Cross-sensitivity reduces the reliability of ambient temperature (T) and refractive index (RI) detection during the process of photothermal therapy (PTT). Current dual-parameter sensors focus on RI and T measurement in spatially separated regions, limiting the advancement of PTT. To tackle this issue, we proposed a curvedly double-polished optical fiber surface plasmon resonance (SPR) sensor based on sandwich nanolayers of gold film–gold nanoparticle (AuNPs)–polydimethylsiloxane (PDMS), which successfully achieved simultaneous dual-parameter detection of refractive index (RI) and temperature (T) within a single spatial region. Fiber bending and polishing techniques deepen the effective penetration distance of the evanescent field, strengthening the coupling between light and electrons in metal layer. The sandwich nanolayers modulate the SPR location in response to the fluctuations of ambient RI and T. Simultaneous detection was achieved by monitoring dual SPR signals. Two typical curvedly double-polished structures, namely side-polished and front-polished, exhibited similar sensitivity but distinctive confinement loss. Key factors including polishing depth, bending radius, Au film, and PDMS thickness for sensing performance were explored. Under optimal conditions, the proposed side-polished and front-polished fiber SPR sensor achieved sensitivities of 1502 nm/RIU and 1.86 nm/°C, 1382 nm/RIU and 1.88 nm/°C, respectively. With a simple structure and high integrability, it provides a viable solution for in vivo cyto-sensing and therapeutic applications.
{"title":"Sandwich Nanolayers Deposited on Curvedly Double-Polished Optical Fiber for Surface Plasmon Resonance Sensor of Simultaneous Dual-Parameter Detection","authors":"Mengmeng Wang;Yongru Li;Siying Li;Mingyue Li;Xian Li;Xing Guo;Zewei Luo;Yixiang Duan","doi":"10.1109/JPHOT.2026.3660069","DOIUrl":"https://doi.org/10.1109/JPHOT.2026.3660069","url":null,"abstract":"Cross-sensitivity reduces the reliability of ambient temperature (T) and refractive index (RI) detection during the process of photothermal therapy (PTT). Current dual-parameter sensors focus on RI and T measurement in spatially separated regions, limiting the advancement of PTT. To tackle this issue, we proposed a curvedly double-polished optical fiber surface plasmon resonance (SPR) sensor based on sandwich nanolayers of gold film–gold nanoparticle (AuNPs)–polydimethylsiloxane (PDMS), which successfully achieved simultaneous dual-parameter detection of refractive index (RI) and temperature (T) within a single spatial region. Fiber bending and polishing techniques deepen the effective penetration distance of the evanescent field, strengthening the coupling between light and electrons in metal layer. The sandwich nanolayers modulate the SPR location in response to the fluctuations of ambient RI and T. Simultaneous detection was achieved by monitoring dual SPR signals. Two typical curvedly double-polished structures, namely side-polished and front-polished, exhibited similar sensitivity but distinctive confinement loss. Key factors including polishing depth, bending radius, Au film, and PDMS thickness for sensing performance were explored. Under optimal conditions, the proposed side-polished and front-polished fiber SPR sensor achieved sensitivities of 1502 nm/RIU and 1.86 nm/°C, 1382 nm/RIU and 1.88 nm/°C, respectively. With a simple structure and high integrability, it provides a viable solution for <italic>in vivo</i> cyto-sensing and therapeutic applications.","PeriodicalId":13204,"journal":{"name":"IEEE Photonics Journal","volume":"18 2","pages":"1-8"},"PeriodicalIF":2.4,"publicationDate":"2026-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11370133","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146223573","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The development and application of tunable lasers have been constrained by a limited tuning range, primarily due to the small quasi-Fermi-level separation (ΔEf) and low carrier band-filling levels. This study demonstrates an InGaAs/GaAs well-cluster composite (WCC) nanostructure, developed based on the indium-rich cluster effect. The ΔEf and gain curves were obtained and analyzed by collecting photoluminescence (PL) spectra emitted from two 500-µm-long multisection regions under varying carrier concentrations (9.0 × 1017–9.6 × 1017 cm−3) and working temperatures (280–330 K). Compared to traditional InGaAs/GaAs quantum well structures under identical working conditions, the ΔEf and gain bandwidth of the WCC structure were observed to be 1.08 and 5.3 times higher. This enhancement is attributed to the formation mechanism of the WCC structure, which contributes to a broader ΔEf and expanded spectral characteristics. This configuration highlights the significant application potential of the WCC nanostructure in advancing tunable laser technology.
