Short Light Research Articles

Dynamic Description of soliton solutions of nonlinear Schrödinger equation with higher order dispersion and nonlinear terms

Abstract The article presents an analytical solution for the higher-order nonlinear Schrödinger equation (NLSE), which describes the propagation of short light pulses in monomode optical fibers. Various traveling wave solutions are obtained using the generalized exponential rational function method, a technique with substantial applications in physics and mathematics. Additionally, the parameters leading to the occurrence of optical bright and multipeak solitons in this medium are provided along with their formation conditions. The derived solutions are graphically displayed to enhance the understanding of the model’s physical phenomena. This approach is credible, potent, and successful in solving a wide variety of different models of this kind that arise in the applied sciences. Its robustness, strength, and efficiency make it suitable for addressing various higher-order nonlinear problems in current research fields, extending beyond the models encountered in the applied sciences.

High performance Au/mix-phase MgZnO/Ga-doped ZnO/In heterojunction solar-blind UV detector with small work voltage

High performance UVC (220 nm–280 nm) detectors with low work voltage is key problem in wide application of UVC optoelectronic device. Here, Au/MgZnO/Ga-doped ZnO/In heterojunction detector is made with both high UVC sensitivity mix-phase MgZnO and high carrier density Ga-doped ZnO conductive layers. The heterostructure detector possess relative high response(0.36A/W)at 254 nm deep UV light without bias voltage. The avalanche breakdown phenomenon within the heterojunction detector, introduced high deep UV response (1390.3 A/W at 3.3 μW/cm2 230 nm) of the Au/MgZnO/Ga-doped ZnO/In heterojunction detector under 5 V bias voltage. The high response of Au/MgZnO/Ga-doped ZnO/In heterojunction detector under low work voltage, is not only much higher than MSM structure MgZnO detector under bias voltage over 25 V, but also higher than reported deep UV detector under small bias voltage. In addition, because of different internal breakdown mechanism, the peak response position of the Au/MgZnO/Ga-doped ZnO/In heterojunction detector is located at shorter wavelength position compared with MSM structure MgZnO detector. Therefore, Au/MgZnO/Ga-doped ZnO/In heterojunction detector is an ideal device structure in low voltage driven detector with relative high response at short wavelength UV light.

Freestanding Germanium Photonic Crystal Waveguide for a Highly Sensitive and Compact Mid-Infrared On-Chip Gas Sensor.

The performance of mid-infrared (MIR) on-chip gas sensors, operating via laser absorption spectroscopy, hinges critically on light-matter interaction dynamics, significantly influenced by external confinement and the effective light path length. Conventional on-chip sensors, however, face challenges in achieving the required limit of detection for highly sensitive applications, primarily due to their intrinsically short effective light path. Furthermore, these sensors are limited in their spectral range coverage within the MIR spectrum by the constraints of standard silicon-based platforms. To overcome these limitations, our research presents a novel approach to fabricate a freestanding germanium (Ge) photonic crystal waveguide (PCW) on a germanium-on-insulator (Ge-OI) platform, utilizing yttrium oxide (Y2O3) as the buried oxide layer. This device leverages the broad transparent windows of Ge and Y2O3, broadening the spectral coverage across the MIR range. The introduction of the PCW and its slow light effect significantly elevate external confinement and light-matter interactions, enabling a notable reduction in waveguide length, which traditionally limits on-chip configurations. The freestanding structure not only expands the sensing region and enhances external confinement but also prevents the emergence of leaky modes within the PCW. As a result, our compact sensor achieves an exceptionally low LoD of 7.56 ppm for carbon dioxide (CO2) sensing at the operational wavelength of 4.23 μm, with a compact waveguide length of only 800 μm.

High precision DSRC and LiDAR data integration positioning method for autonomous vehicles based on CNN

In order to improve the safe driving and automatic positioning capability of autonomous vehicles, a high-precision DSRC and LiDAR data integration positioning technology for autonomous vehicles based on CNN is proposed. Import the data of Dedicated Short Range Communications and Light Detection and Ranging for automatic driving vehicle positioning, carry out kinematic analysis of autonomous driving vehicles under multi-sensor fusion, and transform the data of DSRC and LiDAR sensors into tightly coupled coordinate systems; The CNN depth learning method is used to compensate the position and attitude tracking estimation error under the overall time stamp synchronization of the sensor through adaptive information tracking; The first and second order feedforward compensation is made for the positioning parameters of the autonomous driving vehicle using the PID model, and the point cloud feature matching model is fused to complete the estimation of the positioning attitude parameters of the autonomous driving vehicle. In order to eliminate the noise interference under the DSRC communication mechanism, the Kalman filter function is used to automatically optimize the constraint parameters in the point cloud feature detection model, and the positioning error parameters are dynamically filtered and adjusted; Kinematics analysis is carried out for the driving state of the vehicle, and the positioning error in the vehicle movement is controlled through the difference technology to achieve high-precision DSRC and LiDAR data integration positioning. The simulation results show that this method can integrate and locate the high-precision DSRC and LiDAR data of the autonomous vehicle, and the attitude estimation and positioning accuracy of the vehicle is good, while the error of the attitude parameter estimation of the autonomous vehicle is low.

