Pub Date : 2025-09-28DOI: 10.1016/j.rio.2025.100908
A.Alice Linsie, K. Lalitha, G. Annapoorani
A novel hexagonal Photonic Crystal Fiber (PCF) with good sensitivity for the non-disruptive detection of breast cancer operating over terahertz (THz) regime has been reported in this study. The cladding region of this proposed H-PCF is made up of three layers of hexagonal air holes arranged in a triangular lattice structure. There is one hexagonal air hole in the middle that serves as a hollow core for studying the PCF during sensing operations. This core provides an index difference between the core, cladding, and background material, allowing efficient THz wave propagation and great sensitivity. Through simulation on COMSOL software, the compact arrangement of hexagonal air holes in this way facilitates a birefringence of 1.4 × 10−3, a minimum effective material loss (EML) of 1.22 × 10−3 cm−1, a maximum core power fraction of 91.2 %, a maximum sensitivity of 99.83 %, and a very narrow effective area of 0.0375 µm2 under a wide frequency band of 0.1–1.5 THz. The suggested H-PCF is a good alternative for PCF-based sensing devices because it of these unique features.
{"title":"A computational study of advanced hexagonal PCF (H-PCF) bio sensor for breast cancer identification","authors":"A.Alice Linsie, K. Lalitha, G. Annapoorani","doi":"10.1016/j.rio.2025.100908","DOIUrl":"10.1016/j.rio.2025.100908","url":null,"abstract":"<div><div>A novel hexagonal Photonic Crystal Fiber (PCF) with good sensitivity for the non-disruptive detection of breast cancer operating over terahertz (THz) regime has been reported in this study. The cladding region of this proposed H-PCF is made up of three layers of hexagonal air holes arranged in a triangular lattice structure. There is one hexagonal air hole in the middle that serves as a hollow core for studying the PCF during sensing operations. This core provides an index difference between the core, cladding, and background material, allowing efficient THz wave propagation and great sensitivity. Through simulation on COMSOL software, the compact arrangement of hexagonal air holes in this way facilitates a birefringence of 1.4 × 10<sup>−3</sup>, a minimum effective material loss (EML) of 1.22 × 10<sup>−3</sup> cm<sup>−1</sup>, a maximum core power fraction of 91.2 %, a maximum sensitivity of 99.83 %, and a very narrow effective area of 0.0375 µm<sup>2</sup> under a wide frequency band of 0.1–1.5 THz. The suggested H-PCF is a good alternative for PCF-based sensing devices because it of these unique features.</div></div>","PeriodicalId":21151,"journal":{"name":"Results in Optics","volume":"21 ","pages":"Article 100908"},"PeriodicalIF":3.0,"publicationDate":"2025-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145219342","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 : 2025-09-28DOI: 10.1016/j.rio.2025.100905
Patricia Horta-Fraijo, H.Moreno- García
The study investigated Au-Ag and Au nanoparticles (NPs) synthesized chemically and added to a commercial conductive carbon paint used as electrodes in Bi2S3/PbS thin-film solar cells. I-V measurements were used for device characterization. NPs were found on the carbon paint surface with sizes of 11.1 ± 0.09 nm to 29 ± 7.5 nm. FFT analysis showed a cubic crystal structure for all NPs. Optically, Au-Ag(1) exhibited broad absorption (363–600 nm), Au-Ag(2) peaked at 546 nm, and Au at 521 nm. Devices with NP-modified electrodes with sizes 29 ± 7.5 nm showed enhanced short-circuit current density (JSC), with Au-Ag(2) reaching 7.19 mA/cm2 and a PCE of 0.46 %, compared to the reference JSC of 3.02 mA/cm2 and PCE of 0.11 %. Series resistance dropped from 23 Ω·cm2 to 2 Ω·cm2 (Au-Ag) and 5 Ω·cm2 (Au).
