Pub Date : 2026-02-01DOI: 10.1016/j.rio.2026.100964
Arash Vaghef-Koodehi
This comprehensive theoretical study investigates a novel MXene-based side-illuminated Schottky photodetector (SIMS-PD) integrated on an InP waveguide platform for telecommunication wavelengths. Building on our previous work with graphene-based devices achieving responsivities up to 1.76 A/W, we propose a Ti3C2Tx MXene double-layer structure that theoretically demonstrates superior performance metrics. Through electromagnetic modeling using Lumerical MODE and COMSOL Multiphysics, we predict a responsivity of 2.31 A/W at 1.55 μm—representing a 31% improvement over trilayer graphene devices. The MXene structure exhibits ultra-low dark current (5 × 10−1⁶ A), exceptional detectivity (2.1 × 1013 Jones), and 42 GHz bandwidth capability. These enhanced properties arise from MXene’s unique combination of metallic conductivity (8,500 S/cm), tunable work function (4.1–4.8 eV), and strong optical absorption coefficient (3.8 × 105 cm−1). Comparative analysis reveals MXene’s advantages in terms of solution processability, environmental stability, and voltage tunability (Δμ = 0.8 eV) over graphene counterparts. The proposed device architecture features optimized field confinement at the MXene-InP interface with 85% modal overlap, achieving quantum efficiency of 0.69. This work establishes MXene as a promising alternative to graphene for next-generation integrated photodetectors, particularly for applications in optical communications, quantum technologies, and high-sensitivity sensing systems.
{"title":"High-Performance Ti3C2Tx MXene-InP Side-Illuminated Schottky Photodetector: Theoretical design and performance enhancement beyond Graphene-Based devices","authors":"Arash Vaghef-Koodehi","doi":"10.1016/j.rio.2026.100964","DOIUrl":"10.1016/j.rio.2026.100964","url":null,"abstract":"<div><div>This comprehensive theoretical study investigates a novel MXene-based side-illuminated Schottky photodetector (SIMS-PD) integrated on an InP waveguide platform for telecommunication wavelengths. Building on our previous work with graphene-based devices achieving responsivities up to 1.76 A/W, we propose a Ti<sub>3</sub>C<sub>2</sub>T<sub>x</sub> MXene double-layer structure that theoretically demonstrates superior performance metrics. Through electromagnetic modeling using Lumerical MODE and COMSOL Multiphysics, we predict a responsivity of 2.31 A/W at 1.55 μm—representing a 31% improvement over trilayer graphene devices. The MXene structure exhibits ultra-low dark current (5 × 10<sup>−</sup>1⁶ A), exceptional detectivity (2.1 × 1013 Jones), and 42 GHz bandwidth capability. These enhanced properties arise from MXene’s unique combination of metallic conductivity (8,500 S/cm), tunable work function (4.1–4.8 eV), and strong optical absorption coefficient (3.8 × 105 cm<sup>−</sup>1). Comparative analysis reveals MXene’s advantages in terms of solution processability, environmental stability, and voltage tunability (Δμ = 0.8 eV) over graphene counterparts. The proposed device architecture features optimized field confinement at the MXene-InP interface with 85% modal overlap, achieving quantum efficiency of 0.69. This work establishes MXene as a promising alternative to graphene for next-generation integrated photodetectors, particularly for applications in optical communications, quantum technologies, and high-sensitivity sensing systems.</div></div>","PeriodicalId":21151,"journal":{"name":"Results in Optics","volume":"23 ","pages":"Article 100964"},"PeriodicalIF":3.0,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146079085","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-01DOI: 10.1016/j.rio.2026.100976
Xiaolong Chen , Yong Wang , Lingxi Wei , Yun Wang , Sibei Ren , Wahid Shah , Yu Liu
Rhegmatogenous retinal detachment (RRD) is an ophthalmic emergency characterized by the separation of the neurosensory retina from the retinal pigment epithelium due to retinal breaks. Scleral buckling is a conventional surgical treatment for this condition. This case series aims to illustrate the application of a novel surgical technique—illuminated scleral depressor-assisted scleral buckling for precise break localization—in clinical practice and to evaluate long-term postoperative outcomes in patients.
