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Dental Imaging With Near-Infrared Transillumination Using Random Fiber Laser
摘要： Contrary to the conventional detection method like radiography, the near infrared light source has been demonstrated to be suitable for dental imaging due to different reflectivity among enamel, dentin, and caries lesion. In this paper, three light sources with different bandwidths based on a transillumination method are compared. The contrast among enamel, dentin, and caries lesion is calculated in different situations. The experimental results show that the random fiber laser has the best comprehensive quality in dental imaging due to its high spectral density, low coherence, and deep penetration. This work provides a guidance for light source selection in dental imaging.
关键词： caries detection,Random fiber laser,near infrared,dental imaging
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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All-fiber passively Q-switched erbium-doped laser with Cr <sup>2+</sup> :ZnSe nanocrystals saturable absorber
摘要： We experimentally demonstrate an all-fiber Q-switched erbium-doped laser using polyvinyl alcohol-based Cr2+:ZnSe nanocrystals (NCs) as saturable absorbers (SAs). The Cr2+:ZnSe NCs were produced by femtosecond laser ablation, and were spherical, with an average radius of about 107 nm. The nonlinear saturable absorption was characterized with a saturable optical intensity of 20 MW cm?2 and a modulation depth of ～24%. By placing the SA inside an erbium-doped fiber (EDF) laser cavity, a stable 3.152 μs pulse with a repetition rate of 34.452 kHz centered at 1564 nm was achieved, when pumped at the maximum pumping power of 300 mW. The maximum pulse energy reached 33 nJ and the signal-to-noise ratio was 48 dB. The results indicate that Cr2+:ZnSe NCs are promising for the development of a stable all-fiber passively Q-switched EDF laser.
关键词： Cr2+: ZnSe nanocrystals,passively Q-switched,all-fiber laser
更新于2025-09-23 15:21:01
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[IEEE 2018 Asia Communications and Photonics Conference (ACP) - Hangzhou (2018.10.26-2018.10.29)] 2018 Asia Communications and Photonics Conference (ACP) - Fiber Optic Magnetic Field Sensor Utilizing DFB Fiber Laser and Terfenol-D Material
摘要： We present a novel distributed feedback fiber laser (DFB-FL) fiber laser sensor, which can measure static magnetic field through sweep acoustic wave. A fiber laser is bonded on the giant magnetostrictive material Terfenol-D (Tb0.3Dy0.7Fe1.92) tube oriented along the longitudinal direction. When acoustic wave of different frequency is added to the fiber laser, it has the maximum response at its resonant frequency, which will vary with the external magnetic field. The measurement sensitivity of the sensor is 0.39 Hz/mT to the magnetic field. The experimental results also show that the sensor exhibits excellent linearity and directivity in response to static magnetic field.
关键词： fiber laser,Terfenol-D,magnetic field sensor
更新于2025-09-23 15:21:01
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Frequency comb interference spectroscopy using a fiber laser comb and a multi-colour laser
摘要： In this paper, we demonstrate a rapid high-resolution frequency comb spectrometer involving a mode-locked laser comb and a multi-colour laser. The heterodyne detection of the two lasers enables hundreds of thousands of Doppler-limited molecular spectra to be recorded in a second. With this device, several P-branch transitions of the H13CN (gas) 2ν3-band are simultaneously interrogated at comb-line-defined resolution (54.5 MHz or 0.5 pm) within 3 μs. The single-measurement spectrum spans >200 GHz (~1.6 nm) far beyond the electronic bandwidth (33 GHz) of our acquisition system. Without using asynchronous combs or dispersers and detection arrays, the spectrometer may benefit many gas sensing applications, such as environmental monitoring.
关键词： frequency comb,fiber laser,spectroscopy
更新于2025-09-23 15:21:01
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1579 NM Fiber Laser Source for Spaceborne Monitoring of Carbon Dioxide
摘要： We report on the development of a 1579 nm pulsed fiber laser source with high peak-power, intended to be used as a lidar source for CO2 monitoring from space. We first discuss water-vapor sensitivity of spaceborne CO2 measurements by lidar and point the interest of the 1579 nm wavelength with that respect. Then we detail the current development status of the pulsed fiber laser source.
关键词： CO2 monitoring,lidar,1579 nm,spaceborne,fiber laser
更新于2025-09-23 15:21:01
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Multichannel fiber laser acoustic emission sensor system for crack detection and location in accelerated fatigue testing of aluminum panels
摘要： Detection and location of the source of acoustic emission in a thin aluminum panel is demonstrated using a multichannel fiber laser sensor system. Acoustic emission generated by a crack in an aluminum panel used as a test coupon in an accelerated fatigue experiment is detected and the location of the crack identified. Acoustic emission is detected over a bandwidth of around 0.5 MHz from a serially multiplexed array of four laser sensors and compared with measurements taken from four piezo-electric sensors co-located with the fiber laser sensors. The location of the crack is determined by first estimating time difference of arrival of signals at each sensor using a novel algorithm based on the cumulative distribution transform method with hyperbolic positioning. The fiber laser sensor is shown to match the signal-to-noise ratio of the industry standard (Mistras S9225) piezo-electric acoustic emission sensor.
关键词： location,crack detection,fiber laser,acoustic emission,accelerated fatigue testing
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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Experimental observation of a cyclic dynamics of solitons in a fiber laser
摘要： We report an experimental observation of a singular soliton dynamics in a mode-locked erbium doped fiber laser. This is the first time, to our knowledge, that output intensity exhibits a cyclic transition from a single-pulse to a multi-pulse regime for a fixed value of both pumping power and polarization controllers orientation. Moreover, the pulse duration of the single- and multi-pulse regimes is the same, in contrast with what is usually observed.
关键词： fiber laser,solitons,Dynamics
更新于2025-09-23 15:21:01
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Tunable optical frequency comb from a compact and robust Er:fiber laser
摘要： We report on a compact and robust self-referenced optical frequency comb with a tunable repetition rate, generated by an all-polarization-maintaining (PM) mode-locked Er-doped fiber laser. The spacing between comb teeth can be tuned above 300 kHz at a repetition rate of 101 MHz. The repetition rate and the carrier–envelope offset of the laser are stabilized separately, and the relative residual phase noises are determined to be 336 μrad and 713 mrad (1 Hz–1 MHz). The accurate frequency characteristics and the stable structure show great potential for the use of such a comb in applications of precision measurements.
关键词： fiber laser,optical frequency comb,all-polarization-maintaining,mode-locking
更新于2025-09-23 15:21:01