Adaptive optics (AO) is a powerful tool for optical microscopy to counteract the effects of optical aberrations and improve the imaging performance in biological tissues. The diversity of sample characteristics entails the use of different AO schemes to measure the underlying aberrations. Here, we present an indirect wavefront sensing method leveraging a virtual imaging scheme and a structural-similarity-based shift measurement algorithm to enable aberration measurement using intrinsic structures even with temporally varying signals. We achieved high-resolution two-photon imaging in a variety of biological samples, including fixed biological tissues and living animals, after aberration correction. We present AO-incorporated subtractive imaging to show that our method can be readily integrated with resolution enhancement techniques to obtain higher resolution in biological tissues. The robustness of our method to signal variation is demonstrated by both simulations and aberration measurement on neurons exhibiting spontaneous activity in a living larval zebrafish.
{"title":"Adaptive optical microscopy via virtual-imaging-assisted wavefront sensing for high-resolution tissue imaging","authors":"Zhou, Zhou, Huang, Jiangfeng, Li, Xiang, Gao, Xiujuan, Chen, Zhongyun, Jiao, Zhenfei, Zhang, Zhihong, Luo, Qingming, Fu, Ling","doi":"10.1186/s43074-022-00060-6","DOIUrl":"https://doi.org/10.1186/s43074-022-00060-6","url":null,"abstract":"Adaptive optics (AO) is a powerful tool for optical microscopy to counteract the effects of optical aberrations and improve the imaging performance in biological tissues. The diversity of sample characteristics entails the use of different AO schemes to measure the underlying aberrations. Here, we present an indirect wavefront sensing method leveraging a virtual imaging scheme and a structural-similarity-based shift measurement algorithm to enable aberration measurement using intrinsic structures even with temporally varying signals. We achieved high-resolution two-photon imaging in a variety of biological samples, including fixed biological tissues and living animals, after aberration correction. We present AO-incorporated subtractive imaging to show that our method can be readily integrated with resolution enhancement techniques to obtain higher resolution in biological tissues. The robustness of our method to signal variation is demonstrated by both simulations and aberration measurement on neurons exhibiting spontaneous activity in a living larval zebrafish.","PeriodicalId":93483,"journal":{"name":"PhotoniX","volume":"160 8","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138505312","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}
Free-spectral-range (FSR)-free optical filters have always been a critical challenge for photonic integrated circuits. A high-performance FSR-free filter is highly desired for communication, spectroscopy, and sensing applications. Despite significant progress in integrated optical filters, the FSR-free filter with a tunable narrow-band, high out-of-band rejection, and large fabrication tolerance has rarely been demonstrated. In this paper, we propose an exact and robust design method for add-drop filters (ADFs) with an FSR-free operation capability, a sub-nanometer optical bandwidth, and a high out-of-band rejection (OBR) ratio. The achieved filter has a 3-dB bandwidth of < 0.5 nm and an OBR ratio of 21.5 dB within a large waveband of 220 nm, which to the best of our knowledge, is the largest-FSR ADF demonstrated on a silicon photonic platform. The filter exhibits large tunability of 12.3 nm with a heating efficiency of 97 pm/mW and maintains the FSR-free feature in the whole tuning process. In addition, we fabricated a series of ADFs with different periods, which all showed reliable and excellent performances.
