Frontiers in photonics最新文献

{"title":"New frontiers in intracranial imaging with HF-OCT: Ex vivo human cerebrovasculature evaluation and in vivo intracranial arteries dynamic visualization","authors":"V. Anagnostakou, M. Epshtein, A. Peker, A. Puri, J. Singh, G. Ughi, M. Gounis","doi":"10.3389/fphot.2022.988018","DOIUrl":"https://doi.org/10.3389/fphot.2022.988018","url":null,"abstract":"Optical coherence tomography (OCT) technology is a well-established diagnostic tool in multiple fields of medicine. Intravascular OCT has been used for more than a decade for the clinical imaging of coronary arteries, however, its use for the imaging of the human cerebrovasculature has been delayed by the challenges posed by the elevated vascular tortuosity. A novel high-frequency OCT (HF-OCT) probe designed for neurovascular use was evaluated in tortuous, ex vivo, human intracranial anatomy and, using an in vivo canine model, for the dynamic imaging of intracranial arteries and the subarachnoid trabecula (SAT). Using four cadavers, we investigated HF-OCT probe navigation and imaging performances in human anterior arterial circulation (from the M4 segment to internal carotid artery), in the posterior arterial circulation (from the P4 segment to vertebrobasilar junction) and in a broad range of venous sinuses. HF-OCT was able to gain distal access through elevated tortuosity and generate high-quality imaging data depicting vessel morphology, the vessel wall pathology (e.g., atherosclerotic disease and dissecting lesions), and the subarachnoid trabecula (SAT). Using an in vivo canine model, the HF-OCT probe was used to record stationary dynamic data in multiple intracranial vascular locations. Data showed the motion of the arteries and the SAT, including collisions between vessels, membranes, and the interaction between the SAT and the blood vessels. HF-OCT data allowed for the quantification of the dynamics of the vessels and the SAT, including vessel lateral motion with respect to the parenchyma, and collisions between large and small arteries. Results showed that the HF-OCT probe can overcome delivery obstacles in tortuous cerebrovascular anatomy and provide high-quality and high-resolution imaging at multiple distal locations, including M4 and P4 segments of the anterior and posterior circulations. HF-OCT has the potential to facilitate a better understanding of fine anatomical details of the cerebrovascular and perivascular environment, neurovascular disease, and collect real time information about the dynamics of the subarachnoid space and arteries and become a valuable diagnostic tool.","PeriodicalId":73099,"journal":{"name":"Frontiers in photonics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49265292","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":"Vanadium oxide metal-insulator phase transition in different types of one-dimensional photonic microcavities","authors":"F. Scotognella","doi":"10.3389/fphot.2023.1081521","DOIUrl":"https://doi.org/10.3389/fphot.2023.1081521","url":null,"abstract":"The optical properties of vanadium dioxide (VO2) can be tuned via metal-insulator transition. In this work, different types of one-dimensional photonic structure-based microcavities that embed vanadium dioxide have been studied in the spectral range between 900 nm and 2000 nm. In particular, VO2 has been sandwiched between: i) two photonic crystals made of SiO2 and ZrO2; ii) two aperiodic structures made of SiO2 and ZrO2 that follow the Thue-Morse sequence; iii) two disordered photonic structures, made of SiO2 and ZrO2 in which the disorder is introduced either by a random sequence of the two materials or by a random variation of the thicknesses of the layers; iv) two four material-based photonic crystals made of SiO2, Al2O3, Y2O3, and ZrO2. The ordered structures i and iv show, respectively, one and two intense transmission valleys with defect modes, while the aperiodic and disordered structures ii and iii show a manifold of transmission valleys due to their complex layered configurations. The metal-insulator transition of VO2, controlled by temperature, results in a modulation of the optical properties of the microcavities.","PeriodicalId":73099,"journal":{"name":"Frontiers in photonics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42332775","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":"Generation of counterpropagating and spectrally uncorrelated photon-pair states by spontaneous four-wave mixing in photonic crystal waveguides","authors":"S. Saravi, Yu Zhang, Xiao Chen, M. Afsharnia, F. Setzpfandt, T. Pertsch","doi":"10.3389/fphot.2022.953105","DOIUrl":"https://doi.org/10.3389/fphot.2022.953105","url":null,"abstract":"In this work, we propose and theoretically analyze a new scheme for generation of counterpropagating photon pairs in photonic crystal waveguides through the process of spontaneous four-wave mixing. Using the fundamental properties of periodic Bloch modes in a standard photonic crystal waveguide, we