Pub Date : 2022-07-06DOI: 10.3389/fphot.2022.932913
C. Eisler, Lindsey E. Parsons, Zach Nett, Claire P. Love, A. Schwartzberg, A. Alivisatos
Despite the extraordinary advances in solar cell efficiency in laboratory settings, the deployment of solar cells continues to be limited to low efficiency (<25%) silicon cells because of cost. In this work, we take advantage of the extraordinary optical properties afforded by nanophotonic structures to create a photonic luminescent solar concentrator for an InGaP-Si multijunction concentrator cell. Finite difference time domain (FDTD) simulations demonstrated a concentrator that could effectively capture, downconvert, and guide concentrated light to an InGaP subcell while still transmitting longer wavelengths to a Si subcell. We fabricated the photonic luminescent solar concentrator, which was comprised of CdSe/CdS quantum dots embedded within alternating layers of Si3N4 and SiO2, and experimentally verified the optical performance, showing a 40% increase in light guiding and a significant reduction in reabsorption losses in the plane of the luminescent concentrator as compared to traditional designs. Finally, we utilized modified detailed balance calculations that accounted for cell and optical losses and showed >30% efficiencies are possible with this design, demonstrating the potential to meet the demands for high efficiency, inexpensive solar modules.
{"title":"Photonic Luminescent Solar Concentrator Design for High Efficiency, Low Cost Multijunction Photovoltaics","authors":"C. Eisler, Lindsey E. Parsons, Zach Nett, Claire P. Love, A. Schwartzberg, A. Alivisatos","doi":"10.3389/fphot.2022.932913","DOIUrl":"https://doi.org/10.3389/fphot.2022.932913","url":null,"abstract":"Despite the extraordinary advances in solar cell efficiency in laboratory settings, the deployment of solar cells continues to be limited to low efficiency (<25%) silicon cells because of cost. In this work, we take advantage of the extraordinary optical properties afforded by nanophotonic structures to create a photonic luminescent solar concentrator for an InGaP-Si multijunction concentrator cell. Finite difference time domain (FDTD) simulations demonstrated a concentrator that could effectively capture, downconvert, and guide concentrated light to an InGaP subcell while still transmitting longer wavelengths to a Si subcell. We fabricated the photonic luminescent solar concentrator, which was comprised of CdSe/CdS quantum dots embedded within alternating layers of Si3N4 and SiO2, and experimentally verified the optical performance, showing a 40% increase in light guiding and a significant reduction in reabsorption losses in the plane of the luminescent concentrator as compared to traditional designs. Finally, we utilized modified detailed balance calculations that accounted for cell and optical losses and showed >30% efficiencies are possible with this design, demonstrating the potential to meet the demands for high efficiency, inexpensive solar modules.","PeriodicalId":73099,"journal":{"name":"Frontiers in photonics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-07-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44833665","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 : 2022-07-04DOI: 10.3389/fphot.2022.921438
C. Hägglund
With the success of silicon (Si) solar cell technology, research and development on higher efficiency multijunction solar cells is gaining much attention. Tandem cells with a perovskite top cell and a Si bottom cell show particular potential. However, the optical modeling of such devices is complicated by the broad range of length scales involved; the optically thin layers and nanoscale features of a perovskite solar cell require some version of wave optics or even full field electromagnetic (EM) calculations, while the micrometer scale structuring and large dimensions of Si cells are much more manageable using geometrical (ray) optics. In the present work, a method for combining EM and ray optical calculations is developed and described in detail, with examples provided in the software Comsol Multiphysics. For regions with thin films or nanoscale features, EM wave calculations are performed using the finite element method. These calculations provide the phase and amplitude of the waves diffracted into different orders, of which only the regular reflection and transmission are typically of relevance for nanoscale periodicity. In the ray optics simulation, the corresponding regions are implemented as diffracting interfaces, with deterministic transformations of the Stokes vector components according to the EM wave calculations. Meanwhile, the absorbed intensity of intersecting rays is recorded. The method is applied to separate perovskite and Si solar cells and to a few tandem solar cells of relevance for two- versus four-terminal configurations. Corrections for strongly absorbing media in the ray tracing algorithm, which use generalized versions of the Fresnel coefficients, Snell’s law and the Beer-Lambert law, are also evaluated. In a typical Si solar cell with a front surface structure of inverted pyramids, such corrections are found to reduce the absorption by up to 0.5 percentage units compared to a conventional ray tracing calculation. The difference is concluded to originate mainly from reduced absorption rates of inhomogeneous waves, rather than from enhanced escape probabilities for (quasi-) trapped rays at the Si front surface. The method is further applied to evaluate the effects of a plasmonic nanoparticle array, embedded in a perovskite solar cell stack that is located directly on the microstructured Si surface.
