Fiber Laser Device Research Articles

Ultra-broadband small-size dual-core photonic crystal fiber polarization splitter based on silver coating

We have proposed a novel silver-coated ultra-broadband small-size dual-core photonic crystal fiber (DC-PCF) polarization splitter which achieves a short length, high extinction ratio (ER) and ultra-wide bandwidth at the commonly used communication wavelength band. Finite element method-based numerical simulation is applied to carry out a thorough investigation for wavelength from 1 to 2 μm. According to the simulation results, the coupling qualities of the proposed structure can be improved by resonant coupling between the core guide mode and the surface plasmon polarization (SPP) exciton mode. By analyzing the change of ER with varying wavelength, the ER value of this work are achieved as 67.4 and 67.1 dB when the wavelength are 1.14 and 1.57 μm, respectively. The final splitting length (LS) is 17.17 μm. To the best of our knowledge, it is difficult to achieve in all previous studies. With a splitting bandwidth of 900 nm (1.0–1.9 μm) and the ER value of −50.1 dB at 1.55 μm, the E + S + C + L + U communication bands are completely covered. The proposed model has excellent beam-splitting performance, such as ultra-short LS, ultra-wide splitting bandwidth and good tolerance performance, with potential applications in optical fiber communications or fiber laser devices.

Solid-core anti-resonant fiber based on silicate glass

A silicate-glass-based solid-core anti-resonant fiber was fabricated by drilling and rod-in-tube method in this work. The fiber with a core diameter of 37.5 μm exhibited confinement loss of 1.33 dB/m at the anti-resonant wavelength of 1812.5 nm when subtracting the glass material loss. The laser at 1812.5 nm showed a beam quality with M2 factor of 1.56 after propagating in the anti-resonant fiber with a length of 0.3 m. Future improvement of raw material purity and optimization of fiber uniformity would promote the fiber transmission performance to extend its practical applications in high-power fiber laser and novel fiber device development.

Recent advances in thulium-doped fiber lasers based on saturable absorber materials at 2000 nm

Thulium-doped fiber laser (TDFL) devices are a promising laser source technology for applications in the wavelength of 2000 nm, such as spectroscopy, sensing, medical, among many others. Several pulse regimes employing different approaches have been constantly demonstrated in the scientific literature. Particularly, the development of new saturable absorber (SA) materials with exceptional nonlinear optical properties has become an efficient methodology for generating short pulses in fiber laser cavities at 2000 nm. Looking for clarifying the current state of the art of TDFL technology at 2000 nm, we review in this paper the main achievements of TDFLs in the last five years (2022–2018) based on SA materials. Nonlinear optical properties of these materials, experimental setup arrangements, as well as new avenues are addressed in this review for the advancements in source laser technologies operating at 2000 nm.

Advances in multi-wavelength Brillouin fiber lasers: An outlook across different spectral regions

In recent years, Brillouin fiber lasers have become a promising optical source technology for academic and industrial purposes. Among the promising laser solutions that have emerged with low threshold, high efficiency, small linewidth, and low resonator loss, multi-wavelength architecture has attracted the most attention recently. However, the development of configurations with an increased number of Stokes channels that present high flatness and reasonable optical-to-signal ratio (OSNR) is a challenge that this fiber laser technology still faces, and the development of solutions for this is an open problem. From this perspective, this paper presents a review focused on recent progress in multi-wavelength Brillouin fiber laser (MBFL) devices. Specifically, microwave generation and temperature sensing applications are discussed. Key results in the spectral regions of 1.0μm, 1.3μm, 1.5μm, 1.6μm, and 2.0μm are reported, as well as future perspectives are addressed in this review for the advancements in multi-wavelength fiber laser sources.

Glossary of pre-settings given by laser companies: no consensus!

