Photon Field Research Articles

Skew scattering and ratchet effect in photonic graphene

This paper is devoted to a comprehensive theoretical study of asymmetric (skew) scattering in photonic graphene, with the main focus on its realization with semiconductor microcavity exciton-polaritons. As an important consequence of the skew scattering, we prove the appearance of the ratchet effect in this system. Triangular defects in the form of missing micropillars in a regular honeycomb lattice are considered to be ones that break the spatial inversion symmetry, thus providing the possibility of the ratchet effect. By means of the numerical solution of the effective Schrödinger equation, we provide microscopical insight into the process of skew scattering and determine indicatrices, cross sections, and asymmetry parameters. In a system with multiple coherently oriented triangular defects, a macroscopic ratchet effect occurs as a unidirectional flux upon noiselike initial conditions. Our study broadens the concept of ratchet phenomena in the field of photonics and optics of exciton-polaritons. Published by the American Physical Society 2024

Van der Waals GeSe with Strain- and Gate-Tunable Linear Dichroism for Wearable Electronics.

The direct detection of light polarization poses a crucial challenge in the field of optoelectronics and photonics. Herein, the tunable linear dichroism (LD) in GeSe-based polarized photodetectors is presented through electronic and structural asymmetry modulation, and demonstrate their application prospects in wearable electronics. An improvement in the dichroic ratio up to 34% is achieved under a gate voltage of 20V, and the improvement reaches 44% by applying a tensile strain along the zigzag direction. Theoretical calculations reveal that the gate regulation of barrier height between GeSe and Au electrodes is responsible for the electrical-tunable LD, while the anisotropic optical absorption in response to strains leads to the strain-tunable LD. Moreover, flexible GeSe transistors are developed for wearable applications including motion sensors and glucose monitors. This study offers viable approaches for modulating the optical anisotropy of low-dimensional materials and emphasizes the versatility of van der Waals materials for practical applications in wearable electronic devices.

Chiral Nematic Graphene Films with a mesoporous Structure.

Ordering a crucial material like pure-graphene into the chiral nematic structure can potentially revolutionize the fields of photonics, chiral separation, and energy storage. However, the controlled fabrication of highly ordered graphene films with a long-range chiral nematic mesoporous structure is very challenging and as such, has not been achieved. Here, a chiral-template-directed chemical vapor deposition growth strategy is presented for the precise fabrication of mesoporous chiral nematic graphene films by using nanocrystalline cellulose as templates. It is evidenced that such graphene films possess the left-hand helical ordering, chiral nematic mesoporous structure with adjustable pore sizes (6.4-13.1nm), tailored pitch, excellent electrical conductivity (556 S cm-1), high specific surface area (1508 m2g-1) and mechanical flexibility. By coating Na anode with this film, uniform Na plating is achieved with no dendrite formation, resulting from its unique chiral nematic structure and tunable physicochemical properties. The films also achieved impressive thickness-dependent electromagnetic shielding, i.e., 35-63dB, demonstrating their potentially multi-disciplinary applications.

Phase synthesis method in multi-aperture optical systems based on iterative image processing algorithms

Background. Modern technologies in the field of optics and photonics place high demands on the quality and output power of the radiation source. The fulfillment of these requirements can currently be achieved by creating multi-aperture laser systems with coherent beam addition. The main problem of creating such systems is the development of phase synthesis methods in a multichannel optical system. Aim. In this paper, we consider a phase synchronization method without a reference beam for a coherent addition system with active feedback, which is based on the Gerchberg–Saxton algorithm. This algorithm makes it possible to reconstruct complex field amplitudes in the aperture and focal planes from intensity distributions in these fields. The application of this algorithm for multichannel systems is analyzed and its features, such as the occurrence of stagnation and ambiguity of the solution, are revealed. Methods. Solutions are proposed to eliminate the problem of convergence of the algorithm to side solutions and getting the iterative procedure into the local extremum using global optimization algorithms, methods of reducing the dimension of the problem and the introduction of antisymmetric amplitude modulation. Results. The paper demonstrates the results of phase field reconstruction for a large number of optical sources. For a seven-aperture system, a physical simulation was performed to restore phase information, confirming the results of numerical modeling. Conclusion. The proposed approach is a reasonable alternative to currently existing methods and can be used in the problem of coherent addition in multichannel optical systems.