{"title":"Microscope-assisted scleral buckling with fiber-optic scleral depressor for retinal break localization —— A case series","authors":"Xiaolong Chen , Yong Wang , Lingxi Wei , Yun Wang , Sibei Ren , Wahid Shah , Yu Liu","doi":"10.1016/j.rio.2026.100976","DOIUrl":"10.1016/j.rio.2026.100976","url":null,"abstract":"<div><div>Rhegmatogenous retinal detachment (RRD) is an ophthalmic emergency characterized by the separation of the neurosensory retina from the retinal pigment epithelium due to retinal breaks. Scleral buckling is a conventional surgical treatment for this condition. This case series aims to illustrate the application of a novel surgical technique—illuminated scleral depressor-assisted scleral buckling for precise break localization—in clinical practice and to evaluate long-term postoperative outcomes in patients.</div></div>","PeriodicalId":21151,"journal":{"name":"Results in Optics","volume":"23 ","pages":"Article 100976"},"PeriodicalIF":3.0,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146170124","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-01DOI: 10.1016/j.rio.2026.100992
Arun Kumar , Nishant Gaur , Aziz Nanthaamornphong
This paper presents a supervised recurrent neural network–based partial transmit sequence (S–RNN–PTS) approach for reducing – the – peak-to-average power ratio (PAPR) in optical orthogonal time–sequence multiplexing (OTSM) visible-light communication (VLC) systems. A high PAPR in intensity–modulation/direct–detection (IM/DD) links introduces severe nonlinear distortion owing to LED nonlinearity, degrading power efficiency, and link reliability. The proposed framework integrates supervised learning with the PTS structure to enable search-free phase prediction at a fixed inference complexity, while preserving the conventional OTSM architecture. The performance was evaluated through Monte Carlo simulations using M−QAM−modulated OTSM waveforms over IM/DD VLC channels with nonlinear LED characteristics. The results demonstrate a PAPR reduction of up to 7 dB compared to conventional PTS schemes, and an SNR improvement of approximately 8 dB at a bit-error-rate (BER) of 10−3 for large subcarrier configurations. These gains enhance the spectral compactness and robustness against nonlinear distortion, making the S–RNN–PTS framework highly suitable for high-speed, energy-efficient OTSM–VLC systems.
{"title":"Supervised RNN-PTS framework for PAPR reduction and performance optimization in optical OTSM-VLC systems","authors":"Arun Kumar , Nishant Gaur , Aziz Nanthaamornphong","doi":"10.1016/j.rio.2026.100992","DOIUrl":"10.1016/j.rio.2026.100992","url":null,"abstract":"<div><div>This paper presents a supervised recurrent neural network–based partial transmit sequence (S–RNN–PTS) approach for reducing – the – peak-to-average power ratio (PAPR) in optical orthogonal time–sequence multiplexing (OTSM) visible-light communication (VLC) systems. A high PAPR in intensity–modulation/direct–detection (IM/DD) links introduces severe nonlinear distortion owing to LED nonlinearity, degrading power efficiency, and link reliability. The proposed framework integrates supervised learning with the PTS structure to enable search-free phase prediction at a fixed inference complexity, while preserving the conventional OTSM architecture. The performance was evaluated through Monte Carlo simulations using M−QAM−modulated OTSM waveforms over IM/DD VLC channels with nonlinear LED characteristics. The results demonstrate a PAPR reduction of up to 7 dB compared to conventional PTS schemes, and an SNR improvement of approximately 8 dB at a bit-error-rate (BER) of 10<sup>−3</sup> for large subcarrier configurations. These gains enhance the spectral compactness and robustness against nonlinear distortion, making the S–RNN–PTS framework highly suitable for high-speed, energy-efficient OTSM–VLC systems.</div></div>","PeriodicalId":21151,"journal":{"name":"Results in Optics","volume":"23 ","pages":"Article 100992"},"PeriodicalIF":3.0,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146170216","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-01DOI: 10.1016/j.rio.2026.100980
Ruqayyah Raad Awad , Younis Mohamed Atiah Al-zahy
