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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Widely-Tunable Dual-Wavelength Tm:YLF, Tm:LuAG, and Tm:YAG Lasers
摘要： Dual-wavelength operation of lasers are attractive for many applications such as coherent terahertz wave generation, ultrahigh pulse repetition rate creation by optical beating, and laser ranging. Several methods could be employed for achieving multicolor laser operation including usage of specially coated cavity optics, employment of dual laser crystals, utilization of coupled cavities, and deployment of Fabry-Perot band-pass filters or volume Bragg gratings. Most of the time, these approaches provide multicolor laser operation at a single wavelength pair, and laser power in each line might fluctuate with experimental conditions (such as crystal temperature and pump power variations). In recent years, usage of intracavity birefringent filters (BRFs) was proposed as a flexible method for the generation of multicolor laser operation [1-4]. Advantages of BRFs in multicolor lasing include: (a) low cost, (b) simple operation, (c) one BRF plate empowering multicolor laser operation in many different wavelength pairs, (d) capability to control laser power in each line, (e) ability to use a rich number of filter parameters from a single BRF plate, (f) effectiveness in continuous-wave, gain-switched, Q-switched and cw mode-locked regimes, and (g) universal usage of the device in any laser that lies within the transmission bandwidth of the BRF plate. In our earlier work, we have employed a 3-mm thick, off-surface optic axis crystalline quartz BRF with an optic axis 45° to the surface of the plate to generate two-color cw laser operation in 11 and 10 different transition combinations in Cr:Nd:GSGG and Cr:LiSAF [3], respectively. In this study [5], we have demonstrated that the same BRF plate could also be used for multicolor laser operation of solid-state lasers around 2 μm. Optimization of the rotation angle of the intracavity inserted BRF plate around different orders (rotation angles) facilitated two-color laser operation in 11, 12 and 8 different wavelength pairs in Tm:YLF, Tm:LuAG and Tm:YAG, respectively [5]. For most of the cases, fine tuning of the BRF rotation angle enabled adjustment of laser power in each line. Figure 1 (a) shows sample optical spectra for Tm:YLF, and Fig. 1 (b) demonstrates details of cavity dynamics for synchronous dual-wavelength operation of Tm:YLF at 1868 & 1991 nm pair. To our knowledge, this is the first report of multicolor laser operation in Tm:LuAG and Tm:YAG, and first results with a BRF in Tm:YLF [6]. Moreover, the demonstrated wide-tunability of two-color laser wavelengths is quite rare in literature.
关键词： Tm:YAG,birefringent filters,Tm:YLF,Tm:LuAG,dual-wavelength lasers
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Stable 1100–2400 nm Supercontinuum in YAG with Picosecond Pumping for Simplified OPCPA
摘要： The generation of a supercontinuum (SC) in a bulk material is an inexpensive and effective method for substantially expanding the spectrum of laser pulses. Accordingly, the broad spectrum of SC makes it ideal for seeding an Optical Parametric Chirped Pulse Amplifier (OPCPA). Stable SC in the wavelength range from ~ 500 nm to ~ 1000 nm in a YAG crystal pumped with picosecond pulses [1] simplifies TW-class laser architecture [2] due to the inherent signal and pump synchronization in OPCPA. Moreover, a stable SC in the range up to 2.5 μm would eliminate the idler generation and pave the way for the development a more reliable and compact OPCPA in the IR spectral range. We demonstrate a single-filament SC covering the wavelength range from ~ 1100 nm to more than 2400 nm, with pulse energy stability and beam pointing stability exceeding the Chirped Pulse Amplifier (CPA) - compressor [2] used as a pumping source. Such a highly stable source of broadband seed pulses together with an inexpensive CPA-compressor based on Yb:YAG rods [2] significantly simplifies the development of compact high-intensity OPCPA systems around the 2 μm spectral range.
关键词： laser pulses,picosecond pumping,OPCPA,YAG,supercontinuum
更新于2025-09-12 10:27:22
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Proton generation from hydrocarbon polymer targets for laser ion source
摘要： A laser ion source can provide intense pulsed ion beams from a solid target. On the other hand, generation of a proton beam with a laser ion source requires using compound targets containing hydrogen. In this research, we demonstrated proton generation from three kinds of hydrocarbon polymer targets: polyethylene (C2H4)n, polypropylene (C3H6)n, and polystyrene (C8H8)n. The laser used was a Nd:YAG laser (532 nm/17 ns), and the energy was 0.2 J. The ion current and the fraction of ion species were measured using a Faraday cup and an electrostatic ion analyzer. The results indicated that the peak currents and fraction to total particle number of proton were similar for the different hydrocarbon polymer targets and also showed that increasing the laser intensity effectively increases the number of proton particles because the larger the laser intensity, the larger the total charge.
