1064-nm Wavelength Research Articles

Lower eyelid blepharoplasty combined with ultrasound-guided percutaneous diode laser lipolysis: evaluating effectiveness with long-term outcome.

Laser lipolysis may be considered for selective removal of excess orbital fat via minimally invasive lower blepharoplasty. To control the energy delivery to a precise anatomic location while avoiding complications, ultrasound guidance can be utilized. Under local anesthesia, a diode laser probe (Belody, Minslab, Korea) was introduced percutaneously to the lower eyelid. The tip of the laser device and changes in orbital fat volume were carefully controlled with ultrasound imaging. A 1470-nm wavelength was used for orbital fat reduction (maximal energy 300J), and a 1064-nm wavelength was used to tighten the lower eyelid skin (maximal energy 200J). From March 2015 to December 2019, a total of 261 patients underwent ultrasound-guided diode laser lower blepharoplasty. The procedure took 17min on average. Total energy of 49J-510J (average = 228.31J) was delivered in 1470-nm wavelengths or 45-297J (average = 127.68J) was delivered in 1064-nm wavelengths. Most patients were very satisfied with their results. Fourteen patients experienced complications, including nine cases of transient hypesthesia (3.45%), and three skin thermal burns (1.15%). However, these complications were not observed after strict control of the energy delivery below 500J for each lower lid. Improvement in lower eyelid bags can be achieved using a minimally invasive approach in selected patients with ultrasound-guided laser lipolysis. It is a fast and safe procedure that can be performed in the outpatient setting.

Photoacoustic imaging of hidden dental caries using visible-light diode laser.

Hidden caries is a type of tooth decay that is difficult to identify through visual diagnosis because teeth with hidden caries appear normal on the tooth surface but are damaged underneath. A photoacoustic imaging system based on visible light using a diode laser with a wavelength of 532nm was developed to detect hidden caries in teeth. The results indicate that the average of acoustic intensity level for healthy teeth is -74.2±0.1dB, and the average of acoustic intensity range for teeth with hidden caries is -81.2±0.5dB. The intensity level for the caries area varies depending on the severity of caries. Based on the acoustic intensity level measured by the interaction of teeth with laser light, the photoacoustic imaging system in the study can accurately detect the presence of hidden caries and recognizethe difference between caries teeth and healthy teeth. This research can be developed into a prototype of a simple device that makes it easy to operate in dental practice.

Barium sulfate and pigment admixture for photoacoustic and x-ray contrast imaging of the gut.

X-ray imaging is frequently used for gastrointestinal imaging. Photoacoustic imaging (PAI) of the gastrointestinal tract is an emerging approach that has been demonstrated for preclinical imaging of small animals. A contrast agent active in both modalities could be useful for imaging applications. We aimed to develop a dual-modality contrast agent comprising an admixture of barium sulfate with pigments that absorb light in the second near-infrared region (NIR-II), for preclinical imaging with both x-ray and PAI modalities. Eleven different NIR-II dyes were evaluated after admixture with a 40% w/v barium sulfate mixture. The resulting NIR-II absorption in the soluble fraction and in the total mixture was characterized. Proof-of-principle imaging studies in mice were carried out. Pigments that produced more uniform suspensions were assessed further for photoacoustic contrast signal at a wavelength of 1064nm that corresponds to the output of the Nd:YAG laser used. Phantom imaging studies demonstrated that the pigment-barium sulfate mixture generated imaging contrast in both x-ray and PAI modalities. The optimal pigment selected for further study was a cyanine tetrafluoroborate salt. Ex-vivo and whole-body mouse imaging demonstrated that photoacoustic and x-ray contrast signals co-localized in the intestines for both imaging modalities. These data demonstrate that commercially-available NIR-II pigments can simply be admixed with barium sulfate to generate a dual-modality contrast agent appropriate for small animal gastrointestinal imaging.

Characteristics of Lead and Sulfur Plasma Parameters by Optical Emission Spectroscopy

This study uses the optical emission spectroscopy (OES) technique to find the lead(Pb) and sulfur (S) plasma parameters employing a pulse of Nd: YAG laser (Q-switched 1064nm wavelength) and different laser energies of (400,500,600 and 700 mJ). The electron temperature Te (eV) is calculated using the Boltzmann-Plot method, and the electron density ne (cm-3)is determined by the Stark broadened way. Moreover, Debye length λD (cm) and plasma frequency ωp (Hz) are studied as a function of laser energy. An apparent increase was noted in the electron temperature of lead plasma and a decrease in sulfur plasma. The results also showed that each increase in the laser intensity causes an increase in the optical emission peaks. This experiment was carried out under atmospheric pressure.

