Flexible Laser Research Articles

Selective Generation of Laser Transverse Modes by Gain Regulation With a Digital Micromirror Device

The selective generation of laser transverse modes by gain regulation with a digital micromirror device (DMD) is presented in this letter. The gain regulation in laser medium is adjusted by the switch of the patterns loaded on DMD. Structured pump beam patterns can be obtained after the reflection of the loaded patterns on DMD, and then it’s defocused into a microchip laser medium by a short focal lens, so that the pump patterns can be transferred to the gain medium to regulate the gain distribution. Corresponding structured laser beams can be generated by this laser system. The laser beam pattern can be regulated easily and quickly, by switching the loaded patterns on DMD. Through this method, we show a simple and flexible laser system to generate on-demand laser beam patterns.

High-Density Nanowells Formation in Ultrafast Laser-Irradiated Thin Film Metallic Glass

HighlightsUltrafast laser-induced nano-topography modifications: generation of highly concentrated 20 nm diameter nanowells on the surface with expected applications for storage of chemical and biological active species and for blocking crack propagation.Ultrafast laser-induced structural modifications: turning of a metallic glass to a composite material of monoclinic zirconia crystallites embedded inside amorphous metallic glass.A flexible one-step laser irradiation process without direct mechanical contact for thin film metallic glasses surface functionalization.

The evaluation of the usefulness of CO2 laser in microsurgical resection of brain tumors.

Background: Since its introduction to surgery, the CO2 laser has been used in the treatment of various neurosurgical pathologies as it combines cutting, vaporizing, and coagulating properties in one tool and has a safe penetration depth. In this case series of 29 patients, we present the evaluation of the usefulness of the closed system type – sealed tube surgical CO2 laser in the surgical removal of brain tumors.Methods: The Sharplan 40C model SurgiTouch, sealed tube type CO2 laser, was used in the resection of 29 brain tumors; 13 meningiomas, six metastases, nine gliomas, and one acoustic neuroma. The same senior surgeon (BT) assessed and classified the benefit provided by the CO2 laser in the resection of the neoplasms to considerable (Group 1), moderate (Group 2), and poor (Group 3).Results: Group 1 included 14 patients with 13 meningiomas and one acoustic neuroma, Group 2 included six patients, all of whom had metastases, and Group 3 included nine patients of which six had glioblastoma and three astrocytoma. No complications or technical problems occurred due to the use of the CO2 laser.Conclusion: The CO2 laser is a valuable complementary tool in brain tumor surgery displaying high efficacy and practicality in the resection of neoplasms which are fibrous and have hard consistency. It has high acquisition and maintenance cost and cannot replace the bipolar diathermy. The newest generation of flexible CO2 laser fiber provides more ergonomy and promises new perspectives of its neurosurgical use in the modern era.

10 kW rectangular laser beam generation with incoherent space combiner

In this paper, we report an incoherent space laser beam combiner for rectangular beam combination with 18 fiber-transmitted semiconductor lasers at 972 nm wavelength. The coupled thermo-mechanical properties of all the optical lenses in the combiner were analyzed to evaluate the long-term reliability of the combiner subjected to beyond 10 kW high-power laser irradiation. An experiment-based numerical model was developed on the basis of the multi-beam laser volumetric heat source, and the performance of lenses irradiated by 10 kW combined laser for 1000 s was studied with finite element method (FEM). The maximum temperature among all lenses was 427.27 K which is much lower than the softening point temperature of fused silica material made of lenses. And the 0.1 aperture number corresponding to the maximum thermal deformation of 4.53 µm is much smaller than the conventional optical lens processing tolerance. The maximal stress of 12.73 MPa is far less than the yield stress of 4.5 GPa for the material. The manufactured laser beam combiner realized a highest output power of 10.641 kW at a power combination efficiency of 98.5%, a combination length of 200 mm and a rectangular focal beam spot of 30 mm × 10 mm. Our method provides a valuable choice for realizing fast and flexible laser surface heat treatment.

