Photon Response Research Articles

Flat-field methods for color image sensors

The research provides a detailed analysis of the primary sources of non-uniformity in color CMOS image sensors. It introduces the fundamental theory of traditional photon conversion and the main objective and subjective quality evaluation metrics for images. The theoretical foundations of traditional correction methods are also discussed. Based on the photon response characteristics of the color image sensor, a method for flat-field correction of color image sensors is proposed by analyzing the grayscale response curves of each pixel. This method addresses the non-linearity issue in pixel photon response caused by crosstalk between pixels and improves the non-uniformity problem in pixel response.

Assessing photonic response diversity in STO heterostructures with varying orientations

Assessing photonic response diversity in STO heterostructures with varying orientations

Correction: Impact of coupling mirrors on the photonic response of the planar microcavity

Correction: Impact of coupling mirrors on the photonic response of the planar microcavity

Impact of coupling mirrors on the photonic response of the planar microcavity

Impact of coupling mirrors on the photonic response of the planar microcavity

A single photon resolution integrating chip for silicon microstrip sensors (SSDROC) in High Energy Photon Source

Single-photon counting silicon microstrip detectors play a crucial role in X-ray powder diffraction experiments due to their high sensitivity and low dead-time. The High Energy Photon Source (HEPS) is poised to become a world-leading facility for high-energy synchrotron radiation. The storage ring, being constructed in China, will operate at an electron energy of 6 GeV and an emittance of less than 0.06 nm rad, thereby providing an exceptionally bright synchrotron light beam.Consequently, there is a requirement for detectors at HEPS to possess enhanced photon counting capabilities. Our team developed a dedicated Application-Specific Integrated Circuit (SSDROC) and a readout electronics system for one-dimensional X-ray detection. To resolve the issue of inconsistent photon response across different channels, a novel secondary calibration method has been applied. The detector has undergone various performance tests, and the results show that the entire system has good linearity, high energy resolution, and a high count rate.

High‐Performance Electrode for Energy Storage Developed Using Single‐Source Precursor‐Driven Bas:Cos:La2S3 Trichalcogenide Semiconductor

Using single‐source precursor route, this work reports the synthesis of the novel chalcogenide heterosystem, i.e., BaS:CoS:La2S3 trichalcogenide heterosystem. With the narrowed band gap energy, BaS:CoS:La2S3 expresses excellent photonic response with 3.47 eV of tailored band gap resulting from chemical synergism. This chalcogenide is marked by superior crystallinity and possessed an average crystallite size of 18.29 nm. Morphologically, BaS:CoS:La2S3 exists in the form of the roughly spherical grains arranged in the irregular manner. The developed chalcogenide is assessed for charge storage by fabricating the electrode using a nickel form as a support. In a 0.1 m KOH background electrolyte, the BaS:CoS:La2S3 adorns electrode excelled in achieving a specific capacitance of 967.24 F g−1. In addition, this trichalcogenide expresses the specific power density of 1659 W kg−1. Fabricated electrode retains original capacitance after different cycles. Regarding electrode–electrolyte interactions, the fabricated electrode shows minimal resistance, with an equivalent series resistance (Rs) of 1.42 Ω as indicated by impedance studies. Additional circuit elements, including CPE (Yo = 2.17 × 10−04, n = 0.71) and Rct (6.97 Ω cm−2), are obtained after circuit fitting for the BaS:CoS:La2S3 trichalcogenide decorated electrode. Exhibiting stable behavior for 43 h, the synthesized material demonstrates profound durability and functionality.

A Generic Implementation of the D1S Methodology for Dose Rate Assessment by Monte Carlo Codes in Fusion Applications