Effects of dim-evening lighting optimised for geographical orientation versus standard lighting on mental health: protocol paper for a quasiexperimental study in a psychiatric hospital

IntroductionResearch has provided novel insights into how light stimulates circadian rhythms through specialised retinal ganglion cells to the suprachiasmatic nucleus. In addition, there has been a revolution in light-emitting diode...

The Power of Literary Discourse in Creating Ecological Awareness: First Light by Robert Russell Sassor

While the need to move studies on climate change beyond scientific research and to raise awareness about the issue in society is increasing, there is a need for mechanisms that bring discourses about climate change to the public’s knowledge. In recent days, when nature is gradually disappearing into the hands of man, it has become necessary to develop a new way of communicating with nature and natural resources. As Sassor expressed, art is more than a one-way communication tool and it is one of the most effective ways for people to shape their environmental awareness. Getting people to experience this through short stories is possible. Since short stories are literary discourses that can be read in one sitting, they are a more suitable genre for people in the hustle and bustle of the postmodern world. In this study, Robert Russel Sassor’s short story First Light has been analyzed through a discourse-centered approach. Based on the collocated words around the motifs of ‘death/suicide, regret, longing for the past, nature, sexual identity distortion, and loneliness’ it is observed that Sassor’s concerns about the deterioration of the ecological balance as well as the distortion of sexual identity in the individual come to the fore.

Polarization measurement of vacuum ultraviolet light using visible fluorescence from neon atoms

The polarization state of the vacuum ultraviolet light has been studied with a fluorescence polarimeter based on the conversion of short wavelength light into visible fluorescence via atomic resonance. In addition to the previously established method using helium atoms, the results show that polarization state of vacuum ultraviolet light can be evaluated by observing the visible fluorescence emitted from neon atoms. This study demonstrates that a fluorescence polarimeter can be used in conjunction with a variety of atoms and molecules and thus extends the range of wavelengths to which this method can be applied.

Long wavelength near-infrared and red light-driven consecutive photo-induced electron transfer for highly effective photoredox catalysis

Consecutive photoinduced electron transfer (conPET) processes accumulate the energies of two photons to overcome the thermodynamic limit of traditional photoredox catalysis. However, the excitation wavelength of conPET systems mainly focused on short wavelength visible light, leading to photodamage and incompatibility with large-scale reactions. Herein, we report on conPET systems triggered by near-infrared (NIR) and red light. Specifically, a blue-absorbing conPET photocatalyst, perylene diimide (PDI) is sensitized by a palladium-based photosensitizer to triplet excited state (3PDI*), which generates PDI radical anion (PDI•–) over 100-fold faster than that in the conventional conPET. Accordingly, photoreduction with superior reaction rate and penetration depth, as well as reduced photodamage is detected. More importantly, our work offers comprehensive design rules for the triplet-mediated conPET strategy, whose versatility is confirmed by metal-free dye pairs and NIR-active PtTNP/PDI. Notably, our work achieves NIR-driven atom transfer radical polymerization using an inert aromatic halide as the initiator.

Exploration of different multi-peak solitons and vibrant breather type waves’ solutions of nonlinear Schrödinger equations with advanced dispersion and cubic–quintic nonlinearity, unveiling their applications

Abstract The nonlinear Schrödinger equations (NLSEs) of higher order illustrate the transmission of extremely short light pulses in fiber optics. In this manuscript, we employ the two-variable (1/G, G′/G)-expansion technique to construct bright and multi-peak solitons, periodic multi-solitons, breather type solitary waves, periodic peakon solitons, and other wave solutions of higher-order NLSE in mono-mode optical fiber and generalized NLSE with cubic–quintic nonlinearity. The two-variable (1/G, G′/G)-expansion method is a generalization of the (G′/G)-expansion method, offering a more robust mathematical tool for solving various nonlinear partial differential equations (PDEs) in mathematical physics. We also analyze the characteristics of waves conducive to the formation of bright–dark and other soliton forms within this medium. Additionally, we provide graphical representations of the obtained results to visually depict the dynamical models under consideration. Our findings highlight the potency, reliability, and versatility of the proposed technique, which holds promise for solving a wide array of similar models encountered in applied sciences and engineering.