{"title":"Study of gold, silver-gold nanoparticles incorporated to carbon paint for electrodes application in thin-film solar cells","authors":"Patricia Horta-Fraijo, H.Moreno- García","doi":"10.1016/j.rio.2025.100905","DOIUrl":"10.1016/j.rio.2025.100905","url":null,"abstract":"<div><div>The study investigated Au-Ag and Au nanoparticles (NPs) synthesized chemically and added to a commercial conductive carbon paint used as electrodes in Bi<sub>2</sub>S<sub>3</sub>/PbS thin-film solar cells. I-V measurements were used for device characterization. NPs were found on the carbon paint surface with sizes of 11.1 ± 0.09 nm to 29 ± 7.5 nm. FFT analysis showed a cubic crystal structure for all NPs. Optically, Au-Ag(1) exhibited broad absorption (363–600 nm), Au-Ag(2) peaked at 546 nm, and Au at 521 nm. Devices with NP-modified electrodes with sizes 29 ± 7.5 nm showed enhanced short-circuit current density (J<sub>SC</sub>), with Au-Ag(2) reaching 7.19 mA/cm<sup>2</sup> and a PCE of 0.46 %, compared to the reference J<sub>SC</sub> of 3.02 mA/cm<sup>2</sup> and PCE of 0.11 %. Series resistance dropped from 23 Ω·cm<sup>2</sup> to 2 Ω·cm<sup>2</sup> (Au-Ag) and 5 Ω·cm<sup>2</sup> (Au).</div></div>","PeriodicalId":21151,"journal":{"name":"Results in Optics","volume":"21 ","pages":"Article 100905"},"PeriodicalIF":3.0,"publicationDate":"2025-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145219346","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 : 2025-09-28DOI: 10.1016/j.rio.2025.100911
Seyed Mahmoud Hoseini , Hadi Dehbovid , Seyed Mehdi Abedi Pahnehkolaei , Mehdi Radmehr
A highly sensitive multi-band terahertz wave absorber is proposed, featuring a three-layer structure with a central air gap for blood sample placement, sandwiched by stacked graphene-Kapton layers and backed by a fully reflecting metallic layer. The absorber is modeled using an equivalent impedance circuit and validated by full-wave numerical simulations. The device exhibits seven distinct absorption peaks across the 1 to 9.5 THz frequency range, with absorption levels exceeding 80% for each peak. Sensitivity analysis reveals robust absorption performance with minimal variation against geometrical parameter changes, while demonstrating high sensitivity to refractive index changes within the air gap. Specifically, the absorption spectrum shifts significantly for refractive index variations as small as 0.01, which is critical for non-invasive biosensing applications. These results underscore the absorber’s potential as an accurate, wearable, and reliable building block for healthcare monitoring systems.
{"title":"Multi-band graphene-nested rings terahertz wave absorber with air gap for sensitive healthcare biosensing applications","authors":"Seyed Mahmoud Hoseini , Hadi Dehbovid , Seyed Mehdi Abedi Pahnehkolaei , Mehdi Radmehr","doi":"10.1016/j.rio.2025.100911","DOIUrl":"10.1016/j.rio.2025.100911","url":null,"abstract":"<div><div>A highly sensitive multi-band terahertz wave absorber is proposed, featuring a three-layer structure with a central air gap for blood sample placement, sandwiched by stacked graphene-Kapton layers and backed by a fully reflecting metallic layer. The absorber is modeled using an equivalent impedance circuit and validated by full-wave numerical simulations. The device exhibits seven distinct absorption peaks across the 1 to 9.5 THz frequency range, with absorption levels exceeding 80% for each peak. Sensitivity analysis reveals robust absorption performance with minimal variation against geometrical parameter changes, while demonstrating high sensitivity to refractive index changes within the air gap. Specifically, the absorption spectrum shifts significantly for refractive index variations as small as 0.01, which is critical for non-invasive biosensing applications. These results underscore the absorber’s potential as an accurate, wearable, and reliable building block for healthcare monitoring systems.</div></div>","PeriodicalId":21151,"journal":{"name":"Results in Optics","volume":"21 ","pages":"Article 100911"},"PeriodicalIF":3.0,"publicationDate":"2025-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145219463","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 : 2025-09-26DOI: 10.1016/j.rio.2025.100900
Raad Chegel , Ahmad I. Ayesh
