Pub Date : 2026-01-15DOI: 10.1109/JSTQE.2026.3654052
Yiqin Liu;Wanli Li;Jinxuan Deng;Weiwen Li
Spoof surface plasmon polariton (SSPP) waveguides typically exhibit positive group delay, leading to pulse broadening, which can be compensated by introducing a negative group delay (NGD) circuit. In this work, the self-coupling characteristics of split-ring resonator (SRR) structures are exploited to realize NGD within the SSPP waveguide unit. By vertically stacking multiple SRRs, the NGD value is further enhanced. To compensate for the signal attenuation associated with NGD, an amplifier circuit is designed, and an attenuator is introduced to enable tunable gain. The proposed triple-SRR NGD waveguide achieves approximately – 8 ns group delay at 1.61 GHz. The system provides a tunable S21 range of up to 30 dB, while the delay value and operating frequency remain relatively stable. By compressing the output signal envelope, advanced signal output can be achieved. This circuit system shows great potential for applications in real-time communications and sensing.
{"title":"A Gain-Tunable SSPP Circuit System With Negative Group Delay","authors":"Yiqin Liu;Wanli Li;Jinxuan Deng;Weiwen Li","doi":"10.1109/JSTQE.2026.3654052","DOIUrl":"https://doi.org/10.1109/JSTQE.2026.3654052","url":null,"abstract":"Spoof surface plasmon polariton (SSPP) waveguides typically exhibit positive group delay, leading to pulse broadening, which can be compensated by introducing a negative group delay (NGD) circuit. In this work, the self-coupling characteristics of split-ring resonator (SRR) structures are exploited to realize NGD within the SSPP waveguide unit. By vertically stacking multiple SRRs, the NGD value is further enhanced. To compensate for the signal attenuation associated with NGD, an amplifier circuit is designed, and an attenuator is introduced to enable tunable gain. The proposed triple-SRR NGD waveguide achieves approximately – 8 ns group delay at 1.61 GHz. The system provides a tunable <italic>S</i><sub>21</sub> range of up to 30 dB, while the delay value and operating frequency remain relatively stable. By compressing the output signal envelope, advanced signal output can be achieved. This circuit system shows great potential for applications in real-time communications and sensing.","PeriodicalId":13094,"journal":{"name":"IEEE Journal of Selected Topics in Quantum Electronics","volume":"32 3: Nanophotonics, Metamaterials and Plasmonics","pages":"1-5"},"PeriodicalIF":5.1,"publicationDate":"2026-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146026576","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Chip-scale photonics integrated circuits have attracted great attention in optical communications for decades due to their advantages in material compatibility, power consumption, bandwidth, and integrability. We present a comprehensive introduction to mode-manipulating devices based on three-dimensional (3D) waveguide circuits, where these devices are fabricated by using optical lithography, femtosecond laser direct writing, or 3D printing based on two-photon absorption. We also discuss the future development and applications of the 3D photonic chips, which can find further applications in quantum optics, signal processing, and biosensing, all leveraging mode manipulation.