Generation of Chicken Antibody Libraries and Selection of Antigen Binders.

Chicken antibodies have been widely used for research and diagnostic purposes. Chicken antibodies are often cross-reactive to epitopes shared by humans, nonhuman primates, and other mammals, and can be tested in many mouse disease models, which provides an advantage for their preclinical study and evaluation. In addition, the variable region of chicken antibodies has unique structural characteristics, including noncanonical cysteine residues in the heavy chain complementarity-determining region (CDR)3 and a long heavy chain CDR3, which together with a short light chain CDR enable the formation of unconventional antibody paratopes. As chickens have single functional copies of the V H and J H genes, and the somatic gene conversion process usually involves D H genes, all functional VDJ gene fragments can be obtained from the B-cell repertoire using a single PCR primer set, without any primer bias. As for the light chain, chickens only have a V λ light chain, composed of a single V λ and J λ gene pair. Therefore, the chicken light chain repertoire can also be accurately amplified using a single primer set. This unbiased reconstitution of the chicken B-cell repertoire provides a great advantage not only in the construction of phage display libraries but also for the in silico selection of antigen binders from a virtual B-cell receptor repertoire. Here, we introduce the use of chicken antibodies in research, diagnostic, and therapeutic fields. In addition, the chromosomal organization of chicken immunoglobulin genes and its diversification mechanisms for shaping the antibody repertoire are also discussed.

A sandwich−type photoelectrochemical sensor constructed with a signal amplification strategy based on the upconversion luminescence characteristics of Ag@N−CQDs for sensitive detection of neuron specific enolase

In this paper, Bi2S3/AgBiS2 composite nanomaterials and PDA@Ag@N−CQDs were synthesized, and used as substrates and second antibody label respectively to construct a sandwich photoelectrochemical (PEC) sensor. The upconversion luminescence effect of N−CQDs can convert long wavelength light into short wavelength light that can be utilized by the substrate material, which can provide additional excitation light energy for the substrate material and further enhance the photoelectric response. Besides, Ag has SPR effect and can also promote electron transfer. The proposed sandwich immunosensor achieves detection of NSE in the concentration range of 0.001 ng mL−1 to 100 ng mL−1, with a detection limit of 0.28 pg mL−1 (S/N = 3). What's more, the proposed sensor also exhibits good stability, selectivity, as well as reproducibility, indicating its promising application prospects.

Self-Powered FTO/CdSe/Bi2Se3 Photodetector with Bipolar Photoresponse Characteristics.

Self-powered photodetectors with bipolar photoresponse characteristics are expected to play a critical role in the field of secure optical communication, artificial neuromorphic systems, and intelligent color sensors. In this work, asymmetric heterojunction devices exhibiting wavelength-dependent bipolar photoresponse with a structure of Glass/FTO/CdSe/Bi2Se3/Au were fabricated. Under a short wavelength light irradiation, the top CdSe absorber generates a high carrier concentration; the excited carriers are quickly separated by the built-in electric field induced by the FTO/CdSe diode, resulting in a negative photocurrent. For light with wavelengths beyond the CdSe absorption edge, it is absorbed by the bottom Bi2Se3 absorber, and a positive photocurrent can be observed. Therefore, based on the bandgap difference between the top CdSe absorber and the bottom Bi2Se3 absorber, combined with the photogenerated carriers separated by asymmetric back-to-back diode, a wavelength-dependent bipolar response is realized. In this work, by employing this structure, the responsivities of -33.3 and 0.3 mA/W were achieved under the illumination of 405 and 830 nm, respectively. This work provides important indications in the preparation and performance optimization for wavelength-dependent bipolar photodetectors.

Laser-induced ultrasound in multiple thin layers-An analytical solution.