Flexible ureteroscopy without ureteral access sheath

IntroductionUreteral access sheath (UAS) is widely used in flexible ureteroscopy and laser lithotripsy (FURS) based on better stone-free rates, lower intrarenal pressure and fewer complications. However, it also rises surgical costs and may injure the ureteral wall. The main objective of our study is to compare safety and efficacy of FURS with and without UAS to evaluate whether its use is justified in all cases. Materials and methodsWe performed a retrospective observational analytic study based on a prospective database. A total of 241 consecutive patients who underwent FURS for upper ureter and renal stones between January 2018 and May 2020 were included for analysis and divided into two groups upon UAS use. We compared demographic data, stone characteristics, prestenting, operative time, need for ureteral stent, postoperative urinary tract infection, renal colic and need for ancillary procedures. ResultsA total of 198 patients (82.2%) were included in the group without UAS. Operative time was significantly shorter in the group of patients without UAS than those with UAS (64.6 minutes ± 29.5 vs. 89.9 minutes ± 2.8 respectively; p 0.010). Both groups had similar rates of colic pain and urinary tract infection. Ancillary procedures were more frequent in the UAS group (37.2 vs. 21.2%; p 0.026), but significance was lost in multivariate assessment. ConclusionFURS without UAS seems to be as safe as FURS with UAS but requires less ancillary procedures. An additional advantage is shorter operative time.

Detection of shallow wall-thinning of pipes using a flexible interdigital transducer-based scanning laser Doppler vibrometer

Interdigital transducer (IDT)-based scanning laser Doppler vibrometers (SLDVs) have recently been developed to detect shallow defects in plates. An IDT-based SLDV was augmented with Lamb wave frequency fusion capability to enable the imaging of defects across the entire depth of a plate. Dry-coupled IDTs are a type of field-deployable IDT that do not require the attachment of a couplant to the structure. However, this technique is not applicable to the analysis of shallow wall thinning, because IDTs composed of lead zirconium titanate (PZT) cannot be attached to the curved surface of a structure. To address this issue, we developed a new type of IDT—the flexible IDT—that can be bent along the circumferential direction of a pipe. To set the gap spacing of the flexible IDT, the wavenumber sensitivity and minimum distance from the reference mode (MDRM) was calculated, and the S 0 mode is selected to ensure high-wavenumber sensitivity above the threshold of the MDRM. The proposed flexible IDT-based SLDV was tested by using it to visualize the wall thinning on pipes with 4%, 6%, and 20% thinning. The results of this study will contribute toward the development of systems that improve on existing planar laser scanning schemes and enable shallow defect detection in pipes using laser ultrasonics.

The clinical outcomes of flexible ureteroscopy and laser lithotripsy (FURSL) for treatment of the upper urinary tract calculi

To evaluate efficacy and safety of flexible ureteroscopy and laser lithotripsy (FURSL) for treatment of the upper urinary tract calculi. We retrospectively analyzed 784 patients who underwent FURSL between January 2015 and October 2020 in our unit. All patients were preoperatively evaluated with urine analysis, serum biochemistry, urinary ultrasonography, non-contrast computed tomography and intravenous urography. The procedure was considered as successful in patients with complete stone disappearance or fragments < 4 mm on B ultrasound or computed tomography. The operative parameters, postoperative outcomes and complications were recorded and analyzed respectively. The average operative time and postoperative hospital stay were 46.9±15.8 min and 1.2±1.1 days, respectively, among 784 patients. In addition, 746 patients were followed up and 38 patients were lost. In these patients, 700 (93.8%) cases met the stone removal criteria and 46 cases (6.2%) did not meet the stone removal criteria who need further treatment. The stone free rate (SFR) is 92.5%after 1-3 months and SFR of middle and upper calyceal calculi was higher than that of lower calyceal calculi significantly. The most common complications were fever (58/784, 7.4%), gross hematuria (540/784, 68.9%) and lpsilateral low back pain (47/784, 6.0%). The incidence rate of serious complication was 1.28%(10/784), including 5 cases of septic shock and 5 cases of subcapsular hematoma, which were cured after active treatment. FURSL is a reliable treatment for small and medium calculi patients of upper urinary tract. The curative effect of stone removal is clear. The complications are few and the safety is high. However, there are certain limitations to the efficacy in treating larger stone and lower calyceal calculi.