{"title":"The Improved Quasi-Fermi-Level Separation of InGaAs Well-Cluster Composite Nanostructure for Ultra-Wide Tunable Lasers","authors":"Ru Wang;Zeng Jin;Yihan Zhang;Xinyang Qi;Zixuan Chen;Yujia Liu;Kehan Li;Qingnan Yu;Wei Wang;Sungang Huang","doi":"10.1109/JPHOT.2026.3659485","DOIUrl":"https://doi.org/10.1109/JPHOT.2026.3659485","url":null,"abstract":"The development and application of tunable lasers have been constrained by a limited tuning range, primarily due to the small quasi-Fermi-level separation (Δ<italic>E<sub>f</sub></i>) and low carrier band-filling levels. This study demonstrates an InGaAs/GaAs well-cluster composite (WCC) nanostructure, developed based on the indium-rich cluster effect. The Δ<italic>E<sub>f</sub></i> and gain curves were obtained and analyzed by collecting photoluminescence (PL) spectra emitted from two 500-µm-long multisection regions under varying carrier concentrations (9.0 × 10<sup>17</sup>–9.6 × 10<sup>17</sup> cm<sup>−3</sup>) and working temperatures (280–330 K). Compared to traditional InGaAs/GaAs quantum well structures under identical working conditions, the Δ<italic>E<sub>f</sub></i> and gain bandwidth of the WCC structure were observed to be 1.08 and 5.3 times higher. This enhancement is attributed to the formation mechanism of the WCC structure, which contributes to a broader Δ<italic>E<sub>f</sub></i> and expanded spectral characteristics. This configuration highlights the significant application potential of the WCC nanostructure in advancing tunable laser technology.","PeriodicalId":13204,"journal":{"name":"IEEE Photonics Journal","volume":"18 2","pages":"1-7"},"PeriodicalIF":2.4,"publicationDate":"2026-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11368890","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146175622","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-28DOI: 10.1109/JPHOT.2026.3658708
Fengtao Sun;Xinran Zhu;Xiaoxiao Liu;Minghua Cao;Hefu Li;Xia Zhang;Zhenshan Yang
While most prior studies on the statistical properties of modal dispersion (MD) in multiple-mode fibers have been primarily focused on the strong mode-coupling regime, in this paper we investigate the statistics of 1st- and 2nd-order MD across the full range of weak-, intermediate- and strong-coupling regimes. By simulating and analyzing a randomly-perturbed 6-mode fiber, we show that, under proper normalization of the MD quantities, the probability density functions (PDFs) would change significantly with the fiber length $L$ in the weak coupling regime, while eventually get steady – i.e., no longer change as $L$ further increases – in the strong coupling regime, and the random mode-coupling affects the 2nd-order MD on a considerably larger fiber length scale than that for the 1st-order MD. Furthermore, by calculating the joint bi-variate PDFs, the correlations among the 1st- and 2nd-order MD quantities are analyzed, which reveals that the correlation between the group-delay difference and the frequency variation of the principal modes is much stronger than the correlation between the group-delay difference and its frequency derivative.