{"title":"Tunable narrow-band single-channel add-drop integrated optical filter with ultrawide FSR","authors":"Sun, Chunlei, Yin, Yuexin, Chen, Zequn, Ye, Yuting, Luo, Ye, Ma, Hui, Wang, Lichun, Wei, Maoliang, Jian, Jialing, Tang, Renjie, Dai, Hao, Wu, Jianghong, Li, Junying, Zhang, Daming, Lin, Hongtao, Li, Lan","doi":"10.1186/s43074-022-00056-2","DOIUrl":"https://doi.org/10.1186/s43074-022-00056-2","url":null,"abstract":"Free-spectral-range (FSR)-free optical filters have always been a critical challenge for photonic integrated circuits. A high-performance FSR-free filter is highly desired for communication, spectroscopy, and sensing applications. Despite significant progress in integrated optical filters, the FSR-free filter with a tunable narrow-band, high out-of-band rejection, and large fabrication tolerance has rarely been demonstrated. In this paper, we propose an exact and robust design method for add-drop filters (ADFs) with an FSR-free operation capability, a sub-nanometer optical bandwidth, and a high out-of-band rejection (OBR) ratio. The achieved filter has a 3-dB bandwidth of < 0.5 nm and an OBR ratio of 21.5 dB within a large waveband of 220 nm, which to the best of our knowledge, is the largest-FSR ADF demonstrated on a silicon photonic platform. The filter exhibits large tunability of 12.3 nm with a heating efficiency of 97 pm/mW and maintains the FSR-free feature in the whole tuning process. In addition, we fabricated a series of ADFs with different periods, which all showed reliable and excellent performances.","PeriodicalId":93483,"journal":{"name":"PhotoniX","volume":"160 12","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138505310","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}
We proposed and demonstrated a flexible, endoscopic, and minimally invasive coherent anti-Raman Stokes scattering (CARS) measurement method for single-cell application, employing a tapered optical fiber probe. A few-mode fiber (FMF), whose generated four-wave mixing band is out of CARS signals, was selected to fabricate tapered optical fiber probes, deliver CARS excitation pulses, and collect CARS signals. The adiabatic tapered fiber probe with a diameter of 11.61 μm can focus CARS excitation lights without mismatch at the focal point. The measurements for proof-of-concept were made with methanol, ethanol, cyclohexane, and acetone injected into simulated cells. The experimental results show that the tapered optical fiber probe can detect carbon-hydrogen (C–H) bond-rich substances and their concentration. To our best knowledge, this optical fiber probe provides the minimum size among probes for detecting CARS signals. These results pave the way for minimally invasive live-cell detection in the future.
{"title":"Flexible minimally invasive coherent anti-Stokes Raman spectroscopy (CARS) measurement method with tapered optical fiber probe for single-cell application","authors":"Wang, Tong, Jiang, Junfeng, Liu, Kun, Wang, Shuang, Niu, Panpan, Liu, Yize, Liu, Tiegen","doi":"10.1186/s43074-022-00058-0","DOIUrl":"https://doi.org/10.1186/s43074-022-00058-0","url":null,"abstract":"We proposed and demonstrated a flexible, endoscopic, and minimally invasive coherent anti-Raman Stokes scattering (CARS) measurement method for single-cell application, employing a tapered optical fiber probe. A few-mode fiber (FMF), whose generated four-wave mixing band is out of CARS signals, was selected to fabricate tapered optical fiber probes, deliver CARS excitation pulses, and collect CARS signals. The adiabatic tapered fiber probe with a diameter of 11.61 μm can focus CARS excitation lights without mismatch at the focal point. The measurements for proof-of-concept were made with methanol, ethanol, cyclohexane, and acetone injected into simulated cells. The experimental results show that the tapered optical fiber probe can detect carbon-hydrogen (C–H) bond-rich substances and their concentration. To our best knowledge, this optical fiber probe provides the minimum size among probes for detecting CARS signals. These results pave the way for minimally invasive live-cell detection in the future.","PeriodicalId":93483,"journal":{"name":"PhotoniX","volume":"158 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138505332","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}
Spin light manipulation based on chiral metasurfaces is a striking hotspot that has intrigued huge attention. Circular dichroism, a unique phenomenon of chiral atoms/molecules, has been regarded as another auxiliary dimension for guiding electromagnetic waves, which has been explored in the field of artificial material sciences yet a challenging issue. Here, a generic strategy based on dynamic chiral meta-atom for revealing strong circular dichroism as well as applicable electromagnetic functionality is proposed in microwave regime. We demonstrate a dynamic metasurface that enables the fully independent holograms reconstruction for one circular polarization or the other at the active operating state. On the other hand, the electromagnetic scattering is realized for lowering observable backward reflection at the passive state. Numerical simulation and experimental verification are conducted to manifest the feasibility. It is expected that the proposed strategy can be applied to broaden the horizon for dynamic chiral meta-devices and may find applications in information encryption, anti-counterfeiting, and other dynamic systems.
