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Development of an Interference Filter-Stabilized External-Cavity Diode Laser for Space Applications
摘要： The National Time Service Center of China is developing a compact, highly stable, 698 nm external-cavity diode laser (ECDL) for dedicated use in a space strontium optical clock. This article presents the optical design, structural design, and preliminary performance of this ECDL. The ECDL uses a narrow-bandwidth interference ?lter for spectral selection and a cat’s-eye re?ector for light feedback. To ensure long-term stable laser operation suitable for space applications, the connections among all the components are rigid and the design avoids any spring-loaded adjustment. The frequency of the ?rst lateral rocking eigenmode is 2316 Hz. The ECDL operates near 698.45 nm, and it has a current-controlled tuning range over 40 GHz and a PZT-controlled tuning range of 3 GHz. The linewidth measured by the heterodyne beating between the ECDL and an ultra-stable laser with 1 Hz linewidth is about 180 kHz. At present, the ECDL has been applied to the principle prototype of the space ultra-stable laser system.
关键词： laser diode,interference ?lter,space optical clock,external-cavity diode laser,laser stabilization
更新于2025-09-16 10:30:52
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An Ultra-High-SMSR External-Cavity Diode Laser with a Wide Tunable Range around 1550 nm
摘要： In this paper, a widely tunable external cavity diode laser (ECDL) with an ultra-high side mode suppression ratio (SMSR) was fabricated. Three configurations were constructed to investigate the relationship between the grating features and the SMSR. When a 1200 grooves/mm grating with a first order diffraction efficiency of 91% is utilized in the external-cavity laser system, a maximum SMSR of 65 dB can be achieved. In addition, the tunable range reaches 209.9 nm. The results show that the laser performance can be improved by proper high grating groove number and first-order diffraction efficiency.
关键词： tunable laser,side mode suppression ratio (SMSR),external cavity diode laser (ECDL),diffractive grating
更新于2025-09-16 10:30:52
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Diode laser assisted excision of a gingival pyogenic granuloma: A case report
摘要： Pyogenic granuloma is a non-neoplastic, exuberant, reactive lesion seen in response to local irritation or trauma caused by dental calculus, bacterial plaque, caries and restorations, with a strong predilection for the gingiva. It is among the frequently encountered oral lesions, occurring at a challenging oral site, the gingiva. Herein, we report a 71-year-old medically compromised Caucasian female who presented with a relatively large lobulated pyogenic granuloma on the buccal gingiva of the maxillary molar-premolar region. Total surgical excision was performed with an 840nm diode laser followed by the placement of hyaluronate gel and relevant periodontal dressing. Two weeks after surgical excision, complete healing was observed, but patient denied replacement of dental restoration. After 4 months of follow-up, an overall reduction of associated teeth mobility was also observed, with a minor recurrence in gingival inflammation. The objective of this report is to briefly review clinical, radiographic and histological findings of pyogenic granuloma along with a detailed discussion on its management through a diode laser.
关键词： Laser surgery,Gingiva,Pyogenic granuloma,Diode laser
更新于2025-09-16 10:30:52
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The conversion from a Gaussian-like beam to a flat-top beam in the laser hardening processing using a fiber coupled diode laser source
摘要： In this paper, a laser beam from a fiber coupled diode laser source is converted from a Gaussian-like distribution to a flat-top distribution using a set of homogenization optical system, which makes this diode laser source more favorable for laser hardening. Employing this diode laser source, hardening experiments are performed on 35CrMo metal steel. By optimizing parameters of the hardening processing, at the scanning speed of 1100 mm/min and laser power of 1940 W, a Rockwell hardness of 57 HRC and a hardened depth of 1.6 mm are achieved. Experimental results demonstrate the processing ability of this diode laser source in the industrial laser hardening.
关键词： High power,Laser hardening,Homogeneity,Diode laser
更新于2025-09-16 10:30:52
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Efficacy and safety of 1470-nm Diode Laser Enucleation of the Prostate in Individuals with Benign Prostatic Hyperplasia Continuously Administered Oral Anticoagulants or Antiplatelet Drugs
摘要： Objective: To evaluate the efficacy and safety of 1470-nm Diode Laser Enucleation of the Prostate (DiLEP) in patients with benign prostatic hyperplasia (BPH) continuously receiving oral anticoagulants or antiplatelet drugs. Methods: From January 2016 to June 2017, 144 patients were submitted to 1470-nm DiLEP, including forty-nine (34.0%) continuously administered anticoagulants or antiplatelet drugs per os due to cardiac and/or cerebrovascular diseases (Group A), while ninety-five (66.0%) were not (Group B). Evaluation was performed preoperatively, and at postoperative 3, 6, and 12 months, respectively. Patient baseline features, operative data, perioperative complications and postsurgical outcomes were assessed. Results: Both groups had comparable preoperative parameters, except age (77.3±7.5 vs 73.2±8.8 years, P=0.007). Meanwhile, surgical time, sodium decrease, catheterization duration and hospital stay markedly differed between the two groups. In comparison with group B, group A patients had statistically higher blood loss (14.9±7.3 g/L vs 10.2±7.0 g/L, P<0.001) and increased bladder irrigation time (21.1±10.9h vs 16.1±9.0h, P=0.004). One case required blood transfusion in group A, because of moderate anemia preoperatively. Both groups showed similar blood transfusion and complication rates. IPSS, QoL score, Qmax and PVR were markedly improved in both groups at 3, 6, and 12-months follow-up postoperatively compared with baseline values. However, no statistically significant differences were observed between the two groups in various assessment parameters at follow-up (P>0.05). Conclusions: These findings demonstrated that 1470-nm DiLEP is efficient and safe in BPH cases receiving continuous oral anticoagulant or antiplatelet drugs. Anticoagulation therapy did not significantly influence the results and complication rates.