Development of an Efficient Voltammetric Sensor for the Monitoring of 4-Aminophenol Based on Flexible Laser Induced Graphene Electrodes Modified with MWCNT-PANI.

Sensitive electrodes are of a great importance for the realization of highly performant electrochemical sensors for field application. In the present work, a laser-induced carbon (LIC) electrode is proposed for 4-Aminophenol (4-AP) electrochemical sensors. The electrode is patterned on a commercial low-cost polyimide (Kapton) sheet and functionalized with a multi-walled carbon nanotubes polyaniline (MWCNT-PANI) composite, realized by an in-situ-polymerization in an acidic medium. The LIC electrode modified with MWCNT-PAPNI nanocomposite was investigated by SEM, AFM, and electrochemically in the presence of ferri-ferrocyanide [Fe(CN)6]3−/4− by cyclic voltammetry and impedance spectroscopy. The results show a significant improvement of the electron transfer rate after the electrode functionalization in the presence of the redox mediators [Fe(CN)6]3−/4−, related directly to the active surface, which itself increased by about 18.13% compared with the bare LIG. The novel electrode shows a good reproducibility and a stability for 20 cycles and more. It has a significantly enhanced electro-catalytic activity towards electrooxidation reaction of 4-AP inferring positive synergistic effects between carbon nanotubes and polyaniline PANI. The presented electrode combination LIC/MWCNT-PANI exhibits a detection limit of 0.006 μM for the determination of 4-AP at concentrations ranging from 0.1 μM to 55 μM and was successfully applied for the monitoring in real samples with good recoveries.

Design novel, flexible, and wide-scale CUT-OFF laser filters of Eosin Yellow dye/PVA polymeric composite films: Enhance the electrical conductivity and dielectric properties of PVA

The basic component of optoelectronics technology is the optical filter, particularly the laser cut-off filter. Within this study, casting technique used to prepare polymeric composite film of (Eosin Yellow dye doped poly(vinyl alcohol) (EY/PVA)) for optical filter. This research has been performed on the XRD scan, UV-Vis-NIR and electrical spectroscopic analysis of EY/PVA films. XRD histogram shows reduction of composite films crystallinity. The transmittance of the films reduced as the dye content increases. A significant reduction in the composite's bandgap with Eosin Y doping is observed owing to the interactions between the functional group of the dye molecule and the hydroxide group in the PVA polymer matrix. Higher content of EY/PVA films (10 and 25) wt% can completely block incident light from 200 nm to 630 nm, which emphasizes the composite's strong potential as an effective optical filter. The optical limiting for EY/PVA films was tested with He-Ne laser beam source at the wavelength of 632.8 nm. It demonstrated the best possible optical limit behavior at high dyes content. The frequency dependence was evaluated on the AC electrical conductivity, dielectric constant, and dielectric loss were analyzed. The studied showed an improvement of the electrical conductivity and dielectric properties with increasing the EY-doping. The samples are ideal for the use of optical limits in CUT-OFF selective laser filters, solar cell, and variety of applications in industrial, electronics, pharmaceutical, medical, and related industries.applications.

Ureteroscopia flexible sin vaina de acceso ureteral

IntroductionUreteral access sheath (UAS) is widely used in flexible ureteroscopy and laser lithotripsy (FURS) based on better stone-free rates, lower intrarenal pressure and fewer complications. However, it also rises surgical costs and may injure the ureteral wall. The main objective of our study is to compare safety and efficacy of FURS with and without UAS to evaluate whether its use is justified in all cases. Materials and methodsWe performed a retrospective observational analytic study based on a prospective database. A total of 241 consecutive patients who underwent FURS for upper ureter and renal stones between January 2018 and May 2020 were included for analysis and divided into two groups upon UAS use. We compared demographic data, stone characteristics, prestenting, operative time, need for ureteral stent, postoperative urinary tract infection, renal colic and need for ancillary procedures. ResultsA total of 198 patients (82.2%) were included in the group without UAS. Operative time was significantly shorter in the group of patients without UAS than those with UAS (64.6 minutes ± 29.5 vs. 89.9 minutes ± 2.8 respectively; p 0.010). Both groups had similar rates of colic pain and urinary tract infection. Ancillary procedures were more frequent in the UAS group (37.2 vs. 21.2%; p 0.026), but significance was lost in multivariate assessment. ConclusionFURS without UAS seems to be as safe as FURS with UAS but requires less ancillary procedures. An additional advantage is shorter operative time.