This paper presents a high-sensitivity biosensor based on a Surface Plasmon Resonance (SPR) Photonic Crystal Fiber (PCF). Light is confined in a single mode within the core by a lattice of air holes, while the fiber surface is coated with a circular gold thin film to excite plasmonic waves. The sensing performance was evaluated through numerical simulations using the Finite Element Method (FEM) in COMSOL Multiphysics 6.3. The design was optimized by refining structural parameters, including the air hole diameter (d), lattice pitch (ᴧ), and gold layer thickness (tg), to maximize light-matter interaction and minimize confinement loss. The optimized device demonstrates superior wavelength sensitivity (Sλ) and amplitude sensitivity (SA) across a diverse spectrum of biological analytes. For cervical cancer (HeLa) detection, the sensor achieves an Sλ of 7,333 nm/RIU and a high amplitude sensitivity of 1,942.79 RIU−1, representing a significant improvement over earlier reported value. Other malignancies are detected with high precision, including breast cancer (MDA-MB-231 and MCF-7) at 8,571 nm/RIU and 7,692 nm/RIU respectively, T-lymphocyte cancer (Jurkat) at 5,500 nm/RIU, and adrenal tumors (PC12) at 5,000 nm/RIU. Beyond cellular detection, the platform exhibits an outstanding sensitivity of 3,857 nm/RIU for HIV-infected blood and 4,000 nm/RIU for glucose solutions. Comprehensive numerical analysis across a refractive index range of 1.32 to 1.39 revealed a maximum sensitivity of 8,000 ± 452 nm/RIU and a peak Figure of Merit (FOM) of 291.7 ± 5.78 RIU−1. With a peak detection resolution of 2.5 × 10−6 RIU for biochemical sensing, this PCF-SPR platform offers a promising, cost-effective, and high-precision alternative to conventional diagnostic techniques such as surgical biopsies and chemical assays.
{"title":"Biosensor based on photonic crystal fiber and surface plasmon resonance for glucose, HIV, and cancer cells detection","authors":"Ruqayyah Raad Awad , Younis Mohamed Atiah Al-zahy","doi":"10.1016/j.rio.2026.100980","DOIUrl":"10.1016/j.rio.2026.100980","url":null,"abstract":"<div><div>This paper presents a high-sensitivity biosensor based on a Surface Plasmon Resonance (SPR) Photonic Crystal Fiber (PCF). Light is confined in a single mode within the core by a lattice of air holes, while the fiber surface is coated with a circular gold thin film to excite plasmonic waves. The sensing performance was evaluated through numerical simulations using the Finite Element Method (FEM) in COMSOL Multiphysics 6.3. The design was optimized by refining structural parameters, including the air hole diameter (d), lattice pitch (ᴧ), and gold layer thickness (tg), to maximize light-matter interaction and minimize confinement loss. The optimized device demonstrates superior wavelength sensitivity (S<sub>λ</sub>) and amplitude sensitivity (S<sub>A</sub>) across a diverse spectrum of biological analytes. For cervical cancer (HeLa) detection, the sensor achieves an S<sub>λ</sub> of 7,333 nm/RIU and a high amplitude sensitivity of 1,942.79 RIU<sup>−1</sup>, representing a significant improvement over earlier reported value. Other malignancies are detected with high precision, including breast cancer (MDA-MB-231 and MCF-7) at 8,571 nm/RIU and 7,692 nm/RIU respectively, T-lymphocyte cancer (Jurkat) at 5,500 nm/RIU, and adrenal tumors (PC12) at 5,000 nm/RIU. Beyond cellular detection, the platform exhibits an outstanding sensitivity of 3,857 nm/RIU for HIV-infected blood and 4,000 nm/RIU for glucose solutions. Comprehensive numerical analysis across a refractive index range of 1.32 to 1.39 revealed a maximum sensitivity of 8,000 ± 452 nm/RIU and a peak Figure of Merit (FOM) of 291.7 ± 5.78 RIU<sup>−1</sup>. With a peak detection resolution of 2.5 × 10<sup>−6</sup> RIU for biochemical sensing, this PCF-SPR platform offers a promising, cost-effective, and high-precision alternative to conventional diagnostic techniques such as surgical biopsies and chemical assays.</div></div>","PeriodicalId":21151,"journal":{"name":"Results in Optics","volume":"23 ","pages":"Article 100980"},"PeriodicalIF":3.0,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146170217","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-01DOI: 10.1016/j.rio.2026.100972
Aymen A. Altae , Abdolvahab Ehsani Rad
This study presents an advanced multifunctional graphene-based sensing platform integrating deep neural networks (DNN), phase space reconstruction (PSR), and sophisticated feature engineering for real-time toxic gas monitoring and internal device integrity assessment. The sensor leverages a dual-sensor architecture composed of multilayer graphene and Kapton substrates, modeled through an equivalent circuit model (ECM) that captures subtle electrical impedance changes induced by gas adsorption and structural anomalies. Optical absorption spectra of CO2, NO2, and H2S in the terahertz frequency range reveal distinct molecular fingerprints, enabling precise gas discrimination and concentration quantification with response times as low as 5 s for CO2 detection. The PSR technique transforms