Chiral effects on radiation and energy loss in quark–gluon plasma

The emergent axion excitations in the quark–gluon plasma are generated by the sphaleron transitions. Their interactions with the photon and gluon fields are governed by the axion electro- and chromodynamics, respectively. We discuss the effect of the emergent axion on the photon production and energy loss in the quark–gluon plasma. In particular, we review the Chiral Cherenkov effect, and the impact of the chiral anomaly on bremsstrahlung.

Design of an all-optical tunable 2D photonic crystal in As2S3 film

Amorphous arsenic trisulphide (As2S3) chalcogenide glass is widely used in photonics and optoelectronics due to its wide transparency in the infrared spectral range, its high linear refractive index (nAs2S3 = 2.42), which can be significantly modified by light with a suitable wavelength, and its important optical nonlinearity. In this work, we report the design of an all-optical tunable two-dimensional photonic crystal in a geometry which consists in a hexagonal lattice of holes patterned in As2S3 film with the aim to exhibit photonic band gap in the near infrared domain. We numerically investigated the possibility to all-optically tune the photonic band gap of an already patterned photonic crystal in As2S3 modifying only its refractive index by illumination with light of wavelength λ at the band gap energy (λ = 514.5 nm) or shorter, without affecting the lattice geometry. The influence of the variation of As2S3 refractive index (Δn) on the spectral position of the band gap and on its width has been determined for the light-induced modification of Δn up to the value of 0.09. For this value of Δn, a shift of almost 50 nm of the central wavelength of the photonic band gap has been obtained. These results are of great interest in the field of photonics offering a versatile solution to fabricate all-optical tunable photonic crystals in any optical material whose refractive index can be modified by light.

Rising Tide of Enhanced Crystalline Silicon Luminescence via Optical Resonance.

Since the invention of lasers, research on the luminescence of crystalline silicon (c-Si) has been a longstanding challenge in the field of photonics. Recent advancements in nanofabrication technology, coupled with in-depth investigations into optical resonance and carrier dynamics, have enabled the realization of efficient luminescence in c-Si.

Zero-dimensional lead telluride quantum dots optical modulator for red Pr:YLF ultrashort pulse laser

High-quality lead telluride quantum dots (PbTe QDs) are prepared by a top-down liquid phase exfoliation (LPE) method successfully and used as a novel saturable absorber (SA) to first realize a picosecond continuous-wave mode-locked (CWML) red laser with a Pr:YLF crystal. The nonlinear optical saturable characteristic of the PbTe QDs SA is measured by applying a double-channel synchronous detection technique. Further, a picosecond CWML Pr:YLF laser with a highest average output power of 115 mW is obtained, corresponding to a pulse energy of 1.5 nJ and a peak power of 24.2 W. These findings indicate that high-quality PbTe QDs SA is an effective optical modulator, demonstrating its application prospects in the field of visible ultrafast photonics.

Fabricating 3D Si nanostructure via a novel Ga+ implantation enabled maskless dry etching process

Three-dimensional (3D) nanostructure is the key to the miniaturization of nonlinear photonic and electronic devices. Because of the great demand on the ultra-small nanostructures, the novel nanofabrication technologies with flexible 3D silicon (Si) fabrication capability are of great importance. Herein, by combining Ga+ FIB implantation and ICP dry etching processes, we proposed a novel Ga+ FIB implantation assisted maskless dry etching technology for direct fabrication of 3D Si nanostructures. We found that the implanted Ga+ induced amorphization layer in Si substrate acts as the ‘quasi-mask’ during the ICP dry etching process. The increase of Ga+ concentration in amorphization layer of Si substrate improves the etching resistance of the area. Moreover, enabled by high resolution and flexibility of FIB, the proposed technology is capable of directly fabricating various 3D Si nanostructures in a simple way, such as 3D nanoscale artificial bowtie arrays with sub-10 nm gaps, multi-scale 3D Si nanostructures with arbitrary patterns. More importantly, the proposed technology is compatible to current semiconductor manufacturing process. Benefiting by the advantages of simplicity and high efficiency, the proposed maskless dry etching process promises great application potential in the fields of nonlinear photonics and micro-electronics.

Antithermal-Quenching All-Inorganic Perovskite Crystals with Green Ultralong Persistent Luminescence for Advanced Anticounterfeiting Applications.

