980-nm Diode Laser Research Articles

Catheter laser ablation of superficial veins of the lower extremities in the symptomatic treatment of venous reflux − comparison of the immediate results of two types of laser generators

ntroduction: Catheter-Based Endovenous Laser Ablation (EVLA) is a commonly used alternative to surgical treatment of varicose veins. Recently, catheterization methods have proved to be methods of choice due to the preference of patients who value minimal invasiveness. Research of EVLA currently focuses on optimization of the procedure, which includes study of the benefits of the individual types of laser generators and the wavelengths used. In this observational study we compared our early results in a non-selected population of consecutive patients treated with two different types of lasers. Methods: In the period from February 2010 to June 2017, EVLA was performed in a total of 1747 consecutive patients (74% were female) with venous reflux. The average vein width was 8.5 mm (5−25 mm). Our study sought to compare a more economical 1470nm diode laser (DL) generator (Velas 2, China) – used to operate on 630 patients – with a Nd-Yag crystal generator (Fotona - Slovenia) used in 1117 patients. All operations were performed using the same methodology, in an outpatient setting, in one specialized center. All procedures were completed in local tumescent anesthesia under peroperative ultrasound control. Postoperative sonography was performed in all patients. Results: The results did not show a statistically significant difference in early closure rates (98.8% for Nd-Yag versus 99.8 for DL p-ns). Early recurrence was observed in 9 patients (15 vein segments) and managed successfully with early re-intervention and closure in all cases. The causes of incomplete closure included mainly the known risk factors (anticoagulation therapy, history of varicophlebitis). There was no correlation with larger venous diameter. In 6 patients, thrombus prolapse was observed in the deep femoral vein lumen. All cases were successfully cured after a week of low-molecular-weight heparin therapy. Only one case of low-risk pulmonary embolism was reported in a patient who failed to follow the regime recommendations. Conclusion: This evidence did not show a significant difference in closure reliability and the amount of complications of the endovenous laser abla- tion of large and small saphenous vein with a 1060nm Nd-Yag crystal compared to the more economical 1470nm diode laser generator.

High power diode laser source with a transmission grating for two spectral beam combining

A novel laser-coupling structure is introduced, in which the same transmission grating is simultaneously employed by two spectral beams generated in identical resonant cavities. The novel structure doubles the number of coupled laser emitters and the output power. Eight 800-nm diode laser bars were coupled and combined with polarization multiplexing, achieving a continuous wavelength power of 212 W, a broad spectrum of 19.1 nm, an M2 (times diffraction limited factor) beam quality of 2.2×16.7 and a brightness of 236MW/cm2/sr.

Ефективність транспупілярної діод-лазерної (810 нм) термотерапії за розробленою методикою в лікуванні меланом хоріоїдеї стадії Т1 малих розмірів

Ефективність транспупілярної діод-лазерної (810 нм) термотерапії за розробленою методикою в лікуванні меланом хоріоїдеї стадії Т1 малих розмірів

Photothermal detection of a single gold nanoparticle in water suspension

We study the photothermal response of water solution of 10-, 50-, and 100-nm gold nanoparticles as a function of concentration under irradiation of a continuous wave 6-W 445-nm diode laser. The method allows determining concentrations as low 8 × 10−7 mg/ml, which corresponds to the detection of a single nanoparticle of 100- and 50-nm diameter or about 1000 nanoparticles of 10-nm diameter. The results demonstrate the application for the study of the optical response of a single nanoparticle in water suspension. We discuss the potential applications of the finding for detection of low concentration of biomolecules using a single nanoparticle.

Evaluation of the bactericidal potential of 2780-nm ER,CR:YSGG and 940-nm diode lasers in the root canal system

