{"title":"Development and optimization of a PCA-based terahertz time-domain spectroscopy system for high-resolution material characterization","authors":"Siriwan Pakluea , Jia Yi Chia , Monchai Jitvisate , Chitrlada Thongbai , Sakhorn Rimjaem","doi":"10.1016/j.infrared.2025.106060","DOIUrl":"10.1016/j.infrared.2025.106060","url":null,"abstract":"<div><div>Terahertz time-domain spectroscopy (THz-TDS) is a powerful technique for material characterization, providing amplitude and phase information across a broad frequency range. This study details the design, development, and optimization of the first homemade THz-TDS system in Thailand, addressing the high cost and limited accessibility of commercial systems. The system features in-house-developed photoconductive antennas (PCAs) fabricated from electron-beam-irradiated SI-GaAs and a Ti:Sapphire femtosecond laser oscillator, achieving great signal-to-noise ratios and broad bandwidth. Through careful tuning of operational parameters including laser power, bias voltage, scan range, and resolution, the system achieves high signal quality and broad spectral coverage. The system’s performance was validated through material characterization experiments, including accurate measurements of refractive index and thickness of a silicon wafer. Additionally, challenges in liquid-phase measurements, such as window material selection and internal reflections, were systematically addressed. Integration of the system into a dry-air-filled box minimized moisture absorption, allowing precise characterization of moisture-sensitive materials. This work addresses critical gaps in the THz-TDS field by offering systematic system design, parameter optimization, and liquid-phase analysis. It provides practical guidelines and advancements that enable researchers to develop cost-effective, high-performance THz-TDS systems, in resource-limited settings.</div></div>","PeriodicalId":13549,"journal":{"name":"Infrared Physics & Technology","volume":"151 ","pages":"Article 106060"},"PeriodicalIF":3.4,"publicationDate":"2025-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144996908","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Use of effective medium theory for characterization of optical and dielectric properties of explosive composites in terahertz spectral range","authors":"Rajesh Koalla, Anil Kumar Chaudhary","doi":"10.1016/j.infrared.2025.106129","DOIUrl":"10.1016/j.infrared.2025.106129","url":null,"abstract":"<div><div>This paper reports the optical and dielectric characterization of highly sensitive explosives composites using an Effective Medium Theory approach in Terahertz Time-domain Spectroscopy. For the spectroscopic studies, samples need to be in pellet form. However, making pellets of some of the primary shock-sensitive high-energy materials is risky due to their sensitivity to grinding. Therefore, these sensitive samples must be mixed with an external host medium (Teflon) to form a pellet. We have approached Effective Medium Theory (EMT) analytic relations, such as Maxwell Garnett, Bruggeman, and LLL approaches, to extract the optical and dielectric properties from Teflon/ sensitive explosive composite. The approach was validated by preparing a mixture of three premium explosives, RDX, HMX, and TNT, in a Teflon matrix and extracting their optical and dielectric properties using the Effective Medium Theory method. The obtained properties of the explosives were then compared with those of the pure explosives (without the Teflon matrix). The extracted values show good agreement with those of the pure samples for the explosive mixture in the Teflon matrix (1:5).</div></div>","PeriodicalId":13549,"journal":{"name":"Infrared Physics & Technology","volume":"151 ","pages":"Article 106129"},"PeriodicalIF":3.4,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144996909","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Multi-Feature joint weighted hyperspectral target detection based on optimized Gabor filter","authors":"Jiahui Wang , Fang Li , Liguo Wang , Jianjun He","doi":"10.1016/j.infrared.2025.106131","DOIUrl":"10.1016/j.infrared.2025.106131","url":null,"abstract":"<div><div>With the rapid development of hyperspectral remote sensing technology, target detection technology exhibits a wide range of application prospects in many fields. However, the detection algorithms based on raw spectral features suffer from single feature extraction and insufficient joint spatial-spectral