关键词： anticoagulation,1470-nm diode laser,laser surgery,benign prostatic hyperplasia
更新于2025-09-16 10:30:52
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Near-infrared tunable diode laser absorption spectroscopy-based determination of carbon dioxide in human exhaled breath
摘要： A spectroscopic detection system for the accurate monitoring of carbon dioxide (CO2) in exhaled breath was realized by tunable diode laser absorption spectroscopy (TDLAS) in conjunction with a vertical-cavity surface-emitting laser (VCSEL) and a multipass cell with an effective optical path-length of 20 m. The VCSEL diode emitting light with an output power of 0.8 mW, covered the strong absorption line of CO2 at 6330.82 cm?1 by drive-current tuning. The minimum detectable concentration of 0.769% for CO2 detection was obtained, and a measurement precision of approximately 100 ppm was achieved with an integration time of 168 s. Real-time online measurements were carried out for the detection of CO2 expirograms from healthy subjects, different concentrations were obtained in dead space and alveolar gas. The exhaled CO2 increased significantly with the increasing physical activity, reaches its maximal value at the beginning of respiratory compensation and then decreased slightly until maximal exercise. The developed measurement system has a great potential to be applied in practice for the detection of pulmonary diseases associated with CO2 retention.
关键词： CO2,human health monitoring,Tunable diode laser absorption spectroscopy,carbon dioxide,VCSEL,exhaled breath,TDLAS,vertical-cavity surface-emitting laser
更新于2025-09-16 10:30:52
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An Optimal Genetic Algorithm for Fatigue Life Control of Medium Carbon Steel in Laser Hardening Process
摘要： This study proposes a genetic algorithm-optimized model for the control of the fatigue life of AISI 1040 steel components after a high-power diode laser hardening process. First, the effect of the process parameters, i.e., laser power and scan speed, on the fatigue life of the components after the laser treatment was evaluated by using a rotating bending machine. Then, in light of the experimental findings, the optimization model was developed and tested in order to find the best regression model able to fit the experimental data in terms of the number of cycles until failure. The laser treatment was found to significantly increase the fatigue life of the irradiated samples, thus revealing its suitability for industrial applications. Finally, the application of the proposed genetic algorithm-based method led to the definition of an optimal regression model which was able to replicate the experimental trend very accurately, with a mean error of about 6%, which is comparable to the standard deviation associated with the process variability.
关键词： genetic algorithm,laser hardening,diode laser,fatigue life
更新于2025-09-16 10:30:52
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Photonic crystal spatial filtering in broad aperture diode laser
摘要： Broad aperture semiconductor lasers usually suffer from low spatial quality of the emitted beams. Due to the highly compact character of such lasers, the use of conventional intracavity spatial ?lters is problematic. We demonstrate that extremely compact photonic crystal spatial ?lters, incorporated into a laser resonator, can improve the beam spatial quality and, correspondingly, increase the brightness of the emitted radiation. We report the decrease in the M2 value from 47 down to 28 due to photonic crystal spatial intracavity ?ltering and the increase in the brightness by a factor of 1.5, giving a proof of principle of intracavity photonic crystal spatial ?ltering in broad area semiconductor lasers.
关键词： photonic crystal,spatial filtering,beam quality,broad aperture diode laser,brightness
更新于2025-09-16 10:30:52
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Study of Optical Properties of Surface Layers Produced by Laser Surface Melting and Laser Surface Nitriding of Titanium Alloy
摘要： This study measured optical properties, such as specular, di?use, and total re?ection for 808 nm wavelength, characteristic for high power diode lasers radiation, from the surface of titanium alloy Ti6Al4V at delivery conditions, polished, and oxidized. Moreover, the optical properties of surface layers produced by high power direct diode laser (HPDDL) melting and nitriding were determined. Additionally, a methodology for determining the value of absorption for 808 nm wavelength of the HPDDL radiation on the surface of a melt pool during laser surface melting and nitriding of titanium alloy was proposed. The results show that the distinct di?erences in absorption a?ect the heat transfer, thermal conditions of laser heating and thereby the penetration depth during laser melting and nitriding of the titanium alloy.
关键词： high power diode laser,absorption,titanium nitrides,re?ectivity
更新于2025-09-16 10:30:52
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In vitro effect of diode laser against biofilm of Aggregatibacter actinomycetemcomitans
摘要： Objective: The main objective is to investigate the antibacterial effect of diode laser against Aggregatibacter actinomycetemcomitans biofilm. Materials and Methods: Biofilms of A. actinomycetemcomitans plus Streptococcus sanguinis grown on bovine root surfaces were treated with an 810?nm diode laser using a noncontact pulsed mode with a pulse interval and pulse length of 20 ms. Four protocols, that is, one episode of 1.5 or 2.5 W for 30 s and three episodes of 1.5 or 2.5 W for 30 s were tested. No treatment and 0.2% chlorhexidine treatment served as negative and positive controls, respectively. Viable bacterial number was determined by colony counting. Results: Treatment with chlorhexidine and all laser protocols except that using single episode of 1.5 W reduced the number of A. actinomycetemcomitans in either single?species or dual?species biofilm compared to negative control. A higher percentage of A. actinomycetemcomitans reduction was demonstrated after increasing the power output or repeating the irradiation. Conclusions: The laser protocols used in this study could reduce the number of viable bacteria but not eradicate A. actinomycetemcomitans biofilm.
关键词： biofilm,diode laser,Aggregatibacter actinomycetemcomitans,periodontitis treatment
更新于2025-09-16 10:30:52