Probe Light Research Articles

Optical Nonreciprocity in Rotating Diamond with Nitrogen‐Vacancy Color Centers

AbstractA method to realize optical nonreciprocity in rotating nano‐diamond with nitrogen‐vacancy (NV) centers is theoretically proposed here. Because of the relative motion of the NV center with respect to the propagating fields, the frequencies of the fields are shifted due to the Doppler effect. When the control and probe fields are incident to the NV center from the same direction, the two‐photon resonance still holds as the Doppler shifts of the two fields are the same. Thus, due to the electromagnetically‐induced transparency, the probe light can pass through the NV center nearly without absorption. However, when the two fields propagate in opposite directions, the probe light cannot effectively pass through the NV center as a result of the breakdown of two‐photon resonance.

Three-dimensionally printed spot polymerization light-guide tip attachment

Stabilizing a veneer in its seated position by selective spot photopolymerization of the adhesive resin cement at the center of the veneer has been advocated.1 This procedure facilitates the removal of excess unpolymerized or partially polymerized resin cement at the margin and interproximal region without risk of unseating the veneer.2 Some manufacturers provide small-diameter glass-fibered light guides (Light Probe Pin-Point 6 > 2mm; Ivoclar AG) or attachments (PointCure lens; Ultradent Products, Inc) for this purpose; however, they are not available or compatible with all light-polymerization units.

Imaging ultrafast evolution of subwavelength-sized topography using single-probe structured light microscopy

Imaging ultrafast processes in femtosecond (fs) laser–material interactions such as fs laser ablation is very important to understand the physical mechanisms involved. To achieve this goal with high resolutions in both spatial and temporal domains, a combination of optical pump–probe microscopy and structured illumination microscopy can be a promising approach, but suffers from the multiple-frame method with a phase shift that is inapplicable to irreversible ultrafast processes such as ablation. Here, we propose and build a wide-field single-probe structured light microscopy (SPSLM) to image the ultrafast three-dimensional topography evolution induced by fs lasers, where only a single imaging frame with a single structured probe pulse is required for topography reconstruction, benefiting from Fourier transform profilometry. The second harmonic of the fs laser is used as the structured probe light to improve spatial lateral resolution into the subwavelength region of ∼ 478 nm , and the spatial axial and temporal resolutions are estimated to be ∼ 22 nm and ∼ 256 fs , respectively. With SPSLM, we successfully image the ultrafast topography evolution of a silicon wafer surface impacted by single and multiple fs pulses. The variable formation and evolution of the laser induced periodic surface structures during an ultrashort time are visualized and analyzed. We believe that SPSLM will be a significant approach for revealing and understanding various ultrafast dynamics, especially in fs laser ablation and material science.

Detection of a Spinning Object at Different Beam Sizes Based on the Optical Rotational Doppler Effect

The rotational Doppler effect (RDE), as a counterpart of the conventional well-known linear Doppler effect in the rotating frame, has attracted increasing attention in recent years for rotating object detection. However, the effect of the beam size on the RDE is still an open question. In this article, we investigated the influence of the size of the probe light; i.e., the size of the ring-shaped orbital angular momentum (OAM)-carrying optical vortex (OV), on the RDE. Both the light coaxial and noncoaxial incident conditions were considered in our work. We analyzed the mechanism of the influence on the RDE under the light coaxial, lateral misalignment, and oblique incidence conditions based on the small-scatterer model. A proof-of-concept experiment was performed to verify the theoretical predictions. It was shown that both the signal-to-noise ratio and the frequency spectrum width were related to the OV size. The larger the beam size, the stronger the RDE signal observed in the practical detection. Especially in the lateral misalignment condition, the large OV size effectively reduced the signal spreading and enhanced the signal strength. These findings may be useful for practical application of the optical RDE in remote sensing and metrology.

A proposal for optomechanical bichromatic wavelength switching for two-color up-conversion application