demonstrate how modal phase-matching can be reached between forward-propagating pump modes and counterpropagating signal and idler modes, for generation of degenerate and non-degenerate photon pairs. We then show how this scheme can be used for generation of photon pairs that are nearly uncorrelated in the spectral degree of freedom. Such a source will be highly interesting as a heralded source of single photons, especially as the spectrally separable signal and idler photons are also spatially separated directly at the source. We conduct our investigation based on a design in silicon, yet our design concept is general and can in principle be applied to any nanostructured material platform.","PeriodicalId":73099,"journal":{"name":"Frontiers in photonics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47477444","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":"Plasmonics: The future is ultrafast and ultrasmall","authors":"M. Celebrano","doi":"10.3389/fphot.2022.969233","DOIUrl":"https://doi.org/10.3389/fphot.2022.969233","url":null,"abstract":"Plasmonics has been a flourishing field since the late ‘80s of the last century. Given the number of outstanding developments even without resorting to metrics–it is straightforward to address the 2 decades crossing the new millennium as the golden era of Plasmonics. The unique capabilities of plasmonic nanostructures to collect, direct and enhance light at length scales much below the operating wavelength granted them the name “antennas for light”. These features were crucial for the vast deployment of Plasmonics to a variety of tasks, spanning from light harvesting (Atwater and Albert 2010) to molecular sensing (Homola 2008; Saha et al., 2012), bioimaging (Meola et al., 2018; Bocková et al., 2019; Wu et al., 2019) and plasmonenhanced spectroscopy (Zhang et al., 2013, Ding et al., 2016). Another recently growing field is that of plasmon-enhanced catalysis, which could be of crucial importance for hydrogen synthesis (Ezendam et al., 2022) with significant consequences for sustainability. Despite its indisputable key role in basic and applied research, the disruptive fallout of Plasmonics in life and society is still mainly restricted to medical diagnostic tools, as demonstrated by the antigenic lateral flow test employed to detect SARS-CoV-2, which is massively employed during this last pandemic. The first clinical pilot study of a device for prostate cancer treatment, carried out by Prof. Halas using photothermal ablation via gold nanoshells (Rastinehad et al., 2019), represents another major landmark in nanomedicine. The main hindrances to technological application of classical metal-based Plasmonics are the sizeable ohmic losses at visible wavelengths and the non-trivial integration in semiconductor-based technology. With the aim of targeting a higher technological readiness level, and thanks to the recent advancement in nanofabrication, semiconductor-based Plasmonics has rapidly emerged (Taliercio and Biagioni 2019). Indeed, heavily-doped semiconductors display a sizeable plasma frequency, which can be tuned chemically, optically, or electrically over a broad spectral range. These platforms are extremely appealing for their facile integration in low-cost, mass-fabricated devices, but their operation is yet limited to the midinfrared range. Yet, Plasmonics endures among the liveliest branches in the field of Photonics, thanks to the extreme light confinement achievable and the ultrafast dynamics of the underlying processes. A major technological task still remains, i.e., the improvement of reliability and reproducibility in plasmonic-based devices and techniques (i.e., plasmon-enhanced Raman spectroscopy, sensing). This will require a major effort in nanofabrication in the coming years to control subOPEN ACCESS","PeriodicalId":73099,"journal":{"name":"Frontiers in photonics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-08-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47478045","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":"Plasmonics for advance single-molecule fluorescence spectroscopy and imaging in biology","authors":"C. Zaza, S. Simoncelli","doi":"10.3389/fphot.2022.989570","DOIUrl":"https://doi.org/10.3389/fphot.2022.989570","url":null,"abstract":"The elucidation of complex biological processes often requires monitoring the dynamics and spatial organization of multiple distinct proteins organized on the sub-micron scale. This length scale is well below the diffraction limit of light, and as such not accessible by classical optical techniques. Further, the high molecular concentrations found in living cells, typically in the micro- to mili-molar range, preclude single-molecule detection in confocal volumes, essential to quantify affinity constants and protein-protein reaction rates in their physiological environment. To push the boundaries of the current state of the art in single-molecule fluorescence imaging and spectroscopy, plasmonic materials offer