{"title":"Multiscale Optical Modeling of Perovskite-Si Tandem Solar Cells","authors":"C. Hägglund","doi":"10.3389/fphot.2022.921438","DOIUrl":"https://doi.org/10.3389/fphot.2022.921438","url":null,"abstract":"With the success of silicon (Si) solar cell technology, research and development on higher efficiency multijunction solar cells is gaining much attention. Tandem cells with a perovskite top cell and a Si bottom cell show particular potential. However, the optical modeling of such devices is complicated by the broad range of length scales involved; the optically thin layers and nanoscale features of a perovskite solar cell require some version of wave optics or even full field electromagnetic (EM) calculations, while the micrometer scale structuring and large dimensions of Si cells are much more manageable using geometrical (ray) optics. In the present work, a method for combining EM and ray optical calculations is developed and described in detail, with examples provided in the software Comsol Multiphysics. For regions with thin films or nanoscale features, EM wave calculations are performed using the finite element method. These calculations provide the phase and amplitude of the waves diffracted into different orders, of which only the regular reflection and transmission are typically of relevance for nanoscale periodicity. In the ray optics simulation, the corresponding regions are implemented as diffracting interfaces, with deterministic transformations of the Stokes vector components according to the EM wave calculations. Meanwhile, the absorbed intensity of intersecting rays is recorded. The method is applied to separate perovskite and Si solar cells and to a few tandem solar cells of relevance for two- versus four-terminal configurations. Corrections for strongly absorbing media in the ray tracing algorithm, which use generalized versions of the Fresnel coefficients, Snell’s law and the Beer-Lambert law, are also evaluated. In a typical Si solar cell with a front surface structure of inverted pyramids, such corrections are found to reduce the absorption by up to 0.5 percentage units compared to a conventional ray tracing calculation. The difference is concluded to originate mainly from reduced absorption rates of inhomogeneous waves, rather than from enhanced escape probabilities for (quasi-) trapped rays at the Si front surface. The method is further applied to evaluate the effects of a plasmonic nanoparticle array, embedded in a perovskite solar cell stack that is located directly on the microstructured Si surface.","PeriodicalId":73099,"journal":{"name":"Frontiers in photonics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42113636","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 : 2022-06-30DOI: 10.3389/fphot.2022.906917
Yang Li, Qin-Rui Hu, Xiaoxin Li, Yong-hua Hu, X. Qin, Bin Wang, T. Ren
Purpose: To evaluate the prevalence and correlations of vision impairment (VI) among urban and rural adults in a coastal province of Southern China. Design: Population-based cross-sectional study. Methods: The study was designed to recruit residents aged over 50 years in randomly sampled communities of Fujian Province from 2018 to 2019. Participants completed a questionnaire about socioeconomic and biological factors and underwent visual examinations. Best corrected visual acuity (BCVA) was measured for the participants to assess VI, which was defined as best corrected visual acuity (BCVA) in better eyes of 20/60 or worse. Results: A total of 6,823 participants were included in this report. VI prevalence was higher in inland populations, compared with that in coastal populations (5.08 vs. 2.79%, p < 0.001), but there was no significant difference between urban populations and rural populations (2.97 vs. 3.73%, p = 0.082). VI was significantly associated with sociodemographic and biological factors, which included age, educational background, income, and refractive error. Sex and urbanization were not statistically significantly associated with VI. Conclusion: High prevalence of VI in southeast China suggested need for more accessible services and favorable policies for enhancing eye health in rural and inland elderly people.
