accuracy identification of interferograms between two vortex beams
via deep learning without adequate experimental data
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  Authors: Lu Rui-Jia; Su Zhi-Kun
  First page: 035701
  Abstract: The on-axis interference intensity patterns between a vortex beam and its conjugated beam can be used to measure the fractional topological charge of vortex beams. However, it is still challenging to efficiently recognize these intensity diagrams. On one hand, the difference of the patterns for adjacent modes with interval 0.1 is too subtle to be identified precisely. On the other hand, the interferograms are susceptible to undesirable experimental conditions such as the misalignment of the beams, the unequal arms of the interferometer and the deviation of splitting ratio of the beam splitters in the interferometer. Here, we propose a deep learning method to recognize these intensity diagrams with up to accuracy. In particular, our method has reference values for deep learning model training when there is not adequate experimental data.
  Citation: Journal of Optics
  PubDate: 2023-02-01T00:00:00Z
  DOI: 10.1088/2040-8986/acb36d
  Issue No: Vol. 25, No. 3 (2023)
Numerical analysis of a strip-loaded silicon rich nitride-thin film
lithium niobate hybrid waveguides
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  Authors: Toijam Sunder Meetei; Seong-Jin Son, Byeongchan Park, Yong-Tak Lee Nan Ei Yu
  First page: 035801
  Abstract: Hybrid integration of silicon rich nitride and lithium niobate on insulator (SRN-LNOI) is an emerging material platform for photonic integrated circuits (PIC). In this paper, we present a systematic numerical investigation of the mode properties of a strip-loaded SRN-LNOI hybrid waveguide at 1550 nm wavelength using the full-vectorial finite difference method. Considering the anisotropic nature of the lithium niobate (LN) crystal, the effective refractive indices of the transverse electric and transverse magnetic modes of strip-loaded SRN-LN hybrid waveguides were analyzed. The single-mode condition, zero-birefringence, effective mode area, and power distribution in terms of the geometrical parameters of the strip-loaded SRN-LN hybrid waveguide are discussed in detail. Furthermore, the optical power transmission in both straight and bent waveguides, as well as the different characteristics of the optical power confinement of the fundamental modes in the SRN and LN layers were analyzed. This study provides useful information for designing high-performance photonic devices on a hybrid SRN-LNOI platform for future PIC applications.
  Citation: Journal of Optics
  PubDate: 2023-02-01T00:00:00Z
  DOI: 10.1088/2040-8986/acb44b
  Issue No: Vol. 25, No. 3 (2023)
The trend of structured light-induced force microscopy: a review
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  Authors: Jinwei Zeng; Yajuan Dong, Jinrun Zhang Jian Wang
  First page: 023001
  Abstract: Modern nanotechnology demands advanced microscopy with ever finer resolution and detectivity of both explicit and inexplicit features of matter. While typical optical microscopy can only directly observe the diffraction-limited appearance of a sample, a plethora of novel techniques has been presented to interrogate the intrinsic nature of matter in super-resolution. In particular, photo-induced force microscopy (PiFM) has attracted intense interest from optical scientists due to its unique optical force detection mechanism. Recent works on PiFM suggest that, combined with structured light illumination, the so-called system of structured light-induced force microscopy (SLiFM) can characterize conventionally elusive material properties with fidelity. In this review, we discuss the origin and state-of-art of SLiFM, including the following aspects: (a) the principle of PiFM and how it detects optical forces; (b) the fundamental physics of structured light beams; (c) the fundamental physics of structured light–structured matter interaction; (d) the relation between optical force and local electromagnetic fields. Lastly, we highlight the possible future industrial and academic applications of SLiFM in the characterization and manipulation of opto-magnetism, chirality, etc.
  Citation: Journal of Optics
  PubDate: 2023-02-02T00:00:00Z
  DOI: 10.1088/2040-8986/acad8c
  Issue No: Vol. 25, No. 2 (2023)
Tools for numerical modelling of nonlinear propagation in hollow capillary
fibres and their application
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  Authors: Aurora Crego; Julio San Roman Enrique Conejero Jarque
  First page: 024005
  Abstract: The development of new coherent and ultrashort light sources is of great relevance for exploring fundamental processes and different applications in science. The most successful technique for generating ultrashort laser pulses, in terms of energy and pulse duration, is using hollow capillary fibre (HCF) compressors. The different strategies to further increase the pulse energy and to achieve shorter pulses at non-conventional wavelengths, lead to continuous improvement of this technique. In this work, we present the theoretical framework of the nonlinear propagation in HCFs through the propagation equation and the spatio-temporal effects that appear in the nonlinear dynamics. To numerically study the nonlinear propagation of the pulse in the HCF, we present different numerical models considering only the spatial effects, (1 + 1)D model, the full spatio-temporal dynamics and ionization, (2 + 1)D model, or the case with lack of cylindrical symmetry, (3 + 1)D model. To show the performance of some of these models in a particular case, we study the generation of ultrashort and energetic dispersive waves (DWs) inside the HCF. We show that the emission of a DW at a fixed wavelength for different pump wavelengths is possible by parameter scaling.