information, leading to their poor detection performance in complex scenes. To address these issues, this paper proposes a multi-feature joint weighted hyperspectral target detection based on optimized Gabor filter. First, the conventional 3D Gabor filter is optimized through spectral angle similarity measurement, which adaptively enhances responses in target feature regions. Second, amplitude and phase information are innovatively combined, and representative feature cubes are screened based on four optimization criteria, effectively reducing data redundancy while improving feature representation capability. Finally, a weighted fusion strategy is used to integrate the four preliminary detection maps and iteratively optimized with the fuzzy Otsu algorithm, which significantly improves the detection accuracy and algorithm stability. The method proposed in this paper achieves outstanding detection performance on six hyperspectral datasets.</div></div>","PeriodicalId":13549,"journal":{"name":"Infrared Physics & Technology","volume":"151 ","pages":"Article 106131"},"PeriodicalIF":3.4,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144925467","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Youtong Li , Yongyang Li , Haozhi Xu , Yanguo Guo , Wei Huang , Chen Chen , Chunguang Li , Frank K. Tittel
{"title":"Vibrating cavity off-axis integrated cavity output spectroscopy combined with new uniform phase empirical mode decomposition for CH4 measurement system","authors":"Youtong Li , Yongyang Li , Haozhi Xu , Yanguo Guo , Wei Huang , Chen Chen , Chunguang Li , Frank K. Tittel","doi":"10.1016/j.infrared.2025.106102","DOIUrl":"10.1016/j.infrared.2025.106102","url":null,"abstract":"<div><div>In order to realize CH<sub>4</sub> measurement, a vibrating cavity off-axis integrated cavity output spectroscopy (VC-OA-ICOS) CH<sub>4</sub> sensing system was developed in this paper. The inclusion of a vibration module in the system can effectively suppress cavity mode noise. To further eliminate characteristic cavity mode noise and improve system stability, we proposed a new uniform phase empirical mode decomposition (NUPEMD) method. This method enables the selection of the appropriate number of phases and the amplitude of the masking signal, thereby reducing the impacts of mode mixing and residual noise. The self-contained fitting and mutual correlation signal reconstruction technique employed in NUPEMD is particularly effective in eliminating medium- and high-frequency noise. Analysis of the Fourier frequency domain plots of the system noise revealed that the combination of vibration with the NUPEMD method significantly suppresses medium- and high-frequency residual cavity mode noise. Experimental results demonstrated that utilization of this method enabled the VC-OA-ICOS system to achieve a minimum detection limit (MDL) of 0.381 ppmv within 2 s, resulting in a 5.62-fold improvement in measurement accuracy compared to traditional methods. Furthermore, continuous measurements using this enhanced VC-OA-ICOS system on standard CH<sub>4</sub> samples over a period of 12 h yielded a long-term detection error of no more than 0.47 %, representing a 1.98-fold improvement in stability. The effectiveness and superiority of both the proposed system and the methodology for CH<sub>4</sub> measurement are thoroughly validated through these findings.</div></div>","PeriodicalId":13549,"journal":{"name":"Infrared Physics & Technology","volume":"151 ","pages":"Article 106102"},"PeriodicalIF":3.4,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145004251","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jin Shi , Pei Xiang , Shuxia Qi , Jiangluqi Song , Dong Zhao , Huan Li , Huixin Zhou , Dabao Wang
{"title":"Fast radiometric calibration and measurement technology based on distance correction in infrared systems","authors":"Jin Shi , Pei Xiang , Shuxia Qi , Jiangluqi Song , Dong Zhao , Huan Li , Huixin Zhou , Dabao Wang","doi":"10.1016/j.infrared.2025.106112","DOIUrl":"10.1016/j.infrared.2025.106112","url":null,"abstract":"<div><div>Infrared radiometric measurements can acquire important data for infrared systems. Radiometric calibration is the foundation of the measurement process. Considering the calibration issues such as gray-level drift, cumbersome calibration procedures, excessive calibration points, and high time costs in the infrared radiation measurement system when the detection distance changes, in this paper, we proposed a novel