{"title":"Statistical Distributions and Correlations of Modal Dispersion in All Mode-Coupling Regimes","authors":"Fengtao Sun;Xinran Zhu;Xiaoxiao Liu;Minghua Cao;Hefu Li;Xia Zhang;Zhenshan Yang","doi":"10.1109/JPHOT.2026.3658708","DOIUrl":"https://doi.org/10.1109/JPHOT.2026.3658708","url":null,"abstract":"While most prior studies on the statistical properties of modal dispersion (MD) in multiple-mode fibers have been primarily focused on the strong mode-coupling regime, in this paper we investigate the statistics of 1st- and 2nd-order MD across the full range of weak-, intermediate- and strong-coupling regimes. By simulating and analyzing a randomly-perturbed 6-mode fiber, we show that, under proper normalization of the MD quantities, the probability density functions (PDFs) would change significantly with the fiber length <inline-formula><tex-math>$L$</tex-math></inline-formula> in the weak coupling regime, while eventually get steady – i.e., no longer change as <inline-formula><tex-math>$L$</tex-math></inline-formula> further increases – in the strong coupling regime, and the random mode-coupling affects the 2nd-order MD on a considerably larger fiber length scale than that for the 1st-order MD. Furthermore, by calculating the joint bi-variate PDFs, the correlations among the 1st- and 2nd-order MD quantities are analyzed, which reveals that the correlation between the group-delay difference and the frequency variation of the principal modes is much stronger than the correlation between the group-delay difference and its frequency derivative.","PeriodicalId":13204,"journal":{"name":"IEEE Photonics Journal","volume":"18 2","pages":"1-9"},"PeriodicalIF":2.4,"publicationDate":"2026-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11367272","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146223636","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-28DOI: 10.1109/JPHOT.2026.3657765
Trupti Kamani;Shobhit K. Patel;Abdullah Baz;Om Prakash Kumar
Peptide diagnostics serve an important role for initial disease recognition, pharmaceutical evaluation, and environmental monitoring. Conventional methods for diagnosis typically involve labelling concepts that reduce sensitivity, increase test complexities, and limitations in real-time analysis. In the proposed work, we have introduced Corner-Triangle, Floral Geometry Refractive Index Biosensor (CTFGRIB) for monitoring peptide concentrations by names, Glycylleucine (Gly-Leu), Triglycine (Tri), Glycine (Gly), Glycytyrosine (Gly-Tyr), Diglycine (Dig), and Glycylaspartate (Gly-Asp) with a combination of machine learning evaluation. A periodical arrangement of corner-triangle patterns surrounded by a floral layout, as a distinctive geometry, provides a number of synergistic benefits that directly boost biosensing capabilities. The parametric assessments involve outstanding performance parameters with the favourable values of sensitivity being 1023.25 nm/RIU, and favourable values of detection limit are 0.0733 RIU for the Gly-Leu peptide cell. The favourable quality factor value of 24.0368, and the figure of merit value of 10.9508 RIU-1 have been achieved for the Gly-Leu peptide cell. The favourable transmittance rate of 33.6%, 33.3%, 33.0%, 33.0%, 32.9%, and 32.9% have been observed for Gly-Leu, Tri, Gly, Gly-Tyr, Dig, and Gly-Asp, respectively. The optimised R-squared value of 0.997604 and the MSE value of 9.607930 × 10-05 have been achieved from the machine learning method.
{"title":"Non-Invasive Label-Free Optical Biosensor for Accurate Peptide Detection Using Refractive Index Measurement and Machine Learning","authors":"Trupti Kamani;Shobhit K. Patel;Abdullah Baz;Om Prakash Kumar","doi":"10.1109/JPHOT.2026.3657765","DOIUrl":"https://doi.org/10.1109/JPHOT.2026.3657765","url":null,"abstract":"Peptide diagnostics serve an important role for initial disease recognition, pharmaceutical evaluation, and environmental monitoring. Conventional methods for diagnosis typically involve labelling concepts that reduce sensitivity, increase test complexities, and limitations in real-time analysis. In the proposed work, we have introduced Corner-Triangle, Floral Geometry Refractive Index Biosensor (CTFGRIB) for monitoring peptide concentrations by names, Glycylleucine (Gly-Leu), Triglycine (Tri), Glycine (Gly), Glycytyrosine (Gly-Tyr), Diglycine (Dig), and Glycylaspartate (Gly-Asp) with a combination of machine learning evaluation. A periodical arrangement of corner-triangle patterns surrounded by a floral layout, as a distinctive geometry, provides a number of synergistic benefits that directly boost biosensing capabilities. The parametric assessments involve outstanding performance parameters with the favourable values of sensitivity being 1023.25 nm/RIU, and favourable values of detection limit are 0.0733 RIU for the Gly-Leu peptide cell. The favourable quality factor value of 24.0368, and the figure of merit value of 10.9508 RIU-1 have been achieved for the Gly-Leu peptide cell. The favourable transmittance rate of 33.6%, 33.3%, 33.0%, 33.0%, 32.9%, and 32.9% have been observed for Gly-Leu, Tri, Gly, Gly-Tyr, Dig, and Gly-Asp, respectively. The optimised R-squared value of 0.997604 and the MSE value of 9.607930 × 10-05 have been achieved from the machine learning method.","PeriodicalId":13204,"journal":{"name":"IEEE Photonics Journal","volume":"18 2","pages":"1-9"},"PeriodicalIF":2.4,"publicationDate":"2026-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11363927","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146175911","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-28DOI: 10.1109/JPHOT.2026.3658357
Muhammad Hanif Ahmed Khan Khushik;Shahzadi Bano;Guanliang Yu;Mian Muhammad Kamal;Jamal N.A. Hassan;Tianjun Ma
Coupling light into high-index-core hybrid optical fibers (HOFs) typically results in losses >2 dB. We exploit a photonic nanojet-like effect in a tapered subwavelength core to force fundamental mode expansion into the cladding, effectively solving the mismatch problem. For a 0.30 μm core, this strategy achieves a remarkable coupling loss of 0.31–0.32 dB and reduces Fresnel reflections to negligible levels (<0.1%) by ensuring near-perfect effective index matching with standard fiber. This powerful approach provides a generalized and practical framework for integrating diverse HOF platforms into conventional photonic infrastructure.