Dose rate assessment is of utmost importance in fusion reactors because of the maintenance operations that these facilities will require. The standard way to perform this assessment in ITER is use of the Direct 1-Step (D1S) methodology, which consists of performing neutron transport simulation, material activation, and decay photon transport simulation in one step and thus in one simulation only. Usually, implementation of the D1S methodology requires changing the source files in a reference Monte Carlo code. The purpose of the present work is to develop an easy-to-implement method for Monte Carlo codes to help calculate the dose rate in fusion reactors. To do so, the proposal is to act on nuclear data only and not on source files of the simulation codes. This is done by replacing prompt photon production in evaluation files by suitable decay photon production, taking into account radioactive decays of radionuclides and irradiation history. This study was to be applied first on the TRIPOLI-4® Monte Carlo code for the sake of simplicity. TRIPOLI-4 is the reference code for particle transport at CEA. The verification and validation process relies first on a comparison to the reference Rigorous 2-Step (R2S) methodology and then on an experiment, the so-called Frascati Neutron Generator (FNG) dose experiment. The nuclear database to be changed is of the ENDF-6 format, a recurrent format in neutronics studies. The analysis studied both neutron and photon responses to check if the simulation was performing normally in a physical way and to compare the results with references provided by simulations based on the R2S methodology or by the FNG dose experiment. The simulations have proven to be in good agreement with the experimental results.

Electroluminescence Rectification and High Harmonic Generation in Molecular Junctions.

The field of molecular electronics has emerged from efforts to understand electron propagation through single molecules and to use them in electronic circuits. Serving as a testbed for advanced theoretical methods, it reveals a significant discrepancy between the operational time scales of experiments (static to GHz frequencies) and theoretical models (femtoseconds). Utilizing a recently developed time-linear nonequilibrium Green function formalism, we model molecular junctions on experimentally accessible time scales. Our study focuses on the quantum pump effect in a benzenedithiol molecule connected to two copper electrodes and coupled with cavity photons. By calculating both electric and photonic current responses to an ac bias voltage, we observe pronounced electroluminescence and high harmonic generation in this setup. The mechanism of the latter effect is more analogous to that from solids than from isolated molecules, with even harmonics being suppressed or enhanced depending on the symmetry of the driving field.

Multi-scale structural characterization of ceramic-based photonic glasses for structural colors

Structural colors arise from selective light interaction with (nano)structures, which give them advantages over pigmented colors such as resistance to fading and possibility to be fabricated out of traditional low-cost and non-toxic materials. Since the color arises from the photonic (nano)structures, different structural features can impact their photonic response and thus, their color. Therefore, the detailed characterization of their structural features is crucial for further improvement of structural colors. In this work, we present a detailed multi-scale structural characterization of ceramic-based photonic glasses by using a combination of high-resolution ptychographic X-ray computed tomography and small angle X-ray scattering. Our results uncover the structure-processing-properties’ relationships of such nanoparticles-based photonic glasses and point out to the need of a review of the structural features used in simulation models concomitantly with the need for further investigations by experimentalists, where we point out exactly which structural features need to be improved.

Emphasizing Cherenkov Photons From Bismuth Germanate by Single Photon Response Deconvolution

Emphasizing Cherenkov Photons From Bismuth Germanate by Single Photon Response Deconvolution

Investigation of reflection-based measurements of microwave kinetic inductance detectors in the optical bands

In this paper, we investigate the single photon response from the reflection of the microwave kinetic inductance detector (MKID) array. Reflection measurements are carried out using two configurations: one is measured simultaneously with the transmission, and the other is obtained with a single-ended MKID array terminated with an open load. Compared with the transmission, reflection measurements significantly reduce the readout noise of the single-ended MKID array. This is also reflected in the improvement of the median energy resolving power by around 20%–30% under pulsed photon illumination at λ = 405 nm, mainly due to an increase in the size of the resonance circle on the IQ plane. This method has the potential to be used to read out large MKID arrays.

Semi-Transparent Luminescent Solar Concentrators Based on Intramolecular Energy Transfer in Polyurethane Matrices.

Luminescent solar concentrators (LSCs) are spectral conversion devices offering interesting opportunities for the integration of photovoltaics into the built environment and portable systems. The Förster-resonance energy transfer (FRET) process can boost the optical response of LSCs by reducing energy losses typically associated to non-radiative processes occurring within the device under operation. In this work, a new class of FRET-based thin-film LSC devices is presented, in which the synthetic versatility of linear polyurethanes (PU) is exploited to control the photophysical properties and the device performance of the resulting LSCs. A series of luminescent linear PUs are synthesized in the presence of two novel bis-hydroxyl-functionalized luminophores of suitable optical properties, used as chain extenders during the step-growth polyaddition reaction for the formation of the linear macromolecular network. By synthetically tuning their composition, the obtained luminescent PUs can achieve a high energy transfer efficiency (≈90%) between the covalently linked luminophores. The corresponding LSC devices exhibit excellent photonic response, with external and internal photon efficiencies as high as ≈4% and ≈37%, respectively. Furthermore, their optimized power conversion efficiency combined with their enhanced average visible-light transmittance highlight their suitability for potential use as transparent solar energy devices.