technique for fast radiometric calibration and measurement in target infrared imaging systems. First, a linear response model that correlated target radiation input with system gray value output was established. This model improves the subsequent measurement accuracy via blackbody radiometric calibration. Second, to compensate for radiation attenuation in the path and improve the measurement accuracy of the system, a radiometric calibration model based on two-test-distances was proposed. Finally, to improve the efficiency of system drift compensation, a fast radiometric calibration model was proposed by combining the radiometric calibration considering the integration time and a radiometric calibration model based on two-test-distances. The key advantage of the proposed method is that it enhances measurement accuracy by correcting the radiance measured at various test distances. The experimental results showed that the proposed method improved the calibration efficiency and measurement accuracy of the infrared radiation system. The proposed method enables measurements at different integration times and testing distances.</div></div>","PeriodicalId":13549,"journal":{"name":"Infrared Physics & Technology","volume":"151 ","pages":"Article 106112"},"PeriodicalIF":3.4,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145004252","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jiawei Wu , Lailiang Song , Tianqi Li , Yang Pang , Longjie Tian , Hongcai Li , Yanqiang Yang
{"title":"Study of a multi-parameter fusion Gaussian a priori reconstruction method for hypersonic aero-radiation spectroscopy","authors":"Jiawei Wu , Lailiang Song , Tianqi Li , Yang Pang , Longjie Tian , Hongcai Li , Yanqiang Yang","doi":"10.1016/j.infrared.2025.106130","DOIUrl":"10.1016/j.infrared.2025.106130","url":null,"abstract":"<div><div>The extreme thermodynamic environment created by the high-temperature gas at the optical window in the wake of a hypersonic vehicle leads to strong aero-radiation, which causes significant background noise in star sensor observations. The study of spectral detection of aero-radiation contributes to suppress the background noise it introduces due to its spectral band characteristics. This study analyzes the spectral band characteristics of the aero-radiation spectra. Based on the theoretical framework of compressed sensing, the spectral band features are mapped to a multiple Gaussian distribution, thereby constructing a multi-parameter fused Gaussian prior model. A multi-parameter fused Gaussian prior adaptive reconstruction method is proposed. The method integrates spectral characteristics extracted from physical experimental results with mathematical modeling, enabling non-blind reconstruction of aero-radiation spectra, in which prior information—such as peak positions, widths, and intensities—is explicitly incorporated to improve reconstruction accuracy and robustness. Furthermore, a spectral goodness-of-fit evaluation criterion is proposed in this study to assess the fusion results of physical experimental spectra and simulated reconstructed spectra, serving as a standard for evaluating the quality of spectral reconstruction. The experimental results prove the effectiveness of the proposed method.</div></div>","PeriodicalId":13549,"journal":{"name":"Infrared Physics & Technology","volume":"151 ","pages":"Article 106130"},"PeriodicalIF":3.4,"publicationDate":"2025-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145095071","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Lixia Li , Yurui Huang , Jiabin Zhao , Feiyou Liu , Ning Feng , Yufang Liu
{"title":"Deep learning-enhanced ultra-sensitive fiber optic SPR sensor for mercury ion detection","authors":"Lixia Li , Yurui Huang , Jiabin Zhao , Feiyou Liu , Ning Feng , Yufang Liu","doi":"10.1016/j.infrared.2025.106128","DOIUrl":"10.1016/j.infrared.2025.106128","url":null,"abstract":"<div><div>Mercury ions (Hg<sup>2+</sup>) are highly toxic heavy metal pollutants that pose significant risks to the environment and human health. In this paper, a fiber optic surface plasmon resonance (SPR) sensor is proposed for ultra-sensitive detection of Hg<sup>2+</sup>. The probe features Ag/ Ge<sub>2</sub>Sb<sub>2</sub>Te<sub>5</sub> (GST)/Ag composite film and metal–organic framework (MOF)-sensitized layer functionalized with probe DNA (pDNA). In the presence of Hg<sup>2+</sup>, pDNA interacts with target DNA (tDNA) carrying gold nanoparticles (AuNPs) in the solution through