Laser-induced ultrasound is based on the thermo-elastic conversion of absorbed short light pulses to pressure pulses. In the work presented here, laser-induced ultrasound in a planar structure of interconnected layers with variations in optical, thermal, and mechanical properties is studied. Layered structures can be used for generating wideband ultrasonic pulses specific to a chosen application. An analytical time-domain solution is derived for the resulting pressure transmitted from the layered structure. The solution is derived for an arbitrary number of layers with an arbitrary optical absorption profile. Free space Green's functions with image sources are used to derive the solution. A solution employing the Beer-Lambert law is also proposed. The simplification with reflections only at the boundaries is in agreement with previous published results. The spectral properties of the generated pulse are derived, where the effects of optical absorption coefficients and layer thicknesses are shown. The analytical solution is compared to one-dimensional (1D) simulations and a three-dimensional (3D) simulation, realised as a two-dimensional (2D) axially symmetric case, using the matlab toolbox k-Wave. The 3D simulation on-axis pressure agrees well with the 1D analytical solution when the diameter of the laser beam is larger by approximately 1 order of magnitude than the thickness of the planar layered structure.

Analytical and numerical study of light-induced optical microcavity generation by half-cycle light pulses in the resonant medium

An optical Bragg-like microcavity can be formed when extremely short light pulses interacting coherently with the medium collide in the resonant medium. Here we present an analytical approach, based on the approximate solution of the time-dependent Schrödinger equation, that reveals both the cavity formation and its control by the half-cycle pulses colliding in the medium. This approach allows the calculation of cavity properties in the weak-field regime without the need for complex numerical simulations. Beyond the approximate analytical solutions, our analytical results are confirmed by numerical simulations of the Maxwell-Bloch equations. Grating formation is also studied in the strong-field regime, where collisions of self-induced transparency half-cycle pulses occur. The results presented here reveal, to our knowledge, a new type of spatio-temporal photonic crystal in the form of micro-cavities in a simple atomic medium. The results obtained demonstrate the feasibility of attosecond optical switching in a simple atomic medium with half-cycle pulses.

Shallower radius valley around low-mass hosts: evidence for icy planets, collisions, or high-energy radiation scatter

ABSTRACT The radius valley, i.e. a dearth of planets with radii between 1.5 and 2 Earth radii, provides insights into planetary formation and evolution. Using homogenously revised planetary parameters from Kepler 1-min short cadence light curves, we remodel transits of 72 small planets mostly orbiting low-mass stars, improving the precision and accuracy of planet parameters. By combining this sample with a similar sample of planets around higher mass stars, we determine the depth of the radius valley as a function of stellar mass. We find that the radius valley is shallower for low-mass stars compared to their higher mass counterparts. Upon comparison, we find that theoretical models of photoevaporation underpredict the number of planets observed inside the radius valley for low-mass stars: with decreasing stellar mass, the predicted fraction of planets inside the valley remains approximately constant whereas the observed fraction increases. We argue that this provides evidence for the presence of icy planets around low-mass stars. Alternatively, planets orbiting low-mass stars undergo more frequent collisions and scatter in the stars’ high-energy output may also cause planets to fill the valley. We predict that more precise mass measurements for planets orbiting low-mass stars would be able to distinguish between these scenarios.

From the Pineal Gland to the Central Clock in the Brain: Beginning of Studies of the Mammalian Biological Rhythms in the Institute of Physiology of the Czech Academy of Sciences.

The Institute of Physiology of the Czech Academy of Sciences (CAS) has been involved in the field of chronobiology, i.e., in research on temporal regulation of physiological processes, since 1970. The review describes the first 35 years of the research mostly on the effect of light and daylength, i.e., photoperiod, on entrainment or resetting of the pineal rhythm in melatonin production and of intrinsic rhythms in the central biological clock. This clock controls pineal and other circadian rhythms and is located in the suprachiasmatic nuclei (SCN) of the hypothalamus. During the early chronobiological research, many original findings have been reported, e.g. on mechanisms of resetting of the pineal rhythm in melatonin production by short light pulses or by long exposures of animals to light at night, on modulation of the nocturnal melatonin production by the photoperiod or on the presence of high affinity melatonin binding sites in the SCN. The first evidence was given that the photoperiod modulates functional properties of the SCN and hence the SCN not only controls the daily programme of the organism but it may serve also as a calendar measuring the time of a year. During all the years, the chronobiological community has started to talk about "the Czech school of chronobiology". At present, the today´s Laboratory of Biological Rhythms of the Institute of Physiology CAS continues in the chronobiological research and the studies have been extended to the entire circadian timekeeping system in mammals with focus on its ontogenesis, entrainment mechanisms and circadian regulation of physiological functions. Key words: Pineal, Melatonin, AA-NAT rhythm, Light entrainment, Photoperiod, SCN clock.

Nano PDA@Tur-Modified Piezoelectric Sensors for Enhanced Sensitivity and Energy Harvesting.