Successful endodontic therapy relies on chemomechanical debridement. Laser-assisted irrigation techniques are available for debridement. However, there are limited studies demonstrating the effectiveness of dual lasers for root canal disinfection. Hence, the aim of the present study is to determine if laser activation irrigation using the Er,Cr:YSGG and 940-nm diode laser is as effective as positive pressure needle irrigation using sodium hypochlorite (NaOCl) and ethylenediamine tetraacetic acid (EDTA). Fifty-two caries-free premolars were divided into six groups: G1, sterile water via positive pressure irrigation; G2, EDTA and NaOCl via positive pressure irrigation; G3, sterile water and the Er,Cr:YSGG cleaning and disinfection step; G4, sterile water and the Er,Cr:YSGG cleaning and disinfection step followed by disinfection with the 940-nm diode; G5, sterile water and the Er,Cr:YSGG cleaning step followed by a disinfection step with the Er,Cr:YSGG and diode laser together; and G6, negative controls. S1 samples were validated in both negative and positive control groups via culturing. All teeth, except the negative controls, were inoculated with Enterococcus faecalis. S2 sampling after treatments was completed and tested for bacterial presence via culturing and SEM and CLSM analysis. The data demonstrated that the traditional irrigation group (G2) and the dual laser group (G5) showed the greatest percentage decrease in bacterial counts from the S1 to the S2 group. The data demonstrates that the combination of the Er,Cr:YSGG and 940-nm diode laser wavelengths is safe and more effective than either laser alone and is comparable to needle irrigation with sodium hypochlorite and EDTA.

Underwater wireless optical communication system using a 16-QAM modulated 450-nm laser diode based on an FPGA.

An underwater wireless optical communication (UWOC) system with a 450-nm laser diode and a 150-MHz PIN photodiode is presented. The 16-ary quadrature amplitude modulation scheme is employed and realized on a field-programmable gate array (FPGA) to efficiently provide a high data rate. Experimental results show that this system can achieve data rates up to 50Mbps over a distance of 3m underwater with a bit error rate (BER) of 7.11×10-4 in artificial seawater at 35‰ salinity, where the attenuation coefficient is 0.481. This BER is below the forward error correction target of 3.8×10-3. Thus, this system can provide reliable high-speed communications over short to moderate distance point-to-point UWOC links.

Low-level laser therapy affects dentinogenesis and angiogenesis of in vitro 3D cultures of dentin-pulp complex.

To investigate the effects of gallium-aluminum-arsenide (GaAlAs) diode laser low-level laser therapy (LLLT) on angiogenesis and dentinogenesis of the dentin-pulp complex in a human tooth slice-based in vitro model. Forty tooth slices were prepared from 31 human third molars. Slices were cultured at 37°C, 5% CO2, and 95% humidity and randomly assigned to one of the following groups: group I: no laser treatment, group II: 660-nm diode laser; energy density = 1J/cm2, group III: 660-nm diode laser; energy density = 3J/cm2, group IV: 810-nm diode laser; energy density = 1J/cm2 and group V: 810-nm diode laser; energy density = 3J/cm2. LLLT was applied on the third and fifth days of culture. After 7days, tissues were retrieved for real-time RT-PCR analysis to investigate the expression of VEGF, VEGFR2, DSPP, DMP-1, and BSP in respect to controls. Lower energy density (1J/cm2) with the 660nm wavelength showed a statistically significant up-regulation of both angiogenic (VEGF: 15.3-folds and VEGFR2: 3.8-folds) and odontogenic genes (DSPP: 6.1-folds, DMP-1: 3-fold, and BSP: 6.7-folds). While the higher energy density (3J/cm2) with the 810nm wavelength resulted in statistically significant up-regulation of odontogenic genes (DSPP: 2.5-folds, DMP-1: 17.7-folds, and BSP: 7.1-folds), however, the angiogenic genes had variable results where VEGF was up-regulated while VEGFR2 was down-regulated. Low-level laser therapy could be a useful tool to promote angiogenesis and dentinogenesis of the dentin-pulp complex when parameters are optimized.

Constant temperature operation of fiber-optic hot-wire anemometers.

We demonstrate the constant temperature (CT) operation of a fiber-optic anemometer based on a laser-heated silicon Fabry-Perot interferometer (FPI), where the temperature of the FPI is kept constant by adjusting the heating laser power through a feedback control loop and the output signal is the heating laser power. We show that the CT operation can dramatically improve the frequency response over the commonly used constant power (CP) operation, where the laser heating power is kept constant and the output signal is the temperature of the FPI. For demonstration, we used a 100-μm-diameter, 200-μm-thick silicon FPI attached to the tip of a single-mode fiber as the anemometer. The FPI was heated by a 980-nm diode laser, and the temperature was measured using a 1550-nm diode laser. The effect of flow changes was simulated by exposing the silicon FPI to radiation from an external intensity-modulated laser beam. We show that the 10%-90% rise time of the step response in air was reduced from 625ms for CP operation to 1.8ms for CT operation, and the 3-dB bandwidth was increased from 0.5Hz for CP operation to 2kHz for CT operation. The response of the anemometer also shows good linearity to the radiation power.