This work presents a comprehensive theoretical investigation of the electronic and optical responses of monolayer honeycomb boron antimony (h-BSb) and hexagonal boron phosphide (h-BP) under various biaxial strain conditions, employing a tight-binding approach validated through DFT calculations. Our findings reveal that monolayer h-BSb possesses a direct band gap that can be effectively modulated through mechanical strain: tensile strain raises the band gap, whereas compressive strain decreases it. This strain-induced tunability manifests directly in the optical spectra, where prominent optical peaks exhibit significant redshifts under compressive strain and blueshifts under tensile conditions. The refractive index demonstrates clear strain-dependent modulations, with the zero-frequency value increasing under compressive strain and decreasing under tensile deformation. Additionally, the DC Kerr effect displays a distinctive double-peak structure that shows high sensitivity to mechanical strain. Comparative analysis demonstrates that monolayer h-BSb exhibits lower-energy optical transitions and enhanced sensitivity to strain-induced peak displacement compared to h-BP. This superior performance stems from h-BSb’s small band gap and narrow interband separations at the points of high-symmetry in the Brillouin zone. These characteristics position h-BSb as a highly promising material for strain-engineered optoelectronic applications, particularly in infrared photodetectors and sensors.
{"title":"Investigation of strain-induced modulation on electronic and optical properties of monolayer of BSb","authors":"Raad Chegel , Ahmad I. Ayesh","doi":"10.1016/j.rio.2025.100900","DOIUrl":"10.1016/j.rio.2025.100900","url":null,"abstract":"<div><div>This work presents a comprehensive theoretical investigation of the electronic and optical responses of monolayer honeycomb boron antimony (h-BSb) and hexagonal boron phosphide (h-BP) under various biaxial strain conditions, employing a tight-binding approach validated through DFT calculations. Our findings reveal that monolayer h-BSb possesses a direct band gap that can be effectively modulated through mechanical strain: tensile strain raises the band gap, whereas compressive strain decreases it. This strain-induced tunability manifests directly in the optical spectra, where prominent optical peaks exhibit significant redshifts under compressive strain and blueshifts under tensile conditions. The refractive index <span><math><mrow><mi>n</mi><mo>(</mo><mi>ω</mi><mo>)</mo></mrow></math></span> demonstrates clear strain-dependent modulations, with the zero-frequency value increasing under compressive strain and decreasing under tensile deformation. Additionally, the DC Kerr effect displays a distinctive double-peak structure that shows high sensitivity to mechanical strain. Comparative analysis demonstrates that monolayer h-BSb exhibits lower-energy optical transitions and enhanced sensitivity to strain-induced peak displacement compared to h-BP. This superior performance stems from h-BSb’s small band gap and narrow interband separations at the points of high-symmetry in the Brillouin zone. These characteristics position h-BSb as a highly promising material for strain-engineered optoelectronic applications, particularly in infrared photodetectors and sensors.</div></div>","PeriodicalId":21151,"journal":{"name":"Results in Optics","volume":"21 ","pages":"Article 100900"},"PeriodicalIF":3.0,"publicationDate":"2025-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145219347","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 : 2025-09-25DOI: 10.1016/j.rio.2025.100901
Amir Hossein Abdollahi Nohoji, Parviz Keshavarzi, Mohammad Danaie
In this study, we propose an all-optical neuromorphic photonic crystal synapse structure equipped with a Ge2Sb2Te5 phase-change material (GST-PCM). By leveraging the unique properties of the GST-PCM material, this structure enables the control of the synaptic weight through targeted and focused laser irradiation. 3D simulations employing the finite-difference time-domain (FDTD) and finite element method (FEM) demonstrated optical transmission exceeding 99 % and reflection below −20 dB at a wavelength of 1504 nm within the proposed structure. These features, together with their compact dimensions and low power consumption, make our proposed structure an ideal candidate for optical processing applications and neuromorphic neural networks. Furthermore, we investigated the physical and thermal equations to determine the crystallization fraction of GST-PCM during the synapse weighting process. These equations showed excellent agreement with the simulation results and could accurately calculate the GST-PCM crystallization fraction as a function of time and laser power. Our proposed structure not only has the potential to be extended to neuromorphic systems and optical neural networks but also serves as an innovative platform for all-optical synapses because of its precise control of optical properties, high adaptability, and low power consumption.