Tourmaline is known for its natural negative ion effect and far-infrared radiation function, which promote human blood circulation, relieve pain, regulate the endocrine system, and enhance immunity and other functions. These functions motivate the use of this material for enhanced sensitivity of wearable sensors. In this work, taking advantage of the unique multifunctions of tourmaline nanoparticles (Tur), highly boosted piezoelectricity was achieved by incorporating polydopamine (PDA)-modified Tur in PVDF. The PDA@Tur nanofillers not only effectively increased the β-phase content of PVDF but also played a major role in significantly enhancing piezoelectricity, wettability, elasticity, air permeability, and stability of the piezoelectric sensors. Especially, the maximum output voltage of the fiber membrane with 0.5 wt % PDA@Tur reached 31.0 V, being 4 times that of the output voltage of the pure PVDF fiber membrane. Meanwhile, the sensitivity reached 0.7011 V/kPa at 1-10 N, which was 3.6 times that of pure PVDF film (0.196 V/kPa). The power intensity reached 8 μW/cm2, being 5.55 times that of the pristine PVDF PENG (1.44 μW/cm2), and the piezoelectric coefficient from d33 m/PFM is 5.5 pC/N, higher than that of pristine PVDF PENG (3.1 pC/N). Output signal graphs corresponding to flapping, finger, knee, and elbow movements were detected. The response/recovery time of the sensor device was 24/19 ms. The piezoelectric nanogenerator (PENG) was capable of charging multiple capacitors to 2 V within a short time and lighting up 15 light-emitting diodes bulbs (LEDs) simultaneously with a single beat. In addition, a 4 × 4 row-column multiplexed sensor array was made of PENGs, which showed distinct responses to different stress areas in different sensor modules. This study demonstrated high-performance PDA@Tur PVDF-based PENG being capable of energy harvesting and sensing, providing a guideline for the design and buildup of wearable self-powered devices in healthcare and human-computer interaction.

Optical fractional solitonic structures to decoupled nonlinear Schrödinger equation arising in dual-core optical fibers

This paper explores a specific class of equations that model the propagation of optical pulses in dual-core optical fibers. The decoupled nonlinear Schrödinger equation with properties of M fractional derivatives is considered as the governing equation. The proposed model consists of group-velocity mismatch and dispersion, nonlinear refractive index and linear coupling coefficient. Different types of solutions, including mixed, dark, singular, bright-dark, bright, complex and combined solitons are extracted by using the integration methods known as fractional modified Sardar subequation method and modified F-expansion method. Optical soliton propagation in optical fibers is currently a subject of great interest due to the multiple prospects for ultrafast signal routing systems and short light pulses in communications. In nonlinear dispersive media, optical solitons are stretched electromagnetic waves that maintain their intensity due to a balance between the effects of dispersion and nonlinearity. Furthermore, hyperbolic, periodic and exponential solutions are generated. A fractional complex transformation is applied to reduce the governing model into the ordinary differential equation and then by the assistance of balance principle the methods are used, depending upon the balance number. Also, we plot the different graphs with the associated parameter values to visualize the solutions behaviours with different parameter values. The findings of this work will help to identify and clarify some novel soliton solutions and it is expected that the solutions obtained will play a vital role in the fields of physics and engineering.

Optical microcavity formation and ultrafast control using half-cycle attosecond pulses in two- and three-level media

Light induced population difference gratings have numerous applications in modern optics. The conventional approach of creating them by using monochromatic laser radiation makes it virtually impossible to rapidly control their properties. In recent years, there has been active discussion about using ultra-short light pulses to control such gratings. We show the possibility of ultrafast control of population difference structures, such as dynamic microresonators and Bragg-like grating formations, by the collision of extremely short light pulses in a resonant medium. This work focuses on changes in microcavity properties based on the different parameters, such as the atomic density of the medium, the form of the pulses, and whether the medium is two- or three-level.

Bragg-like microcavity formed by collision of single-cycle self-induced transparency light pulses in a resonant medium.

The coherent interaction of extremely short light pulses with a resonant medium can result in the formation of population difference gratings. Such gratings have been created by pulses that are π/2 or smaller. This paper demonstrates that a microcavity with Bragg-like mirrors can be formed by colliding two single-cycle attosecond self-induced transparency pulses in the center of a two-level medium. The parameters of this structure can be quickly adjusted by increasing the number of collisions, which showcases the ability to control the dynamic properties of the medium on a sub-cycle time scale by using attosecond pulses.