A prospective, comparative evaluation of axillary hair removal with an 808-nm diode laser at different fluences

A prospective, comparative evaluation of axillary hair removal with an 808-nm diode laser at different fluences

Photobiomodulation by a 635nm Diode Laser on Peri-Implant Bone: Primary and Secondary Stability and Bone Density Analysis-A Randomized Clinical Trial.

Introduction Various procedures in dental implantology are performed to enhance the bone healing process and implant stability. One of these methods can be a low-level laser therapy (LLLT). Objectives The aim of our study was to evaluate the stabilization (primary and secondary) and bone density in peri-implant zone after LLLT protocol using a 635 nm diode laser. Material and Methods The research included 40 implants placed in the posterior region of a mandible in 24 patients (8 women and 16 man; age: 46.7 ± 8.7 years). The patients were randomly divided into 2 groups G1 (n=12, 18 implants) and G2 (n=12, 22 implants) according to the treatment procedure; G1 (test): 635 nm laser, with handpiece diameter: 8mm, output power: 100mW, spot area: 0.5024cm2, average power density: 199.04mW/cm2, continuous mode, dose: 4J per point (8J/cm2), time: 40 sec per point, 2 points (irradiation on a buccal and a lingual side of the alveolus/implant), and total energy per session 8J; G2 (control): no laser irradiation. The G1 (test) group's implants were irradiated according to the following protocol: 1 day before surgery, immediately after the surgery and 2, 4, 7, and 14 days after. The total energy after all therapeutic sessions was 48J. The implants stability was measured employing a Periotest device (Periotest Test Value: PTV) (measured immediately after the surgery, 7 days, 2 weeks, 4 weeks, and 2 and 3 months after the surgery) and the bone density using cone-beam computed tomography (grayscale value) (measured immediately after the surgery, 4 weeks and 12 weeks after the treatment). Results The average implant stability at different time points showed lower PTV value (higher stability) at 2nd and 4th week after 635 nm laser irradiation (G1) compared with a control (G2) group (p<0.01). The secondary stability of the implants after 12 weeks observation was not significantly higher for the laser group in contrast to none-irradiated implants (p>0.05). The mean grayscale value at the apical, middle, and cervical level of the titanium implants showed the reduction of pixel grayscale value after 2 weeks and was lower for the G1 group in contrast to the G2 group (p<0.01). The value of grayscale after 12 weeks was significantly higher at the middle and apical level of the implants in the G1group in contrast to the G2 group (p<0.01). Conclusion The application of the 635 nm diode laser enhanced secondary implant stability and bone density. However, to assess the impact of the LLLT on peri-implant bone with different bone densities, further well-controlled long-term trials on larger study groups are needed.

Tunable magnetic and fluorescent properties of Tb3Ga5O12 nanoparticles doped with Er3+, Yb3+, and Sc3+

In this study, we present the synthesis of Tb3Ga5O12 nanoparticles doped with Er3+, Yb3+, and Sc3+ ions, prepared using a co-precipitation method. These materials have well-defined magnetic-fluorescence properties. The effects of Yb3+ ion concentration on the structural characteristics, morphology, luminescence, and magnetic properties of the nanoparticles were investigated in detail using X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, photoluminescence spectroscopy, and vibrating sample magnetometer measurements. Under 980-nm laser diode excitation, the nanoparticles displayed bright up-conversion luminescence, showing evidence of resonant energy transfer from the Yb3+ to Er3+ ions. Intense green and red emissions located at approximately 526, 548, and 656 nm were attributed to the radiant transitions of 2H11/2 → 4I15/2, 4S3/2 → 4I15/2, and 4F9/2 → 4I15/2 of Er3+, respectively. These observations indicate that Tb3Ga5O12:Er3+, Yb3+, Sc3+ magnetic–fluorescent bifunctional nanoparticles are promising materials for use in bioimaging and magnetic bio-separation applications.

Adjunctive efficacy of diode laser in the treatment of peri-implant mucositis with mechanical therapy: A randomized clinical trial.