Compar the Effectiveness of Some Plant Extracts and Nd: YAG Laser in the Tribolium castaneum

The present study was conducted to evaluate the efficiency and effectiveness of some plant extracts of Helianthus annuus L., Sesbania sesban and Olea europea concentrations 100, 500, 1000, 5000 ppm. and the effect of Nd: YAG laser with wavelength of( 1064nm) and different energies which conducted at (10,15 and 20) within (5 pulses/sec) to destruction of the Tribolium castaneum, the study found different results according to the different concentrations used, time period and the different energies of the laser during the treatment. Treatment with plant extracts The extract of the Helianthus annuus L. was hightst to the rest of the plant extracts. It gave a 100% mortality rate at 5000 ppm concentration 72 hours of treatment. Then the seesban seed extract came in terms of effect, giving 96.6% mortality rate at the same concentration after 72 hours. While the effect of Olea europea extract was the last impact"on the insect, where the rate of mortality 86.5% in the same concentration also and within ( 72 hours ) of treatment.
 The results showed that the effect of laser radiation on the life of the insect, where it gave the highest mortality rate 73.6% when irradiation at the highest power of 420mj and exposure time 20Sec. the results were obtained after observation of the effect of plant extracts and Nd : YAG at different time intervals 24, 48 hours and 72 hours after the treatment of the Tribolium castaneum .

Effect of Laser Shock Peening without Coating on Grain Size and Residual Stress Distribution in a Microalloyed Steel Grade

This study aimed to identify the optimal combination of wavelength and laser pulse density to achieve the optimal pulse pressure that can induce the maximum compressive residual stress at the subsurface of microalloyed steel. For this, laser shock peening without coating (LSPwC) was performed on microalloyed steel samples at the fundamental wavelength (1064 nm) with pulse densities of 3, 6, 9, and 12 GW/cm2 and at the second harmonic wavelength (532 nm) with pulse densities of 3, 6, and 9 GW/cm2. The residual stress distributions were studied to a depth of 500 µm in the laser-treated samples. Tensile residual stress was observed at the surface of laser-peened specimens in both wavelength conditions (1064 and 532 nm). The significant impartment of compressive residual stress across the depth was achieved at the fundamental wavelength (1064 nm). The maximum compressive residual stress was attained with a laser pulse density of 9 GW/cm2 in the 1064nm wavelength condition. The optical micrographic analysis in the subsurface regions of the LSPwC specimen at 1064 nm and 9 GW/cm2 shows evidence of a high degree of plastic deformation. Electron backscatter diffraction (EBSD) analysis shows that there is grain refinement due to plastic deformations in samples subjected to the fundamental wavelength. Microhardness distribution analysis across the subsurface region shows work-hardening effects in the laser-processed samples in the 1064 nm condition. This study also shows that there is an indication of a thermal softening effect in the samples treated with the 532 nm wavelength, and it is correlated with lower compressive residual stress across the depth.

Output Power Saturation Effect in Cladding-Pumped Bismuth-Doped Fiber Lasers

In this article, output power characteristics of cladding-pumped lasers based on bismuth-doped phospho- and germanosilicate core glass fibers were thoroughly studied and analyzed. The developed lasers are capable of providing the output power of several hundred milliwatts with the slope efficiency close to 1%. The output power saturation for the Bi-doped germanosilicate fiber laser and absence of the saturation regime for the Bi-doped phosphosilicate fiber one was found. This effect is explained by a relatively long relaxation time of bismuth active centers (BACs), namely a non-radiative transition from the higher-lying pump level to the upper laser (metastable) level in the corresponding energy levels diagram. The experimentally obtained data are in good agreement with the results of numerical simulation. In addition, it was investigated that the relaxation time of the BACs from the higher-lying level can have a significant impact on the laser efficiency and the achieved output power. The consequences caused by the saturation effect is possible to overcome with dual-wavelength pumping (combining cladding-pumping at 808-nm wavelength and core-pumping at a wavelength in the range of 1930 – 2040 nm), which provides both the BACs excitation and the stimulated relaxation of BACs from the excited (pump) state to the upper laser level. Using this approach the output power of the Bi-doped fiber laser was increased by almost two times.

