Combined Laser Research Articles

Efficacy and safety of ablative CO2 fractional laser and narrowband intense pulsed light for the treatment of hypertrophic scars: a prospective, randomized controlled trial

Background and Objectives Hypertrophic scarring is a complex process, and numerous methods have been introduced to treat scars. This study aims to evaluate the effect of combined CO2 fractional laser and narrowband intense pulsed light (IPL) compared to IPL alone in the treatment of hypertrophic scars. Materials and Methods This was a prospective, randomized controlled study enrolled 138 patients with hypertrophic scars. The participants were randomly divided into two groups: CO2-IPL and IPL group, and received three sessions at 10–14-week intervals for 3-month follow-up. Two independent plastic surgeons evaluated the treatments using the Patient and Observer Scar Assessment Scales (POSAS). Overall satisfaction was evaluated using the Patient Satisfaction Scale (PSS). Results 101 subjects completed the study. Compared to single IPL, the combination CO2-IPL group showed a significant improvement in itching, color, stiffness, thickness, and irregularity, except for pain, and an enhancement in vascularization, pigmentation, thickness, relief, and pliability of the scar, assessed by POSAS (p < .01). 100% patients in the combination group were satisfied compared to 84% in IPL alone. Conclusion The combination of CO2 fractional laser and narrowband IPL efficiently improved the appearance and profile of hypertrophic scars, offering a comprehensive and reliable approach for scar therapy.

Study on the Expansion Kinetics of Plasma and Absorption Wave Induced by Millisecond-Nanosecond Combined Pulse Lasers in Fused Quartz

The transient temperature field, the velocity and pressure of plasma, and the absorption wave of fused quartz induced by millisecond-nanosecond combined pulse lasers are simulated. The theoretical model of plasma and absorption wave produced by fused quartz irradiated by a millisecond-nanosecond pulsed laser is established, in which pulse delay and laser energy are essential variables. The results show that the damaged effect of the millisecond-nanosecond combined pulse laser is different under the damaged effect of different pulse delay conditions. When the energy densities of millisecond-nanosecond combined pulse lasers are 800 J/cm2 and 20 J/cm2, respectively, the range of pulse delay is 0 ms &lt; Δt ≤ 3 ms, and the energy coupling efficiency is the highest when Δt = 1 ms. The addition of a nanosecond pulsed laser causes more obvious thermal damage and optical breakdown to fused quartz. The high pressure is concentrated at the plasma expansion interface or the shock wave front. The results can optimize the simulation parameters and be applied to laser plasma processing technology.

Feasibility Demonstration of THz Wave Generation/Modulation Based on Photomixing Using a Single Wavelength-Tunable Laser

The photomixing of two lightwaves is one of the promising methods of generating a terahertz (THz) wave. The conventional photomixing system consisting of two lasers and a modulator results in large transmitter volumes and high power consumption. To solve this issue, we devised a novel THz wave generation and modulation system based on photomixing using a single wavelength-tunable laser in combination with delayed self-multiplexing. We successfully demonstrated the feasibility of 300-GHz wave generation and modulation.

Intra-cavity coherent combining of DBR lasers on an InP generic foundry platform.

We report an intra-cavity coherent combining of two distributed Bragg reflector (DBR) lasers with a combining efficiency of ∼84% on an InP generic foundry platform. The on-chip power of the intra-cavity combined DBR lasers is ∼9.5 mW at the injection current of 42 mA in both gain sections simultaneously. The combined DBR laser operates in a single-mode regime with a side-mode suppression ratio of 38 dB. This monolithic approach paves the way toward high-power and compact lasers, which is useful in scaling integrated photonic technologies.