Long persistent luminescence (PersL) materials have revolutionized many fields of optoelectronics and photonics due to their applications in anticounterfeiting, information encryption, and in vivo bioimaging. Here, we reported a novel PersL crystal prepared by the heterovalent doping of Sb3+ into perovskite tetragonal phase RbCdCl3, comparing with the pristine non-perovskite orthorhombic phase analogue without PersL property. Surprisingly, under the UV light irradiation, the title crystals concurrently exhibit green ultralong PersL (>2400 s), high photoluminescence quantum yield (49.1%), and antithermal quenching in the range from 148 to 328 K. It was revealed by experimental results and theoretical analyses that green ultralong PersL and antithermal quenching of perovskite-phase RbCdCl3/Sb3+ crystals originate from the electron transition between the 5s2 level of the dopant Sb3+ and the electronic defect-induced trap states. Enlightened by the excellent optical properties, the tetragonal perovskite-phase RbCdCl3/Sb3+ PersL materials show promising application prospects in anticounterfeiting and encryption of information.

Complex dark photon dark matter EFT

We construct an effective field theory for complex Stueckelberg dark photon dark matter. Such an effective construction can be realized by writing down a complete set of operators up to dimension six built with the complex dark photon and Standard Model fields. Classifying the effective operators, we find that in order to properly take into account the non-renormalizable nature of an interacting massive vector, the size of the Wilson coefficients should be naturally smaller than naively expected. This can be consistently taken into account by a proper power counting, that we suggest. First we apply this to collider bounds on light dark matter, then to direct detection searches by extending the list of non-relativistic operators to include the case of complex vectors. In the former we correctly find scaling limits for small masses, while in the latter we mostly focus on electric dipole interactions, that are the signatures of this type of dark matter. Simple UV completions that effectively realize the above scenarios are also outlined.

Customizable Generation of Arbitrary‐Order Polarization Vortices by Spin‐Decoupled Geometric Phases

AbstractDue to nontrivial field topologies, polarization vortices carrying polarization singularities have attracted increasing interest in the fields of optics and photonics. However, the conventional methods for generation of polarization vortcies still suffer from the complexity and the heavy bulk. In this work, taking advantage of spin‐decoupled geometric phase in metasurfaces, a novel method is proposed to generate polarization vortices with customizable topological charges. By tailoring spin‐decoupled geometric phases generated by the metasurface, distinct helical phase profiles can be imparted to left‐ and right‐handed circularly polarized components. Consequently, two scalar vortices with different topological charges can be simultaneously generated in the two orthogonal circular polarization components, leading to the generation of the polarization vortices with the needed topological charges and the diverse morphologies. Both simulation and experimental results well demonstrate the method. Owing to the nondispersive feature of geometric phases, the designed metasurface works well in a wide frequency band. The proposed method contributes a reliable and feasible solution for customizing the generation of polarization vortices, which can be further transposed to other frequencies and applied to information encoding and polarization detection etc.

Judd-Ofelt analysis and temperature sensing properties of polyethylmethacrylate (PEMA) networks doped with CdNb2O6: Er3+/Yb3+ phosphors

Research on the sensitivity of temperature measurements and optical thermometry involving rare earth ions has been an area of interest in the field of photonics and materials science. Introducing polymer networks as a new host material has an important role due to their properties including a versatile and stable environment for rare earth ions and rapid response in temperature detection. In this work, linear and crosslinked polyethylmethacrylate (PEMA) networks doped with Er3+/Yb3+ (1.5 mol % Er3+, 2 mol% Yb3+) synthesized by free-radical crosslinking polymerization with 0.1 EMA (weight %) at 60 °C were used to investigate direct and indirect optical bandgap energies and Urbach energy from UV–Visible spectra. The Judd-Ofelt (JO) approach was employed to analyze parameters Ωt (t = 2,4,6), spontaneous transition probabilities (Α), branching ratios (β) and radiative lifetimes (τ) as a function of linear and crosslinked PEMA doped nano-crystalline CdNb2O6: Er3+/Yb3+. The stimulated emission cross-sections of the transitions 2H11/2⟶4I15/2, 2S3/2⟶4I15/2 and 2F9/2⟶4I15/2 of Er3+/Yb3+ were calculated by two different methods; Fuchtbauer-Ladenburg formula and modified theory, respectively. The gain bandwidth cross-section product for the 2H11/2⟶4I15/2 was found to be 162.06. 10−28cm3, 260.94. 10−28cm3 and 461.20. 10−28cm3 of Er3+/Yb3+ embedded in linear, low and high crosslinked PEMA samples, respectively. JO parameters and stimulated emission cross-sections increased; therefore, radiative lifetimes decreased by increasing crosslinking content. In addition, the temperature dependence of upconversion (UC) luminescence was monitored under 975 nm excitation. The fluorescence intensity ratio (FIR) method examined the temperature sensing under two thermally coupled levels at 525 and 548 nm. The maximum sensitivities obtained from the FIR technique within the 300–650 K temperature range shifted to lower temperatures with increasing crosslinker content. Hence, linear and crosslinked polymer hosts doped rare-earth ions can be candidates for remote temperature sensors across various fields.