{"title":"Low-power all-optical photonic crystal synapse using Ge2Sb2Te5 phase-change material","authors":"Amir Hossein Abdollahi Nohoji, Parviz Keshavarzi, Mohammad Danaie","doi":"10.1016/j.rio.2025.100901","DOIUrl":"10.1016/j.rio.2025.100901","url":null,"abstract":"<div><div>In this study, we propose an all-optical neuromorphic photonic crystal synapse structure equipped with a Ge<sub>2</sub>Sb<sub>2</sub>Te<sub>5</sub> phase-change material (GST-PCM). By leveraging the unique properties of the GST-PCM material, this structure enables the control of the synaptic weight through targeted and focused laser irradiation. 3D simulations employing the finite-difference time-domain (FDTD) and finite element method (FEM) demonstrated optical transmission exceeding 99 % and reflection below −20 dB at a wavelength of 1504 nm within the proposed structure. These features, together with their compact dimensions and low power consumption, make our proposed structure an ideal candidate for optical processing applications and neuromorphic neural networks. Furthermore, we investigated the physical and thermal equations to determine the crystallization fraction of GST-PCM during the synapse weighting process. These equations showed excellent agreement with the simulation results and could accurately calculate the GST-PCM crystallization fraction as a function of time and laser power. Our proposed structure not only has the potential to be extended to neuromorphic systems and optical neural networks but also serves as an innovative platform for all-optical synapses because of its precise control of optical properties, high adaptability, and low power consumption.</div></div>","PeriodicalId":21151,"journal":{"name":"Results in Optics","volume":"21 ","pages":"Article 100901"},"PeriodicalIF":3.0,"publicationDate":"2025-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145157217","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 : 2025-09-25DOI: 10.1016/j.rio.2025.100903
Bhaskara Rao Perli , Tathababu Addepalli , Arashpreet K. Sohi , Sivasubramanyam Medasani , Manish Sharma , Imran Mohd Ibrahim , Ahmed J.A.Al–Gburi
This present work investigates a compact 4 × 4 cup-shaped Multi-Input Multi-Output (MIMO) antenna using Characteristic Mode Analysis (CMA). The systematic design procedure with six characteristic modes allows the antenna to operate at the working frequency of 3.5 GHz. Physical insight into one-element and four-element radiating structures is gained by analysing modal significance, modal fields, and surface currents. The 4 × 4 MIMO structure works in a narrow frequency band of 2.8 to 4.6 GHz. The total size of the MIMO model is 53 × 53 × 1.6 mm3 and is printed on an inexpensive flame-retardant substrate. The plus-shaped decoupling network and the orientation of the radiating patch provide a strong isolation of more than 20 dB across the operating band. The diversity MIMO performance the antenna provides good results with ECC < 0.000005, DG > 9.9999 dB, TARC < − 10 dB, CCL < 0.02b/s/Hz, and MEG ≅ − 3.0 dB. These antenna features make the MIMO design suitable for sub-6 GHz 5G communications.