{"title":"On-Chip Photonics Integrated Circuits Formed by Three-Dimensional Waveguides for Mode Manipulation","authors":"Zirou Liu;Yu Huang;Yahao Li;Jun Xue;Chaoyue Wang;Wanyu Wu;Yanping Li;Jiawei Kong;Yue Chen;Zhihang Yan;Sławomir Ertman;Xinyong Dong;Tomasz R. Woliński;Perry Ping Shum;Quandong Huang","doi":"10.1109/JSTQE.2026.3654088","DOIUrl":"https://doi.org/10.1109/JSTQE.2026.3654088","url":null,"abstract":"Chip-scale photonics integrated circuits have attracted great attention in optical communications for decades due to their advantages in material compatibility, power consumption, bandwidth, and integrability. We present a comprehensive introduction to mode-manipulating devices based on three-dimensional (3D) waveguide circuits, where these devices are fabricated by using optical lithography, femtosecond laser direct writing, or 3D printing based on two-photon absorption. We also discuss the future development and applications of the 3D photonic chips, which can find further applications in quantum optics, signal processing, and biosensing, all leveraging mode manipulation.","PeriodicalId":13094,"journal":{"name":"IEEE Journal of Selected Topics in Quantum Electronics","volume":"32 2: 3-D Horizons in Photonics: Integrated Circuits","pages":"1-15"},"PeriodicalIF":5.1,"publicationDate":"2026-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146082317","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The dimensional limit of a single-mode waveguide cross-section is the fundamental roadblock of designing compact and large-scale planar photonic integrated circuits (PICs). The other limitation is the choice of waveguide core materials for designing various passive and active components for the application specific PICs. Fortunately, besides crystalline Si, plenty of other options of waveguide core materials such as epitaxially grown Ge, PECVD/LPCVD grown SiN, AlN, etc., are available for the utilization of advanced CMOS fabrication process compatible silicon photonics technology in silicon-on-insulator (SOI) platform. However, because of the absence of a suitably designed optical via, hybrid structure waveguide components and multi-layered three-dimensional PIC designs couldn’t be effectively implemented till date. Here, we have proposed a low-loss compact optical tunnel via (OTV) design as a solution for 3D photonic integration. Using a standard Maxwell’s equation solver, we have shown that the insertion loss of such a OTV design can be $< $ 0.1 dB for a broad wavelength range of operations around 1550 nm. We have also shown low-loss performance of such OTVs can be arrayed in designing complex PICs with hybrid waveguide components. The materials and design dimensions have been chosen carefully such that the proposed 3D-PICs can be easily manufactured in conventional CMOS foundries. We have also presented wavelength dependent loss (WDL) and polarization dependent loss (PDL) of various OTV designs for hybrid photonic interconnects using 3D-FDTD simulations.
{"title":"CMOS Compatible Low-loss Optical Tunnel Vias for 3D Photonic Integration","authors":"Sarad Subhra Bhakat;Kumar Piyush;Chintapalli Sam;Riddhi Goswami;Arnab Goswami;Eloi Marigo Ferrer;Hor Chee Hoong;Ng Chew Yan;Bijoy Krishna Das","doi":"10.1109/JSTQE.2026.3653717","DOIUrl":"https://doi.org/10.1109/JSTQE.2026.3653717","url":null,"abstract":"The dimensional limit of a single-mode waveguide cross-section is the fundamental roadblock of designing compact and large-scale planar photonic integrated circuits (PICs). The other limitation is the choice of waveguide core materials for designing various passive and active components for the application specific PICs. Fortunately, besides crystalline Si, plenty of other options of waveguide core materials such as epitaxially grown Ge, PECVD/LPCVD grown SiN, AlN, etc., are available for the utilization of advanced CMOS fabrication process compatible silicon photonics technology in silicon-on-insulator (SOI) platform. However, because of the absence of a suitably designed optical via, hybrid structure waveguide components and multi-layered three-dimensional PIC designs couldn’t be effectively implemented till date. Here, we have proposed a low-loss compact optical tunnel via (OTV) design as a solution for 3D photonic integration. Using a standard Maxwell’s equation solver, we have shown that the insertion loss of such a OTV design can be <inline-formula><tex-math>$< $</tex-math></inline-formula> 0.1 dB for a broad wavelength range of operations around 1550 nm. We have also shown low-loss performance of such OTVs can be arrayed in designing complex PICs with hybrid waveguide components. The materials and design dimensions have been chosen carefully such that the proposed 3D-PICs can be easily manufactured in conventional CMOS foundries. We have also presented wavelength dependent loss (WDL) and polarization dependent loss (PDL) of various OTV designs for hybrid photonic interconnects using 3D-FDTD simulations.","PeriodicalId":13094,"journal":{"name":"IEEE Journal of Selected Topics in Quantum Electronics","volume":"32 2: 3-D Horizons in Photonics: Integrated Circuits","pages":"1-14"},"PeriodicalIF":5.1,"publicationDate":"2026-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11348063","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146082307","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The impact of neoadjuvant PD-1 blockade in combination with chemotherapy on the tumor microenvironment of esophageal cancer has not been fully understood. In this paper, multiphoton microscopy and digital pathological imaging analysis were conducted to examine the treatment-driven microenvironment changes among 51 samples with only underwent surgical resection (SG), 49 samples with good pathological reactions (GR) and 34 samples with poor pathological reactions (PR). The results showed that treatment caused the elastic fiber to remodel in the arterioles and led the vascular walls to thicken, which might be related to drug delivery but not to the therapeutic effect. After neoadjuvant therapy, the collagen fibers in the stromal regions immediately adjacent to the tumor mass were degraded, which was a good response to treatment. In the GR group but not the PR group, although neoadjuvant therapy caused significant regression of the tumor mass, some more aggressive subclones of tumor cells were screened out, characterized by rounder nuclear shape, and smaller smoothness, with looser nuclear structure and enlarged nucleoli. In addition, stromal fibrosis also can be observed in the GR group, manifested by the more deposition of collagen fibers, longer and wider collagen fibers, and more orderly arrangement of collagen fibers existing in the stromal regions at 200 μm from the tumor mass after treatment. Correlation analysis showed that the degradation of collagen fibers adjacent to the tumor mass, nuclear morphology of the residual cells, and stromal fibrosis were significantly correlated with therapeutic efficacy.