{"title":"Vision Impairment and Associated Factors in a Coastal Province of Southern China: The Fujian Eye Study","authors":"Yang Li, Qin-Rui Hu, Xiaoxin Li, Yong-hua Hu, X. Qin, Bin Wang, T. Ren","doi":"10.3389/fphot.2022.906917","DOIUrl":"https://doi.org/10.3389/fphot.2022.906917","url":null,"abstract":"Purpose: To evaluate the prevalence and correlations of vision impairment (VI) among urban and rural adults in a coastal province of Southern China. Design: Population-based cross-sectional study. Methods: The study was designed to recruit residents aged over 50 years in randomly sampled communities of Fujian Province from 2018 to 2019. Participants completed a questionnaire about socioeconomic and biological factors and underwent visual examinations. Best corrected visual acuity (BCVA) was measured for the participants to assess VI, which was defined as best corrected visual acuity (BCVA) in better eyes of 20/60 or worse. Results: A total of 6,823 participants were included in this report. VI prevalence was higher in inland populations, compared with that in coastal populations (5.08 vs. 2.79%, p < 0.001), but there was no significant difference between urban populations and rural populations (2.97 vs. 3.73%, p = 0.082). VI was significantly associated with sociodemographic and biological factors, which included age, educational background, income, and refractive error. Sex and urbanization were not statistically significantly associated with VI. Conclusion: High prevalence of VI in southeast China suggested need for more accessible services and favorable policies for enhancing eye health in rural and inland elderly people.","PeriodicalId":73099,"journal":{"name":"Frontiers in photonics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44752927","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 : 2022-06-22DOI: 10.3389/fphot.2022.908931
Nghi Truong, Sadra Shahdadian, Shuyan Kang, Xinlong Wang, H. Liu
This study presented a theoretical or analytical approach to quantify how the signal-to-noise ratio (SNR) of a near infrared spectroscopy (NIRS) device influences the accuracy on calculated changes of oxy-hemoglobin (Δ[HbO]), deoxy-hemoglobin (Δ[HHb]), and oxidized cytochrome c oxidase (Δ[oxCCO]). In theory, all NIRS experimental measurements include variations due to thermal or electrical noise, drifts, and disturbance of the device. Since the computed concentration results are highly associated with device-driven variations, in this study, we applied the error propagation analysis to compute the variability or variance of Δ[HbO], Δ[HHb], and Δ[oxCCO] depending on the system SNR. The quantitative expressions of variance or standard deviations of changes in chromophore concentrations were derived based on the error propagation analysis and the modified Beer-Lambert law. In order to compare and confirm the derived variances versus those from the actual measurements, we conducted two sets of broadband NIRS (bbNIRS) measurements using a solid tissue phantom and the human forearm. A Monte Carlo framework was also executed to simulate the bbNIRS data under two physiological conditions for further confirmation of the theoretical analysis. Finally, the confirmed expression for error propagation was utilized for quantitative analyses to guide optimal selections of wavelength ranges and different wavelength combinations for minimal variances of Δ[HbO], Δ[HHb], and Δ[oxCCO] in actual experiments.
{"title":"Influence of the Signal-To-Noise Ratio on Variance of Chromophore Concentration Quantification in Broadband Near-Infrared Spectroscopy","authors":"Nghi Truong, Sadra Shahdadian, Shuyan Kang, Xinlong Wang, H. Liu","doi":"10.3389/fphot.2022.908931","DOIUrl":"https://doi.org/10.3389/fphot.2022.908931","url":null,"abstract":"This study presented a theoretical or analytical approach to quantify how the signal-to-noise ratio (SNR) of a near infrared spectroscopy (NIRS) device influences the accuracy on calculated changes of oxy-hemoglobin (Δ[HbO]), deoxy-hemoglobin (Δ[HHb]), and oxidized cytochrome c oxidase (Δ[oxCCO]). In theory, all NIRS experimental measurements include variations due to thermal or electrical noise, drifts, and disturbance of the device. Since the computed concentration results are highly associated with device-driven variations, in this study, we applied the error propagation analysis to compute the variability or variance of Δ[HbO], Δ[HHb], and Δ[oxCCO] depending on the system SNR. The quantitative expressions of variance or standard deviations of changes in chromophore concentrations were derived based on the error propagation analysis and the modified Beer-Lambert law. In order to compare and confirm the derived variances versus those from the actual measurements, we conducted two sets of broadband NIRS (bbNIRS) measurements using a solid tissue phantom and the human forearm. A Monte Carlo framework was also executed to simulate the bbNIRS data under two physiological conditions for further confirmation of the theoretical analysis. Finally, the confirmed expression for error propagation was utilized for quantitative analyses to guide optimal selections of wavelength ranges and different wavelength combinations for minimal variances of Δ[HbO], Δ[HHb], and Δ[oxCCO] in actual experiments.","PeriodicalId":73099,"journal":{"name":"Frontiers in photonics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45154979","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 : 2022-06-21DOI: 10.3389/fphot.2022.929031
S. Hassad, K. Ferria, L. Bouamama, P. Picart
This paper proposes an approach for acoustic field imaging using simultaneous multi-view digital holography based on three-color digital off-axis holography. Considering spatio-chromatic multiplexing and the recording with a monochrome sensor, the numerical processing of time-sequences of holograms yields both the amplitude and phase of the acoustic field along three different directions of observation. Distortion analysis is presented and the acousto-optic interaction along the optical beam is discussed using a theoretical modelling. Experimental results with an emitter at 40 kHz establish the proof-of-concept of the proposed multi-view imaging for acoustic fields.