This study focuses on the Optomechanical bichromatic wavelength switching system as an indirect two-color up-conversion process that relies on optical force and nanorod scattering effects. This system is used to control light coupling between four parallel optical waveguides made of silicon nitride (Si3N4) which form two identical parts. The parallel waveguides with 0.5 µm × 0.5 µm cross-section and 220 µm lengths are suspended on a silica (SiO2) substrate embedded with the array of square silicon (Si) nanorods. By mid-IR plane wave illumination, as control light, with different intensities and different wavelengths on nanorods, scattering would increase and result in an improvement in attractive gradient optical force exerted on waveguides. Via bending waveguides toward each other, caused by optical gradient force, two different visible lights, as probe signals, propagating in the first waveguide of each section would couple to the adjacent waveguide. Simulation results reveal that when the distance between the parallel waveguides in the equilibrium position is 100 nm and the intensity of mid-IR light is 1.28 mW/µm2 total coupling would occur in two situations: 1- when the control light is 4.5 µm, the probe light with 713 nm wavelength is transmitted to the output, 2- when the control light is 3 µm, the probe light with 609 nm wavelength is transmitted to the output. In the first case 1.92 pN/µm optical force is needed to bend each waveguide by 9 nm and in the second one, 1.28 pN/µm optical force is needed to bend each waveguide by 6 nm for total coupling. The efficiency of the coupled waveguides system is %88.6 for 609 nm probe light injection and %96.5 for 713 nm probe light injection.

Sublingual microcirculation: comparison between the 415nm blue light and 520nm green light of sidestream dark field videomicroscopes.

Green light with a wavelength of 520nm is commonly used in sidestream dark field (SDF) video microscopes for sublingual microcirculation assessment in clinical practice. However, blue light could obtain a clearer microcirculatory image due to a higher light absorption coefficient of hemoglobin. The aim of this study was to compare the sublingual microcirculatory image quality acquisition and related microcirculatory parameters between 520nm green light and 415nm blue light probes in the SDF device named MicroSee V100. Sublingual microcirculation films from twenty-one healthy volunteers were prospectively collected by blue light and green light probes, and only one video of each wavelength was recorded and analyzed in each volunteer. Moreover, 200 sublingual microcirculation films (100 by blue light probe and 100 by green light probe) of ICU patients were retrospectively scored for microcirculation image quality. Compared to green light, an increase in the perfused vessel density (paired t test, increased by 4.6 ± 4.7mm/mm2, P < 0.0001) and total vessel density (paired t test, increased by 5.1 ± 4.6mm/mm2, P < 0.0001) was observed by blue light in the healthy volunteers. The blue light probe had a significantly lower rate of unacceptable films than the green light probe in the 200 films of ICU patients (10/100 vs. 39/100, P < 0.0001). Blue light provides a higher microcirculatory vessel density and image quality than the existing SDF probe using green light.

Integrated Polarization-Splitting Grating Coupler for Chip-Scale Atomic Magnetometer.

Atomic magnetometers (AMs) are widely acknowledged as one of the most sensitive kind of instruments for bio-magnetic field measurement. Recently, there has been growing interest in developing chip-scale AMs through nanophotonics and current CMOS-compatible nanofabrication technology, in pursuit of substantial reduction in volume and cost. In this study, an integrated polarization-splitting grating coupler is demonstrated to achieve both efficient coupling and polarization splitting at the D1 transition wavelength of rubidium (795 nm). With this device, linearly polarized probe light that experienced optical rotation due to magnetically induced circular birefringence (of alkali medium) can be coupled and split into individual output ports. This is especially advantageous for emerging chip-scale AMs in that differential detection of ultra-weak magnetic field can be achieved through compact planar optical components. In addition, the device is designed with silicon nitride material on silicon dioxide that is deposited on a silicon substrate, being compatible with the current CMOS nanofabrication industry. Our study paves the way for the development of on-chip AMs that are the foundation for future multi-channel high-spatial resolution bio-magnetic imaging instruments.

High-precision Microwave Frequency Measurement Based on Stimulated Brillouin Scattering With Simple Configuration

We propose and implement a microwave frequency measurement (MFM) scheme based on stimulated Brillouin scattering (SBS) and an apodized fiber Bragg grating (AFBG), achieving high accuracy in a wide range of measurement with a highly simplified configuration. By sweeping a reference frequency during SBS process, a frequency-to-power mapping between the reference frequency and the monitored output optical power of the MFM system is established. Unknown frequencies can be identified through a specific numerical relationship among the unknown frequency, reference frequency, and Brillouin frequency shift (BFS). The transmission and reflection properties of the AFBG are exploited to offer pump light and probe light simultaneously for SBS process, thereby reducing complexity of the MFM system. It can be derived theoretically that all frequencies larger than one BFS can be measured except for 3/2 BFS. This measurement blind spot can be eliminated by utilizing two segments of single-mode fibers with different BFSs. A measurement error of less than ±1 MHz within 10.68 GHz to 20 GHz is achieved in a proof-of-concept experiment of the proposed MFM approach. This method has also been proved to be applied to dual microwave frequency measurements.

Surface Morphology of Textured Transparent Conductive Oxide Thin Film Seen by Various Probes: Visible Light, X-rays, Electron Scattering and Contact Probe.