{"title":"Visualization of Alterations in Tumor Microenvironment of Esophageal Squamous Cell Carcinoma Caused by Neoadjuvant Therapy Based on the Combination of Multiphoton Microscopy and Digital Pathological Imaging Analysis","authors":"Bo Liu;Guoping Li;Zhijun Li;Xuan Tao;Ke Zheng;Zhouxu Feng;Shichao Zhang;Shuoyu Xu;Jianhua Chen;Xu Li;Jianxin Chen","doi":"10.1109/JSTQE.2026.3652794","DOIUrl":"https://doi.org/10.1109/JSTQE.2026.3652794","url":null,"abstract":"The impact of neoadjuvant PD-1 blockade in combination with chemotherapy on the tumor microenvironment of esophageal cancer has not been fully understood. In this paper, multiphoton microscopy and digital pathological imaging analysis were conducted to examine the treatment-driven microenvironment changes among 51 samples with only underwent surgical resection (SG), 49 samples with good pathological reactions (GR) and 34 samples with poor pathological reactions (PR). The results showed that treatment caused the elastic fiber to remodel in the arterioles and led the vascular walls to thicken, which might be related to drug delivery but not to the therapeutic effect. After neoadjuvant therapy, the collagen fibers in the stromal regions immediately adjacent to the tumor mass were degraded, which was a good response to treatment. In the GR group but not the PR group, although neoadjuvant therapy caused significant regression of the tumor mass, some more aggressive subclones of tumor cells were screened out, characterized by rounder nuclear shape, and smaller smoothness, with looser nuclear structure and enlarged nucleoli. In addition, stromal fibrosis also can be observed in the GR group, manifested by the more deposition of collagen fibers, longer and wider collagen fibers, and more orderly arrangement of collagen fibers existing in the stromal regions at 200 μm from the tumor mass after treatment. Correlation analysis showed that the degradation of collagen fibers adjacent to the tumor mass, nuclear morphology of the residual cells, and stromal fibrosis were significantly correlated with therapeutic efficacy.","PeriodicalId":13094,"journal":{"name":"IEEE Journal of Selected Topics in Quantum Electronics","volume":"32 4: Adv. Biophoton. in Emerg. Biomed. Tech. and Dev","pages":"1-13"},"PeriodicalIF":5.1,"publicationDate":"2026-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146026619","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Collagen remodelling plays a critical role in the progression of pancreatic intraepithelial neoplasia (PanIN) to pancreatic ductal adenocarcinoma (PDAC), though misdiagnosis often occurs due to the resemblance with chronic pancreatitis (CP). While second harmonic generation (SHG) microscopy is the current gold standard in research for visualizing fibrillar collagen, it is not utilized for routine histopathological use. This study highlights the need for an alternative method for quantitative collagen analysis that is compatible with standard hematoxylin-and-eosin (HE) stained histopathological slides. Using the computational image-to-image translation approach, whole-core standard brightfield HE images of pancreatic tissues were translated into the new collagen images. From these computationally translated collagen images, quantitative collagen measures were extracted for PDAC, PanIN, CP, and normal pancreatic tissues, and their statistical significance was evaluated. Among the four classes, PDAC tissues exhibited the highest collagen alignment (n = 58, p < 0.01, R2 = 0.2594), while normal tissues showed the lowest fiber density (n = 58, p < 0.0001, R2 = 0.3569). Seven machine learning models were assessed to differentiate neoplastic from non-neoplastic tissues cores based on collagen measures extracted from the translated collagen images. Feature importance and ROC-AUC analyses both identified fiber length and collagen deposition area as the most prominent parameters, achieving AUC values of 0.83 and 0.73, respectively, for distinguishing between the tissue classes. The findings demonstrate that the collagen images derived from standard HE-stained tissue microarrays (TMAs) whole-core images enable quantitative assessment of collagen remodelling across pancreatic lesions. Additionally, the study indicates that cross-modality image translation, as a cost-effective alternative, has the potential to offer deeper insights into histopathology and tissue microenvironment analysis without requiring collagen-specific imaging equipment or external labels, thereby further supporting its feasibility for integration into standard clinical workflows.