Since the construction of the first laser, many companies around the world have contributed to the development of new lasers technologies. To be user-friendly, some companies have developed a pre-setting mode in their laser devices. We aimed to review and compare all laser companies' pre-settings (PS) already established in the market. An online search of holmium:YAG (Ho:YAG) and thulium fiber laser (TFL) devices was carried out. Manual and PS mode, pulse width and pulse modulation technology data were collected. The PS parameters were collected directly from the brochure devices or by asking the companies consulting agents. Thirty-nine laser devices were analyzed (33 Ho:YAG and 6 TFL). The power range varies from 15 to 152W and 35W to 60W for Ho:YAG and TFL, respectively. PS are present in 66% of Ho:YAG lasers and the 33% of TFL. Long-pulse modes can be modified in 12 Ho:YAG and 1 TFL lasers. The median (IQR) PS for dusting stones with Ho:YAG laser is 0.4J (0.2-1), 21.5Hz (5-120), and 10W (1.5-28) for energy, frequency and power, respectively; for Ho:YAG fragmentation is 0.8J (0.3-5), 10 (3-15) Hz and 5 (1.5-50) W for energy, frequency, and power, respectively; and for popcorn is 0.8J (0.4-1.2), 10Hz (6-15) and 5W (4-18) for energy, frequency, and power, respectively. Dusting and fragmentation mode of Rocamed MH01 and EMS LaserClast 35 are programmed according to the stone type. Most of these settings do not depend on the size of the fiber being used nor the location and type of stone. For TFL, the pre-sets are divided in bladder stone, dusting, fine dusting, fragmentation, and ureteral stone. There is a huge variability regarding pre-sets offered by companies because there is no consensus. Pre-sets should provide a range to work efficacy and safety.

Performance and structure evolution of fluoindinate glass at high temperatures

AbstractFluoindinate glass (FIG) is considered an ideal material for fiber laser devices and mid‐infrared bulk optics components owing to its ultra‐low phonon energy and broad transparency window. However, the heat generated by devices fabricated with FIG during their operation limits its application. Therefore, there is an urgent need to study its high‐temperature properties. In this study, the thermal properties, microstructure, crystal phase behaviors, and optical and luminescent properties of high‐temperature FIG were comprehensively evaluated. We also attempted to reveal the changes in its structure at high temperatures using variable‐temperature Raman spectroscopy. We first found that the stretching vibration intensity of nonbridging F(Fnb) decreases, and the bending vibration of FIG increases with an increase in temperature, indicating that high temperatures could lead to the fracture of bridge bonds between some [InF6]3− octahedrons. Certainly, this will lead to glass structural instability, which will further increase the tendency of FIG to undergo devitrification in high‐temperature conditions. We believe that this work will provide a reference for the performance improvement and application of fluoride glass at high temperatures.

Er‐Activated Hybridized Glass Fiber for Laser and Sensor in the Extended Wavebands

AbstractEr‐activated fiber lasers are critical for many significant applications, including fiber communication, gas sensing, lidar and military. Although the design of suitable fiber materials has improved the performance of Er‐activated fiber lasers, extension of their operation wavebands still remains a significant challenge. Here, a compact all‐fiber laser is proposed and demonstrated, which can support lasing beyond 1630 nm, based on an Er‐activated hybridized glass fiber. The collaborative theoretical analysis and experimental characterization indicate that various distinct structure units can form in the hybridized fiber. This leads to the notable inhomogeneous spectral broadening. By using this hybridized fiber, a tunable fiber laser device is constructed and the wavelength can be rationally tuned in the range from 1609 to 1631 nm by mechanically stretching the fiber Bragg gratings (FBGs) manufactured by the point‐by‐point femtosecond laser inscription. Furthermore, a new fiber sensor system based on this seldom exploration waveband is built and efficient ethylene detection is demonstrated. The results highlight that rational hybridization mediated short‐ and medium‐structure modification strategy, demonstrated here in Er‐activated fiber laser, can be extended to other rare‐earth glass fiber systems for the exploration of fiber devices at new wavebands.

Hybrids of perovskite nanocrystals and SiO2 microfiber for robust and long-haul transmittable fiber lasers

Fiber lasers have broad prospects for the development of tunable high-performance photonic equipment and active fiber devices. However, they are still facing challenges, such as the limited emission wavelength and relatively high pump energy. Perovskite nanocrystals possess a large absorption cross-section, high quantum efficiency, long Auger lifetime, and tunable emission wavelength, which have been recognized as the promising gain media. In this work, a unique method was developed to form a type of fiber laser device based on high-quality SiO2 microfibers integrated with solution-processed perovskite nanocrystals. By this way, the robust and efficient fiber laser with characteristics of long-haul transmission, tunable laser mode, and high polarization state was effectively obtained. Our results represent a significant advancement in fiber lasers based on favorable perovskite nanocrystals and high-quality SiO2 microfiber and provide new possibilities for active fiber devices.