Fluorine-doped tin oxide thin films (SnO2:F) are widely used as transparent conductive oxide electrodes in thin-film solar cells because of their appropriate electrical and optical properties. The surface morphology of these films influences their optical properties and therefore plays an important role in the overall efficiencies of the solar cells in which they are implemented. At rough surfaces light is diffusely scattered, extending the optical path of light inside the active layer of the solar cell, which in term improves light absorption and solar cell conversion efficiency. In this work, we investigated the surface morphology of undoped and doped SnO2 thin films and their influence on the optical properties of the films. We have compared and analysed the results obtained by several complementary methods for thin-film surface morphology investigation: atomic force microscopy (AFM), transmission electron microscopy (TEM), and grazing-incidence small-angle X-ray scattering (GISAXS). Based on the AFM and TEM results we propose a theoretical model that reproduces well the GISAXS scattering patterns.

Enhancement of vacuum diffraction by interference of signals produced by a probe x-ray free-electron laser with multiple transverse modes

In this paper, we investigate photon-photon scattering in vacuum in the head-on collision of an optical laser and an x-ray free-electron laser (XFEL) of multiple modes. For the XFEL as probe light with focus waist larger than the optical laser, the scattering photons with the same energy of the initial probe XFEL can be separated from the XFEL background due to the different scattering angle at far field. Here, we study the effect of XFEL's transverse profile, due to superposition of modes, in this vacuum diffraction process. Based on the parameters of upcoming facilities with 100-PW optical lasers and intense XFEL, we show that for a given photon number of the probe XFEL, the separable scattering photon number can be greatly enhanced when the XFEL is composed of different Laguerre-Gaussian modes. As an example, with SHINE's setup there will be 185 photons separable from the XFEL background for each shot, which is 2.5 times that of the case with the usual Gaussian profile.

Probing ultrafast dynamics of soot in situ in a laminar diffusion flame using a femtosecond near-infrared laser pump and multi-color Rayleigh scattering probe spectroscopy.

Soot nanoparticles result from incomplete combustion of fossil fuels, and have been exhibited, when released into the atmosphere, to be detrimental to air quality and human health. However, because of the inert and non-luminescent properties, probing the dynamics of soot in situ is still a challenge. Here we report a strong near-infrared laser pump and multi-color Rayleigh scattering probe approach to reveal soot dynamics in situ in a n-pentanol/air laminar diffusion flame at femtosecond time resolution. A size-dependent dynamical process of the pump-laser-induced soot swelling at femtosecond time scale and subsequent shrinking back to its original size at picosecond time scale is observed, in which both the swelling rise time and the shrinking decay time increase monotonically as the initial sizes of soot nanoparticles become larger. By characterizing the evolution time and intensity of the multi-color scattered probe light, the spatial distributions of different sizes of soot particles from the inception to the burnout regions of the flame are mapped, which provide useful information on exploring the formation and growth mechanisms of soot particles in flames.

Temperature and polarization dependence of radiation-induced attenuation in pure-silica-core PANDA optical fiber

Radiation-induced attenuation (RIA) spectra (700–1700 nm) in a pure-silica-core PANDA fiber were measured during and after γ-irradiation at room temperature (RT), −60 °C, and liquid nitrogen temperature (LNT) with the probe light polarization directed along each principal axis. The RIA difference between the polarizations was found to be largest at −60 °C, smaller at LNT and smallest at RT. At −60 °C, RIA for light codirected with the slow axis (RIAslow) proved to be greater than RIAfast throughout the spectrum, the RIA difference at λ = 1550 nm being 15% at the end of irradiation at a dose of 1 kGy (0.80 Gy/s) and increasing to 51% already in 10 min of post-irradiation recovery. RIAslow and RIAfast spectra measured at −60 °C were decomposed into RIA bands due to different types and classes of self-trapped holes (STHs) in the silica network. The origin of the RIA difference at λ = 1550 nm was thus explained in terms of the specific STH bands, of which the amplitudes turned out to be polarization dependent.

