{"title":"On the orbit-induced spin density of tightly focused optical vortex beams: ellipticity and helicity","authors":"Kayn A Forbes","doi":"10.1088/2040-8986/ad5f40","DOIUrl":"https://doi.org/10.1088/2040-8986/ad5f40","url":null,"abstract":"It has recently been established that a linearly-polarized optical vortex possesses spin angular momentum density in the direction of propagation (longitudinal spin) under tight-focusing. The helicity of light has long been associated with longitudinal spin angular momentum. Here we show that the longitudinal spin density of linearly-polarized vortices is anomalous because it has no associated helicity. It was also recently determined that the polarization-independent helicity of tightly-focused optical vortices is associated with their transverse spin momentum density. The key finding of this work is the fact that, in general, longitudinal spin can not necessarily be associated with helicity, and transverse spin is in general not associated with a zero helicity, and such extraordinary behaviour manifests most clearly for optical vortices under non-paraxial conditions.","PeriodicalId":16775,"journal":{"name":"Journal of Optics","volume":"32 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2024-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141570182","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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":"In-plane radiation pattern generated by large particles in dielectric substrates","authors":"Juan M Merlo and Madeleine H Carhart","doi":"10.1088/2040-8986/ad5c7d","DOIUrl":"https://doi.org/10.1088/2040-8986/ad5c7d","url":null,"abstract":"In this work we present the study of in-plane radiation patterns generated by particles with dimensions larger than the excitation wavelength. We studied the in-plane radiation of Au structures focusing on two cases: particles and triangular crystals. We found that the radiation patterns were produced by the scattering of the excitation field at the bottom edges of the studied structures. In addition, we found the in-plane radiation decay exponentially due to the refractive index contrast between the substrate and superstate. Furthermore, we proved that in-plane radiation patterns originating from different structures can interact and generate interesting geometries. Finally, in addition to our experimental studies, we show numerically calculated simulations which agreed with our experimental results and thus confirmed our findings.","PeriodicalId":16775,"journal":{"name":"Journal of Optics","volume":"26 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141551134","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}
Varnam Sherawat, Renuka Bokolia and Ravindra Kumar Sinha
{"title":"Pressure-dependent bandgap characteristics in photonic crystals with sensing applications","authors":"Varnam Sherawat, Renuka Bokolia and Ravindra Kumar Sinha","doi":"10.1088/2040-8986/ad5b73","DOIUrl":"https://doi.org/10.1088/2040-8986/ad5b73","url":null,"abstract":"The present study elucidates a photonic crystal (PhC)-based pressure sensor exploiting the change in refractive index with pressure and the corresponding structural deformation of the dielectric material. The stress-sensitive refractive indices of the constituent materials of the PhC have been considered to study the effect of applied pressure on the photonic bandgap (PBG) characteristics of the structure. The designed pressure sensor, proposed using a two-dimensional hexagonal lattice arrangement of air holes in a dielectric slab, operates in the high-pressure range of 1–6 GPa. A comparative study of the PBG characteristics with the application of high pressure has been reported for three semiconducting materials—GaAs, Ge and Si, used for the dielectric slab in the proposed structure. GaAs is found to exhibit the highest sensitivity to pressure variations and shows more pronounced shifting of the midgap wavelength with pressure in comparison to Ge and Si. The largest PBG is seen in the Ge-based structure, closely followed by the GaAs and Si-based structures. The proposed structure is suitable for high-pressure sensing applications.","PeriodicalId":16775,"journal":{"name":"Journal of Optics","volume":"47 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141551133","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}
Jian Yu Gong, Fang Yao Fang, Rui Lin Xiao and Hai Feng Zhang
{"title":"Electromagnetically induced transparent bimodal to unimodal conversion realized by the nematic liquid crystal","authors":"Jian Yu Gong, Fang Yao Fang, Rui Lin Xiao and Hai Feng Zhang","doi":"10.1088/2040-8986/ad58f2","DOIUrl":"https://doi.org/10.1088/2040-8986/ad58f2","url":null,"abstract":"In this paper, under the action of a gigahertz (GHz) band circularly polarized (CP) wave, a kind of CP metastructure (MS) is proposed. Recently, the nematic liquid crystal (NLC) has received great attention, but it is still difficult to realize the electromagnetically induced transparency (EIT) bimodal to unimodal under the control of NLC. Through the direct mutual coupling of the metal cross resonator, metal ring resonator, and dielectric cross resonator, modes coupling can be formed and generate transparent windows. Two different EIT states (unimodal and bimodal EIT) accompanied by slow light effects can be observed by regulating the NLC with the applied bias voltage (Vbias). When the Vbias is 0 V, two transparent windows can be achieved in the 6.595–8.443 GHz