Ретроградная гибкая уретероскопия с тулиевой волоконной нефролитотрипсией в лечении пациентов с камнем нижней полярной чашечки

Introduction The SuperPulse Thulium (Tm) fiber laser (wavelength of 1.94 m) has been recently introduced as a directed-energy source for urology. Preclinical studies have shown a significant potential of the SuperPulse Tm fiber laser (SP TFL) for lithotripsy. However, clinical reports of using SP TFL to treat urolithiasis are still few and limited. Of special interest are challenging cases, e.g., lower pole stones, when extreme deflection of the instrument is required. Objective To evaluate the effectiveness of the SuperPulse Tm fiber laser in the management of lower pole small calyceal stones during flexible ureteroscopy (F-URS). Method s. The SuperPulse Tm fiber laser device (Urolase 2, IRE Polus, Fryazino, Russia) has been cleared for clinical use by the Ministry of Health of Russian Federation. Study protocol has been approved by the Ethical Review Committee. Between January 2018 and February 2019, 130 patients with kidney stones have undergone Thulium fiber laser lithotripsy during F-URS. We retrospectively analyzed 15 of this patients with a single radiopaque lower pole calculus that were included in the present study. Stone size, stone density, lithotripsy time (from the first to last footswitch press) and lasering (laser emission) time were measured. The SP TFL was used for stone disintegration with different settings in dusting and fragmentation modes (0.1 - 4J, 7-300Hz, 6-40W) via a fiber with a 200-m core diameter. Low dose CT scanning was performed on POD 90 to assess SFR. Results Stone size ranged from 4 to 17 mm and stone density varied from 350 to 1459 HU. The average lithotripsy time was 12 min (3-30 min). The average lasering time was 1.3 min (0.4-2.5 min) and the mean hospital stay was 1.1+/-0.3 days. In all cases we reached the lower pole stone containing calyx with a laser fiber. The complication rates were evaluated by using the Clavien-Dindo grading system and did not exceed GII (6.6%). SFR on POD 90 was achieved in 86.6% of cases. Conclusions F-URS with SuperPulse Tm fiber laser is safe and effective option in the management of lower pole small calyceal stones. The possibility of using small laser fibers gives better instrument deflection which make possible to reach lower pole calyceal stones even with acute lower pole infundibulopelvic angle (IPA).

PD34-06 FLEXIBLE URETEROSCOPY FOR LOWER POLE RENAL STONES: NOVEL SUPERPULSE THULIUM (TM) FIBER LASER LITHOTRIPSY. FIRST CLINICAL RESULTS

