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We demonstrate a passively Q-switched thulium-doped fiber laser by using single-walled carbon nanotube (SWCNT) polyvinyl alcohol (PVA) composite film as the saturable absorber (SA). A relatively large mode area on the SA was employed to avoid damage of the SWCNT/PVA film and benefit pulsed laser operation. Stable pulses of 85?164?kHz repetition rate were generated at 1967?nm with a maximum average output power of 103?mW. The single pulse energy was up to ?0.63??J with ?0.87??s pulse duration.

A self-starting 2 m a fiber passively mode-locked Tm3+-doped fiber laser based on nonlinear loop mirror (NOLM) was demonstrated. The laser operated at a continuous wave or unstable pulses regime after reaching the launched pump power of 3 W. Self-starting mode-locked pulses centered at 2 061.5 nm with an FWHM of 18.1 nm and an average output power of 8.8 mW were achieved when the launched pump power increased to 4.69 W. Continuously increasing to the maximum launched pump power of 7.56 W, stable mode-locked pulses centered at 2 062.2 nm with a FWHM of 17.1 nm were produced at a slope efficiency of 6.2%. The pulses operated at the repetition rate of 4.26 MHz with a single pulse energy up to 65.6 nJ and a pulse width of 424 fs. To the best of our knowledge, this was the first demonstration on mode-locked fiber laser based on NOLM at 2 m region with the highest single pulse energy.

In this paper, the theoretical rate equation model of an in-band pumped gain-switched thulium-doped fiber (TDF) laser is investigated. The analytical formulations of pump energy threshold, peak power extraction efficiency, and pulse extraction efficiency are derived through analyzing the interaction process between the pump pulse and the laser pulse. They are useful for understanding, designing, and optimizing the in-band pumped TDF lasers in a 1.9 μm–2.1 μm wavelength region. The experiment with an all-fiber gain-switched TDF laser pumped by a 1.558-μm pulse amplifier is conducted, and our experimental results show good agreement with theoretical analysis.

We report on a generation of self-starting mode-locked resembling (MLR) pulses in an all-fiber, gain-switched Tm(3+)-doped fiber laser operating at 2 μm wavelength, which we believe to be the first demonstration of such an approach. The laser delivers 100% modulated MLR pulses within an envelope of ~30 ns gain-switched pulse at a repetition rate of 30 kHz. The maximum average output power is 0.4 W and the maximum peak-power of MLR pulses can be as high as 1.1 kW. The performance of the laser is described.

We demonstrate a passively Q-switched Tm3+-doped all-fiber laser (TDFL) at around 2 μm with a graphene-based saturable absorber (SA). The graphene is prepared by the reduction of graphite oxide (GO), deposited on the fiber core and inserted into a linear cavity as the passive Q-switch. A 793 nm laser diode (LD) is used as the pump source, with a maximum power of 200 mW. A maximum output power of ~33.5 mW is obtained at a pump power of 200 mW, with a high optical conversion efficiency of about 17%. The corresponding single pulse energy is 260 nJ and the repetition rate is 128 kHz.

We present an all-fiber gain-switched thulium (Tm) doped fiber laser operating in the eye-safe region at 1940 nm. The fibre Bragg gratings (FBGs) inscribed by phase mask technology are used as cavity mirrors, and the transmission spectra of FBGs are also measured. The output characteristics are studied at pulse repetition frequencies of 10, 20 and 30 kHz, and the maximum output powers of 28.9, 67.0 and 71.0 mW are achieved under incident pump powers of 122, 247 and 250 mW. The narrowest pulse width of 29 ns and shortest pulse built-time of 140 ns are obtained at 10 kHz. The relation between pulse built-time and cavity length are discussed.

We report on stretched-pulse operation of a thulium-doped fiber laser. The laser generated pulses at a center wavelength of 1974 nm with an energy of 4 nJ that could externally be compressed to a duration of 173 fs.

We have constructed a novel ring cavity for a double-clad thulium-doped fiber laser, by placing the fiber's 45 degrees angle-polished output end before the input end and relaunching the pump and the laser power into the fiber. This design can reduce reabsorption by using short fibers without loss of pump efficiency. The dependence of the laser's performance on the fiber's length and the output coupler's reflectivity is investigated experimentally and theoretically. With an 80-cm-long fiber, 2.7-W single-mode continuous-wave output is generated for 11.5 W of launched pump power.