time-series sensor data into multidimensional phase space representations fed into a 3D convolutional neural network, enhancing classification accuracy of both toxic gases and internal defects. Structural anomalies within the sensor, including internal gaps and delamination, are detected through characteristic shifts in absorption spectra, underscoring the platform’s dual capability for environmental monitoring and device fault diagnosis. Comparative analyses demonstrate enhanced capability in sensitivity, selectivity, and rapid response relative to existing sensor technologies. This integrated approach establishes a robust, scalable foundation for next-generation wearable, portable, and embedded sensing systems applicable to environmental safety, industrial emission control, and healthcare diagnostics.
{"title":"Integrated 3D tensor and deep neural network approach for real-time toxic gas monitoring and device integrity assessment","authors":"Aymen A. Altae , Abdolvahab Ehsani Rad","doi":"10.1016/j.rio.2026.100972","DOIUrl":"10.1016/j.rio.2026.100972","url":null,"abstract":"<div><div>This study presents an advanced multifunctional graphene-based sensing platform integrating deep neural networks (DNN), phase space reconstruction (PSR), and sophisticated feature engineering for real-time toxic gas monitoring and internal device integrity assessment. The sensor leverages a dual-sensor architecture composed of multilayer graphene and Kapton substrates, modeled through an equivalent circuit model (ECM) that captures subtle electrical impedance changes induced by gas adsorption and structural anomalies. Optical absorption spectra of CO<sub>2</sub>, NO<sub>2</sub>, and H<sub>2</sub>S in the terahertz frequency range reveal distinct molecular fingerprints, enabling precise gas discrimination and concentration quantification with response times as low as 5 s for CO<sub>2</sub> detection. The PSR technique transforms time-series sensor data into multidimensional phase space representations fed into a 3D convolutional neural network, enhancing classification accuracy of both toxic gases and internal defects. Structural anomalies within the sensor, including internal gaps and delamination, are detected through characteristic shifts in absorption spectra, underscoring the platform’s dual capability for environmental monitoring and device fault diagnosis. Comparative analyses demonstrate enhanced capability in sensitivity, selectivity, and rapid response relative to existing sensor technologies. This integrated approach establishes a robust, scalable foundation for next-generation wearable, portable, and embedded sensing systems applicable to environmental safety, industrial emission control, and healthcare diagnostics.</div></div>","PeriodicalId":21151,"journal":{"name":"Results in Optics","volume":"23 ","pages":"Article 100972"},"PeriodicalIF":3.0,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146170123","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-01DOI: 10.1016/j.rio.2026.100986
Arash Kosari
This paper presents the design, implementation, and experimental evaluation of a compact macrobend-based fiber-optic sensor intended for perimeter intrusion detection with an additional capability for estimating the mass of an intruding object. The sensing principle relies on controlled macrobending of a single-mode optical fiber, which induces radiative power loss that is collected by a secondary fiber and converted into an electrical signal for analysis. Three standard commercial telecom fibers (G.652, G.655, and G.657) were experimentally characterized at four wavelengths (1310, 1490, 1550, and 1625 nm) in order to quantify macrobend sensitivity as a function of bend radius and arc length. The results demonstrate that G.655 exhibits the highest macrobend sensitivity, reaching up to 0.21 dB·mm−1 at 1625 nm, and provides a measurable and approximately linear response suitable for mass estimation. Within the identified linear operating range, the sensor achieves a mass sensitivity of approximately 1.4 dB·kg−1. A compact mechanical macrobend shaper, the complete optical and electronic measurement chain, and an analytical calibration framework linking applied load, induced displacement, bend geometry, and optical attenuation are presented. Repeatability experiments conducted over more than fifty measurement cycles show a coefficient of variation below 5% in the linear regime. The proposed approach offers a low-cost and mechanically simple solution for enhanced perimeter monitoring while highlighting practical trade-offs related to sensitivity, operating range, and calibration stability.