You have accessJournal of UrologyStone Disease: Surgical Therapy V (PD34)1 Apr 2020PD34-06 FLEXIBLE URETEROSCOPY FOR LOWER POLE RENAL STONES: NOVEL SUPERPULSE THULIUM (TM) FIBER LASER LITHOTRIPSY. FIRST CLINICAL RESULTS Dmitry Korolev*, Roman Klimov, Dmitry Tsarichenko, Mikhail Enikeev, Alim Dymov, Stanislav Ali, Gagik Akopyan, Vladimir Lekarev, Mark Taratkin, Leonid Rapoport, Dmitry Enikeev, and Peter Glybochko Dmitry Korolev*Dmitry Korolev* More articles by this author , Roman KlimovRoman Klimov More articles by this author , Dmitry TsarichenkoDmitry Tsarichenko More articles by this author , Mikhail EnikeevMikhail Enikeev More articles by this author , Alim DymovAlim Dymov More articles by this author , Stanislav AliStanislav Ali More articles by this author , Gagik AkopyanGagik Akopyan More articles by this author , Vladimir LekarevVladimir Lekarev More articles by this author , Mark TaratkinMark Taratkin More articles by this author , Leonid RapoportLeonid Rapoport More articles by this author , Dmitry EnikeevDmitry Enikeev More articles by this author , and Peter GlybochkoPeter Glybochko More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000000905.06AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: The SuperPulse Thulium (Tm) fiber laser (wavelength of 1.94 µm) has been recently introduced as a directed-energy source for urology. Preclinical studies have shown a significant potential of the SuperPulse Tm fiber laser (SP TFL) for lithotripsy. However, clinical reports of using SP TFL to treat urolithiasis are still few and limited. Of special interest are challenging cases, e.g., lower pole stones, when extreme deflection of the instrument is required. To evaluate the effectiveness of the SuperPulse Tm fiber laser in the management of lower pole small calyceal stones during flexible ureteroscopy (F-URS). METHODS: The SuperPulse Tm fiber laser device (Urolase 2, IRE Polus, Fryazino, Russia) has been cleared for clinical use by the Ministry of Health of Russian Federation. Study protocol has been approved by the Ethical Review Committee. Between January2018 and February 2019, 130 patients with kidney stones have undergone Thulium fiber laser lithotripsy during F-URS. We retrospectively analyzed 15 of this patients with a single radiopaque lower pole calculus that were included in the present study. Stone size, stone density, lithotripsy time (from the first to last footswitch press) and “lasering” (laser emission) time were measured. The SP TFL was used for stone disintegration with different settings in dusting and fragmentation modes (0.1 – 4J, 7-300Hz, 6-40W) via a fiber with a 200-μm core diameter. Low dose CT scanning was performed on POD 90 to assess SFR. RESULTS: Stone size ranged from 4 to 17 mm and stone density varied from 350 to 1459 HU. The average lithotripsy timewas 12 min (3-30 min). The average “lasering” time was 1.3 min (0.4-2.5 min) and the mean hospital stay was 1.1 ± 0.3 days. In all cases we reached the lower pole stone containing calyx with a laser fiber. The complication rates were evaluated by using the Clavien-Dindo grading system and did not exceed GII. The overall postoperative complication rate was 26.6% (GI 20%; GII 6.6%). SFR on POD 90 was achieved in 86.6% of cases. CONCLUSIONS: F-URS with SuperPulse Tm fiber laser is safe and effective option in the management of lower pole small calyceal stones. The possibility of using small laser fibers gives better instrument deflection which make possible to reach lower pole calyceal stones even with acute lower pole infundibulopelvic angle (IPA). Source of Funding: non © 2020 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 203Issue Supplement 4April 2020Page: e713-e713 Advertisement Copyright & Permissions© 2020 by American Urological Association Education and Research, Inc.MetricsAuthor Information Dmitry Korolev* More articles by this author Roman Klimov More articles by this author Dmitry Tsarichenko More articles by this author Mikhail Enikeev More articles by this author Alim Dymov More articles by this author Stanislav Ali More articles by this author Gagik Akopyan More articles by this author Vladimir Lekarev More articles by this author Mark Taratkin More articles by this author Leonid Rapoport More articles by this author Dmitry Enikeev More articles by this author Peter Glybochko More articles by this author Expand All Advertisement PDF downloadLoading ...

基于石墨烯的光纤功能化传感器件和激光器件

基于石墨烯的光纤功能化传感器件和激光器件

A Microfiber Knot Incorporating a Tungsten Disulfide Saturable Absorber Based Multi-Wavelength Mode-Locked Erbium-Doped Fiber Laser

A novel multi-wavelength mode-locked Erbium-doped fiber laser with tungsten disulfide (WS2) combined with a microfiber knot is described. This hybrid fiber structure facilitates strong light matter interaction between the saturated absorption of the WS2 material and high optical non-linearity of the microfiber knot. It is demonstrated experimentally that the novel fiber laser works stably in the absence of an external comb filter, with the generation of stable multi-wavelength picosecond pulses. In the multi-wavelength lasing regime, up to seven-wavelength stable mode-locked pulses are obtained using a polarization controller with the pump power at ∼250 mW. The pulse period and the pulsewidth are 188.7 ns and 16.3 ps, respectively. In addition, the number of multi-wavelength lasing channels can be changed by simply adjusting the microfiber knot size. Experimental results show the laser to have a stable output over 12-h recording period. The results of this investigation demonstrate that the optical microfiber knot with a WS2 overlay based fiber laser device can operate as a highly nonlinear optical component and a saturable absorber. The proposed multi-wavelength lasing device can therefore be widely used for non-linear and ultrafast photonics and has a number of advantages compared to similar devices using more conventional technologies, including low cost and good stability.

