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Nanotube mode-locked, wavelength and pulsewidth tunable thulium fiber laser
摘要： Mode-locked oscillators with highly tunable output characteristics are desirable for a range of applications. Here, with a custom-made tunable filter, we demonstrate a carbon nanotube (CNT) mode-locked thulium fiber laser with widely tunable wavelength, spectral bandwidth, and pulse duration. The demonstrated laser’s wavelength tuning range reached 300 nm (from 1733 nm to 2033 nm), which is the widest-ever that was reported for rare-earth ion doped fiber oscillators in the near-infrared. At each wavelength, the pulse duration can be regulated by changing the filter’s bandwidth. For example, at ~1902 nm, the pulse duration can be adjusted from 0.9 ps to 6.4 ps (the corresponding output spectral bandwidth from 4.3 nm to 0.6 nm). Furthermore, we experimentally and numerically study the spectral evolution of the mode-locked laser in presence of a tunable filter, a topic that has not been thoroughly investigated for thulium-doped fiber lasers. The detailed dynamical change of the mode-locked spectra is presented and we observed gradual suppression of the Kelly sidebands as the filter’s bandwidth is reduced. Further, using the polarization-maintaiing (PM) cavity ensures that the laser is stable and the output laser’s polarization extinction ratio is measured to exceed 20 dB.
关键词： thulium fiber laser,spectral bandwidth,polarization-maintaiing cavity,Kelly sidebands,tunable wavelength,pulse duration,Mode-locked oscillators,carbon nanotube
更新于2025-11-28 14:23:57
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1.8?μm passively Q-switched thulium-doped fiber laser
摘要： This work demonstrates a simple and reliable passively Q-switched thulium-doped fiber laser capable of generating an output with a peak wavelength at 1.8 μm. Lasing is realized from the shorter wavelength region of a thulium-doped silica fiber gain medium by suppressing lasing at longer wavelengths in combination with a tunable bandpass filter. The laser is modulated by a single-walled carbon nanotube film saturable absorber. The generated Q-switched laser is capable of achieving a high repetition rate of 67.9 kHz and a narrow pulse width of 1.2 μs. As most work on the 1.6–1.8 μm waveband focuses on continuous-wave and mode-locked lasers, to the best of the author’s knowledge, this is the first demonstration of a passively Q-switched thulium-doped fiber laser operating at 1.8 μm with an all-silica fiber setup. The demonstrated laser has potential for various applications including biomedical surgery and polymer-based welding applications.
关键词： 1.8 μm,Thulium,Fiber laser,Q-switched
更新于2025-11-28 14:23:57
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Comparison of the ablation rates, fissures and fragments produced with 150???μm and 272???μm laser fibers with superpulsed thulium fiber laser: an in vitro study
摘要： Introduction Holmium:YAG(Ho:YAG) is currently the standard for lithotripsy. Superpulsed Thulium Fiber Laser(TFL) has been evaluated as an alternative for lithotripsy, using laser fibers with core-diameters(CDF) down to 50 μm and additional available settings suitable for “dusting” technique. This in-vitro study compared ablation rates, fissures and fragments’ size with 150μmCDF or 272μmCDF with different laser settings using TFL and Ho:YAG. Methods 150CDF and 272CDF were compared using three settings for TFL “fine dusting”(FD:0.15 J/100 Hz); “dusting”(D:0.5 J/30 Hz); “fragmentation”(Fr:1 J/15 Hz) and Ho:YAG(D and Fr). An experimental setup consisting of immerged 10 mm cubes of artificial hard(H) or soft(S) stone phantoms was used with a 20 s’ lasing time and a spiral trajectory, in contact mode. Fragments (acquired through sieves) and stones were observed under optical microscopy before three-dimensional scanning to measure fragments and fissures(DOF) mean diameters and ablation volumes. Results Ablation volumes in with 150CDF-TFL and 272CDF-TFL were higher than those for 272CDF-Ho:YAG in both “dusting” (twofold and threefold) and “fragmentation”(1,5-fold and twofold). “Fine dusting” ablation rates with 150CDF-TFL and 272CDF-TFL were respectively at least 1,5-fold and twofold higher than those for 272CDF-Ho:YAG in “dusting”. 150CDF produced significantly smaller DOF than 272CDF in all settings against S and H except in fragmentation. 150CDF produced lower fragments’ diameter than 272CDF in all settings except dusting. Conclusion These preliminary studies demonstrate that at equal settings and CDF, TFL ablation rates are at least two-fold higher than those with Ho:YAG. 150CDF produces smaller fissures and fragments (that meets the definition of “dusting” lithotripsy) than 272CDF and higher ablation volumes than Ho:YAG.