胶原重塑在胰腺上皮内瘤变（PanIN）向胰腺导管腺癌（PDAC）的进展中起着关键作用，尽管由于与慢性胰腺炎（CP）相似，经常发生误诊。虽然二次谐波生成（SHG）显微镜是目前研究可视化纤维胶原蛋白的金标准，但它不用于常规组织病理学用途。本研究强调需要一种定量胶原分析的替代方法，该方法与标准苏木精和伊红（HE）染色的组织病理学切片兼容。利用计算图像到图像的转换方法，将胰腺组织的全核标准亮场HE图像翻译成新的胶原蛋白图像。从这些计算翻译的胶原图像中，提取PDAC、PanIN、CP和正常胰腺组织的定量胶原含量，并评估其统计学意义。四类组织中，PDAC组织的胶原排列最高（n = 58, p < 0.01, R2 = 0.2594），而正常组织的纤维密度最低（n = 58, p < 0.0001, R2 = 0.3569）。根据从翻译的胶原蛋白图像中提取的胶原蛋白测量值，评估了7种机器学习模型来区分肿瘤和非肿瘤组织核心。Feature importance和ROC-AUC分析都发现纤维长度和胶原沉积面积是最重要的参数，AUC值分别为0.83和0.73，用于区分组织类别。研究结果表明，来自标准he染色组织微阵列（TMAs）全核图像的胶原蛋白图像可以定量评估胰腺病变处的胶原蛋白重构。此外，该研究表明，跨模态图像翻译作为一种具有成本效益的替代方法，有可能提供更深入的组织病理学和组织微环境分析，而不需要胶原蛋白特异性成像设备或外部标签，从而进一步支持其整合到标准临床工作流程中的可行性。
{"title":"Virtual Collagen Mapping for Quantitative Microarchitectural Analysis in Whole-Core Pancreatic Tissue Microarrays","authors":"Varun Nair;Gavish Uppal;Ruchi Sinha;Manjit Kaur;Sukrit Gupta;Rajesh Kumar","doi":"10.1109/JSTQE.2026.3651753","DOIUrl":"https://doi.org/10.1109/JSTQE.2026.3651753","url":null,"abstract":"Collagen remodelling plays a critical role in the progression of pancreatic intraepithelial neoplasia (PanIN) to pancreatic ductal adenocarcinoma (PDAC), though misdiagnosis often occurs due to the resemblance with chronic pancreatitis (CP). While second harmonic generation (SHG) microscopy is the current gold standard in research for visualizing fibrillar collagen, it is not utilized for routine histopathological use. This study highlights the need for an alternative method for quantitative collagen analysis that is compatible with standard hematoxylin-and-eosin (HE) stained histopathological slides. Using the computational image-to-image translation approach, whole-core standard brightfield HE images of pancreatic tissues were translated into the new collagen images. From these computationally translated collagen images, quantitative collagen measures were extracted for PDAC, PanIN, CP, and normal pancreatic tissues, and their statistical significance was evaluated. Among the four classes, PDAC tissues exhibited the highest collagen alignment (n = 58, p < 0.01, R<sup>2</sup> = 0.2594), while normal tissues showed the lowest fiber density (n = 58, p < 0.0001, R<sup>2</sup> = 0.3569). Seven machine learning models were assessed to differentiate neoplastic from non-neoplastic tissues cores based on collagen measures extracted from the translated collagen images. Feature importance and ROC-AUC analyses both identified fiber length and collagen deposition area as the most prominent parameters, achieving AUC values of 0.83 and 0.73, respectively, for distinguishing between the tissue classes. The findings demonstrate that the collagen images derived from standard HE-stained tissue microarrays (TMAs) whole-core images enable quantitative assessment of collagen remodelling across pancreatic lesions. Additionally, the study indicates that cross-modality image translation, as a cost-effective alternative, has the potential to offer deeper insights into histopathology and tissue microenvironment analysis without requiring collagen-specific imaging equipment or external labels, thereby further supporting its feasibility for integration into standard clinical workflows.","PeriodicalId":13094,"journal":{"name":"IEEE Journal of Selected Topics in Quantum Electronics","volume":"32 4: Adv. Biophoton. in Emerg. Biomed. Tech. and Dev","pages":"1-14"},"PeriodicalIF":5.1,"publicationDate":"2026-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146082295","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Accurate differentiation of lung adenocarcinoma subtypes is critical for personalized surgical strategies, particularly in intraoperative differentiation between adenocarcinoma in situ (AIS) and invasive adenocarcinoma (IA). However, tissue distortions such as alveolar rupture or collapse induced during surgery frequently lead to subtype misclassification. Conventional histological staining limited by their inability to quantitatively characterize collagen and elastin fibers, fail to address this clinical challenge. To overcome these