{"title":"Development of a fiber-optic sensor for enhancing functional security of perimeter protection","authors":"Arash Kosari","doi":"10.1016/j.rio.2026.100986","DOIUrl":"10.1016/j.rio.2026.100986","url":null,"abstract":"<div><div>This paper presents the design, implementation, and experimental evaluation of a compact macrobend-based fiber-optic sensor intended for perimeter intrusion detection with an additional capability for estimating the mass of an intruding object. The sensing principle relies on controlled macrobending of a single-mode optical fiber, which induces radiative power loss that is collected by a secondary fiber and converted into an electrical signal for analysis. Three standard commercial telecom fibers (G.652, G.655, and G.657) were experimentally characterized at four wavelengths (1310, 1490, 1550, and 1625 nm) in order to quantify macrobend sensitivity as a function of bend radius and arc length. The results demonstrate that G.655 exhibits the highest macrobend sensitivity, reaching up to 0.21 dB·mm<sup>−1</sup> at 1625 nm, and provides a measurable and approximately linear response suitable for mass estimation. Within the identified linear operating range, the sensor achieves a mass sensitivity of approximately 1.4 dB·kg<sup>−1</sup>. A compact mechanical macrobend shaper, the complete optical and electronic measurement chain, and an analytical calibration framework linking applied load, induced displacement, bend geometry, and optical attenuation are presented. Repeatability experiments conducted over more than fifty measurement cycles show a coefficient of variation below 5% in the linear regime. The proposed approach offers a low-cost and mechanically simple solution for enhanced perimeter monitoring while highlighting practical trade-offs related to sensitivity, operating range, and calibration stability.</div></div>","PeriodicalId":21151,"journal":{"name":"Results in Optics","volume":"23 ","pages":"Article 100986"},"PeriodicalIF":3.0,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146170117","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this study, three TiO2-based thin film samples were fabricated, and their thickness-dependent optical properties and crystal structures were systematically investigated. The films, with thicknesses of 72 nm, 125 nm, and 283 nm, were deposited onto Si(111) substrates using the DC magnetron sputtering technique. The structural, morphological, and optical properties of the TiO2 thin films were comprehensively characterized using a combination of analytical techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, and spectroscopic ellipsometry. XRD analysis confirmed that the films predominantly crystallized in the anatase phase with a high degree of crystallinity, while SEM images revealed smooth surface morphologies with a low density of structural defects.
Raman spectroscopic results demonstrated the strong influence of film thickness and substrate effects on the optical and structural characteristics of the films. In particular, the increased intensity and narrowing of anatase-related phonon modes with increasing thickness indicated a progressive enhancement of crystalline ordering. FTIR spectroscopy and spectroscopic ellipsometry were employed to determine the optical band gap (Eg) values for each film thickness.