  Citation: Journal of Optics
  PubDate: 2023-01-03T00:00:00Z
  DOI: 10.1088/2040-8986/acab13
  Issue No: Vol. 25, No. 2 (2023)
Nonlinear orbital angular momentum conversion with spatial-amplitude
independence
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  Authors: Jia-Qi Jiang; Hai-Jun Wu, Bing-Shi Yu, Chun-Yu Li, Xin-Yu Zhang, Xiao-Peng Hu, Bao-Sen Shi Zhi-Han Zhu
  First page: 024004
  Abstract: Nonlinear optics with structured light can provide a host of important functions for shaping the spatial and temporal structure of light, and the most commonly used is frequency conversion. In this work, we propose and demonstrate a novel nonlinear toolkit capable of tuning the frequency and orbital angular momentum (OAM) of signal beams simultaneously, and importantly that does not change the spatial amplitude structure of the signal. This unique frequency interface is enabled by using a special structured pump called a vortex super-Gaussian beam that has a flattop amplitude distribution and tunable vortex wavefront. This technique provides a dual interface of frequency and OAM, and may inspire many potential applications involving OAM beams.
  Citation: Journal of Optics
  PubDate: 2022-12-22T00:00:00Z
  DOI: 10.1088/2040-8986/ac9b72
  Issue No: Vol. 25, No. 2 (2022)
High-efficiency broadband blazed metagrating working in visible light
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  Authors: Yu Lin; Yeming Han, Chengmiao Wang, Bowen Li, Jianyu Zhang Yongbo Deng
  First page: 025002
  Abstract: A simple 1D blazed metagrating is proposed. The metagrating consists of SiO2 film sandwiched by Ag substrate and Ag nanostrips, which can achieve high-efficiency −1st-order diffraction in the range of 550 nm to 700 nm, and the peak efficiency is nearly 98%. The SiO2 dielectric layer in previous designs is used chiefly as a waveguide layer to support a guided mode. In comparison, it is introduced here to suppress the unwanted diffraction order (zero-order), which helps achieve high-efficiency diffraction at a high diffraction order. For analysis, the metagrating is disassembled into two parts, including a flat plate and a grating. By analysing the far-field radiation pattern of scattered waves and the reflection phase of a specific mode for these two parts, we conclude that the cause of high-efficiency blazing draws support from suppressing zero-order based on destructive interference. This work provides an intuitive physical image for this type of metagrating and an idea to design high-efficiency diffraction and beam deflection devices from the perspective of interference.
  Citation: Journal of Optics
  PubDate: 2022-12-29T00:00:00Z
  DOI: 10.1088/2040-8986/acac40
  Issue No: Vol. 25, No. 2 (2022)
Photonic band gaps and waveguide slow-light propagation in
Bravais–Moiré two-dimensional photonic crystals
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  Authors: H A Gómez-Urrea; J G Cardona, F J Caro-Lopera M E Mora-Ramos
  First page: 025101
  Abstract: Photonic band gap widths and slow-light optical guided modes are theoretically investigated for Bravais–Moiré (BM) photonic crystals (PCs) made of cylindrical dielectric cores which are formed from the combination of two square Bravais lattices. The Moiré pattern forms due to a commensurable rotation of one of these lattices with respect to the other. The analysis of gap maps is made versus the radii of dielectric cores—both rotated and unrotated—contained in the BM unit cell (UC). Guided modes are considered within the framework of coupled-resonator optical waveguides (CROWs), built from the generation of a point defect chain along the direction of electromagnetic wave propagation. For the analyzed structures, rather wide photonic band gaps were found. It was noticed that changing the core radii can significantly affect the dielectric contrast in the UC, leading to wider gaps. In addition, due to the kind of crystal cell structure considered, guided modes with group velocities smaller than those typically observed in PCs with simple square lattices were found for the investigated CROWs.
  Citation: Journal of Optics
  PubDate: 2022-12-28T00:00:00Z
  DOI: 10.1088/2040-8986/aca0aa
  Issue No: Vol. 25, No. 2 (2022)
Asymmetric dynamics of the orbital angular momentum of vector beam
propagation in nonlocal nonlinear media with PT -symmetric azimuthal
potentials
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  Authors: Yubin Deng; Kekai Huang, Jun Lin, Zhaoxu Sun, Weiyong Ye, Shihong Huang, Wu Zhang Bingzhi Zhang
  First page: 025603
  Abstract: We study the dynamics of vector beams (VBs) propagating in nonlocal nonlinear media with -symmetric azimuthal potentials. It is found that there is an apparent clockwise/counterclockwise symmetry (similar to left/right symmetry) breaking for the sub-beam with the opposite value of orbital angular momentum (OAM) of the VB. This symmetry breaking leads to the obvious asymmetric evolution of OAM, which results in net OAM generation. We numerically confirm that this phenomenon is induced by the -symmetric azimuthal potential.
  Citation: Journal of Optics
  PubDate: 2022-12-29T00:00:00Z
  DOI: 10.1088/2040-8986/aca108
  Issue No: Vol. 25, No. 2 (2022)