limitations, we developed a quantitative Multiphoton Elastin-Collagen Imaging (qMECI) method, specifically targeting diagnostic ambiguities between AIS and IA. qMECI employs label-free multiphoton microscopy to simultaneously capture microarchitectural features of collagen and elastin fibers, extracting ten quantitative metrics encompassing fiber distribution patterns, spatial arrangement, and morphological parameters. Experimental results demonstrate that qMECI identifies critical discriminative signatures of extracellular matrix remodeling, including collagen-elastin coverage, hyperplastic reorganization, and vascular-aligned growth patterns. By integrating quantitative biomarkers such as relative fiber distribution and area ratios, qMECI enables objective differentiation of two diagnostically challenging scenarios: alveolar collapse-type AIS versus acinar-pattern IA and alveolar rupture-type AIS versus papillary IA. This method holds significant potential to refine intraoperative diagnosis workflows, thereby reducing misdiagnosis risks and overtreatment.
{"title":"Quantitative Multiphoton Elastin-Collagen Imaging Differentiates Histologically Ambiguous Lung Adenocarcinoma Subtypes","authors":"Ming-Lian Qiu;Jun-Lin Pan;Jian-Ping Huang;De-Yong Kang;Hou-Qiang Li;Ruo-Lan Lin;Shou-Zhi Wang;Bing-Hua Tang;Jing-Xiang Lu;Zhan Zhuang;Xu Li;Feng Huang;Shu Wang;Jian-Xin Chen","doi":"10.1109/JSTQE.2026.3651647","DOIUrl":"https://doi.org/10.1109/JSTQE.2026.3651647","url":null,"abstract":"Accurate differentiation of lung adenocarcinoma subtypes is critical for personalized surgical strategies, particularly in intraoperative differentiation between adenocarcinoma in situ (AIS) and invasive adenocarcinoma (IA). However, tissue distortions such as alveolar rupture or collapse induced during surgery frequently lead to subtype misclassification. Conventional histological staining limited by their inability to quantitatively characterize collagen and elastin fibers, fail to address this clinical challenge. To overcome these limitations, we developed a quantitative Multiphoton Elastin-Collagen Imaging (qMECI) method, specifically targeting diagnostic ambiguities between AIS and IA. qMECI employs label-free multiphoton microscopy to simultaneously capture microarchitectural features of collagen and elastin fibers, extracting ten quantitative metrics encompassing fiber distribution patterns, spatial arrangement, and morphological parameters. Experimental results demonstrate that qMECI identifies critical discriminative signatures of extracellular matrix remodeling, including collagen-elastin coverage, hyperplastic reorganization, and vascular-aligned growth patterns. By integrating quantitative biomarkers such as relative fiber distribution and area ratios, qMECI enables objective differentiation of two diagnostically challenging scenarios: alveolar collapse-type AIS versus acinar-pattern IA and alveolar rupture-type AIS versus papillary IA. This method holds significant potential to refine intraoperative diagnosis workflows, thereby reducing misdiagnosis risks and overtreatment.","PeriodicalId":13094,"journal":{"name":"IEEE Journal of Selected Topics in Quantum Electronics","volume":"32 4: Adv. Biophoton. in Emerg. Biomed. Tech. and Dev","pages":"1-12"},"PeriodicalIF":5.1,"publicationDate":"2026-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146026611","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-05DOI: 10.1109/JSTQE.2025.3650463
Kung-An Lin;Thu Huong Bui;Lucas Yang;Chao-Hsin Wu