{"title":"Photonic Nanojet-Enabled Mode Matching for Ultralow-Loss Hybrid Fiber Interconnects","authors":"Muhammad Hanif Ahmed Khan Khushik;Shahzadi Bano;Guanliang Yu;Mian Muhammad Kamal;Jamal N.A. Hassan;Tianjun Ma","doi":"10.1109/JPHOT.2026.3658357","DOIUrl":"https://doi.org/10.1109/JPHOT.2026.3658357","url":null,"abstract":"Coupling light into high-index-core hybrid optical fibers (HOFs) typically results in losses >2 dB. We exploit a photonic nanojet-like effect in a tapered subwavelength core to force fundamental mode expansion into the cladding, effectively solving the mismatch problem. For a 0.30 μm core, this strategy achieves a remarkable coupling loss of 0.31–0.32 dB and reduces Fresnel reflections to negligible levels (<0.1%) by ensuring near-perfect effective index matching with standard fiber. This powerful approach provides a generalized and practical framework for integrating diverse HOF platforms into conventional photonic infrastructure.","PeriodicalId":13204,"journal":{"name":"IEEE Photonics Journal","volume":"18 2","pages":"1-8"},"PeriodicalIF":2.4,"publicationDate":"2026-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11364267","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146175587","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-26DOI: 10.1109/JPHOT.2026.3658073
Daniela Serien;Aiko Narazaki
Ultrafast laser direct writing (LDW) is a versatile 3D microfabrication technology with a high spatial resolution, reduced heat accumulation, and a diverse range of applications usually tied to the applied precursor material. When using a protein precursor, it is possible to fabricate proteinaceous microstructures with the native protein function retained for use in cell cultures, lab-on-a-chip, and soft robotics. It is common to fabricate such proteinaceous microstructures by adhering them to glass. However, when we perform so-called free-form fabrication, without any substrate adhesion, we observe size changes during the fabrication process. This study quantified the in-precursor size changes to increase predictability. We also evaluated a potential mechanism for these changes by examining the role of protein hydration shells. These findings are expected to contribute to the fabrication of desired designs and promote the use of this technology.
{"title":"Size-Change Behavior of Free-Form Microstructures During Ultrafast Laser Direct Writing Within Pure-Protein Precursors","authors":"Daniela Serien;Aiko Narazaki","doi":"10.1109/JPHOT.2026.3658073","DOIUrl":"https://doi.org/10.1109/JPHOT.2026.3658073","url":null,"abstract":"Ultrafast laser direct writing (LDW) is a versatile 3D microfabrication technology with a high spatial resolution, reduced heat accumulation, and a diverse range of applications usually tied to the applied precursor material. When using a protein precursor, it is possible to fabricate proteinaceous microstructures with the native protein function retained for use in cell cultures, lab-on-a-chip, and soft robotics. It is common to fabricate such proteinaceous microstructures by adhering them to glass. However, when we perform so-called free-form fabrication, without any substrate adhesion, we observe size changes during the fabrication process. This study quantified the in-precursor size changes to increase predictability. We also evaluated a potential mechanism for these changes by examining the role of protein hydration shells. These findings are expected to contribute to the fabrication of desired designs and promote the use of this technology.","PeriodicalId":13204,"journal":{"name":"IEEE Photonics Journal","volume":"18 2","pages":"1-7"},"PeriodicalIF":2.4,"publicationDate":"2026-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11363912","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146175613","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-22DOI: 10.1109/JPHOT.2026.3656488
Ziming Liu;Lilong Zhao;Xiang Yao;Yaya Mao;Xiumin Song;Tingting Sun
This paper proposes a security-enhanced NOMA scheme based on dynamically concealed key-accompanying transmission. To improve security, in this paper, the 3D-LHemon model is utilized to encrypt the bit stream, symbols and subcarriers of high-power quadrature phase shift keying (QPSK) signals. The key is placed in a low-power binary phase shift keying (BPSK) signal, which is transmitted in parallel and superimposed with the high-power QPSK signal. Meanwhile, the phase points of the constellation diagram of the low-power signal are subjected to chaotic perturbation through Sinusoidal mapping. At the receiver, successive interference cancellation (SIC) decodes the high-power and low-power signals sequentially. Experimental results demonstrate the transmission of a 56 Gb/s orthogonal frequency division multiplexing (OFDM) signal over a 2-km 7-core optical fiber. Furthermore, the proposed scheme achieves an expansive key space of up to 10^87, effectively ensuring robust physical layer security. In contrast to existing chaos-based physical layer encryption for Non-Orthogonal Multiple Access (NOMA), this method applies chaotic encryption to high-power and low-power signals independently. This dual-layer approach significantly enhances system security without increasing computational overhead. Consequently, this scheme is capable of supporting a larger user base and holds promising potential for application in future optical networks.