The usefulness and ergonomics of a new robotic system for flexible ureteroscopy and laser lithotripsy for treating renal stones.

To investigate the usefulness and ergonomics of a newly developed robotic system for flexible ureteroscopy (easyUretero). During in vitro testing, six participants performed renal stone removal four times in an artificial kidney-ureter-bladder model. Each participant manipulated a single-use digital flexible ureteroscope (LithoVue) with their hands and the robotic system, sequentially. We compared the task completion times of each participant. The ergonomics of and operational satisfaction with each procedure were assessed by questionnaires. In vivo tests evaluated the operability and safety of the robotic system in two live female pigs. We checked that all the steps of flexible lithotomy for renal stones could be completed individually. The task completion time with the robotic system during in vitro testing was significantly longer than with manual ureteroscopy regardless of the operator's competence level (expert professors: 282.6±92.4 seconds vs. 73.6±43.3 seconds, p<0.001; fellows: 247.5±57.7 seconds vs. 95.8±43.7 seconds, p<0.001; residents: 281.3±111.0 seconds vs. 188.6±138.6 seconds, p<0.001). The residents took more time to remove the upper and mid caliceal stones with the robotic system. The ergonomic evaluation was better for the robotic system, but operational satisfaction was lower, and there was no statistical difference among the groups. In vivo tests showed that all the steps of robotic flexible ureteroscopy could be completed without difficulty. No safety issues were encountered during the procedure. The robotic system (easyUretero) was ergonomic and safe for flexible ureteroscopy and laser lithotripsy for renal stones.

Outcomes of Ureterorenoscopy for Lower Pole Kidney Stones (≤3 cm) to the Omar Bongo Ondimba Army Instruction Hospital

Introduction: The management of kidney stones has benefited from endoscopic techniques, in particular the development of flexible ureteroscopy (ureterorenoscopy). This endoscopic treatment has made it possible to treat many upper urinary tract stones, with satisfactory results and less morbidity. This innovative minimally invasive technique was introduced in our country in 2018. It is not practiced in all health structures. We report our experience. Objectives: The aim of our study was to evaluate the place of flexible ureteroscopy laser, its feasibility, and the results on stones up to 30 mm in size only in the lower calicial group, while assessing the postoperative quality of life. Patients and Methods: We conducted a monocentric observational retrospective study at the Omar Bongo Ondimba Army Training Hospital (OBO ATH) on 22 patients with symptomatic inferior caliciel stones, over a period of January 2019 and December 2020 treated by flexible ureteroscopy laser (FUR-L), once or twice depending on the size of the residual fragments. Results: All the patients had symptomatic urolithiasis, diagnosed on the clinical elements, and confirmed in 77% by urinary computed tomography. The average age was 35.47 years ± 12, with a clear female predominance (64%). All the stones sat in the lower chalice. 66.5% of stones were larger than 10 mm. 75% of patients were “stones free” after one FUR-L session, and 100% after the second session. 10% of patients still had residual pain at 01 month which was absent at 03 month. 18% of postoperative urinary tract infections were treated with antibiotics. 90% of the patients had resumed an activity prior to 1 month. At 1 month and 3 months, 82% and 100% respectively were satisfied with the mode of treatment according to self-questioning. Conclusion: FUR-L remains a therapeutic modality for stones in the lower calicial group, for stones whose diameter is close to 30 mm. A sequential approach should be considered for diameter stone up to 30 mm.