Due to the inconclusive findings on the effect of laser therapy in the management of peri-implant diseases, the aim of this study was to analyze the adjunctive clinical efficacy of 980-nm diode laser (DL) irradiation in the treatment of peri-implant mucositis with mechanical debridement. Two hundred and twenty patients with one implant diagnosed with peri-implant mucositis (probing depth [PD]≥4mm and bleeding on probing [BoP] [primary outcome]) were randomly allocated to test and control treatments. Patients in the control group (n=110) received debridement using curettes and ultrasonic devices, while patients allocated in the test group (n=110) received mechanical therapy in combination with DL irradiation (setting 980nm, 2.5W, 10kHz, pw, 30s). BoP, presence of plaque, and PD were recorded at baseline, 1month, and 3months after treatment. Both therapeutic modalities yielded similar clinical improvements with comparable reductions in the number of BoP-positive sites, plaque scores, and PD values at 3months (all p-values>0.05). Complete disease resolution was obtained in 38/110 (34.5%) implants in the test group compared with 34/110 (30.9%) implants in the control group at the end of the observation period. Based on these results, the adjunct use of DL did not yield any statistically significant clinical benefit as compared to nonsurgical mechanical treatment alone in controlling peri-implant inflammation at 3months.

Effects of diode laser setting for laryngeal surgery in a rabbit model.

To study the damaging effect of different diode laser settings on vocal folds 7 days after injury in a rabbit model. Twenty-one male New Zealand white rabbits were randomized into three groups with seven animals per group. A 980-nm diode laser was used to create a single spot injury in each vocal fold. Different modulation frequencies (10Hz versus 1000Hz) in pulsed mode, different powers (3W versus 5W), and distinct wave modes of radiation (pulsed versus continuous) were compared. The extent of the inflammatory infiltrate and ablation crater were greater when using 5-W optical power compared with 3W. The extent and depth of the inflammatory infiltrate, and the width and depth of the ablation crater were greater with continuous wave mode compared with pulsed mode. The density of collagen fibers only increased when using the laser in continuous wave mode. The use of the 980-nm diode laser with an output power of 5W produced an increased extent of thermal injury compared to an output power of 3W and, more importantly, using continuous rather than pulsed wave mode significantly increased the extent and depth of thermal injury in rabbit vocal folds.

971 - Comparing transurethral endoscopic enucleation of the prostate using 980nm diode laser vs. bipolar-plasmakinetic: Dual-centre, noninferiority, randomized controlled trial with 2-year follow-up results

971 - Comparing transurethral endoscopic enucleation of the prostate using 980nm diode laser vs. bipolar-plasmakinetic: Dual-centre, noninferiority, randomized controlled trial with 2-year follow-up results

A Low-Cost Experimental Kit for Teaching Wave Optics Based on the CDIO Approach

We constructed a low-cost experimental kit consisting of a compact 532-nm diode laser, optics, and optomechanical components that arrange on a small honeycomb breadboard. The kit is flexible enough to construct five typical wave optic experiments, e.g., double-slit interference, Michelson and Mach-Zehnder interferometers, diffraction, and Malus’s law of polarization. It is useful to use in both classrooms and laboratories to enhance experimental skills and creativity based on the CDIO (Conceive-Design-Implement-Operate) approach.

Adjusting white light in Er3+/Tm3+/Yb3+ tridoped ZrO2/WO3 nanocrystals

To develop a white light-emitting diode (LED) phosphor with a better performance, we will make an Er3 + / Tm3 + / Yb3 + tridoped ZrO2 / WO3 composite nanophosphor through the sol–gel method. Using a 975-nm laser diode, we analyze the upconversion luminescence performance of the sample. The result shows that the Er3 + / Tm3 + / Yb3 + tridoped sample can emit strong white light and its color temperature is adjustable. The study helps to explore efficient, complex nanophosphors for white LEDs.

Posterior laryngofissure using a surgical contact diode laser: an experimental feasibility study.

To evaluate the feasibility of a 980-nm contact diode laser (CDL) as a method for creating a posterior laryngofissure in live pigs. Twenty-eight Landrace pigs (15-20kg) were anesthetized, intubated, ventilated, and submitted to a cervical tracheostomy. An anterior and posterior midline longitudinal laryngofissure incision was created according to randomization-control (n = 4), posterior laryngofissure with a scalpel blade; electrocautery (n = 12), posterior laryngofissure by electrocautery (10, 15, 20, 25W powers); CDL (n = 12), posterior laryngofissure by the CDL (10, 15, 20, 25W peak powers in pulsed mode). Larynx and proximal trachea were excised, prepared for histopathology, and digital morphometric analysis. Measurements in and within each group were analyzed (Kruskal-Wallis and Dunn test) with a level of significance of p < 0.05. Incision width was not different between the groups, as well as in the powers used in CDL (p = 0.161) and electrocautery group (p = 0.319). The depth of the incisions was smaller in the Laser group compared to control (p = 0.007), and in the electrocautery compared to control (p = 0.026). Incision area was smaller in CDL compared with the control (p = 0.027), and not different between laser and electrocautery groups (p = 0.199). The lateral thermal damage produced by electrocautery was the largest, with a significant difference between laser and electrocautery (p = 0.018), and between electrocautery and control (p = 0.004), whereas the comparison between laser and control showed no significant differences (p = 0.588). The posterior laryngofissure incision using a 980-nm CDL is feasible resulting in smaller incisional area and less lateral thermal damage.