For the 72 nm thick film, the optical band gap was estimated to be Eg ≈ 3.8–2.84 eV. At this low thickness, the substrate contribution remains significant, and the presence of mixed interfacial phases is evident. The 125 nm thick film exhibited an apparent band gap of Eg ≈ 4.13 eV. At this intermediate thickness, incomplete surface coverage and residual substrate influence result in an upward shift of the interband transition features. In contrast, the 283 nm thick film showed a band gap in the range of Eg ≈ 3.1–3.3 eV, which is consistent with the intrinsic optical properties of anatase TiO2. At this thickness, the film fully covers the substrate, effectively suppressing substrate-related optical contributions.
These results confirm that the TiO2 thin films produced in this study exhibit high structural and optical quality, making them promising candidates for applications in photocatalytic and optoelectronic devices. Overall, the findings highlight that precise control of film thickness and thermal treatment parameters is crucial for optimizing the optical and photocatalytic performance of TiO2-based thin films.
{"title":"Comprehensive analysis of thickness-dependent structural, morphological, and optical properties of TiO2 based thin films","authors":"B.D. Igamov , I.R. Bekpulatov , A.M. Normamatov , A.I. Kamardin , F.Sh. Kodirova , Gunel Imanova","doi":"10.1016/j.rio.2026.100993","DOIUrl":"10.1016/j.rio.2026.100993","url":null,"abstract":"<div><div>In this study, three TiO<sub>2</sub>-based thin film samples were fabricated, and their thickness-dependent optical properties and crystal structures were systematically investigated. The films, with thicknesses of 72 nm, 125 nm, and 283 nm, were deposited onto Si(111) substrates using the DC magnetron sputtering technique. The structural, morphological, and optical properties of the TiO<sub>2</sub> thin films were comprehensively characterized using a combination of analytical techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, and spectroscopic ellipsometry. XRD analysis confirmed that the films predominantly crystallized in the anatase phase with a high degree of crystallinity, while SEM images revealed smooth surface morphologies with a low density of structural defects.</div><div>Raman spectroscopic results demonstrated the strong influence of film thickness and substrate effects on the optical and structural characteristics of the films. In particular, the increased intensity and narrowing of anatase-related phonon modes with increasing thickness indicated a progressive enhancement of crystalline ordering. FTIR spectroscopy and spectroscopic ellipsometry were employed to determine the optical band gap (Eg) values for each film thickness.</div><div>For the 72 nm thick film, the optical band gap was estimated to be Eg ≈ 3.8–2.84 eV. At this low thickness, the substrate contribution remains significant, and the presence of mixed interfacial phases is evident. The 125 nm thick film exhibited an apparent band gap of Eg ≈ 4.13 eV. At this intermediate thickness, incomplete surface coverage and residual substrate influence result in an upward shift of the interband transition features. In contrast, the 283 nm thick film showed a band gap in the range of Eg ≈ 3.1–3.3 eV, which is consistent with the intrinsic optical properties of anatase TiO<sub>2</sub>. At this thickness, the film fully covers the substrate, effectively suppressing substrate-related optical contributions.</div><div>These results confirm that the TiO<sub>2</sub> thin films produced in this study exhibit high structural and optical quality, making them promising candidates for applications in photocatalytic and optoelectronic devices. Overall, the findings highlight that precise control of film thickness and thermal treatment parameters is crucial for optimizing the optical and photocatalytic performance of TiO<sub>2</sub>-based thin films.</div></div>","PeriodicalId":21151,"journal":{"name":"Results in Optics","volume":"23 ","pages":"Article 100993"},"PeriodicalIF":3.0,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146170113","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-01DOI: 10.1016/j.rio.2026.100991
Teng Wang , Yalong Wen , Haoyu Wang , Suxuan Cao , Jiancun Zuo
We propose an all-fiber mode filter based on multi-core fiber, which efficiently selects or filters out specific modes. Based on the mode coupling principle, we designed all-fiber mode filters using dual-core fiber (DCF) and three-core fiber (TCF) structures to achieve multifunctional mode filtering. In the DCF structure, any mode can be filtered out; taking 1550 nm as the working wavelength, the mode filter achieves remarkable efficiency exceeding 90% for LP01, LP11 and LP21 modes, achieving bandwidths of approximately 110 nm, 117 nm, and 117 nm, respectively. In the TCF structure, the beam containing LP11, LP21 and LP31 modes is transmitted, filtering out both the LP11 and LP21 modes while maintaining high transmission of the LP31 mode, and the transmission ratio can reach 90%. To the best of our knowledge, this is the first report on mode filter based on all-fiber structure. This method offers the promising solutions for advanced optical communication systems and photonic device integration.