Flip-chip bonding is a promising technique for integrating Vertical-Cavity Surface-Emitting Lasers (VCSELs) in Co-Packaged Optics (CPO) for high-speed applications, but it requires careful optimization of Gold (Au) bumps bonding parameters to address thermal management, ensure efficient optical coupling, and enhance device performance. This study investigates the packaging performance of a VCSEL array integrated onto silicon interposers using flip-chip bonding with Au bumps under various bonding conditions. Emphasis is placed on the effects of bump flattening and alignment accuracy on bonding quality and overall device performance. Au bumps with flattened surfaces and optimized misalignment were analyzed through SEM imaging, luminescence testing, and L-I-V (Light–Current–Voltage) characterization. Results show that flattening Au bumps and a small misalignment between the two Au bumps significantly improve surface planarity and enhance both electrical and optical performance. Finite Element Analysis (FEA) simulations are also conducted to compare with experimental results and provide further insight into stress distribution and structural behavior. The findings underscore the importance of bump flattening and precise alignment in ensuring mechanical reliability and achieving optimal performance in VCSEL-based optical interconnects for next-generation CPO systems.
{"title":"3D Heterogeneous Integration of Back-Emitting VCSEL Arrays via Flip-Chip Bonding for Co-Packaged Optics Systems","authors":"Kung-An Lin;Thu Huong Bui;Lucas Yang;Chao-Hsin Wu","doi":"10.1109/JSTQE.2025.3650463","DOIUrl":"https://doi.org/10.1109/JSTQE.2025.3650463","url":null,"abstract":"Flip-chip bonding is a promising technique for integrating Vertical-Cavity Surface-Emitting Lasers (VCSELs) in Co-Packaged Optics (CPO) for high-speed applications, but it requires careful optimization of Gold (Au) bumps bonding parameters to address thermal management, ensure efficient optical coupling, and enhance device performance. This study investigates the packaging performance of a VCSEL array integrated onto silicon interposers using flip-chip bonding with Au bumps under various bonding conditions. Emphasis is placed on the effects of bump flattening and alignment accuracy on bonding quality and overall device performance. Au bumps with flattened surfaces and optimized misalignment were analyzed through SEM imaging, luminescence testing, and L-I-V (Light–Current–Voltage) characterization. Results show that flattening Au bumps and a small misalignment between the two Au bumps significantly improve surface planarity and enhance both electrical and optical performance. Finite Element Analysis (FEA) simulations are also conducted to compare with experimental results and provide further insight into stress distribution and structural behavior. The findings underscore the importance of bump flattening and precise alignment in ensuring mechanical reliability and achieving optimal performance in VCSEL-based optical interconnects for next-generation CPO systems.","PeriodicalId":13094,"journal":{"name":"IEEE Journal of Selected Topics in Quantum Electronics","volume":"32 2: 3-D Horizons in Photonics: Integrated Circuits","pages":"1-8"},"PeriodicalIF":5.1,"publicationDate":"2026-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146026538","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Terahertz (THz) waves located in an important electromagnetic frequency band have unique characteristics and great application prospects in rapid, non-destructive, and marker-free biomedical detection. Benefiting from Fano resonance has the advantages of high local field enhancement and low loss, we propose a graphene-integrated asymmetric U-type split-ring (Gr-AUSR) Fano resonance metasurfaces THz biosensor. Experimental results show that the Fano resonance intensity of the proposed Gr-AUSR sensor can be altered by the Fermi level shift of chemical vapor deposition (CVD) graphene under slight external stimuli, achieving a minimum midkine (MK) detection limit of 125 pg/ml. Moreover, we extract the maximum wavelet coefficient from the two-dimensional wavelet time-frequency diagram, combining with the Fano resonance amplitude and effective transmission area to construct a multiscale pyramid-shaped model, where its volumes intuitively correspond to different MK concentrations. This work paves the way toward designing and developing of ultra-sensitive biosensors for picogram-levels biological detection at THz frequencies.