{"title":"A Security-Enhanced NOMA Scheme Based on Dynamically Concealed Key- Accompanying Transmission","authors":"Ziming Liu;Lilong Zhao;Xiang Yao;Yaya Mao;Xiumin Song;Tingting Sun","doi":"10.1109/JPHOT.2026.3656488","DOIUrl":"https://doi.org/10.1109/JPHOT.2026.3656488","url":null,"abstract":"This paper proposes a security-enhanced NOMA scheme based on dynamically concealed key-accompanying transmission. To improve security, in this paper, the 3D-LHemon model is utilized to encrypt the bit stream, symbols and subcarriers of high-power quadrature phase shift keying (QPSK) signals. The key is placed in a low-power binary phase shift keying (BPSK) signal, which is transmitted in parallel and superimposed with the high-power QPSK signal. Meanwhile, the phase points of the constellation diagram of the low-power signal are subjected to chaotic perturbation through Sinusoidal mapping. At the receiver, successive interference cancellation (SIC) decodes the high-power and low-power signals sequentially. Experimental results demonstrate the transmission of a 56 Gb/s orthogonal frequency division multiplexing (OFDM) signal over a 2-km 7-core optical fiber. Furthermore, the proposed scheme achieves an expansive key space of up to 10^87, effectively ensuring robust physical layer security. In contrast to existing chaos-based physical layer encryption for Non-Orthogonal Multiple Access (NOMA), this method applies chaotic encryption to high-power and low-power signals independently. This dual-layer approach significantly enhances system security without increasing computational overhead. Consequently, this scheme is capable of supporting a larger user base and holds promising potential for application in future optical networks.","PeriodicalId":13204,"journal":{"name":"IEEE Photonics Journal","volume":"18 2","pages":"1-7"},"PeriodicalIF":2.4,"publicationDate":"2026-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11361037","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146102962","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this work, we investigate the effects of two distinct physical mechanisms, the antenna effect and plasmon resonance, on electric field enhancement in representative geometrical structures and at the apex of a sharp tip. The three-dimensional (3D) apertureless surface near-field optical microscopy (a-SNOM) configuration is numerically investigated using a finite element method (FEM). Our results show good agreement with analytical predictions and prior numerical benchmarks. Accounting for both antenna effects and plasmon resonances is crucial for accurate modeling of local field amplification in nanostructured probes. Through a systematic parametric numerical study, we show that field enhancement is strongly influenced by illumination conditions, polarization angle, and tip geometry. Finally, these results clarify how intrinsic material properties, extrinsic geometric features, and optical excitation govern field enhancement in nanostructures.