encouraging perspectives. From thin metallic films to complex nano-antenna structures, the near-field electromagnetic coupling between the electronic transitions of single emitters and plasmon resonances can be exploited to expand the toolbox of single-molecule based fluorescence imaging and spectroscopy approaches. Here, we review two of the most current and promising approaches to study biological processes with unattainable level of detail. On one side, we discuss how the reduction of the fluorescence lifetime of a molecule as it approaches a thin metallic film can be exploited to decode axial information with nanoscale precision. On the other, we review how the tremendous progress on the design of plasmonic antennas that can amplify and confine optical fields at the nanoscale, powered a revolution in fluorescence correlation spectroscopy. Besides method development, we also focus in describing the most interesting biological application of both technologies.","PeriodicalId":73099,"journal":{"name":"Frontiers in photonics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-08-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45605990","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":"Liprobe, a vital dye for lipid aggregates detection in imaging and high-content screens","authors":"S. Vieira, Raquel Nunes da Silva, Mariana Q Alves, Roberto Alexandre Dias, Ana M. Meireles Sousa, Fátima Camões, A. Maia, Mónica Almeida, J. Rocha, Artur M. S. Silva, Samuel Guieu","doi":"10.3389/fphot.2022.963778","DOIUrl":"https://doi.org/10.3389/fphot.2022.963778","url":null,"abstract":"Pathological lipid accumulation is a hallmark of several metabolic disorders, and detection of lipid aggregates is an essential step for initial diagnosis and drug screening purposes. However, low-cost, simple, and reliable detection fluorescent probes are not widely available. Here, six push-pull-push dyes were studied, and proved to be highly sensitive to the polarity of the medium, presenting potential to distinguish structures with different hydrophobic indexes. Importantly, in the presence of lipid aggregates their staining specificity highly increased and the fluorescence wavelength blue shifted. One of the compounds, named Liprobe, was physiologically inert in cells, as witnessed by mass-spectrometry and metabolic assays. Liprobe was not toxic to living zebrafish embryos, and differentially stained the muscle and bone tissues. In triglyceride solutions, a high correlation was observed between Liprobe’s 558 and 592 nm emissions and the 0–2.5 mg dl−1 triglyceride range. Confocal and cell-based high content screens revealed that this fluorophore was able to selectively detect lipid droplets and ceramide loads in normal and Farber’s disease human fibroblasts, respectively. Our results demonstrate that Liprobe is a suitable fluorescing probe for vital staining of lipid aggregates, compatible with a rapid and cheap high content screening assays for preliminary diagnosis of Farber’s disease and, potentially, of other lipidosis.","PeriodicalId":73099,"journal":{"name":"Frontiers in photonics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44152650","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":"Editorial: Advanced opto-electrical modeling of photovoltaic materials and devices","authors":"J. Krč, M. Schmid, R. Santbergen","doi":"10.3389/fphot.2022.977946","DOIUrl":"https://doi.org/10.3389/fphot.2022.977946","url":null,"abstract":"Research and innovation in photovoltaic (PV) materials and devices have been expanding over the last decades, aiming at continuously improved performance and broadened applications. Thus, the strive for new solutions and the motivation to design, analyze and test new solutions and concepts is growing. In this respect, modeling and simulations play a central role in the entire chain of photovoltaic research and development, including materials, devices, and systems. Computer simulation can replace time-consuming experimental parameter variations and testing, when searching for optimized materials and device configurations. Furthermore, they enable to perform comprehensive analyses and contribute to physical insight into material properties and device or system operation. Modeling and simulations also present a strong predictive tool. The models used for PV material and device simulations should account for optical and electrical properties. Careful optical design and optimization of state-of-the-art solar cells and PV modules require advanced modeling approaches to be used, taking into OPEN ACCESS","PeriodicalId":73099,"journal":{"name":"Frontiers in photonics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41553202","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":"Dynamic vascular optical spectroscopy for monitoring peripheral arterial disease patients undergoing a surgical intervention","authors":"A. Marone, N. Maheshwari, S. Kim, D. Bajakian, A. Hielscher","doi":"10.3389/fphot.2022.938144","DOIUrl":"https://doi.org/10.3389/fphot.2022.938144","url":null,"abstract":"Peripheral