关键词： Laser,Lithotripsy,Endourology,Thulium fiber laser
更新于2025-09-23 15:21:01
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Thulium fiber laser: ready to dust all urinary stone composition types?
摘要： Purpose To evaluate whether stone dust can be obtained from all prevailing stone composition types using the thulium fiber laser (TFL) for lithotripsy. Where applicable, stone dust was further characterized by morpho-constitutional analysis. Methods Human urinary stones were submitted to in vitro lithotripsy using a FiberLase U2 TFL generator with 150 μm silica core fibers (IPG Photonics?, IPG Medical?, Marlborough, MA, USA). Laser settings were 0.05 J, 320 Hz and 200 μs. A total of 2400 J were delivered to each stone composition type. All evaluated stones had a > 90% degree of purity (calcium oxalate monohydrate, calcium oxalate dihydrate, uric acid, carbapatite, struvite, brushite and cystine). Spontaneously floating stone particles were considered as stone dust and collected for analysis by scanning electron microscopy and Fourier transform infrared spectroscopy. Results Stone dust could be retrieved from all evaluated urinary stones after TFL lithotripsy. Most stone dust samples revealed changes in crystalline organization, except for calcium oxalate monohydrate and carbapatite, which conserved their initial characteristics. Mean maximal width of stone dust particles did not exceed 254 μm. Conclusions The TFL is capable to produce stone dust from all prevailing stone types. Morpho-constitutional changes found in stone dust suggest a photothermal interaction of laser energy with the stone matrix during TFL lithotripsy.
关键词： Urolithiasis,Stone dust,Fourier transform infrared spectroscopy,Lithotripsy,Scanning electron microscopy,Thulium fiber laser
更新于2025-09-23 15:21:01
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Effect of temporal pulse shape on urinary stone phantom retropulsion rate and ablation efficiency using Holmium:YAG and Super Pulse Thulium Fiber lasers
摘要： Objective: To investigate the effects of laser temporal pulse shaping of the super pulse Thulium fiber laser (SPTFL) and to compare them in controlled in vitro conditions with various Ho:YAG pulse delivery modes. Materials and methods: SPTFL (Urolase SP, IRE-Polus, Fryazino, Russia) with an emission wavelength of 1.94 μm and a Ho:YAG laser (P120H, Lumenis, Yokneam, Israel) with Moses technology were compared. Pulse shape, stone retropulsion, and ablation efficiency were evaluated using Begostones and compared for each laser modality: short (SP), long (LP), and Moses pulse (MP) for Ho:YAG, regular pulse (RP) and dual pulse (DP) for SPTFL. Results: Ho:YAG SP mode exhibited an asymmetrical pulse shape with steep leading slope and much more gradual trailing slope, without any flat section. Pulses generated by SPTFL were significantly longer and therefore had lower peak power (Ppeak) than those generated by Ho:YAG laser at equivalent energy settings. Retropulsion for Ho:YAG LP and MP modes was similar and lower than that of SP, but higher than for SPTFL (all p ≤0.02), with an average stone displacement about 4 times and 2 times lower for SPTFL as compared to Ho:YAG. Comparison of ablation volumes indicated that SPTFL induced significantly higher (2-fold) ablation than Ho:YAG laser. Conclusions: Magnitude and initial velocity of stone retropulsion decrease with longer pulse duration and lower pulse peak power, but without sacrificing ablation efficiency. These observations are manifest when comparing Ho:YAG laser with SPTFL. The novel SPTFL provides greater versatility and control of pulse parameters than Ho:YAG laser. Further clinical investigation of practical benefits achievable with pulse-shaping SPTFL modes is warranted.