and 8.443–10.161 GHz bands. When Vbias is 20 V, only one transparent window can be achieved in the 6.891–8.682 GHz band. Due to the high symmetry, the MS has the polarization insensitivity to CP waves. These extremely excellent properties make this MS have a wide application prospect. Noteworthy, the theoretical calculation result of EIT is verified by the two-oscillator theory model and circuit model, the results obtained are basically consistent with the simulation results.","PeriodicalId":16775,"journal":{"name":"Journal of Optics","volume":"25 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2024-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141529379","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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":"Plasmon-enhanced chiral absorption through electric dipole–electric quadrupole interaction","authors":"Hanwei Wang and Yang Zhao","doi":"10.1088/2040-8986/ad535e","DOIUrl":"https://doi.org/10.1088/2040-8986/ad535e","url":null,"abstract":"Enantioselective interactions of chiral molecules include distinct absorptions to opposite-handed circularly polarized light, known as chiral absorption. Traditionally, chiral absorption has been primarily attributed to electric dipole (ED) and magnetic dipole (MD) interaction with molecular chirality. However, this approach falls short for large molecules that support high-order multipolar components, such as electric quadrupole (EQ) moment. Here, we introduce a theoretical model to study the chiral absorption of large molecules in the presence of plasmonic nanostructures. This model considers both ED–MD interaction and ED–EQ interaction enhanced by a resonant structure. We numerically study such interactions of the chiral molecular solution in the vicinity of an achiral plasmonic nano-resonator. Our results show the distinct spectral information of the chiral medium on- and off-resonance of the resonator.","PeriodicalId":16775,"journal":{"name":"Journal of Optics","volume":"29 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2024-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141529381","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}
Bo Wang, Yifan Li, Yilong Cui, Chenxuan Xiang, Kenan Guo, Shuyuan Xiao and Tingting Liu
{"title":"Switchable image displays in tri-channel phase-change metasurfaces","authors":"Bo Wang, Yifan Li, Yilong Cui, Chenxuan Xiang, Kenan Guo, Shuyuan Xiao and Tingting Liu","doi":"10.1088/2040-8986/ad569c","DOIUrl":"https://doi.org/10.1088/2040-8986/ad569c","url":null,"abstract":"Optical metasurfaces enable to manipulate light fields across multiple physical dimensions, significantly enhancing information density, security, and system integration. Here, we propose a general platform of multi-functional phase-change metasurfaces for dynamic image displays in the visible range, enabled by active manipulation of optical spectrum, amplitude, and phase, leading to threefold dynamic exhibition functions. Through elaborately encoding the tri-channel information using a single-cell metasurface composed of nanobricks, three distinct functions are integrated and the flexibility of dynamic switch is allowed. Leveraging the tunable properties of between amorphous and crystalline states, the switchable displays are realized, including a structural-color image, and grayscale and holographic images with independent-encryption polarization freedom. The proposed metasurfaces open new avenues in multi-functional meta-devices for optical storage, displays, and security applications.","PeriodicalId":16775,"journal":{"name":"Journal of Optics","volume":"62 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2024-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141529380","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}
Jaegang Jo, Sangbin Lee, Munseong Bae, Damian Nelson, Kenneth B Crozier, Nanfang Yu, Haejun Chung and Sejeong Kim
{"title":"Inverse designed WS2 planar chiral metasurface with geometric phase","authors":"Jaegang Jo, Sangbin Lee, Munseong Bae, Damian Nelson, Kenneth B Crozier, Nanfang Yu, Haejun Chung and Sejeong Kim","doi":"10.1088/2040-8986/ad53df","DOIUrl":"https://doi.org/10.1088/2040-8986/ad53df","url":null,"abstract":"Increasing attention is being paid to chiral metasurfaces due to their ability to selectively manipulate right-hand circularly polarized light or left-hand circularly polarized light. The thin nature of metasurfaces, however, poses a challenge in creating a device with effective phase modulation. Plasmonic chiral metasurfaces have attempted to address this issue by increasing light–matter interaction, but they suffer from metallic loss. Dielectric metasurfaces made from high-index materials enable phase modulation while being thin. Very few materials, however, have high refractive index and low loss at visible wavelengths. Recently, some 2D materials have been shown to exhibit high refractive index and low loss in the visible wavelengths, positioning them as promising platforms for meta-optics. This study introduces and details a planar chiral metasurface with a geometric phase composed of WS2 meta-units. By employing adjoint optimization techniques, we achieved broadband circular dichroism ( 0.5 in the wavelength range of 653–796 nm) and a high extinction ratio (19.6 dB at λ = 675 nm).","PeriodicalId":16775,"journal":{"name":"Journal of Optics","volume":"156 