We demonstrate operation of a tunable mode-locked thulium-doped fiber laser, based on a wavelength-selective chirped fiber Bragg grating (CFBG). By applying strain to the CFBG, we shift its reflection band and can thereby tune the emission-wavelength of the fiber laser between 2022nm and 2042 nm. We obtain a pulse train at 9.4MHz repetition rate and a pulse duration between 9.0 and 12.8 ps. To the best of our knowledge, we report the first tunable mode-locked thulium-doped fiber laser using a tunable CFBG as wavelength-selective element.

We report the development of a widely tunable mode-locked thulium-doped fiber laser based on a robust chirped fiber Bragg grating (CFBG). By applying mechanical tension and compression to the CFBG, an overall tunability of 20.1 nm, spanning from 2022.1 nm to 2042.2 nm, was achieved. The observed mode-locked pulse train from this fiber laser has a repetition rate of 9.4 MHz with an average power of 12.6 dBm and a pulse duration between 9.0 ps and 12.8 ps, depending on the central wavelength. To the best of our knowledge, this is the first demonstration of a tunable mode-locked thulium-doped fiber laser operating beyond 2 mu m using a CFBG as a wavelength-selective element. (C) 2022 Optica Publishing Group

We report SESAM mode-locked, linear cavity thulium-doped fiber laser based on a highly Ge-doped active fiber and operating in the anomalous dispersion regime at 1.88 μm, producing 900-fs pulses amplified up to the 3.7-nJ energy.

In this paper, we present monolithic thulium-doped fiber laser (TDFL) emitting in the region around 2 μm. To our knowledge, this is the first rare-earth-doped fiber laser with a FBG pair written with deep UV femtosecond laser radiation.

Up to ∼0.16 μJ noise-like-toped dissipative soliton resonances at ∼1954.7 nm are directly produced from a thulium-doped fiber laser with ∼1.04 km ultra-long cavity. Cladding-pumping is utilized for overcoming the accumulated large attenuation loss of silica fiber at 2 μm band.

Few-layer graphene oxide depositing on broadband reflective mirror as a novel saturable absorber for mode-locking of a thulium-doped fiber laser at 2007 nm, which generated 0.56 nJ single pulse energy at 3.17 MHz repetition rate.

Ultrashort pulse fiber lasers with monotonically positively chirped pulse operation schemes have been intensively investigated in the past decade, since this propagation scheme allows for generation of very high pulse energies without limitation by optical wave-breaking or similar nonlinear effects. Pulse energies of several 10 nJ could be generated directly from the oscillator while maintaining fs pulse duration with relatively simple setups [1]. In contrast to other pulse propagation schemes, the pulse energy was found not to be generally limited by the stability of the propagation scheme itself in spite of large nonlinear phase accumulation, but typically by technical issues like the maximum available pump power or overdriving of the saturable absorber mechanism [1,2].

Intense, ultrafast laser systems with an emission wavelength at around 2 μm have become popular tools for many scientific research activities such as nonlinear frequency conversion into the long-wave mid-infrared [1] as well as the soft X-ray spectral region [2], in order to address numerous subsequent applications. There is, however, a strong application-driven demand for an increase in photon-flux, i.e. repetition rate and average power, of the driving laser systems. Thulium-doped fiber lasers are an average-power scalable laser concept at around 2 μm emission wavelength. They have been demonstrated with >100 W average power and show great promise to deliver peak powers of several tens of GW [3, 4]. Another advantage is the large gain bandwidth offered by Tm-doped fused silica, spanning from 1.8–2 μm [5].

Dissipative solitons from an all-fiber Thulium-doped fiber (TDF) ring oscillator are generated by using optically deposited single-wall carbon nanotubes as the saturable absorber (SA) and high numerical aperture (NA) fiber of measured normal dispersion is introduced to produce large net normal dispersion at 1.9μm.

Most of the FBGs used in continues-wave thulium-doped fiber lasers are made in foreign companies. So we built up a fiber Bragg grating (FBG) writing platform to produce different parameter FBG for research, and a homemade FBG-based thulium-doped fiber laser testing system was experimentally demonstrated in this paper. Here homemade uniform FBGbased thulium fiber laser output characteristic was explored. The thulium-doped fiber laser was built up with two 793nm laser diodes as pump source, a thulium-doped fiber, a combiner and a pair of homemade FBGs. A 1916 nm thulium-doped fiber laser with output power of 20.87 W and slope efficiency of 41.29% and a 1917 nm thulium-doped fiber laser with output power of 19.53 W and slope efficiency of 38.56% were obtained by optimizing the thulium-doped fiber length, the operation temperature of the grating and the center wavelength of the grating.