Diode Laser Irradiation Effects on Miniscrew Stability and IL-1β and TGF-β1 Levels: A Split-Mouth Randomized Controlled Clinical Trial

Introduction: This study aimed to assess the effect of low-level laser therapy (LLLT) on miniscrew stability and concentrations of interleukin-1β (IL-1β) and transforming growth factor-beta (TGF-β1) in peri-miniscrew crevicular fluid in the course of orthodontic treatment. Methods: This randomized split-mouth double-blind clinical trial evaluated 18 patients requiring anterior retraction along with maximum anchorage. Miniscrews were placed between the maxillary second premolar and first molar. A diode laser was irradiated with a 980-nm wavelength and 100-mW output power in continuous-wave mode at four time points: T0 (1 hour after miniscrew placement), T1 (1 week later), T2 (at 1 month) and T3 (at 3 months) in one quadrant of the maxilla (laser group). The other quadrant of the maxilla underwent the pseudo-application of the laser (control group). The primary stability of miniscrews was measured by Periotest M and reported as Periotest value (PTV). Also, at each time point, samples were collected from the peri-miniscrew crevicular fluid one hour after laser irradiation to assess the concentration of IL-1β and TGF-β1. Results: The mean PTV (inverse of the stability) was smaller in the laser group compared with the control group at all time points; this difference was significant at T2 and T3. The mean concentration of IL-1β in the laser group was lower than that in the control group at all time points, and this difference was significantly remarkable at T0 and T3. The mean concentration of TGF-β1 in the laser group was lower than that in the control group at T0, T1 and T3; however, the difference was not statistically significant. Conclusion: The current results supported the efficacy of LLLT in increasing the miniscrew stability and decreasing the level of IL-1β pro-inflammatory cytokine.

Hyperfine Observation and Forecasting of the Sandstorm Intrusion Process

The temporal and spatial resolutions of spaceborne lidar are insufficient, and traditional 1064-/532-/355-nm wavelength lidar devices have difficulty in performing horizontal observations in urban areas due to the eye safety problems. Therefore, there is no mature method of horizontal pollution observation that satisfies hyperfine environmental management and control in urban areas. Recently, 1.5- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> eye-safe lidars were used to build a Jinan quantum lidar network (JQLN), which can observe horizontal aerosol pollution with a radius of 6 km and with high spatial and temporal resolutions of 15 m and 8 min, respectively. In this study, sudden particulate matter (PM) pollution occurred in Jinan from February 21 to 22, 2021. Spaceborne lidar was used to perform a large-scale analysis, and the detailed transport path of pollution was measured by lidar. Pollution transport path forecasting within half an hour and 180 km2 was performed. The forecasting results were in good agreement with the 11 national monitoring stations (NMSs) distributed within the region. The forecasting errors were within minutes and hundreds of meters, and the maximum errors of the pollution arrival time and distribution distance were less than 3 min and 200 m, respectively. This study and the JQLN are promising methods for hyperfine environmental management and control in urban areas.

A Composite Cavity for Mode Control in Broad-Area Diode Laser

A unstable cavity structure composed of the arc-shaped cavity, Fabry-Perot cavity, and sidewall saw-tooth microstructure is proposed to achieve mode selection in high-power broad-area diode laser with 980nm wavelength. In this cavity, the loss difference between the higher-order modes and the fundamental mode is increased to suppress the lasing of higher-order modes. The lateral divergence is reduced by about 28%. The number of modes in the near-field spot is reduced and the light intensity is concentrated towards the center of the Near-field profile. Also, the lateral beam parameter product decreases by 15%.

Numerical demonstration of low-reflective wire grid polarizers with a patterned Fe2O3 absorptive layer.

Absorptive polarizers are pivotal components for realizing a low ambient reflection in liquid crystal displays (LCDs) and organic light-emitting diodes (OLEDs). Different types of absorptive polarizers have been proposed. Nevertheless, the realization of compact and efficient absorptive polarizers remains challenging. Wire grid polarizers (WGPs) are a promising solution because of their high durability and relatively thin thickness. In this paper, two structures of absorptive-WGPs have been proposed and optimized at the target wavelength of 532nm: one is based on a patterned F e 2 O 3/A l bi-layer on top of a S i O 2 substrate, and the second one builds on the first one by depositing a S i O 2 layer in the gaps of Al. The optimal solutions exhibit a reflectance less than 5%, a transmittance over 45%, and an extinction ratio over 40dB. To evaluate the manufacturing feasibility, their sensitivity to the wire's dimensional parameters is investigated. Their great spectral performance and large acceptance angles demonstrate that such polarizers have the potential to significantly promote the development of current display technologies.