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2024-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141506332","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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":"Tripartite entanglement in a detuned non-degenerate optical parametric oscillator","authors":"Jun Guo, Jianfeng Tian and Hengxin Sun","doi":"10.1088/2040-8986/ad52a2","DOIUrl":"https://doi.org/10.1088/2040-8986/ad52a2","url":null,"abstract":"Continuous variable multipartite entanglement is an important resource in quantum optics and quantum information. Non-degenerate optical parametric oscillator (NOPO), generally working in a resonant regime, can generate high quality tripartite entanglement. However, the detuning in a real experiment is inevitable and sometimes necessary, for instance, in an optomechanical system. We calculate the tripartite entanglement from a detuned triply quasi-resonant NOPO. Unlike the previous literature using inseparability criterion, we use the positivity of partial transpose, a sufficient and necessary criterion, to characterize the tripartite entanglement with full inseparability generated from a detuned NOPO. We also consider the influence of the pump and signal/idler losses on the tripartite entanglement. The results show that, the tripartite entanglement could exist even with a large detuning of several times cavity linewidth, and may be better for a detuned regime than for the resonant one under some conditions. With a fixed non-zero loss which always exists in a real experiment, an appropriate value of non-zero detuning could lead to the best entanglement. What’s more, unlike the bipartite entanglement, which exists both below and above threshold, the tripartite entanglement only occurs for a nonzero classical amplitude of signal/idler field. The jumping between the tripartite and bipartite entanglement could make the NOPO become a quantum state switch element, which promises a potential application on the multiparty quantum secret sharing.","PeriodicalId":16775,"journal":{"name":"Journal of Optics","volume":"171 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2024-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141506333","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}
Pooja Kumari, Shrey Mehta, Raghwinder Singh Grewal and R P Singh
{"title":"Double Hanle resonance dependence on light polarization angle and transverse magnetic field direction","authors":"Pooja Kumari, Shrey Mehta, Raghwinder Singh Grewal and R P Singh","doi":"10.1088/2040-8986/ad53e0","DOIUrl":"https://doi.org/10.1088/2040-8986/ad53e0","url":null,"abstract":"We present experimental and theoretical investigations of the dependence of double Hanle resonance spectrum on the light polarization angle and the direction of the applied transverse magnetic field (TMF). The experiments are done for transition of 87Rb D1 line using a rubidium vapor cell containing buffer gas. We show that a small light polarization component along the direction of TMF introduces asymmetry in the double Hanle resonance signal. Both the magnitude and sign of asymmetry in the signal are sensitive to the TMF orientation, suggesting a possible method for in-situ measurement of the direction of the magnetic fields generated by the coils. The physical origin of this asymmetry is explained by considering the redistribution of population among the ground-state Zeeman sublevels in the presence of TMF. In addition, we systematically vary both the polarization angle and TMF direction to study their effect on the line profile of Hanle resonances. We demonstrate that a double Hanle resonance changes to a dark Hanle resonance by rotating the light polarization vector irrespective of the TMF direction. We have developed a simple theoretical model based on a degenerate two-level system to explain our experimental observations.","PeriodicalId":16775,"journal":{"name":"Journal of Optics","volume":"67 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2024-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141506385","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}
Roberta De Simone, Francesco Chiadini, Vincenzo Fiumara and Akhlesh Lakhtakia
{"title":"Electromagnetic surface waves guided by the interface of a metal and a tightly interlaced matched ambidextrous bilayer","authors":"Roberta De Simone, Francesco Chiadini, Vincenzo Fiumara and Akhlesh Lakhtakia","doi":"10.1088/2040-8986/ad52a1","DOIUrl":"https://doi.org/10.1088/2040-8986/ad52a1","url":null,"abstract":"The existence and characteristics of electromagnetic surface waves (ESWs) whose propagation is guided by the planar interface of metal and a tightly interlaced matched ambidextrous bilayer (TIMAB) were theoretically investigated, a TIMAB being a periodic unidirectionally nonhomogeneous material whose unit cell consists of one period each of two structurally chiral materials that are identical except in structural handedness. Thus, the structural handedness flips in the center of the unit cell. A canonical boundary-value problem was formulated and a dispersion equation was solved, the ESWs being classified as surface-plasmon-polariton (SPP) waves. Flipping the structural handedness once in the unit cell can greatly enhance the number of possible SPP waves, one or more of which may be superluminal.","PeriodicalId":16775,"journal":{"name":"Journal of Optics","volume":"66 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2024-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141529383","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}