{"title":"Design and Theory of Characteristic Mode Analysis (TCMA) of 4 × 4 high isolation MIMO antenna for sub-6GHz 5G communications","authors":"Bhaskara Rao Perli , Tathababu Addepalli , Arashpreet K. Sohi , Sivasubramanyam Medasani , Manish Sharma , Imran Mohd Ibrahim , Ahmed J.A.Al–Gburi","doi":"10.1016/j.rio.2025.100903","DOIUrl":"10.1016/j.rio.2025.100903","url":null,"abstract":"<div><div>This present work investigates a compact 4 × 4 cup-shaped Multi-Input Multi-Output (MIMO) antenna using Characteristic Mode Analysis (CMA). The systematic design procedure with six characteristic modes allows the antenna to operate at the working frequency of 3.5 GHz. Physical insight into one-element and four-element radiating structures is gained by analysing modal significance, modal fields, and surface currents. The 4 × 4 MIMO structure works in a narrow frequency band of 2.8 to 4.6 GHz. The total size of the MIMO model is 53 × 53 × 1.6 mm3 and is printed on an inexpensive flame-retardant<!--> <!-->substrate<sub>.</sub> The plus-shaped decoupling network and the orientation of the radiating patch provide a strong isolation of more than 20 dB across the operating band. The diversity MIMO performance the antenna provides good results with ECC < 0.000005, DG > 9.9999 dB, TARC < − 10 dB, CCL < 0.02b/s/Hz, and MEG ≅ − 3.0 dB. These antenna features make the MIMO design suitable for sub-6 GHz 5G communications.</div></div>","PeriodicalId":21151,"journal":{"name":"Results in Optics","volume":"21 ","pages":"Article 100903"},"PeriodicalIF":3.0,"publicationDate":"2025-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145219345","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 : 2025-09-25DOI: 10.1016/j.rio.2025.100902
Tae Young Kang , ByungSuk Lee , Seunghun Lee , Seonyong An , Robert A. Taylor , Kyoungchun Kwon , Kyujung Kim
The miniaturization and enhanced functionality of LiDAR systems present critical challenges in automotive sensing technologies, particularly in achieving efficient wide-angle beam scanning while maintaining compact form factors. We demonstrate a novel dual-wavelength polarization-selective concave metalens operating at 904 nm and 940 nm wavelengths, the standard operating wavelengths for LiDAR systems. By engineering rectangular TiO2 nanopillars on a quartz substrate, we achieved simultaneous polarization filtering and concave phase profile functionality within a single metasurface layer. The optimized 600 nm × 600 nm unit cell design with 1.7 μm height nanopillars enables full 2π phase coverage while maintaining high transmission efficiency for the desired polarization state. Our fabricated metalens exhibits remarkable polarization extinction ratios (ER) of 124:1 and 102:1 at 904 nm and 940 nm wavelengths, respectively. Angular-resolved measurements demonstrate wide beam divergence angles of 148° and 138° at the respective wavelengths, with 50 % of total power contained within ± 38° and ± 25°.