arterial disease (PAD) patients experience a reduction in blood supply to the extremities caused by an accumulation of plaque in their arterial system. In advanced stages of PAD, surgical intervention is often required to reopen arteries and restore limb perfusion to avoid necrosis and amputations. To determine the success of an intervention, it is necessary to confirm that reperfusion was achieved after the intervention in areas of the foot that lacked perfusion before the intervention. The standard procedure to obtain this information is to perform repeated X-ray angiography. However, this approach requires a relatively high radiation dose and the extensive use of contrast agents. To overcome these issues, our lab has developed a system that uses dynamic vascular optical spectroscopy (DVOS) to monitor perfusion in the foot in real-time before, during, and after an intervention. In the explorative study presented in this paper, we monitored ten patients undergoing revascularization surgery. We found that there is a clear change in the DVOS signal in cases when reperfusion to affected areas in the foot is established. It was also possible to assess the effects that balloon inflations and deflations and contrast agent injections had on the downstream vasculature of the patients.","PeriodicalId":73099,"journal":{"name":"Frontiers in photonics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46311477","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":"Group-index-matched frequency conversion in lithium niobate on insulator waveguides","authors":"Pawan Kumar , Mohammadreza Younesi , Sina Saravi , Frank Setzpfandt , Thomas Pertsch ","doi":"10.3389/fphot.2022.951949","DOIUrl":"https://doi.org/10.3389/fphot.2022.951949","url":null,"abstract":"Sources of spectrally engineered photonic states are a key resource in several quantum technologies. Of particular importance are the so-called factorizable biphoton states, which possess no spectral entanglement and hence, are ideal for heralded generation of high-purity single photons. An essential prerequisite for generating these states through nonlinear frequency conversion is the control over the group indices of the photonic modes of the source. Here, we show that thin-film lithium niobate on insulator (LNOI) is an excellent platform for this purpose. We design and fabricate periodically poled ridge waveguides in LNOI to demonstrate group index engineering of its guided photonic modes and harness this control to experimentally realize on-chip group index matched type-II sum-frequency generation (SFG). Also, we numerically study the role of the top cladding layer in tuning the dispersion properties of the ridge waveguide structures and reveal a distinctive difference between the air and silica-clad designs which are currently among the two most common device cladding configurations in LNOI. We expect that these results will be relevant for various classical and quantum applications where dispersion control is crucial in tailoring the nonlinear response of the LNOI-based devices.","PeriodicalId":73099,"journal":{"name":"Frontiers in photonics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-08-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69647091","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":"High-throughput artifact-free slightly off-axis holographic imaging based on Fourier ptychographic reconstruction","authors":"Qian Shen, Jiasong Sun, Yao Fan, Zhuoshi Li, P. Gao, Qian Chen, C. Zuo","doi":"10.3389/fphot.2022.936561","DOIUrl":"https://doi.org/10.3389/fphot.2022.936561","url":null,"abstract":"Slightly off-axis digital holographic microscopy (DHM) has recently gained considerable attention due to its unique ability to improve the space-bandwidth product (SBP) of the imaging system while separating the object information from the background intensity to a certain extent. In order to obtain a decent image reconstruction, the spectral aliasing problem still needs to be addressed, which, however, is difficult to be achieved by the conventional linear Fourier domain filtering. To this end, in this paper, we propose a high-throughput artifact-free slightly off-axis holographic reconstruction method based on Fourier ptychographic microscopy (FPM). Inspired by the nonlinear optimized phase reconstruction algorithm of FPM, we perform constrained updates between the real and Fourier domains in an iterative manner to reconstruct the complex amplitude by the hologram intensity. Experimental results on live HeLa cell samples show that the proposed method can provide higher reconstruction accuracy and better image quality compared with the conventional Fourier method and the Kramers–Kronig (KK) relation-based method.","PeriodicalId":73099,"journal":{"name":"Frontiers in photonics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45229189","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}