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Science Bulletin Jun 2022
Topics: Optics and Photonics; Photons
PubMed: 36546145
DOI: 10.1016/j.scib.2022.04.021 -
Sensors (Basel, Switzerland) May 2014In this paper, we propose a new method for color image-based authentication that combines multispectral photon-counting imaging (MPCI) and double random phase encoding...
In this paper, we propose a new method for color image-based authentication that combines multispectral photon-counting imaging (MPCI) and double random phase encoding (DRPE) schemes. The sparsely distributed information from MPCI and the stationary white noise signal from DRPE make intruder attacks difficult. In this authentication method, the original multispectral RGB color image is down-sampled into a Bayer image. The three types of color samples (red, green and blue color) in the Bayer image are encrypted with DRPE and the amplitude part of the resulting image is photon counted. The corresponding phase information that has nonzero amplitude after photon counting is then kept for decryption. Experimental results show that the retrieved images from the proposed method do not visually resemble their original counterparts. Nevertheless, the original color image can be efficiently verified with statistical nonlinear correlations. Our experimental results also show that different interpolation algorithms applied to Bayer images result in different verification effects for multispectral RGB color images.
Topics: Algorithms; Color; Image Interpretation, Computer-Assisted; Optics and Photonics; Photons; Random Allocation
PubMed: 24854208
DOI: 10.3390/s140508877 -
Analytical Chemistry Dec 2010An experimentally simple photon counting method is demonstrated providing 7 orders of magnitude in linear dynamic range (LDR) for a single photomultiplier tube (PMT)...
An experimentally simple photon counting method is demonstrated providing 7 orders of magnitude in linear dynamic range (LDR) for a single photomultiplier tube (PMT) detector. In conventional photon/electron counting methods, the linear range is dictated by the agreement between the binomially distributed measurement of counted events and the underlying Poisson distribution of photons/electrons. By explicitly considering the log-normal probability distribution in voltage transients as a function of the number of photons present and the Poisson distribution of photons, observed counts for a given threshold can be related to the mean number of photons well beyond the conventional limit. Analytical expressions are derived relating counts and photons that extend the linear range to an average of ∼11 photons arriving simultaneously with a single threshold. These expressions can be evaluated numerically for multiple thresholds extending the linear range to the saturation point of the PMT. The peak voltage distributions are experimentally shown to follow a Poisson weighted sum of log-normal distributions that can all be derived from the single photoelectron voltage peak-height distribution. The LDR that results from this method is compared to conventional single photon counting (SPC) and to signal averaging by analog to digital conversion (ADC).
Topics: Electrons; Models, Statistical; Optics and Photonics; Photons; Poisson Distribution
PubMed: 21114249
DOI: 10.1021/ac102219c -
Applied Optics Oct 2007The quantitative analysis of fluorescence perturbation experiments such as fluorescence recovery after photobleaching (FRAP) requires suitable analytical models to be...
The quantitative analysis of fluorescence perturbation experiments such as fluorescence recovery after photobleaching (FRAP) requires suitable analytical models to be developed. When diffusion in 3D environments is considered, the description of the initial condition produced by the perturbation (i.e., the photobleaching of a selected region in FRAP) represents a crucial aspect. Though it is widely known that bleaching profiles approximations can lead to errors in quantitative FRAP measurements, a detailed analysis of the sources and the effects of these approximations has never been conducted until now. In this study, we measured the experimental 3D bleaching distributions obtained in conventional and two-photon excitation schemes and analyzed the deviations from the ideal cases usually adopted in FRAP experiments. In addition, we considered the non-first-order effects generated by the high energy pulses usually delivered in FRAP experiments. These data have been used for finite-element simulations mimicking FRAP experiments on free diffusing molecules and compared with FRAP model curves based on the ideal bleach distributions. The results show that two-photon excitation more closely fits ideal bleaching patterns even in the event of fluorescence saturation, achieving estimations of diffusion coefficients within 20% accuracy of the correct value.
Topics: Computer Simulation; Diffusion; Fluorescence Recovery After Photobleaching; Imaging, Three-Dimensional; Kinetics; Microscopy, Confocal; Models, Statistical; Normal Distribution; Optics and Photonics; Photons
PubMed: 17952174
DOI: 10.1364/ao.46.007401 -
Physical Review Letters Oct 2019When the feature size of photonic structures becomes comparable or even smaller than the wavelength of light, the fabrication imperfections inevitably introduce disorder...
When the feature size of photonic structures becomes comparable or even smaller than the wavelength of light, the fabrication imperfections inevitably introduce disorder that may eliminate many functionalities of subwavelength photonic devices. Here we suggest a novel concept to achieve a robust band gap which can endure disorder beyond 30% as a result of the transition from photonic crystals to Mie-resonant metamaterials. By utilizing Mie-resonant metamaterials with high refractive index, we demonstrate photonic waveguides and cavities with strong robustness to position disorder, thus providing a novel approach to the band-gap-based nanophotonic devices with new properties and functionalities.
Topics: Models, Theoretical; Optics and Photonics; Photons
PubMed: 31702361
DOI: 10.1103/PhysRevLett.123.163901 -
Optics Express Aug 2010The two modes of the Einstein-Podolsky-Rosen quadrature entangled state generated by parametric down-conversion interfere on a beam splitter of variable splitting ratio....