{"title":"Fano-Resonant Asymmetric U-Type Metasurfaces Integrating Graphene for Trace Biosensing at Thz Frequencies","authors":"Tongling Wang;Qiyu Ying;Xiangyuan Meng;Yilong Xin;Ziqi Li;Mingyao Wang;Changshun Wu;Li Wang;Maosheng Yang;Xiuwei Yang;Wenjing Zheng;Maojing Liu","doi":"10.1109/JSTQE.2025.3649886","DOIUrl":"https://doi.org/10.1109/JSTQE.2025.3649886","url":null,"abstract":"Terahertz (THz) waves located in an important electromagnetic frequency band have unique characteristics and great application prospects in rapid, non-destructive, and marker-free biomedical detection. Benefiting from Fano resonance has the advantages of high local field enhancement and low loss, we propose a graphene-integrated asymmetric U-type split-ring (Gr-AUSR) Fano resonance metasurfaces THz biosensor. Experimental results show that the Fano resonance intensity of the proposed Gr-AUSR sensor can be altered by the Fermi level shift of chemical vapor deposition (CVD) graphene under slight external stimuli, achieving a minimum midkine (MK) detection limit of 125 pg/ml. Moreover, we extract the maximum wavelet coefficient from the two-dimensional wavelet time-frequency diagram, combining with the Fano resonance amplitude and effective transmission area to construct a multiscale pyramid-shaped model, where its volumes intuitively correspond to different MK concentrations. This work paves the way toward designing and developing of ultra-sensitive biosensors for picogram-levels biological detection at THz frequencies.","PeriodicalId":13094,"journal":{"name":"IEEE Journal of Selected Topics in Quantum Electronics","volume":"32 3: Nanophotonics, Metamaterials and Plasmonics","pages":"1-8"},"PeriodicalIF":5.1,"publicationDate":"2025-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146026586","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In SD-OCT, linear-in-wavenumber spectrometers play a key role in direct k-domain sampling, which eliminates interpolation artifacts and reduces computational load. However, prevalent designs in the 850 nm band using 1200 lines/mm gratings face a fundamental trade-off between imaging depth, system size and cost: achieving a large imaging depth necessitates large-volume, costly optics with long focal lengths and large apertures. To overcome this limitation, we present the design and experimental validation of a linear-in-wavenumber spectrometer employing a 1800 lines/mm grating. The high dispersion of this grating enables a compact system that achieves an imaging depth of ∼4.8 mm with a 76 nm spectral detection range, compatible with single-SLD sources. Compared to the conventional 1200 lines/mm design, our spectrometer reduces the total optical length from ∼325 mm to ∼190 mm and the entrance pupil diameter from 11 mm to 7.2 mm, allowing for smaller and more cost-effective components. Furthermore, our optimization method incorporates wavenumber nonlinearity introduced by the focusing group, overcoming the limitations of traditional approaches that neglect lens aberrations. Experimental results demonstrate a considerable wavenumber linearity (R2 = 0.9999995) and a system sensitivity of 103.4 dB. High-quality in vivo imaging of human skin and nailfold, revealing microvasculature and layered structures, validates the practical utility. This work provides a high-linearity, compact, and cost-effective spectrometer solution, particularly suited for SD-OCT applications requiring large imaging depths.