Continuously Tunable Optical Notch Filter With Functions of a Mirror and a Beam Splitter

The objective of this study was to develop continuously tunable optical notch filters by combining four left- and right-handed circular cholesteric liquid crystal (CLC) cells without subsidiary optical components. By rotating each filter, the photonic band position could be continuously blue shifted over 100-nm spectral range. Using four notch filter sets with four different chiral dopant concentrations, spectral range from 440 to 870 nm could be covered. Since each CLC cell has only one chiral dopant concentration, it could be stable for a long time. Each filter is independent of polarization in the spectral range. Filter performance was highly enhanced by introducing an anti-reflection layer on the filter device. There was no light leakage inside the photonic band. Outside the band, transmittance was about 70%-100%. In addition, these filters had stable operation under extremely high laser intensity (~124 W/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> of CW 532-nm diode laser and ~4.43 MW/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> of Nd: YAG pulse laser operation for 2 h) without showing damage. Such filters also have functions as a mirror and a beam splitter. Depending on CLC materials, this simple and easy strategy could be used to prepare filters for applications in VIS and NIR spectral range devices.

Effect of Root Canal Disinfection with a Diode Laser on Postoperative Pain After Endodontic Retreatment.

Objective: The aim of this randomized clinical trial was to evaluate the influence of root canal disinfection with a 940-nm diode laser on the intensity of pain after endodontic retreatment. Background data: Microorganisms are the most common causes of tooth pain. Therefore, clinical studies are needed to explore the effect of disinfection techniques on postoperative pain. Methods: Eighty-four patients scheduled for endodontic retreatment were allocated to two groups in a 1:1 ratio (n = 42 each). After root canal filling removal and chemomechanical procedures, the root canals were disinfected with a 940-nm diode laser in one group [laser disinfection (LD) group]. In the other group, a mock application of laser was made with the power off [pseudo-laser disinfection (PLD) group]. All retreatment procedures were completed in a single visit. The patients assessed their pain levels at 24, 48, and 72 h after retreatment using a numeric rating scale. The number of analgesic pills used during this period was also recorded. The collected data were statistically analyzed using Mann-Whitney U and Wilcoxon tests. Results: Postoperative pain on the first 2 days was significantly lesser in the LD group than in the PLD group (p < 0.05), and the difference became insignificant on the third day (p > 0.05). Moreover, analgesic intake over 3 days and pain on percussion on the fourth day were significantly lesser in the LD group than in the PLD group (p < 0.05). Conclusions: Elimination of microorganisms from root canals is important for preventing postoperative complications. Our findings suggest that diode LD can reduce postoperative pain and provide comfort after endodontic retreatment. This study is registered in www.ClinicalTrials.gov database with the identifier number NCT03584880.

Laser ignitibility of energetic crystals doped with gold nanoparticles

Laser ignition mechanism enhances the safety of explosive applications. However, optical sensitisation of the energetic materials is required for their optical absorption. In this research, explosive Cyclotrimethylene Trinitramine (RDX) was doped with gold nanoparticles during recrystallisation to provide a suitable optical sensitisation method. The relationship between the precipitation rate used during RDX recrystallisation and the subsequent laser ignition properties using an 808-nm continuous wave diode laser was studied. Faster initial precipitation was found to reduce the laser ignition delay times and smaller nanoparticle size reduced ignition thresholds. It was shown that recrystallized RDX particle size, which is determined by both nanoparticle induced nucleation and precipitation rate, affects the ignition delay time and quality of the crystals. The largest crystals in each batch were investigated using both high-speed photography and microscopic etching, revealing that in contrast to the bulk sample (which was generally a powder), a slower precipitation seems to achieve better doping. The largest crystals in each sample therefore do not represent the bulk sample, a useful indication as such large crystals are easier to handle and therefore tend to be selected for detailed characterisation work.