{"title":"Dispersive near-infrared metalens integrated with linear polarization filtering functionality","authors":"Tae Young Kang , ByungSuk Lee , Seunghun Lee , Seonyong An , Robert A. Taylor , Kyoungchun Kwon , Kyujung Kim","doi":"10.1016/j.rio.2025.100902","DOIUrl":"10.1016/j.rio.2025.100902","url":null,"abstract":"<div><div>The miniaturization and enhanced functionality of LiDAR systems present critical challenges in automotive sensing technologies, particularly in achieving efficient wide-angle beam scanning while maintaining compact form factors. We demonstrate a novel dual-wavelength polarization-selective concave metalens operating at 904 nm and 940 nm wavelengths, the standard operating wavelengths for LiDAR systems. By engineering rectangular TiO<sub>2</sub> nanopillars on a quartz substrate, we achieved simultaneous polarization filtering and concave phase profile functionality within a single metasurface layer. The optimized 600 nm × 600 nm unit cell design with 1.7 μm height nanopillars enables full 2π phase coverage while maintaining high transmission efficiency for the desired polarization state. Our fabricated metalens exhibits remarkable polarization extinction ratios (ER) of 124:1 and 102:1 at 904 nm and 940 nm wavelengths, respectively. Angular-resolved measurements demonstrate wide beam divergence angles of 148° and 138° at the respective wavelengths, with 50 % of total power contained within ± 38° and ± 25°.</div></div>","PeriodicalId":21151,"journal":{"name":"Results in Optics","volume":"21 ","pages":"Article 100902"},"PeriodicalIF":3.0,"publicationDate":"2025-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145265257","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 : 2025-09-25DOI: 10.1016/j.rio.2025.100898
Hang Chen , Zhenduo Ma , Ziyi Zhang , Zhengjun Liu
This article proposes an audio signal encryption method based on the Gerchberg-Saxton (G-S) phase recovery algorithm in the fractional Fourier transform domain. The algorithm first encodes the original audio signal into an image format and encrypts it. Subsequently, the G-S phase recovery algorithm is used in the fractional Fourier domain to extract the phase information of the audio signal. On this basis, the original audio phase is replaced with a reference phase representing the secret information to achieve information embedding. This technology can select two different types of keys according to encryption requirements, further increasing the difficulty of decryption and ensuring information security. Ultimately, the encrypted image can be decrypted and restored to the original audio signal. This scheme achieves effective embedding and extraction of secret information in audio signals through the replacement and recovery of phase information.
{"title":"Optical audio signal hiding algorithm based on fractional Fourier transform domain and Gerchberg Saxton phase recovery","authors":"Hang Chen , Zhenduo Ma , Ziyi Zhang , Zhengjun Liu","doi":"10.1016/j.rio.2025.100898","DOIUrl":"10.1016/j.rio.2025.100898","url":null,"abstract":"<div><div>This article proposes an audio signal encryption method based on the Gerchberg-Saxton (G-S) phase recovery algorithm in the fractional Fourier transform domain. The algorithm first encodes the original audio signal into an image format and encrypts it. Subsequently, the G-S phase recovery algorithm is used in the fractional Fourier domain to extract the phase information of the audio signal. On this basis, the original audio phase is replaced with a reference phase representing the secret information to achieve information embedding. This technology can select two different types of keys according to encryption requirements, further increasing the difficulty of decryption and ensuring information security. Ultimately, the encrypted image can be decrypted and restored to the original audio signal. This scheme achieves effective embedding and extraction of secret information in audio signals through the replacement and recovery of phase information.</div></div>","PeriodicalId":21151,"journal":{"name":"Results in Optics","volume":"21 ","pages":"Article 100898"},"PeriodicalIF":3.0,"publicationDate":"2025-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145157218","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 : 2025-09-24DOI: 10.1016/j.rio.2025.100899
Zhao Chen , Fei Li , Wenpeng Liu , Yufa Zhang , Qingli Zhang
YAG/Nd:YAG and YAG/Nd:YAG/YAG composite laser crystals were fabricated through thermal bonding method. The temperature distribution and laser properties of Nd:YAG, YAG/Nd:YAG and YAG/Nd:YAG/YAG crystals under LD end-pumping conditions were studied. Laser outputs with wavelengths of 1064 nm and 946 nm have been achieved. Temperature simulation results revealed that at 20 W pump power, the YAG/Nd:YAG/YAG crystal exhibited 15 K lower temperature compared to Nd:YAG crystal, with a 33 K reduction in end-face temperature. Under 20 W pumping, the maximum continuous-wave output powers of YAG/Nd:YAG/YAG crystal reached 4.412 W at 1064 nm and 668 mW at 946 nm, corresponding to slope efficiencies of 34.66 % and 6.68 %, and optical-to-optical conversion efficiencies of 34.77 % and 5.99 %, respectively. These values represent 1.6-fold and 1.8-fold improvements in output power, 13.4 % and 4.33 % enhancements in slope efficiency, as well as 9.31 % and 3.92 % increases in conversion efficiency compared to Nd:YAG crystal. Moreover, the YAG/Nd:YAG/YAG crystal demonstrated superior beam quality with lower M2 factors than both Nd:YAG/YAG composite crystal and Nd:YAG crystal. It is shown that the composite YAG/Nd:YAG/YAG crystal has better cooling efficiency, which is beneficial to reduce the thermal lens effect and improve the laser efficiency.