Novel Technique of 23G Pars Planar Vitrectomy (TPPV) with Alcon Centurion Silver System Gravity -FMS (ACenSS) and ACenSS Vitrectomy Probe (23G) with an External Light Source in Teaching Hospital Rathnapura Sri Lanka

Dual pneumatic 23G vitrectomy cutters of both Alcon Constellation Vision System (AConsVS) and ACenSS have cut rates of 5000 cpm. Aims: To report a novel technique of using ACenSS 23G Vitrectomy cutter for trocar surgery with an external light source in Teaching hospital Rathnapura Sri Lanka from 01/03/2022 to 30/09/2022. Methods: 23G Alcon light probes were used with Retikare (ICON Medicare Tamil Nadu India) external light source for endoillumination. Infusion pressure was set at 65cmH2O (47.81 mmHg) and infusion line connected to eye through a 3 ways tap. ACenSS-GFMS aspiration line connected to aspiration line of vitrectomy probe. Cryopexy used to seal retinal tears as no endolaser facility. Volk surgical corneal lenses with Zeiss Lumera I microscope provided the viewing. ACenSS foot pedal was programmed to 3 modes of vitrectomy with navigation, cutter on/ off function and on/pause of continuous irrigation. A gravity driven another infusion line is used to keep the infusion when endo diathermy is used. Results: When working on maximum cut rate of the ACenSS GFMS (5000 cpm) for long duration machine automatically stops and a restart with reprime needed. Therefore, cut rates were set at a lower rate to work without interruption (core vitrectomy2000 cpm, peripheral trim- 3000cpm and for epinucleus removal 4000 cpm). No retinal traction or ridging of retina was observed at peripheral trim. Total of 210 TPPVs were performed with this technique. Conclusions: 23G TPPV with ACenSS using an external light source is a simple, safe and a cost-effective technique with equal outcome to AConsVS.

Exciton–polariton mediated nonlinear optics in a hybrid optomechanical system

We investigate the nonlinear optics mediated by exciton–polariton in an optomechanical system, constituted of an optical cavity, a quantum well, and a mechanical oscillator. We show that quantum interference occurs only when the cavity photon is coupled either with the moving-end mirror (mechanical mode) of the cavity or with the exciton in a quantum well, or with both. We demonstrate that when the cavity mode is only coupled with the mechanical mode or an exciton, the quantum interference phenomenon produces a single electromagnetically induced transparency window, but when the cavity mode is coupled with both, two transparency windows are produced. Further, we report the existence of double Fano resonances, which become broader as the coupling parameters are increased. The enhancement of slow light is illustrated, and it is deduced that increasing the photon–exciton coupling strength can significantly slow down the transmission of probe light. Our proposed scheme has the potential to provide significant guiding in future polaritonic devices.

Applicability Assessment of Different Materials for Standards Ensuring Comparability of Optical and Tactile Coordinate Measurements.

Multisensor CMMs are systems with an established position on the market, but their popularity still grows, as they provide access to the advantages offered by tactile and contactless measurement methods. Yet there are still questions of the comparability of results obtained using the optical and tactile operation modes of multisensor system. This phenomenon can be assessed by measuring appropriate gauges, most often reference rings or spheres. Due to the completely different nature of probing processes for tactile and contactless measurements, the material from which reference object is made may significantly affect measurement results. In order to assess the influence of this factor on measurement accuracy, three reference spheres made from different materials were measured on optical multisensor CMMs. Measurements involved tactile measurements as well as optical measurements made using different probing systems: a video probe and white light sensor. Results obtained from performed experiments show large differences depending on the material used for spherical standard production. On the basis of obtained results, it can be stated that the best material for a reference object that can be used for comparability tests of tactile and optical measurements is a composite of alumina with at least one oxidic additive.

Photon Doppler velocimetry surface return study for common surface preparations

Photon Doppler velocimetry (PDV) is a ubiquitous diagnostic method in dynamic compression experiments. It typically requires the roughening of the test surface to ensure scattering of the probe light back into the PDV probe at non-normal angles of incidence. Although surface scattering plays an essential role in the quality of PDV data, surface scattering properties for common materials and preparations have not previously been studied with specific relevance to PDV. Here, we present detailed measurements of the bidirectional reflectance distribution function for four different surface preparations (Scotch-Brite hand and drill roughened, ball-rolled, and grit blasted) and four different materials (copper, aluminum, stainless steel, and tantalum). These measurements employ a conventional PDV probe and obtain a diffraction limited angular resolution with 10 pW accuracy and 2.6% repeatability. In addition to scattering data, we employ scattering theory and simulations to accurately emulate the measured data. We also present a straightforward method to derive the average scattering distribution from surface profilometry and observe several qualitative aspects of the scattering data that may help to optimize PDV signals.

An ultrahigh-bandwidth Phase Contrast Imaging system for fusion plasmas

A novel Phase Contrast Imaging system that uses probing light in the near infrared region has been developed to image electron density fluctuations in fusion plasmas. As compared to standard systems operating in the mid infra-red region, the spectral response of the system is extended in wave-number and frequency response by 7 and 100 times, respectively. The internal structure of turbulence and radio-frequency waves is therefore accessible across an unprecedented wavelength and frequency range, extending into the electron gyro-radius scale and the GHz frequency region.