The two modes of the Einstein-Podolsky-Rosen quadrature entangled state generated by parametric down-conversion interfere on a beam splitter of variable splitting ratio. Detection of a photon in one of the beam splitter output channels heralds preparation of a signal state in the other, which is characterized using homodyne tomography. By controlling the beam splitting ratio, the signal state can be chosen anywhere between the single-photon and squeezed state.
Topics: Electronic Data Processing; Equipment Design; Models, Theoretical; Optics and Photonics; Photons; Quantum Theory; Vacuum
PubMed: 20721217
DOI: 10.1364/OE.18.018254 -
Frontiers in Bioscience (Elite Edition) Jan 2011In fluorescence correlation spectroscopy (FCS) and photon counting histogram (PCH) analysis the same experimental fluorescence intensity fluctuations are used, but each...
In fluorescence correlation spectroscopy (FCS) and photon counting histogram (PCH) analysis the same experimental fluorescence intensity fluctuations are used, but each analytical method focuses on a different property of the signal. The time-dependent decay of the correlation of fluorescence fluctuations is measured in FCS yielding, for instance, molecular diffusion coefficients. The amplitude distribution of these fluctuations is calculated by PCH yielding the molecular brightness. Both FCS and PCH give information about the molecular concentration. Here we describe a global analysis protocol that simultaneously recovers relevant and common parameters in model functions of FCS and PCH from a single fluorescence fluctuation trace. The global analysis approach is described and tested with experimental fluorescence fluctuation data of enhanced green-fluorescent protein (eGFP) and dimeric eGFP (two eGFP molecules connected by a six amino acid long linker) in aqueous buffer. Brightness values and diffusion constants are recovered with good precision elucidating novel excited-state and motional properties of both proteins.
Topics: Dimerization; Green Fluorescent Proteins; Models, Theoretical; Optics and Photonics; Photons; Software; Spectrometry, Fluorescence; Time Factors
PubMed: 21196329
DOI: 10.2741/e264 -
Nature Communications Oct 2022Silicon photonics is promising for artificial neural networks computing owing to its superior interconnect bandwidth, low energy consumption and scalable fabrication....
Silicon photonics is promising for artificial neural networks computing owing to its superior interconnect bandwidth, low energy consumption and scalable fabrication. However, the lack of silicon-integrated and monitorable optical neurons limits its revolution in large-scale artificial neural networks. Here, we highlight nonlinear germanium-silicon photodiodes to construct on-chip optical neurons and a self-monitored all-optical neural network. With specifically engineered optical-to-optical and optical-to-electrical responses, the proposed neuron merges the all-optical activation and non-intrusive monitoring functions in a compact footprint of 4.3 × 8 μm. Experimentally, a scalable three-layer photonic neural network enables in situ training and learning in object classification and semantic segmentation tasks. The performance of this neuron implemented in a deep-scale neural network is further confirmed via handwriting recognition, achieving a high accuracy of 97.3%. We believe this work will enable future large-scale photonic intelligent processors with more functionalities but simplified architecture.
Topics: Germanium; Neural Networks, Computer; Optics and Photonics; Photons; Silicon
PubMed: 36229465
DOI: 10.1038/s41467-022-33877-7 -
Scientific Reports Aug 2022A major roadblock to the development of photonic sensors is the scattering associated with many biological systems. We show the conservation of photonic states through...
A major roadblock to the development of photonic sensors is the scattering associated with many biological systems. We show the conservation of photonic states through optically self-arranged biological waveguides, for the first time, which can be implemented to transmit light through scattering media. The conservation of optical properties of light through biological waveguides allows for the transmission of high bandwidth information with low loss through scattering media. Here, we experimentally demonstrate the conservation of polarization state and orbital angular momentum of light through a self-arranged biological waveguide, several centimeters long, in a sheep red blood cell suspension. We utilize nonlinear optical effects to self-trap cells, which form waveguides at 532 nm and 780 nm wavelengths. Moreover, we use the formed waveguide channels to couple and guide probe beams without altering the information. The formed biological waveguides are in a sub-diffusive scattering regime, so the photons' information degrades insignificantly over several centimeters of propagation through the scattering media. Our results show the potential of biological waveguides as a methodology for the development of novel photonic biosensors, biomedical devices that require optical wireless communication, and the development of new approaches to noninvasive biomedical imaging.
Topics: Animals; Motion; Optics and Photonics; Photons; Scattering, Radiation; Sheep
PubMed: 35986206
DOI: 10.1038/s41598-022-18483-3 -
Sensors (Basel, Switzerland) Dec 2022Traditional temperature detection has limitations in terms of sensing accuracy and response time, while chip-level photoelectric sensors based on the thermo-optic effect...
Traditional temperature detection has limitations in terms of sensing accuracy and response time, while chip-level photoelectric sensors based on the thermo-optic effect can improve measurement sensitivity and reduce costs. This paper presents on-chip temperature sensors based on polysilicon (p-Si) waveguides. Dual-microring resonator (MRR) and asymmetric Mach-Zehnder interferometer (AMZI) sensors are demonstrated. The experimental results show that the sensitivities of the sensors based on AMZI and MRR are 86.6 pm/K and 85.7 pm/K, respectively. The temperature sensors proposed in this paper are compatible with the complementary metal-oxide-semiconductor (CMOS) fabrication technique. Benefitting from high sensitivity and a compact footprint, these sensors show great potential in the field of photonic-electronic applications.
Topics: Semiconductors; Optics and Photonics; Electronics; Photons; Temperature
PubMed: 36502058
DOI: 10.3390/s22239357