{"title":"Multi-View Acoustic Field Imaging With Digital Color Holography","authors":"S. Hassad, K. Ferria, L. Bouamama, P. Picart","doi":"10.3389/fphot.2022.929031","DOIUrl":"https://doi.org/10.3389/fphot.2022.929031","url":null,"abstract":"This paper proposes an approach for acoustic field imaging using simultaneous multi-view digital holography based on three-color digital off-axis holography. Considering spatio-chromatic multiplexing and the recording with a monochrome sensor, the numerical processing of time-sequences of holograms yields both the amplitude and phase of the acoustic field along three different directions of observation. Distortion analysis is presented and the acousto-optic interaction along the optical beam is discussed using a theoretical modelling. Experimental results with an emitter at 40 kHz establish the proof-of-concept of the proposed multi-view imaging for acoustic fields.","PeriodicalId":73099,"journal":{"name":"Frontiers in photonics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45080055","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 : 2022-06-20DOI: 10.3389/fphot.2022.929936
M. Askari, Jae-Hyeung Park
In this paper, we report an implementation of a computer-generated holographic projection technique to display a holographic scene like a measuring graticule around the magnified sample image in a reflected bright-field microscopy. The implemented system acts as a gauging tool for lateral and longitudinal measurements of a sample that is being observed under a microscope through the assistance of a holographic measuring graticule. Numerical and experimental verifications have been performed, demonstrating the successful augmentation of a holographic projection system as a measuring tool with a conventional bright-field microscopic system.
{"title":"Augmentation of 3D Holographic Image Graticule With Conventional Microscopy","authors":"M. Askari, Jae-Hyeung Park","doi":"10.3389/fphot.2022.929936","DOIUrl":"https://doi.org/10.3389/fphot.2022.929936","url":null,"abstract":"In this paper, we report an implementation of a computer-generated holographic projection technique to display a holographic scene like a measuring graticule around the magnified sample image in a reflected bright-field microscopy. The implemented system acts as a gauging tool for lateral and longitudinal measurements of a sample that is being observed under a microscope through the assistance of a holographic measuring graticule. Numerical and experimental verifications have been performed, demonstrating the successful augmentation of a holographic projection system as a measuring tool with a conventional bright-field microscopic system.","PeriodicalId":73099,"journal":{"name":"Frontiers in photonics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41319000","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 : 2022-06-16DOI: 10.3389/fphot.2022.919050
Yulian Cao, Byambadorj Chagnaadorj, Nomin-Erdene Dalkhaa, G. Baasantseren
A high-resolution enhanced point light source integral imaging display is proposed. Using additional light sources to create extra point light sources in the point light source plane, the point light sources appeared on the plane that deviated from the expected values because of aberrations in the lens. Previously, only the lens array aberration was corrected and the distance along the horizontal and vertical axes was corrected too. The objective of this paper is to simultaneously correct the aberration between the lens array and the collimating lens, plus the horizontal and vertical axes, and correct the error along the z-axis. So, we determined the distance between the central light source and the additional light source to compensate for lens aberrations. From the experimental results, our technique precisely increased the resolution 3 times in both vertical and horizontal dimensions when compared to a traditional point light source display. Our method is applicable to 3D displays and compensates for the lens array and collimating lens aberrations.