Unusual thermal response of tellurium near-infrared luminescence in phosphate laser glass.

We report an unusual thermal response of tellurium (Te) near-infrared (NIR) luminescence in phosphate laser glass, where the luminescence first increases and then decreases with heat-treatment temperatures increasing from 250°C to the glass transition temperature (Tg). This is followed by a distinct revival of Te NIR luminescence at temperatures above Tg. This result differs from the scenario in conventional rare-earth (Er3+, Nd3+, and Yb3+)-doped phosphate glasses, where the rare-earth NIR emission decreases with increasing heat-treatment temperature. The difference may originate from conversion between Te4 and other Te species, which depends on the evolution of the glass structure and molecular motion during the reheating processes, leading to unusual thermal response of Te NIR luminescence. The increase in Te4 clusters enhances Te NIR emission, indicating that Te NIR luminescence is assigned to the Te4 cluster, in contrast to previous studies. Heating and cooling cycles between 50°C and 250°C reveal strong dependence of the thermal degradation on glass structure. Te-doped phosphate laser glass with zero thermal degradation can be realized by stabilizing NIR luminescence center Te4 by adjusting the glass structure with reduced network crosslinking. The superior optical performance has been confirmed in our previous study that the NIR luminescence properties can be well maintained in Te-doped fiber. The findings indicate that Te-doped phosphate glass with unusual thermal responses can potentially be used in fiber laser devices.

Ultralong \u03c0-phase shift fiber Bragg grating empowered single-longitudinal mode DFB phosphate fiber laser with low-threshold and high-efficiency

Phosphate glass fiber is one of the candidates for building compact fiber lasers because of its capability of high-concentration of rare-earth ions doping in fiber core. Nevertheless, it is challenging for the integration of UV-written intra-core fiber Bragg gratings into the fiber laser cavity due to the low photosensitivity of phosphate glass fiber. The research presented in this paper will focus on demonstration of UV-written Bragg gratings in phosphate glass fiber and its application in direct-written short monolithic single-frequency fiber lasers. A 5-cm-long strong π-phase shift Bragg grating structure is direct-inscribed into the Er/Yb co-doped gain fiber using an excimer laser. The fiber laser device emits output power of 10.44 mW with a slope efficiency of 21.5% and the threshold power is about 42.8 mW. Single-longitudinal mode operation is validated by radio frequency spectrum measurement. Moreover, the output spectrum at the highest power shows an excellent optical signal to noise ratio of about 70 dB. These results, to the best of our knowledge, show the lowest power threshold and highest efficiency among the reports that using the same structure to achieve single-longitudinal mode laser output.