{"title":"Temperature distribution simulation and laser performance of Nd:YAG composite laser crystals","authors":"Zhao Chen , Fei Li , Wenpeng Liu , Yufa Zhang , Qingli Zhang","doi":"10.1016/j.rio.2025.100899","DOIUrl":"10.1016/j.rio.2025.100899","url":null,"abstract":"<div><div>YAG/Nd:YAG and YAG/Nd:YAG/YAG composite laser crystals were fabricated through thermal bonding method. The temperature distribution and laser properties of Nd:YAG, YAG/Nd:YAG and YAG/Nd:YAG/YAG crystals under LD end-pumping conditions were studied. Laser outputs with wavelengths of 1064 nm and 946 nm have been achieved. Temperature simulation results revealed that at 20 W pump power, the YAG/Nd:YAG/YAG crystal exhibited 15 K lower temperature compared to Nd:YAG crystal, with a 33 K reduction in end-face temperature. Under 20 W pumping, the maximum continuous-wave output powers of YAG/Nd:YAG/YAG crystal reached 4.412 W at 1064 nm and 668 mW at 946 nm, corresponding to slope efficiencies of 34.66 % and 6.68 %, and optical-to-optical conversion efficiencies of 34.77 % and 5.99 %, respectively. These values represent 1.6-fold and 1.8-fold improvements in output power, 13.4 % and 4.33 % enhancements in slope efficiency, as well as 9.31 % and 3.92 % increases in conversion efficiency compared to Nd:YAG crystal. Moreover, the YAG/Nd:YAG/YAG crystal demonstrated superior beam quality with lower M<sup>2</sup> factors than both Nd:YAG/YAG composite crystal and Nd:YAG crystal. It is shown that the composite YAG/Nd:YAG/YAG crystal has better cooling efficiency, which is beneficial to reduce the thermal lens effect and improve the laser efficiency.</div></div>","PeriodicalId":21151,"journal":{"name":"Results in Optics","volume":"21 ","pages":"Article 100899"},"PeriodicalIF":3.0,"publicationDate":"2025-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145219344","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 : 2025-09-22DOI: 10.1016/j.rio.2025.100895
C. Dlamini , M.R. Mhlongo , V.M. Maphiri , T.D. Malevu , L.F. Koao , T.E. Motaung , T.T. Hlatshwayo , S.V. Motloung
Mixed-phases of the SrCO3/Sr3Al2O6/SrAl2O4/SrAl4O7/SrAl12O19 (hereafter called SSSSS) doped with Gd3+ (SSSSS: 0.05 % Gd3+) nanopowders were prepared using the citrate sol–gel method. The effect of annealing temperature (Ta) on the structure, morphology, and photoluminescence (PL) properties was investigated. The Ta was varied in a range of 600–1300 °C, while the dopant concentration was kept constant at 0.05 % Gd3+. X-ray diffraction (XRD) results revealed that the prepared nanopowders consist of a mixture of orthorhombic (SrCO3), cubic (Sr3Al2O6), monoclinic (SrAl2O4 and SrAl4O7), and hexagonal SrAl12O19 structures. It was noted that increasing the phase composition depends on the Ta. The Fourier-transform infrared spectroscopy (FTIR) shows several peaks at around 529, 874, 1181, 1442, 2947, and 3421 cm−1. The Energy dispersive spectroscopy (EDS) confirmed the elementary composition of the Sr, C, O, and Al. The scanning electron microscope (SEM) images showed that the phase composition highly depends on the Ta. Transmission electron microscope (TEM) showed that the particle sizes are in the nanoscale. The ultraviolet–visible (UV–vis) diffuse reflection spectroscopy results showed that the absorption peaks below 300 nm are influenced by the Ta. The PL results showed three emission peaks located around 431, 541, and 657 nm when excited at 272 nm. These emission peaks were attributed to SrCO3, SrAl2O4, and Sr3Al2O6 crystal lattice, respectively. The results showed that the luminescence intensity and lifetime of the prepared samples depends on the Ta. The chromaticiy coordinate showed that all samples emit in a blue region and the color purity was influenced by the Ta.