关键词： retropulsion,lithotripsy,ablation,Ho:YAG,Thulium fiber laser
更新于2025-09-23 15:21:01
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Development of a Thulium Fiber Laser for an Atomic Spectroscopy Experiment
摘要： A convenient thulium ?ber laser source is described with 3 W of output power operating at a wavelength of 2059 nm with a slope e?ciency of 49% with respect to input pump power and 60% with respect to absorbed pump power. The laser was applied in an atomic helium spectroscopy experiment to quench 3He (2058.63 nm) and 4He (2058.69 nm) meta-stable singlets (21S0), allowing for further investigation of the helium ?ne structure. The customized laser e?ectively eliminates the singlet counts to well below a background level (1%). A simpli?ed analysis describes the basic laser performance with ?tted constants in reasonable agreement with previous work.
关键词： fiber,thulium fiber laser,laser,spectroscopy,fiber laser,rare-earth elements,optics,thulium
更新于2025-09-23 15:19:57
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Temperature changes during laser lithotripsy with Ho:YAG laser and novel Tm-fiber laser: a comparative in-vitro study
摘要： Aim The aim of this study was to compare the thermal effects of Ho:YAG and Tm-fiber lasers during lithotripsy in an in-vitro model via real-time temperature measurement. Methods We compared a Ho:YAG laser (pav up to 100 W, Lumenis, Yokneam, Israel) and a superpulse Tm-fiber laser (SP TFL, pav up to 40 W, NTO IRE-Polus, Fryazino, Russia), both equipped with 200 μm bare-ended fibers. The following settings were used: 0.2 J, 40 Hz (nominal pav 8 W). Power meter FieldMaxII-TO (Coherent, Santa Clara, CA, USA) was used to verify output laser power (pav). Each laser was fired for 60 s in two setups: (1) thermos-insulated (quasi-adiabatic) cuvette; (2) actively irrigated setup with precise flow control (irrigation rates 0, 10, 35 mL/min). Results Power measurements performed before the test revealed a 10% power drop in Ho:YAG (up to 7.2 ± 0.1 W) and 6.25% power drop in SP TFL (up to 7.5 ± 0.1). At the second step of our experiment, irrigation reduced the respective temperatures in the same manner for both lasers (e.g., at 35 mL/s SP TFL ? 1.9 °C; for Ho:YAG laser ? 2.8 °C at 60 s). Conclusion SP TFL and Ho:YAG lasers are not different in terms of volume-averaged temperature increase when the same settings are used in both lasers. Local temperature rises may fluctuate to some degree and differ for the two lasers due to varying jet streaming caused by non-uniform heating of the aqueous medium by laser light.
关键词： Ho:YAG laser,Laser lithotripsy,Thermal effect,Thulium fiber laser,In-vitro
更新于2025-09-23 15:19:57
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Q-switched Thulium-doped fiber laser at 1860?nm and 1930?nm using a Holmium-doped fiber as an amplified spontaneous emission filter
摘要： This work demonstrates an all fiber, passively Q-switched Thulium-doped fiber (TDF) laser with a center operating wavelength at 1860 nm and 1930 nm. The laser initially generates an output at ~1930 nm which is then shifted to ~1860 nm by integrating a Holmium-doped fiber (HDF) into the cavity to serve as an amplified spontaneous emission filter. Q-switching operation is achieved using a molybdenum tungsten disulfide or MoWS2 thin film acting as a passive optical modulator. At 1930 nm, the generated Q-switched laser has a high repetition rate of 66.3 kHz and a narrow pulse width of 2.1 μs. After the Holmium-filter is employed, the wavelength shifts to 1860 nm while still retaining a modulated output with a maximum repetition rate of 48.9 kHz as well as narrowest pulse width of 2.3 μs. This work demonstrates the use of the absorption characteristics of HDF to access the shorter wavelength region of the TDF.