{"title":"Metasurface with dynamic chiral meta-atoms for spin multiplexing hologram and low observable reflection","authors":"Wang, He, Qin, Zhe, Huang, Lingling, Li, Yongfeng, Zhao, Ruizhe, Zhou, Hongqiang, He, Haoyang, Zhang, Jieqiu, Qu, Shaobo","doi":"10.1186/s43074-022-00057-1","DOIUrl":"https://doi.org/10.1186/s43074-022-00057-1","url":null,"abstract":"Spin light manipulation based on chiral metasurfaces is a striking hotspot that has intrigued huge attention. Circular dichroism, a unique phenomenon of chiral atoms/molecules, has been regarded as another auxiliary dimension for guiding electromagnetic waves, which has been explored in the field of artificial material sciences yet a challenging issue. Here, a generic strategy based on dynamic chiral meta-atom for revealing strong circular dichroism as well as applicable electromagnetic functionality is proposed in microwave regime. We demonstrate a dynamic metasurface that enables the fully independent holograms reconstruction for one circular polarization or the other at the active operating state. On the other hand, the electromagnetic scattering is realized for lowering observable backward reflection at the passive state. Numerical simulation and experimental verification are conducted to manifest the feasibility. It is expected that the proposed strategy can be applied to broaden the horizon for dynamic chiral meta-devices and may find applications in information encryption, anti-counterfeiting, and other dynamic systems.","PeriodicalId":93483,"journal":{"name":"PhotoniX","volume":"161 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138505309","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}
{"title":"Intracavity spherical aberration for selective generation of single-transverse-mode Laguerre-Gaussian output with order up to 95","authors":"Q. Sheng, Aihua Wang, Yuanyuan Ma, Sijia Wang, Meng Wang, Zheng Shi, Junjie Liu, Shijie Fu, W. Shi, Jianquan Yao, T. Omatsu","doi":"10.1186/s43074-022-00050-8","DOIUrl":"https://doi.org/10.1186/s43074-022-00050-8","url":null,"abstract":"","PeriodicalId":93483,"journal":{"name":"PhotoniX","volume":"3 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"65801147","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 : 2022-01-11DOI: 10.21203/rs.3.rs-1236950/v1
Huanyu Sun, Shiling Wang, Xiao-Xiang Hu, Hongjie Liu, Xiaoyan Zhou, Jin Huang, Xinglei Cheng, Feng Sun, Yubo Liu, Dong Liu
Surface defects (SDs) and subsurface defects (SSDs) are the key factors decreasing the laser damage threshold of optics. Due to the spatially stacked structure, accurately detecting and distinguishing them has become a major challenge. Herein a detection method for SDs and SSDs with multisensor image fusion is proposed. The optics is illuminated by a laser under dark field condition, and the defects are excited to generate scattering and fluorescence lights, which are received by two image sensors in a wide-field microscope. With the modified algorithms of image registration and feature-level fusion, different types of defects are identified and extracted from the scattering and fluorescence images. Experiments show that two imaging modes can be realized simultaneously by multisensor image fusion, and HF etching verifies that SDs and SSDs of polished optics can be accurately distinguished. This method provides a more targeted reference for the evaluation and control of the defects of optics, and exhibits potential in the application of material surface research.
{"title":"Detection of surface defects and subsurface defects of polished optics with multisensor image fusion","authors":"Huanyu Sun, Shiling Wang, Xiao-Xiang Hu, Hongjie Liu, Xiaoyan Zhou, Jin Huang, Xinglei Cheng, Feng Sun, Yubo Liu, Dong Liu","doi":"10.21203/rs.3.rs-1236950/v1","DOIUrl":"https://doi.org/10.21203/rs.3.rs-1236950/v1","url":null,"abstract":"Surface defects (SDs) and subsurface defects (SSDs) are the key factors decreasing the laser damage threshold of optics. Due to the spatially stacked structure, accurately detecting and distinguishing them has become a major challenge. Herein a detection method for SDs and SSDs with multisensor image fusion is proposed. The optics is illuminated by a laser under dark field condition, and the defects are excited to generate scattering and fluorescence lights, which are received by two image sensors in a wide-field microscope. With the modified algorithms of image registration and feature-level fusion, different types of defects are identified and extracted from the scattering and fluorescence images. Experiments show that two imaging modes can be realized simultaneously by multisensor image fusion, and HF etching verifies that SDs and SSDs of polished optics can be accurately distinguished. This method provides a more targeted reference for the evaluation and control of the defects of optics, and exhibits potential in the application of material surface research.","PeriodicalId":93483,"journal":{"name":"PhotoniX","volume":" ","pages":"1-14"},"PeriodicalIF":0.0,"publicationDate":"2022-01-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47654335","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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