the T-Hg<sup>2+</sup>-T structure, immobilizing AuNPs on the sensing surface and inducing a spectral red shift. By combining GST’s high dielectric constant and MOF’s large surface area with strong pDNA affinity, the sensor achieves a maximum refractive index (RI) sensitivity of 11471 nm/RIU, detecting Hg<sup>2+</sup> as low as 10 pM. Furthermore, the deep learning model based on the residual neural network (ResNet) is employed to classify and recognize the SPR spectra corresponding to six distinct concentrations of Hg<sup>2+</sup>, achieving a training accuracy of 99.88 % and a test accuracy of 97.5 %. Therefore, ultra-sensitive fiber optic SPR sensor with deep learning delivers high-performance sensing while enabling rapid, precise, and sensitive quantification of Hg<sup>2+</sup> detection.</div></div>","PeriodicalId":13549,"journal":{"name":"Infrared Physics & Technology","volume":"151 ","pages":"Article 106128"},"PeriodicalIF":3.4,"publicationDate":"2025-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144922273","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A compact local oscillator distribution network design for Leighton Chajnantor Telescope based on a center frequency of 115 GHz","authors":"Donghong Cao , Yi Ji , Yiwen Zhang","doi":"10.1016/j.infrared.2025.106125","DOIUrl":"10.1016/j.infrared.2025.106125","url":null,"abstract":"<div><div>Superconductor-insulator-superconductor (SIS) receivers are widely applied in millimeter/submillimeter astronomical observations. Developing multi-beam focal plane arrays (FPAs) is an effective approach for enhancing the observational efficiency. Herein, we designed and simulated a novel local oscillator (LO) distribution network for a 1 × 3 pixel array, a key component of multi-beam FPAs, with a central frequency of around 115 GHz. Compared to SIS arrays assembled using traditional methods, this design offers superior compactness and scalability. The simulation results demonstrate that the design achieves uniform LO signal distribution across all output ports within the 107–128 GHz frequency band. The relative amplitude difference is less than 0.8 dB, with return loss and isolation better than −20 dB, and isolation between output ports exceeding −15 dB. The compactness, wide bandwidth, and high isolation of the LO distribution network provide a foundation for upgrading Leighton Chajnantor Telescope's multi-beam system.</div></div>","PeriodicalId":13549,"journal":{"name":"Infrared Physics & Technology","volume":"151 ","pages":"Article 106125"},"PeriodicalIF":3.4,"publicationDate":"2025-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145007487","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Shuyuan Lv , Duoduo Duan , Xiaohui Li , Wenfeng Luo , Tingting Zhang
{"title":"Research on narrow-linewidth erbium-doped fiber lasers based on composite double-ring structures","authors":"Shuyuan Lv , Duoduo Duan , Xiaohui Li , Wenfeng Luo , Tingting Zhang","doi":"10.1016/j.infrared.2025.106101","DOIUrl":"10.1016/j.infrared.2025.106101","url":null,"abstract":"<div><div>This work presents an innovative erbium-doped fiber laser with ultra-narrow linewidth and single longitudinal mode operation. In this paper, a composite double-ring cavity composed of double couplers combined with a uniform fiber Bragg grating with a reflection bandwidth of only 0.25 nm is used to achieve good performance of single longitudinal mode laser and narrow linewidth output. The experimental results clearly show that under room temperature conditions, the output central wavelength of this laser is 1558.31 nm, the optical signal-to-noise ratio is as high as 61.71 dB, and the slope efficiency is 1.34 %. After a continuous measurement process of 60 min, the fluctuation amplitude of the output wavelength is only 0.05 nm, and the fluctuation amplitude of power is 0.008 dB, fully confirming that the designed laser has good wavelength stability and power stability. The delay self-heterodyne method is used to measure its linewidth, and the results show that the linewidth of the laser is as low as 352 Hz. Such lasers have broad application prospects in cutting-edge fields such as lidar and space optical communication systems.</div></div>","PeriodicalId":13549,"journal":{"name":"Infrared Physics & Technology","volume":"151 ","pages":"Article 106101"},"PeriodicalIF":3.4,"publicationDate":"2025-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145018513","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}