{"title":"A Compact Linear-in-Wavenumber Spectrometer With a 1800 Lines/mm Grating for 4.8 mm Imaging Depth in SD-OCT","authors":"Liangqi Cao;Haozhe Zhong;Duohao Zhao;Wenxin Zhang;Jianfeng Huang;Jiacheng Zhang;Xiao Zhang","doi":"10.1109/JSTQE.2025.3649911","DOIUrl":"https://doi.org/10.1109/JSTQE.2025.3649911","url":null,"abstract":"In SD-OCT, linear-in-wavenumber spectrometers play a key role in direct k-domain sampling, which eliminates interpolation artifacts and reduces computational load. However, prevalent designs in the 850 nm band using 1200 lines/mm gratings face a fundamental trade-off between imaging depth, system size and cost: achieving a large imaging depth necessitates large-volume, costly optics with long focal lengths and large apertures. To overcome this limitation, we present the design and experimental validation of a linear-in-wavenumber spectrometer employing a 1800 lines/mm grating. The high dispersion of this grating enables a compact system that achieves an imaging depth of ∼4.8 mm with a 76 nm spectral detection range, compatible with single-SLD sources. Compared to the conventional 1200 lines/mm design, our spectrometer reduces the total optical length from ∼325 mm to ∼190 mm and the entrance pupil diameter from 11 mm to 7.2 mm, allowing for smaller and more cost-effective components. Furthermore, our optimization method incorporates wavenumber nonlinearity introduced by the focusing group, overcoming the limitations of traditional approaches that neglect lens aberrations. Experimental results demonstrate a considerable wavenumber linearity (R<sup>2</sup> = 0.9999995) and a system sensitivity of 103.4 dB. High-quality in vivo imaging of human skin and nailfold, revealing microvasculature and layered structures, validates the practical utility. This work provides a high-linearity, compact, and cost-effective spectrometer solution, particularly suited for SD-OCT applications requiring large imaging depths.","PeriodicalId":13094,"journal":{"name":"IEEE Journal of Selected Topics in Quantum Electronics","volume":"32 4: Adv. Biophoton. in Emerg. Biomed. Tech. and Dev","pages":"1-8"},"PeriodicalIF":5.1,"publicationDate":"2025-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146026587","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this study, we demonstrate GaN-based photonic crystal surface-emitting lasers (PCSELs) employing two distinct air hole geometries: circular (CC) and right-isosceles-triangle (RIT). By systematically tuning the fill factor (FF) and lattice constant, the lasing wavelengths are maintained between 420–425 nm, enabling direct comparison of device performance. Optical simulations and experimental results confirm that the CC structure, characterized by high in-plane symmetry (C4v group), supports degenerate Bloch modes at the Γ point, resulting in strong lateral confinement, low vertical radiation loss, and high Q-factors. These features enable low-threshold lasing. In contrast, the RIT structure intentionally breaks the in-plane rotational symmetry, lifting mode degeneracy via geometric asymmetry. This mode splitting selectively enhances the vertical radiation coupling of the desired B-mode while suppressing competing modes, facilitating stable single-mode operation. Although the RIT design yields a higher threshold due to the increased vertical loss, it also demonstrates superior slope efficiency beyond the threshold. The declining threshold trend with increasing FF in both configurations matches the simulated predictions.
{"title":"Impact of Air Hole Geometry on the Performance of InGaN/GaN Photonic Crystal Surface-Emitting Lasers","authors":"Wen-Hsuan Hsieh;Kuo-Bin Hong;Ching-Han Lin;Chen-Yu Yang;Tien-Chang Lu;Chia-Yen Huang","doi":"10.1109/JSTQE.2025.3650007","DOIUrl":"https://doi.org/10.1109/JSTQE.2025.3650007","url":null,"abstract":"In this study, we demonstrate GaN-based photonic crystal surface-emitting lasers (PCSELs) employing two distinct air hole geometries: circular (CC) and right-isosceles-triangle (RIT). By systematically tuning the fill factor (FF) and lattice constant, the lasing wavelengths are maintained between 420–425 nm, enabling direct comparison of device performance. Optical simulations and experimental results confirm that the CC structure, characterized by high in-plane symmetry (C<sub>4v</sub> group), supports degenerate Bloch modes at the Γ point, resulting in strong lateral confinement, low vertical radiation loss, and high Q-factors. These features enable low-threshold lasing. In contrast, the RIT structure intentionally breaks the in-plane rotational symmetry, lifting mode degeneracy via geometric asymmetry. This mode splitting selectively enhances the vertical radiation coupling of the desired B-mode while suppressing competing modes, facilitating stable single-mode operation. Although the RIT design yields a higher threshold due to the increased vertical loss, it also demonstrates superior slope efficiency beyond the threshold. The declining threshold trend with increasing FF in both configurations matches the simulated predictions.","PeriodicalId":13094,"journal":{"name":"IEEE Journal of Selected Topics in Quantum Electronics","volume":"32 6: Special on Advances in VCSELs and PCSELs","pages":"1-6"},"PeriodicalIF":5.1,"publicationDate":"2025-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146006901","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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