Probing light vector mediators with coherent scattering at future facilities

Future experiments dedicated to the detection of Coherent Elastic Neutrino-Nucleus Scattering may be powerful tools in probing light new physics. In this paper we study the sensitivity on light Z′ mediators of two proposed experiments: a directional low pressure Time Projection Chamber detector, νBDX-DRIFT, that will utilize neutrinos produced at the Long Baseline Neutrino Facility, and several possible experiments to be installed at the European Spallation Source. We compare the results obtained with existing limits from fixed-target, accelerator, solar neutrino and reactor experiments. Furthermore, we show that these experiments have the potential to test unexplored regions that, in some case, could explain the anomalous magnetic moment of the muon or peculiar spectral features in the cosmic neutrino spectrum observed by IceCube.

The Paleo-Tethys subduction and related mineralization in the SW Yangtze Block: Evidence from the Zhesang Carlin-type gold deposit

The Zhesang gold deposit is a Carlin-type gold deposit located in the “Golden Triangle” structural belt of Yunnan-Guizhou-Guangxi. Pyrite and arsenopyrite are important gold-bearing minerals of the deposit. In order to understand the typomorphic characteristics of pyrite and arsenopyrite and the enrichment mechanism of gold, morphological and structural features of these sulphides and the occurrence state of gold were investigated by using reflected light microscope and electron probes (EPMA). The results show that pyrites are characterized mainly by medium-fine broken pentagonal-dodecahedron crystal forms. Most of the arsenopyrites display needle and columnar crystal forms. Compositionally, pyrite is depleted in both Fe and S, whereas arsenopyrite is As-depleted but S-enriched. The w(Co)/w(Ni) of pyrite is between 1.731 and 3.215 (i.e., within the range of ratio of the hydrothermal pyrite, which is between 1 and 5). The crystal forms and compositional features of pyrite and arsenopyrite indicate that the Zhesang gold deposit is typical of medium-low temperature hydrothermal origin. The positive correlation between As and Au and the Au/As (mol%) ratio are lower than the solubility limit of Au in arsenic pyrite. Combined with previous studies, our data suggest that gold is likely to exist in the form of Au+ complex. Arsenic pyrite and arsenopyrite condensed Au in unsaturated ore-forming hydrothermal fluids relative to Au0 through surface voids and/or defects and the As content, forming a Zhesang Carlin-type gold deposit. Based on the age data of the Mesozoic polymetallic deposits in South China, it can be concluded that the age of the Zhesang gold deposit (215.3 ± 1.9 Ma), is consistent with the age of the main body of the Mesozoic polymetallic deposits (230–200 Ma) in South China Plate and the age of the granites (230–200 Ma) related to tungsten-tin mineralization in the Cathaysian Block. Therefore, we believe that the Zhesang gold deposit is the product of the subduction regime of the Paleo-Tethys Ocean in the Middle-Late Triassic.

Could trapped quintessence account for the laser-detuning-dependent acceleration of cold atoms in varying-frequency time-of-flight experiments?

Using a trapped quintessence model, a series of time-of-flight (TOF) experiments with a different frequency of probe light were designed and performed. The varying-frequency TOF (VFTOF) experiments demonstrated that the fall acceleration of test atoms is dependent on the detuning of the probe light frequency with respect to the atomic transition frequency. In appropriately designed experiments, if the scalar field in the model accounts for the accelerated expansion of the Universe entirely, the field will result in an observable fifth force. Meanwhile, the trapped quintessence model still satisfies all experimental bounds on deviations from general relativity due to both the saturation effect and the short interaction range of the scalar field. The scalar saturates at a value corresponding to the cosmological constant when the microscopic nonrelativistic matter density is large enough. The interaction range of the scalar is inversely proportional to the square root of the microscopic nonrelativistic matter density. The interaction range has been estimated to be several $\mu \rm{m}$ in the current cosmic density. The Universe is assumed to be permeated with fuzzy dark matter, which means that the microscopic nonrelativistic matter density defined through the quantum wavefunctions of the ultralight particles can be used on the cosmic scale. By measuring the fall acceleration of the test atoms with the TOF method step-by-step in the detuning frequency domain of the probe light, we derived the dispersion curves of the measured acceleration versus the frequency detuning of the probe light. When the nonrelativistic matter density of the source increased due to the energy gained from the laser light, the test atoms were pulled to the center of the source, and vice versa.