On the possibility of domain structure formation in lithium niobate by low energy (< 5 keV) electron beam

The authors' assumption about the possibility of nanodomain generation in the ferroelectric LiNbO3 by relatively low energy (< 5 keV) electron beams has been experimentally confirmed. The calculated electron-induced electric fields and changes in the polarization state of the near-surface layer in the -Z cut of LiNbO3 agree with the experimental results at the energies of the primary electrons Eb = 1 and 3 keV. In the proposed four-layer model of surface charging by low-energy electrons, electron-stimulated desorption of compensating atoms and molecules from the contaminated absorbing film into a vacuum plays an important role. The presented new results confirming the formation of domains in the near-surface layer at low electron beam energy can expand the possibilities of domain engineering using electron beam technologies, especially in the field of photonics.

Molecular design of −substituted boron difluoride curcuminoids: Tuning luminescence and nonlinear optical properties

Boron β-diketonates are prospective fluorescent dyes for functional organic materials to new technologies in the fields of chemistry, NLO-optics, photonics and bio-imaging. The novel NIR-to-NIR luminophors – curcuminoids of boron difluoride with different substituents at the central carbon atom (at the γ-position) of the chelate ring 1,7-bis(4′-N,N′-dimethylaminophenyl)-4-organyl-gept-1,6-dien-3,5-dionate of boron difluoride (1–5) were synthesized. Luminescence in solutions, crystals and polymer matrices, photobiological properties and NLO properties in polystyrene (PS) and polymethylmethacrylate (PMMA) were studied. The crystal structure has been determined for 1. For 1–5, in PS film, upon excitation by laser (365 nm), two luminescence bands are observed in the blue (430 nm) and red (650–700 nm) regions of the spectrum. For 1–5, two-photon luminescence is recorded in PS and PMMA films. PS 1 films demonstrate high photostability. The synthesized dyes turned out to be almost non-toxic for HCT116 tumor cells both in a long-term dark experiment (72 h) and after photoexcitation in accordance with absorption maxima in the submicromolar concentration range. The compounds were rapidly accumulated by cells within 3 h, demonstrating cytoplasmic distribution and the potential for use as cellular photoimaging agents. The accumulation of dyes with hydrocarbon γ-substitutes (methyl, iso-propyl, phenyl) after 3 and 24 h is more effective compared to dye 2 (commercial product Cranad-2).

Continuous harmonic mode-locked pulsed ultrafast fiber laser based on PtS2 saturable absorber

Saturable absorbers (SAs) play an important role in mode-locked fiber lasers. The search for SAs with excellent modulation properties has become a hot topic in the field of ultrafast photonics. PtS2 is a ideal material for SA due to its suitable band gap and Easily peelable layer structure. We prepared PtS2-SA by liquid-phase exfoliation (LPE) and tapered fiber. Subsequently, we measured the modulation depth of the prepared SA using the two-arm detection method as 6.4%, and the saturation intensity is 4.5 MW/cm2. By varying the input power in the annular cavity, a conventional solitons (CS) with a center wavelength is 1530.3 nm and a repetition frequency of 6.1 MHz was obtained. Continuing to increase the power, a stable second-fourth orders harmonic mode-locked (HML) was obtained. Our work shows that PtS2-SA has excellent modulation in mode-locked fiber lasers. It also proves that PtS2 has good saturable absorption properties and improves the knowledge of research workers about the performance of PtS2. There is hope in future research work to further exploit the output properties of PtS2.

Novel 3S-shaped biophotonic sensor utilizing MoS2–NSs/ZnO–NWs/AuCu–NCs for rapid detection of Shigella flexneri bacteria