Enhanced photogalvanic effect in Janus PtSSe-HfSSe lateral heterojunctions

The enhancement of photogalvanic effect (PGE) is vital for the application of optoelectronics. We use the ab initio quantum transport method to study the possible enhancement of PGE by importing a lateral PtSSe-HfSSe heterojunction. Under irradiation of linearly polarized light with photon energies (Eph) of 0.8–6.2 eV, the overall increase ratio of the PGE photocurrent is over 20/50 along the armchair/zigzag direction. The lateral PtSSe-HfSSe photodetector along the armchair direction exhibits a better photon response than the photodetector along the zigzag direction. The maximal PGE photocurrent is 42.26 a02/photon at Eph = 2.0 eV, and the highest extinction ratio is 2.5 × 104 at Eph = 1.6 eV. Our study indicates that the lateral PtSSe-HfSSe heterojunction is a favorable candidate for optoelectronics.

Blue-light-enhanced avalanche photodiode with amulti-finger grating structure for fluorescence detection.

The responsiveness of the photodetectors is critical to the accuracy of the fluorescent fiber optical temperature sensor. However, the current gain and signal-to-noise ratio (SNR) of traditional photodiodes (PDs) is low, which makes it difficult to meet the high-precision detection requirements of the system. In response to the above problems, this paper achieves a novel, to the best of our knowledge, multi-finger grating (MFG) avalanche photodiode (APD). The device combines the polysilicon gate and the space charge region formed by P+/N-Well to detect photon signals. The conversion capability of the photodetector can be significantly enhanced by the MFG structure. The principle of the device is simulated and verified by technology-computer-aided design (TCAD). The standard grating APD (SG-APD), 2-finger grating APD (2FG-APD), 3-finger grating APD (3FG-APD), and 4-finger grating APD (4FG-APD) are fabricated based on 0.18µm CMOS process. The optoelectronic detection characteristics of these devices are analyzed by establishing an optoelectronic test platform. At 480nm, the responsivity of 2FG-APD, 3FG-APD, and 4FG-APD increases by 79.3%, 96.9%, and 70.2%, respectively, compared to SG-APD (4.021A/W). The test results indicate that 3FG-APD exhibits a strong photon response in the blue light range. The device has broad application prospects in the field of fluorescence detection.

Structure and Photonic Properties of a Perylenediimide Monolayer Assembled by the Langmuir-Blodgett Technique.

The photonic responses of densely packed dye molecule assemblies are strongly dependent on their organization and environment. The precise control of molecular orientations and distances relative to the substrate and to each other is thus a key point in the design of photonic molecular materials. Herein, we report the preparation of a homogeneous and well-organized single monolayer of the perylenediimide (PDI) derivative by means of the Langmuir-Blodgett technique. Its optical properties disclose an intense charge-transfer excitonic absorption band related to important intermolecular coupling. Furthermore, an important immunity to photobleaching is observed for such a molecular assembly. The dipolar orientations of the molecules along the substrate have been unambiguously determined by angle-of-incidence-resolved polarized absorption and back-focal-plane fluorescence mapping. In addition, time-resolved spectroscopy reveals a fast two-dimensional diffusion of excitons consistent with strong π-stacking of adjacent PDI molecules.

Localising and identifying radionuclides via energy-resolved angular photon responses

A technique for the in-situ localisation of radioactivity is described whereby the energy-resolved angular photon response of a collimated inorganic scintillation detector is used to derive the spatial arrangement of a variety of radioactive source configurations. The influence of photon radiation (X- and γ ray) incident on the collimated detector is expressed mathematically, by way of a sinc transform embedded to a dynamic linear regression model, to increase the spatial accuracy of the localisation. This approach is tested experimentally with two pairs of like radionuclides, two pairs of different combinations of radionuclides and three different radionuclides to demonstrate its combined isotopic discrimination and spatial localisation capabilities. A fit based on the model referred to above is observed to reproduce the data for the combined X- and γ-ray regions of interest effectively. This allows for increased resolution via interpolation between the data which is observed to improve location accuracy significantly. This research is relevant to applications in autonomous robotic exploration tasks and for the characterisation of contaminated environments associated with nuclear legacies and radiological emergencies.