Flexible Random Laser from a Porous Polymer Film

Flexible Random Laser from a Porous Polymer Film

Role of low- versus high-power laser in the treatment of lower pole stones: prospective non-randomized outcomes from a university teaching hospital.

Introduction:Ureteroscopy and laser stone fragmentation [flexible ureteroscopy and laser lithotripsy (FURSL)] has risen over the last two decades. Laser technology has also evolved over the time, shifting from low- to high-power lasers with the addition of MOSES technology that allows for ‘dusting and pop-dusting’ of stones. The aim of the study was to look at the outcomes of FURSL in lower pole stones (LPS) using low- and high-power lasers.Patient and Methods:In this study, we compared the outcomes of low-power holmium laser (group A, 20 W) and high-power holmium laser (group B, including both 60 W MOSES integrated system and 100 W lasers) for all patients with LPS treated with laser lithotripsy. Data were collected for patient demographics, stone location, size, pre- and postoperative stent, length of stay, complications and stone free rate (SFR).Results:A total of 284 patients who underwent FURSL procedure for LPS were analysed (168 group A, 116 group B). Outcomes showed that compared with group A, group B had a higher SFR (91.6% versus 96.5%, p = 0.13) and shorter operative time (52 versus 38 min, p < 0.001). The median length of stay was <24 h in all groups (day-case procedures). The complication rate was comparable between the two groups but with more infectious complications (n = 7) noted in group A compared with group B (n = 3) (p = 0.53).Conclusion:Compared with low-power laser, the use of high-power laser for LPS significantly reduced the use of ureteral access sheath (UAS), postoperative stent and procedural time. Although non-statistically significant, the SFR was higher in the high-power group even for relatively larger stone sizes, which was also reflected in a reduction of sepsis-related complication rates with these lasers.

A Case of Huge Vocal Polyp in a Patient With Difficult Laryngeal Exposure Treated by Fiberoptic Laryngeal Laser Surgery Under Local Anesthesia

Indications of fiberoptic laryngeal laser surgery (FLS) procedure have broadened by the development of flexible fiberoptic endoscopes and flexible laser systems. FLS procedure performed under local anesthesia and it is the unique value of FLS. The surgery can be performed on patients who are impossible to undergo general anesthesia and difficult to be exposed by laryngeal microsurgery. Main indication of FLS procedure was small to moderate sized hemorrhagic vocal polyp, but we experienced a case of huge vocal polyp with difficult laryngeal exposure treated by FLS procedure under local anesthesia. The vocal polyp was removed successfully without vocal fold scar through fiberoptic laryngeal laser surgery under local anesthesia.

Estimation of optical properties and design of a flexible tunable laser from a green conjugated copolymer

A distributed feedback-based flexible laser with broadband tunability was fabricated using a green conjugated copolymer (CP) poly [(9,9-dioctylfluorenyl-2,7-diyl)-co-(1,4-diphenylene-vinylene-2-methoxy-5-{2-ethylhexyloxy}-benzene)] (PFO-co-PPV-MEHB) as an active medium. The CP was embedded in a solid-state host polymer made of commercially available ethylene vinyl acetate/terpene phenol (1%) [EVA-TPR (1%), or EVA] composite to retain the transparency and efficiency of the solution. To design a suitable distributed feedback (DFB) system, we calculated the effective Bragg length (Λeff) for the CP/EVA composite. The absorption, fluorescence, transmission, and reflectance of the PFO-co-PPV-MEHB films were measured experimentally. The experimental data were used to calculate the refractive index and other properties of the CP/EVA composite. The Λeff of the DFB system was chosen based on the fluorescence region and the change in Bragg length (ΔΛeff) for tunability resolution of wavelength (Δλ). A flexible aluminum master grating was selected. The DFB film was either embossed or molded on the CP/EVA composite. The CP/EVA (DFB) composite was pumped by pulsed Nd: YAG laser (3rd harmonics). Bending (strain) of the active media was used for wavelength tuning. The emitted laser had a full-width half maximum (FWHM) of 1.5 ± 0.5 nm, and the range of tunability was 45 nm (495–535 nm). The solid-state DFB active media is stable up to 3000 compressions.