{"title":"Aberration Compensated Point Light Source Display With High-Resolution","authors":"Yulian Cao, Byambadorj Chagnaadorj, Nomin-Erdene Dalkhaa, G. Baasantseren","doi":"10.3389/fphot.2022.919050","DOIUrl":"https://doi.org/10.3389/fphot.2022.919050","url":null,"abstract":"A high-resolution enhanced point light source integral imaging display is proposed. Using additional light sources to create extra point light sources in the point light source plane, the point light sources appeared on the plane that deviated from the expected values because of aberrations in the lens. Previously, only the lens array aberration was corrected and the distance along the horizontal and vertical axes was corrected too. The objective of this paper is to simultaneously correct the aberration between the lens array and the collimating lens, plus the horizontal and vertical axes, and correct the error along the z-axis. So, we determined the distance between the central light source and the additional light source to compensate for lens aberrations. From the experimental results, our technique precisely increased the resolution 3 times in both vertical and horizontal dimensions when compared to a traditional point light source display. Our method is applicable to 3D displays and compensates for the lens array and collimating lens aberrations.","PeriodicalId":73099,"journal":{"name":"Frontiers in photonics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42634705","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 : 2022-06-09DOI: 10.3389/fphot.2022.907847
Ju Tang, Jiawei Zhang, Ji Wu, Jianglei Di, Jianlin Zhao
In digital holography, the coherent noise affects the measurement accuracy and reliability greatly due to the high spatial and temporal coherence of the laser. Especially, compared with the speckle noise of intensity in digital holography, the coherent noise of phase contains more medium- and low-frequency characteristics, which hinders the effectiveness of noise suppression algorithms. Here, we propose a single-shot untrained self-supervised network (SUSNet) for the coherent noise suppression of phase, requiring only one noisy phase map to complete the optimization and learning. The SUSNet can smoothen and suppress the background fluctuations, parasitic fringes, and diffraction loops in a noisy phase and shows good generalization performance for samples with different shapes, sizes, and phase ranges. Compared with the traditional algorithms and the ground truth-supervised neural network (DnCNN), the SUSNet has the best noise suppression performance and background smoothing effect. As a result, the SUSNet can suppress the fluctuation range to ∼20% of the original range.
{"title":"Coherent Noise Suppression of Single-Shot Digital Holographic Phase Via an Untrained Self-Supervised Network [Invited]","authors":"Ju Tang, Jiawei Zhang, Ji Wu, Jianglei Di, Jianlin Zhao","doi":"10.3389/fphot.2022.907847","DOIUrl":"https://doi.org/10.3389/fphot.2022.907847","url":null,"abstract":"In digital holography, the coherent noise affects the measurement accuracy and reliability greatly due to the high spatial and temporal coherence of the laser. Especially, compared with the speckle noise of intensity in digital holography, the coherent noise of phase contains more medium- and low-frequency characteristics, which hinders the effectiveness of noise suppression algorithms. Here, we propose a single-shot untrained self-supervised network (SUSNet) for the coherent noise suppression of phase, requiring only one noisy phase map to complete the optimization and learning. The SUSNet can smoothen and suppress the background fluctuations, parasitic fringes, and diffraction loops in a noisy phase and shows good generalization performance for samples with different shapes, sizes, and phase ranges. Compared with the traditional algorithms and the ground truth-supervised neural network (DnCNN), the SUSNet has the best noise suppression performance and background smoothing effect. As a result, the SUSNet can suppress the fluctuation range to ∼20% of the original range.","PeriodicalId":73099,"journal":{"name":"Frontiers in photonics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47226773","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 : 2022-06-09DOI: 10.3389/fphot.2022.940902
V. Hoang, Y. Boussafa, L. Sader, S. F'evrier, V. Couderc, B. Wetzel
Multi-photon microscopy has played a significant role in biological imaging since it allows to observe living tissues with improved penetration depth and excellent sectioning effect. Multi-photon microscopy relies on multi-photon absorption, enabling the use of different imaging modalities that strongly depends on the properties of the sample structure, the selected fluorophore and the excitation laser. However, versatile and tunable laser excitation for multi-photon absorption is still a challenge, limited by e.g. the narrow bandwidth of typical laser gain medium or by the tunability of wavelength conversion offered by optical parametric oscillators or amplifiers. As an alternative, supercontinuum generation can provide broadband excitations spanning from the ultra-violet to far infrared domains and integrating numerous fluorophore absorption peaks, in turn enabling different imaging modalities or potential multiplexed spectroscopy. Here, we report on the use of machine learning to optimize the spectro-temporal properties of supercontinuum generation in order to selectively enhance multi-photon excitation signals compatible with a variety of fluorophores (or modalities) for multi-photon microscopy. Specifically, we numerically explore how the use of reconfigurable (femtosecond) pulse patterns can be readily exploited to control the nonlinear propagation dynamics and associated spectral broadening occurring in a highly-nonlinear fiber. In this framework, we show that the use of multiple pulses to seed optical fiber propagation can trigger a variety of nonlinear interactions and complex propagation scenarios. This approach, exploiting the temporal dimension as an extended degree of freedom, is used to maximize typical multi-photon excitations at selected wavelengths, here obtained in a versatile and reconfigurable manner suitable for imaging applications. We expect these results to pave the way towards on-demand and real time supercontinuum shaping, with further multi-photon microscopy improvements in terms of spatial 3D resolution, optical toxicity, and wavelength selectivity.