关键词： hydrocarbon polymer targets,Nd:YAG laser,proton generation,electrostatic ion analyzer,ion current,laser ion source
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Low-Jitter, Narrow-Bandwidth, Single Longitudinal Mode Passively Q-Switched Nd:YAG Ring Laser Oscillator with External Feedback
摘要： Fourier-limited, also called single-frequency or single-longitudinal-mode (SLM) nanoseconds lasers at 1 μm are key elements for several applications, such as optical communications, data storage and high-resolution spectroscopy. Some special application such as high spectral resolution LIDAR [1], require very high spectral purity (tens of MHz bandwidth), resulting in long pulse durations in the range of several tens of ns. Microchip lasers with large free spectral range (FSR) comparable to the active medium gain bandwidth (about 160 GHz for Nd:YAG) allow easy SLM selection, but with much shorter pulses. Recently, we demonstrated a Cr:YAG Passively Q-Switched (PQS) Nd:YVO4 ring laser oscillator delivering 50-ns, 80-μJ SLM pulses at 0.1-10 kHz repetition rate employing a specifically designed intracavity etalon to enhance SLM operation [2]. For SLM PQS operations, Nd:YAG offers some advantages if compared to Nd:YVO4. Namely, the higher saturation fluence relaxes the fulfilment of the second PQS threshold condition, the ~2 times longer fluorescence lifetime enhances energy storage and the narrower gain bandwidth favours SLM operation.
关键词： Nd:YAG,single-longitudinal-mode,passively Q-switched,external feedback,ring laser
更新于2025-09-12 10:27:22
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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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Treatment of Hypertrophic Burn and Traumatic Scars With a 2,940-nm Fractional Ablative Erbium-doped Yttrium Aluminium Garnet Laser
摘要： BACKGROUND In recent years, fractional ablative lasers at low density have proven to be the centerpiece in a multimodality approach to treating hypertrophic burn scars. OBJECTIVE To determine the safety and efficacy of fractional ablative erbium-doped yttrium aluminium garnet (Er:YAG) laser in the treatment of hypertrophic burn scars. METHODS Eleven patients received 3 fractional ablative Er:YAG laser to hypertrophic burn scars at 400 to 800 mm, density 11%, no coagulation, and single pass at 4-week intervals. RESULTS Overall, average improvement was noted to be 2.27 of 3 as determined by blinded observers. A significant improvement was noted in all measured parameters including dyschromia, atrophy hypertrophy, vascularity, and texture. CONCLUSION This is a pilot study showing the safety and efficacy of fractional ablative Er:YAG laser treatment is a safe and effective treatment modality in the treatment of hypertrophic scars.
关键词： laser therapy,scar treatment,fractional ablative Er:YAG laser,hypertrophic burn scars
更新于2025-09-12 10:27:22
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Treatment of Congenital Melanocytic Nevi in the Eyelid and Periorbital Region With Ablative Lasers
摘要： Background: Congenital melanocytic nevi (CMN) that occur on the eyelid and periorbital region cause cosmetic disfiguring. Laser treatment has aroused interest as an alternative treatment method, and resurfacing lasers have shown promising results. Objective: This study aimed to evaluate the efficacy and safety of carbon dioxide laser and erbium:yttrium aluminum garnet laser to treat CMN of the eyelid and periorbital region. Methods and Materials: Twenty patients with CMN were included in this study and were treated with either the CO2 or erbium:yttrium aluminum garnet laser. Clinical efficacy outcomes were evaluated by visual assessment and L*a*b* color space evaluation at least 6 months after treatment. Results: The average (SD) visual evaluation improvement, assessed on a 5-point scale, was 2.8 (1.27). The mean (SD) values of the relative L* improvement rate and blanching rate of the CMN lesion were 32.0% (47.9%) and 34.1% (36.2%), respectively. Spearman rank correlation coefficient between the objective and subjective evaluations was significant (P < 0.001). Three cases developed partial hypopigmentation. No patient developed hypertrophic scars. Conclusion: The outcomes after laser treatment were variable, although half of the patients achieved greater than 50% clearance. It provides an alternative to surgical excision for the removal of CMN in the difficult regions. Surgery excision is inevitable for some patients.