Investigation of microstructure, mechanical, and corrosion properties of Inconel 617 joints welded by laser–MIG hybrid welding

The demand for Nickel-based superalloy of Inconel 617 material is increasing for manufacturing hot section components of gas turbines, chemical, and nuclear power plants. It has excellent corrosion resistance in high-temperature environments. In the present study, laser–MIG hybrid welding consisting of a 3.5 kW CO2 laser in combination with a MIG welding system was utilized to weld 10 mm thick Inconel 617 plates with the wire feed rates (WFR) of 10 and 11 m/min in a single pass to analyze the welds microstructure, mechanical, and corrosion properties. The results revealed that the microstructure of the weld zone is composed of cellular crystals with dendrites and equiaxed sub-grains. Electron backscattered diffraction (EBSD) studies revealed coarse columnar dendrites and equiaxed grains at the center of weld joints with the same crystallographic orientation across the fusion boundary. The XRD analysis revealed the dominant gamma and gamma prime (γ/γ′) [(Ni/Ni3(AlTi))] phases along with the presence of minor carbide peaks such as Ti (C, N), M23C6, Cr (C, N), and M6C. The BM has a lower hardness (232 HV) and higher impact energy (236 J) than the weld joints. Similarly, the increase in WFR results in a decrease in microhardness (268–256 HV) values and an increase in impact energy (199–212 J). The weld joints exhibit good bend ductility without any cracks. The potentiodynamic polarization results revealed a lower corrosion rate of 0.212 mpy for the base metal than for the weld joints. The increase of WFR increased the weld metal corrosion rate from 0.342 to 0.427 mpy due to an increase in heat input (0.516–0.615 kJ/mm) and solidification time, which caused the coarsening of the grains resulting in lower grain boundary density and anode reaction to accelerate, which deteriorated the corrosion resistance of the welds.

Endoscopic Laser Dissection Combined With Laparoscopic Pneumovesical Repair of Vesicovaginal Fistula: A Novel Technique and Case Report

IntroductionWe present a novel technique that combined endoscopic laser dissection and a transvesical laparoscopic approach for VVF repair in a transmasculine patient who received vaginal colpectomy. A literature review of VVF repair was also conducted. Technical ConsiderationsSurgical repair of VVF has been described extensively in the literature. Transvaginal and transabdominal laparoscopic approaches are currently the most common techniques for VVF management. However, for transmasculine patients, neither of these methods is ideal due to either a previous history of vaginal colpectomy or the position of the fistula. This case report demonstrates the feasibility of applying a combined endoscopic laser dissection and transvesical laparoscopic approach for VVF repair. ConclusionThe patient had an uneventful recovery, and the VVF healed over time. The advantages of this technique include a precise incision and dissection of the fistula orifice, clear exposure of the anatomic plane between the bladder and vaginal wall, and minimal injury to normal tissue. More cases are needed to demonstrate the effectiveness and complication rate of this technique in the future.

All-fiber cascaded combiners for high-power adjustable-ring mode laser beam with a flattop central beam

An all-fiber structure that obtains an adjustable-ring mode (ARM) beam with a uniformly distributed central beam is put forward for the first time based on the beam combining technology. This structure is all-fiber cascaded combiners consisting of a 3 × 1 combiner and a (6 + 1) × 1 combiner in series. A multi-mode fiber with core diameter of 50 µm acts as the connective fiber, transmitting the combined laser of the first 3 × 1 combiner into the center guide core of the output fiber by the well-designed (6 + 1) × 1 combiner. Through the independent transmission of the center and ring beams, an 8.8 kW uniformly distributed central output laser with a transmission efficiency of 96.2 % and M2 of 5.24 is obtained by the cascaded combiners. The feasibility of ARM laser beam with a 10 kW-level flattop central beam provides a new approach for high-power laser welding.