V03-02 FIRST CLINICAL STUDY ON SUPERPULSE THULIUM FIBER LASER FOR LITHOTRIPSY

You have accessJournal of UrologyUrolithiasis & Endourology1 Apr 2018V03-02 FIRST CLINICAL STUDY ON SUPERPULSE THULIUM FIBER LASER FOR LITHOTRIPSY Olivier Traxer, Leonid Rapoport, Dmitry Tsarichenko, Alim Dymov, Dmitry Enikeev, Nikolay Sorokin, Stanislav Ali, Gagik Akopyan, Dmitry Korolev, Alexandra Proskura, Vladimir Lekarev, and Roman Klimov Olivier TraxerOlivier Traxer More articles by this author , Leonid RapoportLeonid Rapoport More articles by this author , Dmitry TsarichenkoDmitry Tsarichenko More articles by this author , Alim DymovAlim Dymov More articles by this author , Dmitry EnikeevDmitry Enikeev More articles by this author , Nikolay SorokinNikolay Sorokin More articles by this author , Stanislav AliStanislav Ali More articles by this author , Gagik AkopyanGagik Akopyan More articles by this author , Dmitry KorolevDmitry Korolev More articles by this author , Alexandra ProskuraAlexandra Proskura More articles by this author , Vladimir LekarevVladimir Lekarev More articles by this author , and Roman KlimovRoman Klimov More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2018.02.827AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Ho:YAG laser wavelength of 2.1 μm is off the peak of water absorption and the efficiency of stone fragmentation can be improved by using a laser with wavelength matching peak water absorption at 1.94 μm, where water absorbs 4.5 times more efficiently than at 2.1 μm. Previous in vitro studies have shown that thulium (Tm) fiber laser operating at wavelength 1.94 μm can be effective for stone fragmentation. Recently, we have evaluated in vitro performance of Super-Pulse Tm fiber laser prototype and found its efficiency to be higher than the leading Ho:YAG laser for fragmentation (x1.7 times) and dusting (x2.3 to 4 times) for equal energy and rep rate settings. This is pilot clinical evaluation of the first commercially available Super-Pulse Tm fiber laser system for lithotripsy. METHODS The Super-Pulse Tm fiber laser device has been cleared for clinical use by the Ministry of Health of Russian Federation and the protocol has been approved by the institutional Ethical Review committee. We prospectively analyzed 40 patients who underwent Super-Pulse Tm fiber laser lithotripsy for renal (n=29), ureteral (n=9), and bladder stones (n=2) with various laser settings. Size of the stone, its density, operation time, “laser on” time were measured. Based on surgeon’s feedback, retropulsion and intraoperative visibility were assessed. Post–operative parameters were recorded. RESULTS For renal stones, the average size was 15.6 mm (5.5 – 27 mm), for ureteral stones – 9.6 mm (5 – 13 mm), for bladder stones – 28 mm (15 – 42 mm). The average stone density for renal stones was 1217 HU (524 – 2053 HU), for ureteral stones - 1262.2 HU (700 – 1782 HU), for bladder stones – 839.5 HU (779 – 900 HU). The average time to complete renal stone fragmentation (to dust or small fragments and their washing out) was 30.2 min (10 – 50 min), for ureteral stones – 19.2 min (10 – 28 min), for bladder stones – 23 min (21 – 25 min). The retropulsion during miniPCNL and URS in the vast majority of cases was insignificant especially when using dusting mode with energy level less than 0.5 J. Visibility was estimated as optimal by surgeons in most cases. Fragmentation mode with energy level 2 to 6 J and repetition rate 5-10 Hz was most suitable for bladder stone disintegration. CONCLUSIONS Our preliminary data indicate high efficiency and safety of the novel Super-Pulse Tm fiber laser lithotripter with wavelength 1.94 μm for urinary stone disintegration. Wide range of settings (0.05 to 6 J; 5 to 2000 Hz) available for this laser allows efficient destruction of stones of any composition and location in both dusting and fragmentations modes. Further studies will confirm those results. © 2018FiguresReferencesRelatedDetails Volume 199Issue 4SApril 2018Page: e321-e322 Advertisement Copyright & Permissions© 2018MetricsAuthor Information Olivier Traxer More articles by this author Leonid Rapoport More articles by this author Dmitry Tsarichenko More articles by this author Alim Dymov More articles by this author Dmitry Enikeev More articles by this author Nikolay Sorokin More articles by this author Stanislav Ali More articles by this author Gagik Akopyan More articles by this author Dmitry Korolev More articles by this author Alexandra Proskura More articles by this author Vladimir Lekarev More articles by this author Roman Klimov More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Effect of ethanol infiltration on the zero dispersion wavelength of solid core photonic crystal fiber

In this paper, a hexagonal structure of ethanol filled solid core photonic crystal fiber having dispersion shifted properties is presented. The guiding properties, like effective mode area and dispersion, of the ethanol filled photonic crystal fiber are studied by using the full vectorial finite element method. The numerical simulation results show that the selectively filling of the ethanol in the cladding holes of photonic crystal fiber shifts the zero dispersion wavelength from near infrared region (0.98μm) to mid infrared region (1.55μm). This kind of photonic crystal fiber structure is very useful for dispersion compensating tool, sensing applications, fiber laser devices and non-linear applications like supercontinuum generation.