{"title":"Design and analysis of all-fiber mode filter based on multi-core fiber","authors":"Teng Wang , Yalong Wen , Haoyu Wang , Suxuan Cao , Jiancun Zuo","doi":"10.1016/j.rio.2026.100991","DOIUrl":"10.1016/j.rio.2026.100991","url":null,"abstract":"<div><div>We propose an all-fiber mode filter based on multi-core fiber, which efficiently selects or filters out specific modes. Based on the mode coupling principle, we designed all-fiber mode filters using dual-core fiber (DCF) and three-core fiber (TCF) structures to achieve multifunctional mode filtering. In the DCF structure, any mode can be filtered out; taking 1550 nm as the working wavelength, the mode filter achieves remarkable efficiency exceeding 90% for LP<sub>01</sub>, LP<sub>11</sub> and LP<sub>21</sub> modes, achieving bandwidths of approximately 110 nm, 117 nm, and 117 nm, respectively. In the TCF structure, the beam containing LP<sub>11</sub>, LP<sub>21</sub> and LP<sub>31</sub> modes is transmitted, filtering out both the LP<sub>11</sub> and LP<sub>21</sub> modes while maintaining high transmission of the LP<sub>31</sub> mode, and the transmission ratio can reach 90%. To the best of our knowledge, this is the first report on mode filter based on all-fiber structure. This method offers the promising solutions for advanced optical communication systems and photonic device integration.</div></div>","PeriodicalId":21151,"journal":{"name":"Results in Optics","volume":"23 ","pages":"Article 100991"},"PeriodicalIF":3.0,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146170114","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
TiO2-SiO2 composites with varying molar ratios were synthesized and systematically evaluated for the photocatalytic degradation of methylene blue (MB) under UV irradiation. X-ray diffraction and spectroscopic analyses revealed that the incorporation of amorphous SiO2 reduced TiO2 crystallinity, suppressed rutile phase formation, and promoted the generation of structural defects, particularly non-bridging oxygen species. Among the investigated compositions, the TiO2-SiO2 1:1 composite exhibited the highest defect density and the smallest crystallite size, indicating enhanced interfacial interaction and surface reactivity. Photocatalytic experiments demonstrated that the TiO2-SiO2 1:1 composite achieved approximately 90% MB degradation within 160 min, significantly outperforming pure TiO2 and other TiO2-SiO2 ratios. The corresponding apparent kinetic rate constant reached 0.0134 min−1, which is nearly four times higher than that of pure TiO2 (0.0034 min−1), confirming the decisive role of defect-rich structures in accelerating photocatalytic reactions. The enhanced performance is attributed to the synergistic effects of optimized crystallinity, defect generation, and increased surface hydroxylation induced by SiO2 incorporation. These findings provide clear evidence that compositional control–driven defect engineering is a key strategy for improving the photocatalytic efficiency of TiO2-SiO2 composites for organic wastewater treatment.