Optical properties study of high-throughput horizontal composition gradient FeSe1-xTex thin film based on ellipsometry

The high-throughput superconductivity research model can effectively accelerate the material synthesis and physical characterization process. It can rapidly form a database of materials and reveal the hidden key physical laws, which provides significant assistance to the research of superconducting materials, especially the exploration of superconductivity mechanism. In this work, FeSe1-xTex thin film with spread composition was grown by combined laser molecular beam epitaxy, the third generation combined thin film preparation technique. The film thickness and surface morphology were obtained by atomic force microscopy, which showed that the sample surface was relatively smooth. In addition, we measured the distribution of critical elements and c-axis lattice constants within the different microzones along the direction of composition variation on the surface of the film, by X-ray photoelectron spectroscopy and X-ray diffraction, respectively, which verified that the film was prepared in accordance with a continuous composition gradient. Based on this, nine microzones of the film were tested using the ellipsometer equipped with a focused light spot. The dispersion model of the FeSe1-xTex layer was established using the Drude-Lorentz oscillator, and the optical constants of the film with horizontal composition gradient were obtained by inversion and fitting of the data within each microzone. The results indicate that the FeSe1-xTex thin film shows an obvious composition-dependent optical property. Our work reports the optical constants of FeSe1-xTex composition-spread thin film by using a nondestructive and accurate method, spectroscopic ellipsometry, which enriches the database of this material. This work may provide a reference for establishing the correlation between the optical and superconducting properties of FeSe-based superconductors.

Effect of exercise training with laser phototherapy on homeostasis balance resistant to hypercoagulability in seniors with obesity: a randomized trial

The prevalence of obesity has increased the incidence of obesity-related coagulation disorders. The current study assessed the effectiveness of combined aerobic exercise and laser phototherapy on the coagulation profile and body measurements in older adults with obesity compared to aerobic exercise alone, which has not been adequately explored. We included 76 obese people (50% women and 50% men) with a mean age of 67.83 ± 4.84 years and a body mass index of 34.55 ± 2.67 kg/m2. The participants were randomly assigned to the experimental group (which received aerobic training with laser phototherapy) and the control group (which received aerobic training alone) for three months. From the baseline to the final analysis, the absolute changes in specific coagulation biomarker levels (fibrinogen, fibrin fragment D, prothrombin time, Kaolin-Cephalin Coagulation Time), and contributing parameters (C-reactive protein and total cholesterol), were assessed. In comparison to the control group, the experimental group showed significant improvements in all evaluated measures (p < 0.001). So, in comparison to aerobic exercise alone, combined aerobic exercise and laser phototherapy had superior positive effects on coagulation biomarkers and decreased the risk of thromboembolism throughout a three-month intervention period in senior obese persons. Therefore, we suggest adopting laser phototherapy for individuals with a greater risk of hypercoagulability.The research was entered into the database of clinical trials under the identification NCT04503317.

Simplified intensity- and phase-modulated transmitter for modulator-free decoy-state quantum key distribution

Quantum key distribution (QKD) allows secret key exchange between two users with unconditional security. For QKD to be widely deployed, low cost and compactness are crucial requirements alongside high performance. Currently, the majority of QKD systems demonstrated rely on bulk intensity and phase modulators to generate optical pulses with precisely defined amplitude and relative phase difference—i.e., to encode information as signal states and decoy states. However, these modulators are expensive and bulky, thereby limiting the compactness of QKD systems. Here, we present and experimentally demonstrate a novel optical transmitter design to overcome this disadvantage by generating intensity- and phase-tunable pulses at GHz clock speeds. Our design removes the need for bulk modulators by employing directly modulated lasers in combination with optical injection locking and coherent interference. This scheme is, therefore, well suited to miniaturization and photonic integration, and we implement a proof-of-principle QKD demonstration to highlight potential applications.