{"title":"Optimizing supercontinuum spectro-temporal properties by leveraging machine learning towards multi-photon microscopy","authors":"V. Hoang, Y. Boussafa, L. Sader, S. F'evrier, V. Couderc, B. Wetzel","doi":"10.3389/fphot.2022.940902","DOIUrl":"https://doi.org/10.3389/fphot.2022.940902","url":null,"abstract":"Multi-photon microscopy has played a significant role in biological imaging since it allows to observe living tissues with improved penetration depth and excellent sectioning effect. Multi-photon microscopy relies on multi-photon absorption, enabling the use of different imaging modalities that strongly depends on the properties of the sample structure, the selected fluorophore and the excitation laser. However, versatile and tunable laser excitation for multi-photon absorption is still a challenge, limited by e.g. the narrow bandwidth of typical laser gain medium or by the tunability of wavelength conversion offered by optical parametric oscillators or amplifiers. As an alternative, supercontinuum generation can provide broadband excitations spanning from the ultra-violet to far infrared domains and integrating numerous fluorophore absorption peaks, in turn enabling different imaging modalities or potential multiplexed spectroscopy. Here, we report on the use of machine learning to optimize the spectro-temporal properties of supercontinuum generation in order to selectively enhance multi-photon excitation signals compatible with a variety of fluorophores (or modalities) for multi-photon microscopy. Specifically, we numerically explore how the use of reconfigurable (femtosecond) pulse patterns can be readily exploited to control the nonlinear propagation dynamics and associated spectral broadening occurring in a highly-nonlinear fiber. In this framework, we show that the use of multiple pulses to seed optical fiber propagation can trigger a variety of nonlinear interactions and complex propagation scenarios. This approach, exploiting the temporal dimension as an extended degree of freedom, is used to maximize typical multi-photon excitations at selected wavelengths, here obtained in a versatile and reconfigurable manner suitable for imaging applications. We expect these results to pave the way towards on-demand and real time supercontinuum shaping, with further multi-photon microscopy improvements in terms of spatial 3D resolution, optical toxicity, and wavelength selectivity.","PeriodicalId":73099,"journal":{"name":"Frontiers in photonics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43175834","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 : 2022-05-18DOI: 10.3389/fphot.2022.889837
Rik van Heerden, P. Procel, L. Mazzarella, R. Santbergen, O. Isabella
Organic-inorganic metal halide perovskites have attracted a considerable interest in the photovoltaic scientific community demonstrating a rapid and unprecedented increase in conversion efficiency in the last decade. Besides the stunning progress in performance, the understanding of the physical mechanisms and limitations that govern perovskite solar cells are far to be completely unravelled. In this work, we study the origin of their hysteretic behaviour from the standpoint of fundamental semiconductor physics by means of technology computer aided design electrical simulations. Our findings identify that the density of shallow interface defects at the interfaces between perovskite and transport layers plays a key role in hysteresis phenomena. Then, by comparing the defect distributions in both spatial and energetic domains for different bias conditions and using fundamental semiconductor equations, we can identify the driving force of hysteresis in terms of slow recombination processes and charge distributions.
{"title":"Slow Shallow Energy States as the Origin of Hysteresis in Perovskite Solar Cells","authors":"Rik van Heerden, P. Procel, L. Mazzarella, R. Santbergen, O. Isabella","doi":"10.3389/fphot.2022.889837","DOIUrl":"https://doi.org/10.3389/fphot.2022.889837","url":null,"abstract":"Organic-inorganic metal halide perovskites have attracted a considerable interest in the photovoltaic scientific community demonstrating a rapid and unprecedented increase in conversion efficiency in the last decade. Besides the stunning progress in performance, the understanding of the physical mechanisms and limitations that govern perovskite solar cells are far to be completely unravelled. In this work, we study the origin of their hysteretic behaviour from the standpoint of fundamental semiconductor physics by means of technology computer aided design electrical simulations. Our findings identify that the density of shallow interface defects at the interfaces between perovskite and transport layers plays a key role in hysteresis phenomena. Then, by comparing the defect distributions in both spatial and energetic domains for different bias conditions and using fundamental semiconductor equations, we can identify the driving force of hysteresis in terms of slow recombination processes and charge distributions.","PeriodicalId":73099,"journal":{"name":"Frontiers in photonics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-05-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44169426","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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