关键词： carbon dioxide laser,eyelid and periorbital region,congenital melanocytic nevi,ablative laser,Erbium:YAG laser
更新于2025-09-12 10:27:22
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Long Term Follow-up of Intralesional Laser Photocoagulation for Head and Neck Lymphatic Malformations Using Neodymium-Yttrium-Aluminium-Garnet Laser
摘要： Lymphatic malformations remain a challenge for patients and plastic surgeons. Promising results have been reported using intralesional laser photocoagulation (ILP) for treating vascular anomalies. The objective of our study is to review the long-term results of a large series of lymphatic malformations in patients treated with ILP. A retrospective review of 190 head and neck lymphatic malformations in patients were treated by ILP with an neodymium-yttrium-aluminum-garnet (Nd:YAG) laser (1064 nm) over a period of 20 years (January 1997–January 2016). Patients' ages ranged from 10 months to 12 years and 6 months (mean, 1 year and 11 months). The patient group consisted of 98 female and 92 male patients. Patients were treated with an Nd:YAG laser (Sharplan Inc, Allendale, New Jersey) delivered through a 600-μm optical fiber. Laser power was set at 7 to 15 W and delivered with a pulse duration of 7 to 15 seconds. All patients demonstrated improvement as judged by clinical assessment of the reduction in lesion size (range, 65%–100%; mean reduction, 85%). One hundred fifty-two (80%) patients had a more than 65% reduction of the volume in lymphatic malformations at 3 months after 1 treatment, and 171 (90%) patients had a more than 85% reduction of the volume after 2 treatments. Excellent results were seen in 19 (10%) patients after 3 treatments. Postoperative complications were related to photocoagulation that was delivered too extensively or superficially, with resultant ulceration, infection, induration, and scarring. Throughout the course of our long-term study, ILP using an Nd:YAG laser is an effective treatment modality for lymphatic malformations. Complications can be avoided if the potential for harm is kept in mind.
关键词： lymphatic malformation,Nd:YAG laser,intralesional laser photocoagulation (ILP)
更新于2025-09-12 10:27:22
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The evaluation of long‐pulsed Nd:YAG laser efficacy and side effects in the treatment of cutaneous vessels on the face and legs
摘要： Background: Long‐pulsed Nd:YAG lasers have been used for the treatment of cutaneous vascular lesions on face and leg veins. Objective: To report our experience with long‐pulsed Nd:YAG lasers for the treatment cutaneous vessels on the face and legs. Materials and Methods: A total of 145 patients with cutaneous vessels on the face and the legs were included in this study. All patients received two treatment sessions, first at the beginning and second after four weeks. Patients were evaluated three times: first at the beginning of the therapy, and second and third after the four weekly follow‐ups. The laser settings of each treatment session were recorded. The physician's assessment of treatment efficiency was taken by comparing gross photograph and clinical evaluation. The grade of improvement, as the percent of reduction in the severity of veins after laser treatment, was determined as follows: <25% improvement (mild); 25%–50% improvement (moderate); 51%–75% improvement (good); and >75% improvement (excellent). The side effects were also recorded. Results: Of the 145 patients who completed the study, 63.6% of patients had vessels on the face, and 36.4% had them on the legs. After the first session, 82.8% of patients have good improvement (51%–75%). After the second session, 78.6% of patients have excellent improvement (>75%). The clinical improvement after the second treatment session was significantly higher than the first treatment session (P ? .05). There were no statistical differences between the treatment areas (P ? .05). The most common side effect was erythema in 12.4% (P ? .05). Conclusion: The Nd:YAG laser is an effective and safe treatment option for the treatment of cutaneous vessels on the face and the legs.
关键词： cutaneous vessels,legs,vascular lesions,long‐pulsed Nd:YAG laser,face
更新于2025-09-12 10:27:22
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[IEEE 2019 3rd International Conference on Circuits, System and Simulation (ICCSS) - Nanjing, China (2019.6.13-2019.6.15)] 2019 3rd International Conference on Circuits, System and Simulation (ICCSS) - A Packaging Method to Improve Monocrystalline Silicon Solar Cells with YAG:Ce Phosphors
摘要： A packaging method to improve the conversion efficiency of monocrystalline silicon solar cells is presented. In this method, Ce-doped yttrium aluminum garnet (YAG:Ce) phosphor particles as luminescence down-shifting materials are coated on the surface of the solar cells which are then packaged with ethylene vinyl acetate (EVA) and glass. The experimental results show that, after being packaged, the increase in the conversion efficiency is from 17.24% to 18.13%. The enhancement can be attributed to the luminescence down-shifting effect of YAG:Ce phosphors which convert ultraviolet/blue light into yellow light, the reduced reflection in the wavelength range below 480nm and the absorption of the light which is emitted from the phosphor particles and reflected back at air/glass interface. This method provides a potential way to improve the solar cells through the packaging processes, which is appliable for industries.
关键词： conversion efficiency,down-shifting,packaging,YAG:Ce phosphors
更新于2025-09-12 10:27:22