CYTOMORPHOLOGICAL CHANGES IN MCF7-DOX CELLS AND THEIR CORRELATION WITH THE ACTIVITY OF THE CELL CYCLE REGULATOR P21 AFTER COMBINED EXPOSURE TO INFRARED LASER AND DOXORUBICIN

Introduction: In recent years, studies of infrared laser irradiation effect on tumor cells in combination with various chemotherapeutic agents have been developing dynamically. Objective: To study the effect of infrared laser in combination with low doses of doxorubicin on cytomorphological characteristics of MCF-7DOX culture cells and p21 expression level. Materials and Methods: MCF-7DOX tumor cells were cultured in DMEM medium with 10% fetal calf serum (FCT) and 40 μg/ml gentamicin. Doxorubicin was added to the cells to a final concentration of 2 μg/ml and 0.5 μg/ml. Cells were irradiated with infrared laser (Fotonika-Plus, Ukraine) with a wavelength of 810 nm (irradiation time — 5 min, power density — 50 mV/cm², irradiation dose 15 J/cm²). Photomicrographs of cells were taken using a Carl Zeiss microscope, Germany. An immunocytochemical study was also conducted using monoclonal antibodies to the factor p21 (Thermo Scientific, USA). Results: The evaluation of morphological characteristics in micropreparations testifies to the antitumor effectiveness of the combined effect of infrared laser irradiation and doxorubicin. It is noteworthy that the cytotoxic effects of chemotherapy in combination with photobiomodulation were observed when using different doses of doxorubicin: 2 μg/ml and 0.5 μg/ml. When studying the biological activity of cells using immunocytochemistry, it was established that the combination of doxorubicin and infrared laser irradiation led to an increase in the expression of p21, and it is important to note that a similar effect was observed at both concentrations of doxorubicin: as at 2.0 μg/ ml and 0.5 μg/ml. The simultaneous destructive effect on tumor cells and the increase in p21 expression allows us to make a preliminary cautious assumption that the proposed technique of combination of infrared laser irradiation with doxorubicin determines the effect of the p21 factor in the role of a tumor suppressor. Conclusions: The results of the study allow us to consider the use of doxorubicin in combination with infrared laser as a promising method of cytotoxic effect on tumor cells.

Study on picosecond laser stealth dicing of 4H-SiC along [[formula omitted]] and [[formula omitted]] crystal orientations on Si-face and C-face

Stealth dicing of semi-insulating 4H-SiC along [112¯0] and [11¯00] crystal orientations on Si-face and C-face was conducted by using infrared picosecond laser in combination with three-point bending split. It was demonstrated that the laser ablation points inside 4H-SiC samples, the critical fracture load, and the dicing quality of 4H-SiC samples were closely related to the crystal orientation. The critical fracture load of 4H-SiC along [112¯0] orientation is smaller than that along [11¯00] orientation. The longitudinal lengths of the laser ablation points increase with the increase of laser incident distance. For the same laser-modified layer, as laser was incident from C-face and processed along [112¯0] orientation, the laser ablation points have larger longitudinal length. The reasons for the impact of crystal orientation on laser-modified points were analyzed. The fractured 4H-SiC samples have chipping width less than 3 μm and section roughness less than 500 nm. Moreover, the dicing quality along [112¯0] orientation is better than that along [11¯00] orientation. This research can provide technical support for precision dicing of SiC wafers in semiconductor industry.

High Brightness Diode Laser Based on V-Shaped External Cavity and Beam-Waist Splitting Polarization Combining

A beam combining method to improve the brightness of diode lasers is proposed based on a V-shaped external cavity spectral beam and beam-waist splitting polarization combination. This design has the outstanding advantages of improving the beam quality, brightness, and versatility of the diode laser. Specifically, an output power over 16W with M2 factors of 1.79 × 3.92 (Beam Parameter Product BPP = 0.55 × 1.22 mm mrad) at 40 A in the fast and slow axis is demonstrated for a commercial standard cm-bar. Furthermore, the slow axis M2 of the combined laser is improved by 56% compared with that of a single emitter. Additionally, the brightness of 262 MW·cm−2·sr−1, 136% higher than that of spectral beam combining without using beam-waist splitting polarization, was realized.