Adaptive dispersion compensation using a photonic integrated circuit finite impulse response filter.

Optical equalization can be used for chromatic dispersion compensation in optical communication systems to improve the system performance; however, optical signal processing (OSP) is generally specifically designed for transmission channels, that is non-adaptive to dynamic transmission distortions compared with digital signal processing (DSP). In this contribution, we demonstrate optical equalization using a photonic integrated circuit (PIC) filter for chromatic dispersion compensation, with static and adaptive techniques: (a) the static optical equalizer is calibrated based on the known fiber dispersion and length, by using the fractional delay reference method; (b) the adaptive optical equalizer is updated iteratively to compensate transmission impairments based on a least-mean squares (LMS) algorithm. Experimental results show that both the static optical equalizer and the adaptive optical LMS equalizer can give an 18-dB Q-factor for a 14-Gbd QPSK signal transmitting over 30 km. To highlight the capability of the optical equalizers, we use simulations to show the improvement in dispersion compensating characteristics by implementing additional taps.

Simulation of Hp(0,07) beta and photon response of a BeOSL finger ring dosemeter.

Simulation of a dosemeter's energy and angular response lowers development cost and time. To support development of a new beta sensitive dosemeter we simulate both the dosemeter and the skin dose in a rod phantom as there are no fluence to dose conversion coefficients in the ICRU Report 47 for electrons. Published spectra for BSS2, N-Series and S-Cs and S-Co were used to define sources, with CAD models used to define the simulation geometry. Simulation tools were validated with experimental beta and photon responses available for the BeOSL photon ring. The developed toolchain was then used to simulate several iterations of a beta sensitive detector element inside a beta ring holder, with the goal to minimise the need for repeated prototype fabrication and characterisation. Simulation results for the final design were compared to measurements on 3D printed prototypes with all radiation qualities, except 90Sr/90Y 0°, falling within measurement uncertainty.

Nonreciprocal Electromagnetic Wave Manipulation via a Single Reflection

Electromagnetic field manipulation plays a key role in applications such as electron acceleration, nonlinear light–matter interaction, and radiation engineering. Nonreciprocal materials, such as Weyl semimetals, enable the manipulation of the electromagnetic field in a full photonic manner, owing to their intrinsic time‐reversal symmetry breaking, leading to asymmetric material response for photons with and momenta. Herein, the results suggest that a simple planar interface between semi‐infinite air and a nonreciprocal material can achieve spatiotemporal manipulation of the electromagnetic field. In particular, this work presents three compelling scenarios for electromagnetic wave manipulation: radiation pattern redistribution (with closed‐form expressions provided), carrier‐envelope‐phase control, and spatial profile control. The presented results pave the way for electromagnetic field manipulation using pattern‐free nonreciprocal materials.

Theoretical Investigation on the Metamaterials Based on the Magnetic Template-Assisted Self-Assembly of Magnetic-Plasmonic Nanoparticles for Adjustable Photonic Responses.

The assembly of artificial nano- or microstructured materials with tunable functionalities and structures, mimicking nature's complexity, holds great potential for numerous novel applications. Despite remarkable progress in synthesizing colloidal molecules with diverse functionalities, most current methods, such as the capillarity-assisted particle assembly method, the ionic assembly method based on ionic interactions, or the field-directed assembly strategy based on dipole-dipole interactions, are confined to focusing on achieving symmetrical molecules. But there have been few examples of fabricating asymmetrical colloidal molecules that could exhibit unprecedented optical properties. Here, we introduce a microfluidic and magnetic template-assisted self-assembly protocol that relies mainly on the magnetic dipole-dipole interactions between magnetized magnetic-plasmonic nanoparticles and the mechanical constraints resulting from the specially designed traps. This novel strategy not only requires no specific chemistry but also enables magnetophoretic control of magnetic-plasmonic nanoparticles during the assembly process. Moreover, the assembled asymmetrical colloidal molecules also exhibit interesting hybridized plasmon modes and produce exotic optical properties due to the strong coupling of the individual nanoparticle. The ability to fabricate asymmetrical colloidal molecules based on the bottom-up method opens up a new direction for the fabrication of novel microscale structures for biosensing, patterning, and delivery applications.