This paper describes a unique, extremely sensitive biophotonic sensor with a three-tier S-tapered (3S) structure. It is designed for the real-time detection of Shigella flexneri (S. flexneri), a common foodborne pathogen that causes severe gastrointestinal diseases. The sensor development includes three distinct diameters of S-tapered structures. The performance of tapered sections was improved by using molybdenum disulfide nanosheets (MoS2-NSs), zinc oxide nanowires (ZnO-NWs), and photoluminescent bimetallic gold–copper nanoclusters (AuCu–NCs). These nanoparticles greatly improve the sensor’s performance. The sensor is further functionalized using anti-S. flexneri antibodies, allowing for the precise detection and capture of the target bacterium. The results show that the sensor can detect S. flexneri rapidly and accurately, with a linear detection range of 1–108 colony-forming units per milliliter (CFU/ml) and a low detection limit of 4.412 CFU/ml. In addition, the sensor’s ability to identify S. flexneri biofilms is demonstrated. Biofilm detection allows us to better understand and control biofilm concerns in the environment, equipment, and biomedical devices. Aptamer examines confirm the sensor’s ability to detect S. flexneri from the lateral direction. This study makes a significant contribution to the field of biosensing because no biophotonic sensor has previously been developed specifically for the detection of S. flexneri, fulfilling a critical gap in the arena of food safety and pathogen detection. The 3S sensor’s performance, robustness, and potential for practical applications make it an important addition to the field of photonics.

Dose conversion in retrospective dosimetry: Results and implications from an inter-laboratory comparison featuring a realistic exposure scenario

Dose conversion coefficients attempt to harmonize the material-, location-, and exposure-dependent results from retrospective dosemeters. The issues and uncertainties arising from dose conversion are explored within the framework of an interlaboratory comparison exercise in which mobile phones were positioned around anthropomorphic phantoms and exposed to non-uniform photon fields, with the glass and resistors they contain employed as fortuitous dosemeters. The difficulties of adopting pre-calculated tables of generic conversion coefficients are evaluated first, and then compared against those arising through the use of bespoke data derived by Monte Carlo modelling, and also against not converting the doses measured by the phones. It is seen that the different subjective choices that users might make when selecting ‘optimal’ generic data can lead to a significant source of uncertainty (up to around 70 %), though may be improved (to around 30 %) by appropriate quality controls. Use of generic coefficients typically led to over-estimates of the organ doses: an average discrepancy of ca. a factor of 2 was found, but this is still better than the factor of around 3 observed when no conversion coefficients were applied. Use of bespoke conversion factors led to the best estimates of organ doses, although they still over-estimated by approximately 1.5 on average, and an uncertainty of around 20 % was associated with generating their values. Overall, applying bespoke conversion data improves but does not guarantee correct dose categorization of individuals, with the inconsistences in the measured results found generally to be the limiting factor in obtaining accurate dose assessments.

Low-Symmetry Van der Waals Dielectric GaInS3 Triggered 2D MoS2 Giant Anisotropy via Symmetry Engineering.

Low-symmetry structures in van der Waals materials have facilitated the advancement of anisotropic electronic and optoelectronic devices. However, the intrinsic low symmetry structure exhibits a small adjustable anisotropy ratio (1-10), which hinders its further assembly and processing into high-performance devices. Here, a novel 2D anisotropic dielectric, GaInS3 (GIS), which induces isotropic MoS2 to exhibit significant anisotropic optical and electrical responses is demonstrated. With the excellent gate modulation ability of 2D GIS (dielectric constant k ∼12), MoS2 field effect transistor (FET) shows an adjustable conductance ratio from isotropic to anisotropic under dual-gate modulation, up to 106. Theoretical calculations indicate that anisotropy originates from lattice mismatch-induced charge density deformation at the interface. Moreover, the MoS2/GIS photodetector demonstrates high responsivity (≈4750 A W-1) and a large dichroic ratio (≈167). The anisotropic van der Waals dielectric GIS paves the way for the development of 2D transition metal dichalcogenides (TMDCs) in the fields of anisotropic photonics, electronics, and optoelectronics.

Minimal-gain-printed silicon nanolaser.

While there have been notable advancements in Si-based optical integration, achieving compact and efficient continuous-wave (CW) III-V semiconductor nanolasers on Si at room temperature remains a substantial challenge. This study presents an innovative approach: the on-demand minimal-gain-printed Si nanolaser. By using a carefully designed minimal III-V optical gain structure and a precise on-demand gain-printing technique, we achieve lasing operation with superior spectral stability under pulsed conditions and observe a strong signature of CW operation at room temperature. These achievements are attributed to addressing both fundamental and technological issues, including carrier diffusion, absorption loss, and inefficient thermal dissipation, through minimal-gain printing in the nanolaser. Moreover, our demonstration of the laser-on-waveguide structure emphasizes the integration benefits of this on-demand gain-printed Si nanolaser, highlighting its potential significance in the fields of Si photonics and photonic integrated circuits.