Self‐Injection Locked Frequency Conversion Laser

AbstractHigh‐coherence visible and near‐visible laser sources are centrally important to the operation of advanced position/navigation/timing systems as well as classical/quantum sensing systems. However, the complexity and size of these bench‐top lasers are an impediment to their transition beyond the laboratory. Here, a system‐on‐chip that emits high‐coherence near‐visible lightwaves is demonstrated. The devices rely upon a new approach wherein wavelength conversion and coherence increase by self‐injection locking are combined within a single nonlinear resonator. This simplified approach is demonstrated in a hybridly‐integrated device and provides a short‐term linewidth of around 4.7 kHz (10 kHz before filtering). On‐chip converted optical power over 2 mW is also obtained. Moreover, measurements show that heterogeneous integration can result in a conversion efficiency higher than 25% with an output power over 11 mW. Because the approach uses mature III–V pump lasers in combination with thin‐film lithium niobate, it can be scaled for low‐cost manufacturing of high‐coherence visible emitters. Also, the coherence generation process can be transferred to other frequency conversion processes, including optical parametric oscillation, sum/difference frequency generation, and third‐harmonic generation.

Laser Thermo-Photobiomodulation of Bone Marrow Mesenchymal Stem Cells

We studied the effect of laser radiation of moderate intensity with a wavelength of 970 nm on the efficiency of colony formation of rat bone marrow mesenchymal stem cells (MSC) in vitro. In this case, photobimodulation and thermal heating of MSC occur simultaneously. This combined laser treatment allows increasing the number of colonies by 6 times in comparison with the control and by more than 3 times in comparison with thermal heating alone. The mechanism of such an increase is associated with combined thermal and light effects of laser radiation of moderate intensity, which stimulates cell proliferation. This phenomenon can be used as the basis for solving the most important task of cell transplantation, associated with the expansion of autologous stem cells and activation of their proliferative potential.

Coats' Disease in a Patient With Cornelia de Lange Syndrome: Management With Laser and Bevacizumab.

Cornelia de Lange syndrome is a congenital disorder with multisystem abnormalities including multiple ocular findings. The authors report a case of Coats' disease in a patient with Cornelia de Lange syndrome who was successfully treated with laser and intravitreal bevacizumab. This case demonstrates the importance of fluorescein angiography in making the diagnosis and directing treatment and the efficacy of combined laser with intravitreal anti-vascular endothelial growth factor therapy for persistent vascular leakage associated with Coats' disease in Cornelia de Lange syndrome. [J Pediatr Ophthalmol Strabismus. 2023;60(4):e45-e48.].

Smart Nanosensitizers for Activatable Sono-Photodynamic Immunotherapy of Tumors by Redox-Controlled Disassembly.

Tumor-targeted and stimuli-activatable nanosensitizers are highly desirable for cancer theranostics. However, designing smart nanosensitizers with multiple imaging signals and synergistic therapeutic activities switched on is challenging. Herein, we report tumor-targeted and redox-activatable nanosensitizers (1-NPs) for sono-photodynamic immunotherapy of tumors by molecular co-assembly and redox-controlled disassembly. 1-NPs show a high longitudinal relaxivity (r1 =18.7±0.3 mM-1 s-1 ), but "off" dual fluorescence (FL) emission (at 547 and 672 nm), "off" sono-photodynamic therapy and indoleamine 2,3-dioxygenase 1 (IDO1) inhibition activities. Upon reduction by glutathione (GSH), 1-NPs rapidly disassemble and remotely release small molecules 2-Gd, Zn-PPA-SH and NLG919, concurrently switching on (1) dual FL emission, (2) sono-photodynamic therapy and (3) IDO1 inhibition activities. After systemic injection, 1-NPs are effective for bimodal FL and magnetic resonance (MR) imaging-guided sono-photodynamic immunotherapy of orthotropic breast and brain tumors in mice under combined ultrasound (US) and 671-nm laser irradiation.