GHz pulsed thulium-doped fiber laser with stabilized repetition rate can enable a wide range of applications. By employing regenerative mode-locking and cavity stabilization technique, we have for the first time demonstrated a 10 GHz polarization-maintaining thulium-doped fiber laser, which has a long-term repetition-rate stabilization and picosecond timing-jitter. In our experiment, a RF circuitry is designed to extract the 10 GHz longitudinal clock signal so that stable regenerative mode-locking is achieved. A piezo actuator-based phase-lock-loop is used to lock the regeneratively mode-locked pulses to a local reference synthesizer. The regeneratively mode-locked pulses with picosecond pulse width exhibit a high super-mode suppression ratio of 60 dB. In addition, the repetition rate of the laser shows good long-term stability with a variation of 8 Hz in 8 hours, corresponding to a cavity free spectral range fluctuation of less than 16 mHz. Meanwhile, the Allan deviation of the stabilized 10 GHz regeneratively mode-locked pulses is measured to be as low as 2 × 10−12 over 1000 s average time, which is only limited by the stability of the reference synthesizer. Such an ultra-stable 10 GHz pulsed thulium fiber laser may find potential application in 2 µm optical communication, material processing and spectroscopy.

Intense, ultrafast laser sources with an emission wavelength beyond the well-established near-IR are important tools for exploiting the wavelength scaling laws of strong-field, light-matter interactions. In particular, such laser systems enable high photon energy cut-off HHG up to, and even beyond, the water window thus enabling a plethora of subsequent experiments. Ultrafast thulium-doped fiber laser systems (providing a broad amplification bandwidth in the 2 μm wavelength region) represent a promising, average-power scalable laser concept in this regard. These lasers already deliver ~100 fs pulses with multi-GW peak power at hundreds of kHz repetition rate. In this work, we show that combining ultrafast thulium-doped fiber CPA systems with hollow-core fiber based nonlinear pulse compression is a promising approach to realize high photon energy cut-off HHG drivers. Herein, we show that thulium-doped, fiber-laser-driven HHG in argon can access the highly interesting spectral region around 90 eV. Additionally, we show the first water window high-order harmonic generation experiment driven by a high repetition rate, thulium-doped fiber laser system. In this proof of principle demonstration, a photon energy cut-off of approximately 400 eV has been achieved, together with a photon flux

A Q-switched noise-like pulse operation was observed in a nonlinear polarization evolution based thulium-doped fiber laser. This novel phenomena formed in a noise like background. When the pump power was properly controlled and the polarization controller was carefully adjusted, a noise like mode locked pulse was modulated by a Q-switched pulse envelope, which resulted in the Q-switched noise-like pulse formation. In a single pulse envelope, there exist many mode locked pulses that have fundamental repetition rate which is corresponded to the cavity period. When the pump power was carefully increased from 760 mW to 1000 mW, the repetition rate of the adjacent pulse envelope can increased from 34 to 41.1 kHz, and then intra-cavity pulse energy of a envelope reached about 609 nJ. This phenomenon was first observed in thulium-doped fiber laser. It will add experimental basis for studying of the pulse dynamics in fiber lasers.

We present the technical realization of a compact system for performing experiments with cold $^{87}{\text{Rb}}$ and $^{39}{\text{K}}$ atoms in microgravity in the future. The whole system fits into a capsule to be used in the drop tower Bremen. One of the advantages of a microgravity environment is long time evolution of atomic clouds which yields higher sensitivities in atom interferometer measurements. We give a full description of the system containing an experimental chamber with ultra-high vacuum conditions, miniaturized laser systems, a high-power thulium-doped fiber laser, the electronics and the power management. In a two-stage magneto-optical trap atoms should be cooled to the low $\mu$K regime. The thulium-doped fiber laser will create an optical dipole trap which will allow further cooling to sub-$\mu$K temperatures. The presented system fulfills the demanding requirements on size and power management for cold atom experiments on a microgravity platform, especially with respect to the use of an optical dipole trap. A first test in microgravity, including the creation of a cold Rb ensemble, shows the functionality of the system.