Study of the optical properties of BiFeO3 under different heat treatment temperatures

It is known that the optical absorption property of a material is linked to its crystal structure. Therefore, it can be modified or displaced when the material is subjected to thermal treatments, generating displacements of the unit cell, atomic positions and bond angles of its atoms. In this work, the analysis of three samples of BiFeO3 powders subjected to different heat treatment temperatures was carried out to study their optical properties by analyzing the crystal structure, diffuse reflectance, Raman scattering spectroscopy, density of state and band structure. In the results, the pure phase and the hexagonal structure of the samples were identified, showing an increase in the angles between the Fe-O-Fe atoms when the material is thermally treated. The band gap (Egexperimental) of the BiFeO3 samples without and with treatment temperature showed direct and indirect transitions according to the Tauc equation, these values were 2.36, 2.11 and 2.19 eV for direct band gaps and 2.10, 1.58 and 1.85 eV for indirect band gaps. In the Raman scattering spectroscopy analysis, overtones were observed in the samples when a green laser with a wavelength of 532nm (2.33 eV) was applied. In the density of states, the maximum valence band formed by the O(2p) state and the minimum of the conduction band formed by the hybridization of the Fe(3d) and O(2p) states were identified. In the electronic band structure, indirect band gap values (Egtheoretical) of 2.274, 2.216 (500 °C) and 2.217 eV (600 °C) were found for the samples without and with heat treatment. It is concluded that BiFeO3 absorbs visible light and that its band gap can decrease by increasing the bond angle of Fe-O-Fe atoms when the sample is subjected to heat treatment. These results demonstrate the semiconductor property of BiFeO3 and can be applied to solar cells, batteries, hydrogen production, among other applications.

(Cd,Mg)Te crystals for picosecond-response optical-to-x-ray radiation detectors.

We demonstrate a photodetector sensitive to both optical and x-ray picosecond pulses based on our in-house grown cadmium magnesium telluride (Cd,Mg)Te single crystal. Specifically, we developed In-doped Cd0.96Mg0.04Te material and discuss its femtosecond optical photoresponse, as well as the detector performance, such as <100-pA dark current and up to 0.22-mA/W responsivity for 780-nm wavelength optical radiation. The detector exposed to Ti fluorescence (K alpha) x-ray pulses at 4.5keV, generated by a free-electron laser beam with the central energy of 9.8keV and <100fs pulse width, exhibited readout-electronics-limited 200-ps full-width-at-half-maximum photoresponse, demonstrating that it is suitable for coarse timing in free-electron laser x-ray/optical femtosecond pump-probe spectroscopy applications.

Experimental study on laser polishing additive manufacturing Ti6Al4V

As a new precision processing technology, laser polishing is widely used in metal and non-metal. Laser polishing technology is especially suitable for parts with high hardness and small size. In this paper, a full factor experimental were carried out to investigate the effect of continues wave laser with a wavelength of 1064nm on the surface quality of additive manufacturing Ti6Al4V. The experimental result shows that a smooth surface can be obtained and the average roughness is reduced from 14.95μm to 1.756μm with the reduction rate is as high as 88.3% when laser power is 170W and scan speed is 60mm/s. And the height of the peaks and valleys on the sample surface has also been greatly reduced in condition of the optimized laser processing parameters.

355-nm direct-detection Doppler wind lidar for vertical atmospheric motion measurement.

A compact and simple 355-nm direct-detection Doppler wind lidar (DDDWL) was developed to measure the line-of-sight (LOS) wind speed of the background atmosphere from atmospheric molecule return signals with and without aerosols and clouds. A receiver design with a Fabry-Perot etalon interferometer (FPEI) without an inside deposited step coating or fiber coupling is considered for the DDDWL using the double-edge technique. The receiver with the double-edge technique uses a FPEI and wedge prism to form a double-edge filter. The development of the double-edge filter in this combination is, to the best of our knowledge, an improvement at 355-nm wavelength. Considerations for the DDDWL receiver with a FPEI revealed that a full-angle light beam divergence into the FPEI and a working FPEI aperture are significant factors for the receiver design. Preliminary experimental evaluation demonstrated that the DDDWL had the potential of LOS wind speed measurements with a random error of less than 1 m/s when the signal-to-noise ratio was approximately 300. The DDDWL-measured vertical LOS wind speed profile was consistent with that of a 2-µm coherent Doppler wind lidar within the measurement error range. The preliminary experimental LOS wind measurement results demonstrated the capability of the DDDWL to measure low LOS wind speeds.

Multielectron effects in CO ionization by orthogonal two-color laser fields

We study the single ionization of CO molecule in orthogonally polarized two-color laser fields using time-dependent Hartree–Fock method. Employing the coherent superposition consisting of a fundamental field and its second harmonic, we consider different wavelengths (780 and 390nm) and intensities (1×1014, 1.5×1014 and 2×1014 W/cm2) of the fundamental field for which different ionization mechanisms are involved. Our numerical results reveal that the contributions of the three highest occupied molecular orbitals are strongly influenced by the intensity ratio and time delay between the two components of the bichromatic field. At the fundamental wavelength of 780nm and intensity of 2×1014 W/cm2, the two outermost molecular orbitals display a dominant response to the orthogonal two-color laser field when the second harmonic field is stronger than the fundamental field.