{"title":"Temperature-dependent phase evolution of the Gd3+ doped strontium compounds: Structural and optical properties","authors":"C. Dlamini , M.R. Mhlongo , V.M. Maphiri , T.D. Malevu , L.F. Koao , T.E. Motaung , T.T. Hlatshwayo , S.V. Motloung","doi":"10.1016/j.rio.2025.100895","DOIUrl":"10.1016/j.rio.2025.100895","url":null,"abstract":"<div><div>Mixed-phases of the SrCO<sub>3</sub>/Sr<sub>3</sub>Al<sub>2</sub>O<sub>6</sub>/SrAl<sub>2</sub>O<sub>4</sub>/SrAl<sub>4</sub>O<sub>7</sub>/SrAl<sub>12</sub>O<sub>19</sub> (hereafter called SSSSS) doped with Gd<sup>3+</sup> (SSSSS: 0.05 % Gd<sup>3+</sup>) nanopowders were prepared using the citrate sol–gel method. The effect of annealing temperature (T<sub>a</sub>) on the structure, morphology, and photoluminescence (PL) properties was investigated. The T<sub>a</sub> was varied in a range of 600–1300 °C, while the dopant concentration was kept constant at 0.05 % Gd<sup>3+</sup>. X-ray diffraction (XRD) results revealed that the prepared nanopowders consist of a mixture of orthorhombic (SrCO<sub>3</sub>), cubic (Sr<sub>3</sub>Al<sub>2</sub>O<sub>6</sub>), monoclinic (SrAl<sub>2</sub>O<sub>4</sub> and SrAl<sub>4</sub>O<sub>7</sub>), and hexagonal SrAl<sub>12</sub>O<sub>19</sub> structures. It was noted that increasing the phase composition depends on the T<sub>a</sub>. The Fourier-transform infrared spectroscopy (FTIR) shows several peaks at around 529, 874, 1181, 1442, 2947, and 3421 cm<sup>−1</sup>. The Energy dispersive spectroscopy (EDS) confirmed the elementary composition of the Sr, C, O, and Al. The scanning electron microscope (SEM) images showed that the phase composition highly depends on the T<sub>a</sub>. Transmission electron microscope (TEM) showed that the particle sizes are in the nanoscale. The ultraviolet–visible (UV–vis) diffuse reflection spectroscopy results showed that the absorption peaks below 300 nm are influenced by the T<sub>a</sub>. The PL results showed three emission peaks located around 431, 541, and 657 nm when excited at 272 nm. These emission peaks were attributed to SrCO<sub>3</sub>, SrAl<sub>2</sub>O<sub>4</sub>, and Sr<sub>3</sub>Al<sub>2</sub>O<sub>6</sub> crystal lattice, respectively. The results showed that the luminescence intensity and lifetime of the prepared samples depends on the T<sub>a</sub>. The chromaticiy coordinate showed that all samples emit in a blue region and the color purity was influenced by the T<sub>a</sub>.</div></div>","PeriodicalId":21151,"journal":{"name":"Results in Optics","volume":"21 ","pages":"Article 100895"},"PeriodicalIF":3.0,"publicationDate":"2025-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145157219","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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