关键词： 1.8 μm,Thulium,Fiber laser,Q-switched,Holmium
更新于2025-09-16 10:30:52
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How Lasers Ablate Stones: In-vitro Study of Laser Lithotripsy (Ho:YAG and Tm-fiber lasers) in Different Environments
摘要： Introduction. There are two main mechanisms of stone ablation with long‐pulsed infrared lasers: photothermal and photomechanical. Which of them is primary in stone destruction is still a matter of discussion. Water holds importance in both mechanisms but plays a major role in the latter. We sought to identify the prevailing mechanism of stone ablation by evaluating the stone mass‐loss after lithotripsy in different media. Material and methods. We tested a Ho:YAG laser (100W, Lumenis, USA), a Tm‐fiber laser U1 (TFL U1), (120W, NTO IRE‐Polus, Russia) and a Superpulse Tm‐fiber laser U2 (TFL U2) (500W, NTO IRE‐Polus, Russia). A single set of laser parameters (15 W = 0.5 J × 30 Hz) was used. Contact lithotripsy was performed in phantoms (BegoStones) in different settings: a) hydrated phantoms in water; b) hydrated phantoms in air; с) dehydrated phantoms in water; d) dehydrated phantoms in air. Laser ablation was performed with total energy of 0.3 kJ. Phantom mass‐loss was defined as the difference between the initial phantom mass and the final phantom mass of the ablated phantoms. Results. All lasers demonstrated effective ablation in hydrated phantoms ablated in water, no visual differences between the lasers were detected. The ablation of dehydrated phantoms in air was also effective with visible vapor during ablation and condensation on the cuvette wall. Dehydrated phantoms in water and in air shown minimal to no ablation accompanied with formation of white crust on phantoms surface. Among laser types, TFL U2 had the highest phantom mass‐loss in all groups except for dehydrated phantoms ablated in air. Conclusions. Our results suggest that both photothermal and thermomechanical ablation mechanisms (explosive vaporization) occur in parallel during laser lithotripsy. In Ho:YAG and TFL U2 stone ablation, explosive vaporization prevail, while in TFL U1 ablation, photothermal mechanism appear to predominate.
关键词： laser lithotripsy,Ho:YAG laser,Thulium fiber laser,stone disease
更新于2025-09-12 10:27:22
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Efficacy and safety of 1927 nm fractional Thulium fiber laser for the treatment of melasma: a retrospective study of 100 patients
摘要： Background: Melasma is an acquired hyperpigmentation of the skin that mostly affects areas exposed to the sun. The treatment of melasma can be challenging as it is prone to relapse. Recently, new laser and light-based treatment options have been used; one of these treatment modalities is the 1927 nm fractional Thulium fiber laser. Objective: This study aimed to retrospectively evaluate the efficacy and safety of a 1927 nm fractional Thulium fiber laser for the treatment of melasma. Materials and methods: This study retrospectively evaluated patients who were admitted to the dermatology outpatient clinic between September 2015 and March 2018 and treated with a 1927 nm fractional Thulium fiber laser. The MASI score was used to assess improvements of the lesions. Results: The current study included a total of 100 patients who received 1927 nm fractional Thulium fiber laser treatment. Each patient received two treatments at one month intervals. The mean baseline MASI score was 11.8 ± 6.3, the mean MASI score after the first session was 6.7 ± 4.1, and the mean MASI score after the second session was 3.4 ± 3.8. The differences between these three MASI scores were significant, and the laser treatment had no major side effects. Conclusion: Results of this study indicate that the 1927 nm fractional Thulium fiber laser is a safe and effective treatment option for melasma.
关键词： Melasma,1927 nm thulium fiber laser,fractional laser
更新于2025-09-12 10:27:22