{"title":"Enhanced photocatalytic performance of TiO2-SiO2 composites: The role of structural defects and optimal composition","authors":"Senny Widyaningsih , Muhamad Diki Permana , D’ April Sabriantie Mulus , Kiki Maesaroh , Rudiawan Edwin , Joddy Arya Laksmono , Apang Djafar Shieddieque , Iman Rahayu , Diana Rakhmawaty Eddy","doi":"10.1016/j.rio.2026.100989","DOIUrl":"10.1016/j.rio.2026.100989","url":null,"abstract":"<div><div>TiO<sub>2</sub>-SiO<sub>2</sub> composites with varying molar ratios were synthesized and systematically evaluated for the photocatalytic degradation of methylene blue (MB) under UV irradiation. X-ray diffraction and spectroscopic analyses revealed that the incorporation of amorphous SiO<sub>2</sub> reduced TiO<sub>2</sub> crystallinity, suppressed rutile phase formation, and promoted the generation of structural defects, particularly non-bridging oxygen species. Among the investigated compositions, the TiO<sub>2</sub>-SiO<sub>2</sub> 1:1 composite exhibited the highest defect density and the smallest crystallite size, indicating enhanced interfacial interaction and surface reactivity. Photocatalytic experiments demonstrated that the TiO<sub>2</sub>-SiO<sub>2</sub> 1:1 composite achieved approximately 90% MB degradation within 160 min, significantly outperforming pure TiO<sub>2</sub> and other TiO<sub>2</sub>-SiO<sub>2</sub> ratios. The corresponding apparent kinetic rate constant reached<!--> <!-->0.0134 min<sup>−1</sup>, which is nearly<!--> <!-->four times higher than that of pure TiO<sub>2</sub> (0.0034 min<sup>−1</sup>), confirming the decisive role of defect-rich structures in accelerating photocatalytic reactions. The enhanced performance is attributed to the synergistic effects of optimized crystallinity, defect generation, and increased surface hydroxylation induced by SiO<sub>2</sub> incorporation. These findings provide clear evidence that compositional control–driven defect engineering is a key strategy for improving the photocatalytic efficiency of TiO<sub>2</sub>-SiO<sub>2</sub> composites for organic wastewater treatment.</div></div>","PeriodicalId":21151,"journal":{"name":"Results in Optics","volume":"23 ","pages":"Article 100989"},"PeriodicalIF":3.0,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146170234","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study presents a theoretical study of ground-state exciton and biexciton properties in strongly prolate ellipsoidal GaAs quantum dot. Using a variational approach with trial wave functions constructed from single-particle states, we examine the dependence of exciton and biexciton energies on the dot’s geometric parameters. The oscillator strengths of exciton–biexciton transitions are analyzed as functions of the major and minor semiaxes. We further investigate the third-order optical susceptibility near single- and two-photon resonances, elucidating the role of exciton–biexciton interactions. The results show that one-photon resonances dominate the nonlinear response, with contributions exceeding those of two-photon resonances by approximately four orders of magnitude. Absorption coefficients for exciton and biexciton transitions are evaluated for a fixed major semiaxis and varying minor semiaxis, along with the biexciton two-photon absorption coefficient. Finally, we analyze biexciton-induced nonlinear refractive index modulation, which exhibits a sign reversal across resonance and a pronounced peak–dip structure, indicating strong dispersive behavior and significant excitonic phase modulation.
{"title":"Non-linear optical properties of excitonic complexes in prolate ellipsoidal quantum dot","authors":"Y.Y. Bleyan , M.Y. Vinnichenko , N. Zeiri , C.A. Duque , D.B. Hayrapetyan","doi":"10.1016/j.rio.2026.100982","DOIUrl":"10.1016/j.rio.2026.100982","url":null,"abstract":"<div><div>This study presents a theoretical study of ground-state exciton and biexciton properties in strongly prolate ellipsoidal GaAs quantum dot. Using a variational approach with trial wave functions constructed from single-particle states, we examine the dependence of exciton and biexciton energies on the dot’s geometric parameters. The oscillator strengths of exciton–biexciton transitions are analyzed as functions of the major and minor semiaxes. We further investigate the third-order optical susceptibility near single- and two-photon resonances, elucidating the role of exciton–biexciton interactions. The results show that one-photon resonances dominate the nonlinear response, with contributions exceeding those of two-photon resonances by approximately four orders of magnitude. Absorption coefficients for exciton and biexciton transitions are evaluated for a fixed major semiaxis and varying minor semiaxis, along with the biexciton two-photon absorption coefficient. Finally, we analyze biexciton-induced nonlinear refractive index modulation, which exhibits a sign reversal across resonance and a pronounced peak–dip structure, indicating strong dispersive behavior and significant excitonic phase modulation.</div></div>","PeriodicalId":21151,"journal":{"name":"Results in Optics","volume":"23 ","pages":"Article 100982"},"PeriodicalIF":3.0,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146170115","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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