{"title":"Numerical Analysis of Localized Electric Field Enhancement in Apertureless Near Field Optical Microscopy","authors":"Ayushman Ramola;Amit Kumar Shakya;Yarden Mazor;Nezah Balal;Arik Bergman","doi":"10.1109/JPHOT.2026.3656404","DOIUrl":"https://doi.org/10.1109/JPHOT.2026.3656404","url":null,"abstract":"In this work, we investigate the effects of two distinct physical mechanisms, the antenna effect and plasmon resonance, on electric field enhancement in representative geometrical structures and at the apex of a sharp tip. The three-dimensional (3D) apertureless surface near-field optical microscopy (a-SNOM) configuration is numerically investigated using a finite element method (FEM). Our results show good agreement with analytical predictions and prior numerical benchmarks. Accounting for both antenna effects and plasmon resonances is crucial for accurate modeling of local field amplification in nanostructured probes. Through a systematic parametric numerical study, we show that field enhancement is strongly influenced by illumination conditions, polarization angle, and tip geometry. Finally, these results clarify how intrinsic material properties, extrinsic geometric features, and optical excitation govern field enhancement in nanostructures.","PeriodicalId":13204,"journal":{"name":"IEEE Photonics Journal","volume":"18 2","pages":"1-10"},"PeriodicalIF":2.4,"publicationDate":"2026-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11359981","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147440597","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-21DOI: 10.1109/JPHOT.2026.3656585
Xiaoxiao Wei;Jintao Chen;Miao Fan;Hao Zhang;Yunfeng Nie
Autofocus (AF) technology plays a critical role in applications such as microscopic measurement, 3D visual scanning, and semiconductor defect inspection. Conventional photoelectric sensor-based AF systems in microscopy face challenges in simultaneously achieving high precision and a large operational range, primarily due to distortions introduced by objective lenses. To address this limitation, this paper presents a conjugate line-laser-based autofocus method. The proposed approach employs a semicircular light-blocking diaphragm to generate a line-semi-ellipse laser spot on the sample surface. Combined with a laser spot image feature extraction algorithm and mathematical modeling, the system achieves an autofocus range of 500 μm with a positioning accuracy within ±1/5 of the depth of field (DOF) when using a 20× objective lens. The developed AF system offers a simple, robust, and efficient solution for high-speed, high-precision microscopic autofocusing, enabling extended range without compromising accuracy.
{"title":"Design and Experimental Validation of a Line-Laser Autofocusing System With Extended Working Range","authors":"Xiaoxiao Wei;Jintao Chen;Miao Fan;Hao Zhang;Yunfeng Nie","doi":"10.1109/JPHOT.2026.3656585","DOIUrl":"https://doi.org/10.1109/JPHOT.2026.3656585","url":null,"abstract":"Autofocus (AF) technology plays a critical role in applications such as microscopic measurement, 3D visual scanning, and semiconductor defect inspection. Conventional photoelectric sensor-based AF systems in microscopy face challenges in simultaneously achieving high precision and a large operational range, primarily due to distortions introduced by objective lenses. To address this limitation, this paper presents a conjugate line-laser-based autofocus method. The proposed approach employs a semicircular light-blocking diaphragm to generate a line-semi-ellipse laser spot on the sample surface. Combined with a laser spot image feature extraction algorithm and mathematical modeling, the system achieves an autofocus range of 500 μm with a positioning accuracy within ±1/5 of the depth of field (DOF) when using a 20× objective lens. The developed AF system offers a simple, robust, and efficient solution for high-speed, high-precision microscopic autofocusing, enabling extended range without compromising accuracy.","PeriodicalId":13204,"journal":{"name":"IEEE Photonics Journal","volume":"18 2","pages":"1-9"},"PeriodicalIF":2.4,"publicationDate":"2026-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11359988","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146102976","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-20DOI: 10.1109/JPHOT.2026.3655716
C. Bartoli;N. D’Abbondanza;F. Gala;C. Marzaro;E. Pontecorvo;G. Ruocco;G. Zanini;L. Zhang;M. G. Garone;V. de Turris;A. Giuliani;G. di Timoteo;I. Bozzoni;A. Rosa;C. Testi
We propose a label-free, high-resolution approach to investigate pathological protein aggregation and aberrant phase behavior in living cells. Intracellular protein aggregates associated with neurodegenerative diseases are increasingly recognized for their impact on cellular mechanics and pathophysiology. Proteins involved in these disorders tend to misfold and form insoluble inclusions, via aberrant liquid–to-solid phase transitions within stress granules and other biomolecular condensates. Despite their importance, probing the viscoelastic properties of these heterogeneous assemblies in living cells remains challenging due to their small size and rapid molecular turnover. Building on our previous study on Brillouin frequency shifts, here we employ a stabilized Brillouin microscope to quantify the full width at half maximum of the Brillouin peak, revealing viscosity-related mechanical signatures of pathological condensates. Combined with FRAP, our analysis shows that ALS-related proteins form condensates with broader linewidths than physiological stress granules, indicating increased viscosity and a more solid-like state. These findings demonstrate that Brillouin linewidth imaging can distinguish liquid-like from solid-like condensates in situ and uncover dissipative mechanical alterations relevant to neurodegenerative disease mechanisms.
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