Focus variation due to near infrared laser in a confocal microscope.

Focus precision and stability is crucial in confocal microscopy not only for image sharpness but also to avoid radiometric fluctuations that can wrongly be interpreted as variations of the fluorescence intensity in the sample. Here we report a focus variation provoked by a continuous wave laser of 810-nm wavelength introduced along the optical path of an inverted confocal microscope with an oil immersion ×60 objective. When the laser is turned on or off, the focus position drifts toward lower or high values of the vertical coordinate z, respectively. The maximum drift observed was 2.25𝜇m for a laser power of 40 mW at the sample and over a 600-s exposure time. The temporal evolution of the focus position is well fitted by exponential curves that mimic temperature variations due to a heat source. Our analysis strongly suggests that the focus drift is due to heating of the immersion oil.

Non-linear optical characteristics of sand glass

In this work the nonlinear optical characteristics of sand glass which is the origin of quartz crystal were evaluated, sand glass particles from mining site waste were prepared by washing, drying, magnetic separation and sieving. The particles are soaked in sulphonic acid H2 SO4 acidic solution with 30% concentration for 100 hours, the new compound with optical characteristics was formed at different volume fractions of sandglass such as 20%,40%,60%, and 80% respectively. The new machine was developed for manufacturing the new compound from sand glass. The optical nonlinear absorption coefficient of the sand glass-ceramics material was investigated using the Z-scan technique, provided with nanosecond pulses of second harmonic (green Nd:YAG laser with 532nm wavelength). The effect of lattice structure and particles concentration on the non-linear optical properties were also discussed. The conclusions and recommendations for the best material and concertation for nonlinear optical material were mentioned. The research end with conclusions and recommendation for the development of new optical materials based on micro and nanoparticles from natural resources.

Effect of delayed photobiomodulation therapy on neurosensory recovery in patients with mandibular nerve neurotmesis following traumatic mandibular fracture: A randomized triple-blinded clinical trial.

There is a possibility of neurotmesis of the inferior alveolar nerve (IAN) in mandibular fractures, which leads to neurosensory impairment. In this study, we aimed to investigate the efficacy of photobiomodulation therapy (PBMT) in patients with neurotmesis following trauma and mandibular fracture. This triple-blind randomized trial was carried out on patients who suffered neurotmesis of the IAN following mandibular angle and body fracture at least for 6months. In the intervention group, laser irradiation was applied with a low-level GaAlAs diode laser (continuous wave of 810nm wavelength, power of 200mW, and energy density of 12-14J/cm2). In the control group, the laser probe was turned off and placed on the affected area. LLLT was done for 12 sessions (2 times/week for 6weeks). Light touch sensations, two-point discrimination, thermal discrimination (cold and warm stimulus), electric pulp test (EPT), and oral health impact profile (OHIP)-14 questionnaire were performed before the intervention, immediately after each PBMT session, and after 3, 6, 9 and 12months. In both groups, 3 and 23 patients were female and male, respectively. The results showed significantly improved light (cotton swab), light (wooden cotton swab), and sharp (dental needle) touch sensations, and two-point discrimination test in the PBMT group after the 10th, 11th, 10th, and 10th session, respectively. Two-way repeated measure ANOVA revealed that the trend of light touch sensation with cotton swab and two-point discrimination test was statistically significant (p-value=0.002 and 0.001, respectively). The results of OHIP-14 test showed a significantly higher mean in the PBMT group 3months after PBMT. There was no statistically significant difference in EPT and thermal discrimination tests regarding the patients' group. PBMT could be an effective treatment for late post-traumatic nerve neurotmesis following a traumatic mandibular fracture.

Photonic Nanolaser with Extreme Optical Field Confinement.

We proposed a photonic approach to a lasing mode supported by low-loss oscillation of polarized bound electrons in an active nano-slit-waveguide cavity, which circumvents the confinement-loss trade-off of nanoplasmonics, and offers an optical confinement down to sub-1-nm level with a peak-to-background ratio of ∼30 dB. Experimentally, the extremely confined lasing field is realized as the dominant peak of a TE_{0}-like lasing mode around 720-nm wavelength, in 1-nm-level width slit-waveguide cavities in coupled CdSe nanowire pairs. The measured lasing characteristics agree well with the theoretical calculations. Our results may pave a way towards new regions for nanolasers and light-matter interaction.