NEW NONLINEAR ANALYSIS, CHAOS THEORY AND INFORMATION TECHNOLOGY APPROACH TO STUDYING DYNAMICS OF THE THE ERBIUM ONE-RING FIBRE LASER

Within new non-linear analysis, chaos theory and information technology approach it is numerically investigated chaos dynamics generation in the erbium one-ring fibre laser (EDFL, 20.9 mV strength, l = 1550.190 nm) with the control parameters: the modulation frequency f and dc bias voltage of the electro-optical modulator. It is shown that in depending upon f, V values there are realized 1-period (f = 75 MHz, V = 10 V and f = 60 MHz, V = 4 V), 2-period (f = 68 MHz, V = 10 V or f = 60 MHz, V = 6 V), chaotic (f = 64 MHz, V = 10 V and f = 60 MHz, V = 10 V) regimes. There are calculated the Lyapunov’s exponents, correlation, embedding, Kaplan-York dimensions, Kolmogorov entropy. Theoretically it is shown that a chaos in the erbium fiber laser device is generated via intermittency by increasing the DC bias voltage and period-doubling bifurcation by reducing the modulation frequency.

Homogenization of Carbides in Ni60/WC Composite Coatings Made by Fiber Laser Remelting

In the current study, the effect of laser remelting on homogenization of carbides in WC-reinforced Ni60 composite coatings was investigated. Ni60 + 50 wt% WC composite coatings were fabricated on the surface of Q550 steel by LDF4000-100 fiber laser device. First cladding layer was made by rectangle laser spot and then circular laser spot was utilized to remelt the coatings. Microstructure characteristics were investigated by optical microscope and scanning electron microscopy. Elemental distribution and phase constitution were analyzed by energy disperse spectroscopy and X-ray diffraction. The results showed that accumulation of residual WC particles was sufficiently eliminated under the effect of laser remelting. The irregularly shaped carbides in first cladding layer were transformed into well-distributed polygonal carbides by laser remelting. Statistical analysis indicated median size of reinforcement particles decreased from 35.40 to 5.62 µm. Microhardness of remelted region had a smooth profile and decreased by −50 HV0.1 than that of first cladding region. Homogenization of carbides in nickel composite coating was well realized by laser remelting.

Investigation on cored-eutectic structure in Ni60/WC composite coatings fabricated by wide-band laser cladding

Ni60 composite coatings reinforced with WC particles were fabricated on the surface of Q550 steel using LDF4000-100 fiber laser device. The wide-band laser and circular beam laser used in laser cladding were obtained by optical lens. Microstructure, elemental distribution, phase constitution and wear properties of different composite coatings were investigated. The results showed that WC particles were partly dissolved under the effect of wide-band fiber laser irradiation. A special cored-eutectic structure was synthesized due to dissolution of WC particles. According to EDS and XRD results, the inside cores were confirmed as carbides of M23C6 enriched in Cr, W and Fe. These complex carbides were primarily separated out in the molten metal when solidification started. Eutectic structure composed of M23C6 carbides and γ-Ni(Fe) grew around carbides when cooling. Element content of Cr and W is lower at the bottom of cladding layer. In consequence, the eutectic structure formed in this region did not have inside carbides. The coatings made by circular laser beam were composed of dendritic matrix and interdendritic eutectic carbides, lacking of block carbides. Compared to coatings made by circular laser spot, the cored-eutectic structure formed in wide-band coatings had advantages of well-distribution and tight binding with matrix. The uniform power density and energy distribution and the weak liquid convection in molten pool lead to the unique microstructure evolution in composite coatings made by wide-band laser. Experiment results indicated the wear resistance and microhardness of composite coatings were both significantly improved.

Extending single mode performance of all-solid large-mode-area single trench fiber.

We report a novel "single trench fiber" design for mode area scaling of the fundamental mode while offering effective single mode operation for a compact fiber laser device. This fiber design allows very high suppression of the higher order modes by offering high loss and power delocalization. It has the advantages of low cost and easy fabrication thanks to all solid fiber design, cylindrical symmetry, and higher refractive index of core as that of the cladding. A Yb-doped single trench fiber with a 40 µm core diameter has been fabricated from modified chemical vapor deposition process in conjunction with solution-doping offering an effective mode area of as large as ~1,000 µm(2) at 1,060 nm for the bend radius of 20 cm. Detailed characterizations confirm a robust single mode behavior of the fiber. Comparative analysis with other fiber designs shows significant performance enhancement of effective single mode operation suitable for fiber laser applications.