Combined Endovenous Laser and Mechanochemical Ablation to Reduce Sclerosant for Three or Four Veins with Chronic Venous Insufficiency

Background: A large amount of sclerosant is needed for the treatment of saphenous vein insufficiency with mechanochemical ablation (MOCA) for three or four veins with chronic venous insufficiency. In addition, what constitutes a safe amount is not clearly defined. In this study, we evaluate the feasibility of the combined endovenous laser and mechanochemical ablation to reduce the amount of sclerosant as compared with mechanochemical ablation monotherapy. Methods: A total of 327 patients diagnosed with superficial vein insufficiency between June 2018 and May 2020 and treated in a single center by one surgeon were evaluated retrospectively. There were 130 patients included who were treated with mechanochemical ablation (MOCA, Group I) and 197 patients who were treated with combined endovenous laser ablation and mechanochemical ablation (EVLA and MOCA, Group II). Results: The amount of sodium tetradecyl sulfate (STD) used per number of limbs was 5.5 ± 2.05 mL in Group I and 4.51 ± 1.2 mL in Group II (p &lt; 0.001). The amount of STD used per number of veins was 4.77 ± 1.91 mL versus 3.12 ± 1.02 mL in Groups I and II, respectively, (p &lt; 0.001). Recanalization rates within 52 weeks were 0% (0/130) in Group I and 5.58% (11/197) in Group II, while after 52 weeks they were 2.31% (3/130) in Group I and 6.60% (13/197) Group II and were not statistically significant. Complications within 4 weeks were 3.84% and 7.11% in Groups I and II, respectively. Conclusions: The results of this study show that combined EVLA and MOCA reduces the amount of sclerosant per the number of veins and legs treated as compared with MOCA monotherapy for three or four veins with chronic venous insufficiency. The combined EVLA and MOCA treatment in patients with three or four varicose veins has few side effects, reduces the amount of sclerotic agent, and can be considered to be an effective treatment method for inducing venous occlusion.

Mechanical characterization and microstructure of fiber laser welded TWIP980 steel depending on welding speed and focal distance

The TWIP steels are preferred in the automotive industry due to excellent strength and ductility. In this study, the effect of fiber laser welding parameters has been investigated on the mechanical properties and microstructural points of view twinning-induced plasticity (TWIP) steel. The variation of the mechanical properties depending on fiber laser welding parameters has been determined. The samples were laser-welded with different speeds and focal distances the laser power constant at 4 kW. The stress and elongation decreased when the welding speed increased. The highest stress was obtained at + 1 focal distance. The best energy absorption was seen in b-3 combination (laser power 4 kW, welding speed 130 mm/s, focal distance +1 mm).

Study of the dynamics of material removal processes in combined pulse laser drilling of alumina ceramic

Combined pulse laser (CPL), one of the hybrid laser processing technologies, has proven to be a reliable tool for the high-quality and high-efficiency material processing. In CPL drilling, the nanosecond laser has been proven that it can improve the drilling performance of the millisecond laser by increasing the laser absorption or improving the sputtering of the melt. However, the dynamics of material removal processes regarding CPL drilling have not been systematically investigated. In this paper, a numerical model of the CPL drilling of alumina ceramic was built to reveal the dynamic processes of the energy absorption, phase transformation, and micro-hole deformation process. The millisecond laser absorption enhanced by the ablated keyhole was quantified and considered as saturation (100 %), thus improving the drilling efficiency. In addition, the shock wave generated by the nanosecond laser accelerated the removal of the melt with a sputtering velocity of up to 23.8 mm/ms, which was much higher than the recoil pressure generated by the saturation vapor pressure, ensuring the drilling quality. Also, the experimental results showed that well drilling quality (1.09° taper angle, 0.96 circularity) were obtained for 1 mm thick alumina ceramic with a material removal rate as high as 1.9 × 104 μm3/μJ. The analysis and summary of the CPL drilling mechanism helps to further improve the drilling performance and provide a new technological route for high-speed processing of ceramic substrates.