Symptomatic renal papillary varicosities and medullary nephrocalcinosis

BackgroundNephrocalcinosis is often asymptomatic but can manifest with renal colic or hematuria. There is no reported association between nephrocalcinosis and renal vascular malformations, which may also be a source of hematuria. We herein present a case of a patient with hematuria related to nephrocalcinosis and renal papillary varicosities. These varicosities were diagnosed and successfully treated with flexible ureteroscopy and laser fulguration.Case presentationA 24-year-old female with a history of epilepsy (on zonisamide), recent uncomplicated pregnancy, and new diagnosis of nephrocalcinosis presented with right flank pain and intermittent gross hematuria. Imaging revealed intermittent right sided hydronephrosis. A cystoscopy identified hematuria from the right ureteral orifice. Diagnostic flexible ureteroscopy revealed numerous intrapapillary renal stones and varicose veins of several renal papillae. A 200 μm holmium laser fiber was used to unroof these stones and fulgurate the varicosities with resolution of her symptoms for several months. She later presented with left-sided symptoms and underwent left ureteroscopy with similar findings and identical successful treatment.ConclusionUnilateral hematuria from discrete vascular lesions of the renal collecting system may be obscured by other benign co-existing conditions, such as nephrocalcinosis and nephrolithiasis. Although a simultaneous presentation is rare, flexible ureteroscopy with laser fulguration offers an ideal diagnostic and therapeutic modality for these concurrent conditions if symptoms arise.

Mechanical and nonlinear optical properties of two-dimensional LiXY2 (X=Al, Ga, In; Y[dbnd]S, Se, Te) monolayers

Two-dimensional (2D) nonlinear optical (NLO) materials with large flexibility possess application advantages for phototransistors and flexible laser fields. In this work, we studied the electronic, mechanical and NLO properties of 2D LiXY2 (X = Al, Ga, In; YS, Se, Te) monolayers via first-principles calculations. Theoretical results suggest that their bandgaps, which determine laser damage threshold (LDT) and harmful two-photon absorption (TPA), are as wide as that of typical 2D NLO materials single-layer GaSe and MoS2. The large energy gap between In-5s and Y-pz states will help single-layer LiXY2 to avoid TPA in a wide range of optical energies. Their NLO coefficients are comparable to that of bulk AgGaS2 and single-layer GaSe. Moreover, 2D LiXY2 monolayers are stable under mechanical distortion, and even more flexible than single-layer GaSe and MoS2. Overall, this work supplies a group of 2D materials exhibiting superiority as flexible NLO devices in nanotechnology.

Anti-Counterfeiting White Light Printed Image Multiplexing by Fast Nanosecond Laser Processing.

Passive plasmonic metasurfaces enable image multiplexing by displaying different images when altering the conditions of observation. Under white light, three-image multiplexing with polarization-selective switching has been recently demonstrated using femtosecond-laser-processed random plasmonic metasurfaces. Here, the implementation of image multiplexing is extended, thanks to a color-search algorithm, to various observation modes compatible with naked-eye observation under incoherent white light and to four-image multiplexing under polarized light. The laser-processed random plasmonic metasurfaces enabling image multiplexing exhibit self-organized patterns that can diffract light or induce dichroism through hybridization between the localized surface plasmon resonance of metallic nanoparticles and a lattice resonance. Improved spatial resolution makes the image quality compatible with commercial use in secured documents as well as the processing time and cost thanks to the use of a nanosecond laser. This high-speed and flexible laser process, based on energy-efficient nanoparticle reshaping and self-organization, produces centimeter-scale customized tamper-proof images at low cost, which can serve as overt security features.

Flexible fiber laser for rapid material processing

AbstractLaser experts from Saxony and Israel are jointly testing a novel laser for industrial use at the Fraunhofer Institute for Material and Beam Technology IWS in Dresden. The system is based on the coherent beam combining (CBC) method, which is still new for high‐power lasers.