In this contribution we demonstrate the nonlinear pulse compression of an ultrafast thulium-doped fiber laser down to 14 fs FWHM duration (sub-3 optical cycles) at a record average power of 43 W and 34.5 μJ pulse energy. To the best of our knowledge, we present the highest average power few-cycle laser source at 2 μm wavelength. This performance level in combination with GW-class peak power makes our laser source extremely interesting for driving high-harmonic generation or for generating mid-infrared frequency combs via intra-pulse frequency down-conversion at an unprecedented average power. The experiments were enabled by an ultrafast thulium-doped fiber laser delivering 110 fs pulses at high repetition rates, and an argon gas-filled antiresonant hollow-core fiber (ARHCF) with excellent transmission and weak anomalous dispersion, leading to the self-compression of the pulses. We have shown that ARHCFs are well-suited for nonlinear pulse compression around 2 μm wavelength and that this concept features excellent power handling capabilities. Based on this result, we discuss the next steps for energy and average power scaling including upscaling the fiber dimensions in order to fully exploit the capabilities of our laser system, which can deliver several GW of peak power. This way, a 100 W-class laser source with mJ-level few-cycle pulses at 2 μm wavelength is feasible in the near future.

In this work, sub-kilowatt, compact thulium-doped fiber laser systems, operating at a wavelength of 1940 nm, have been presented. The continuous-wave laser power generated out of a single oscillator was 90 W with a slope efficiency of 56.7%. Applying a master oscillator – power amplifier configuration, an output power of 120.5 W with a slope efficiency of 58.2% was demonstrated. These are the first results of the works aimed at developing kW-class “eye-safe” laser systems in Poland. Full Text: PDF References Z. Liu, et al., "Implementing termination analysis on quantum programming", Sci. China Inf. Sci. 62, 41301 (2019) CrossRef S. D. Jackson, A. Sabella, D.G Lancaster, "Application and Development of High-Power and Highly Efficient Silica-Based Fiber Lasers Operating at 2 μm", IEEE J. Sel. Top. Quantum Electron. 13, 567, (2007). CrossRef E. Russell, N. Kavanagh, K. Shortiss, and F. C. G. Gunning, "Development of thulium-doped fibre amplifiers for the 2μm waveband", Proc. SPIE 10683, 106832Q (2018) CrossRef P. Peterka, B. Faure, W. Blanc, M. Karasek, and B. Dussardier, "Theoretical modelling of S-band thulium-doped silica fibre amplifiers", Opt. Quantum Electron. 36, 201 (2004) CrossRef M. Eichhorn, "Pulsed 2 μm fiber lasers for direct and pumping applications in defence and security", Proc. SPIE 7836, 78360B (2010). CrossRef O. Traxer and E. X. Keller, "Thulium fiber laser: the new player for kidney stone treatment? A comparison with Holmium:YAG laser", World J. Urol. 2019 Feb 6. doi: 10.1007/s00345-019-02654-5 CrossRef S. Das, "Optical parametric oscillator: status of tunable radiation in mid-IR to IR spectral range based on ZnGeP 2 crystal pumped by solid state lasers", Opt. Quant. Electron. 51, 70 (2019) CrossRef M. Michalska, P. Hlubina, and J. Swiderski, "Mid-infrared Supercontinuum Generation to ∼4.7 μm in a ZBLAN Fiber Pumped by an Optical Parametric Generator", IEEE Photon. J 9, 3200207 (2017) CrossRef https://www.ipgphotonics.com DirectLink M.D. Burns, P. C. Shardlow, P. Barua, T. L. Jefferson-Brain, J. K. Sahu, and W. A.Clarkson, "47 W continuous-wave 1726 nm thulium fiber laser core-pumped by an erbium fiber laser", Opt. Lett. 44, 5230 (2019) CrossRef S.D. Jackson, "Cross relaxation and energy transfer upconversion processes relevant to the functioning of 2 μm Tm 3+ -doped silica fibre lasers", Opt. Commun. 230, 197 (2004). CrossRef X. Wang, P. Zhou, X. Wang, H. Xiao, and L. Si, "102 W monolithic single frequency Tm-doped fiber MOPA", Opt. Express 21, 32386 (2013) CrossRef K. Yin, R. Zhu, B. Zhang, G. Liu, P. Zhou, and J. Hou, "300 W-level, wavelength-widely-tunable, all-fiber integrated thulium-doped fiber laser", Opt. Express 24, 11085 (2016) CrossRef G. D. Goodno, L. D. Book, and J. E. Rothenberg, "600-W, single-mode, single-frequency thulium fibre laser amplifier", Proc. SPIE 7195, 71950Y (2009). CrossRef T. Ehrenreich, R. Leveille, I. Majid, K. Tankala, G. Rines, and P. Moulton, "1-kW, all-glass Tm: fiber laser", Proc. SPIE 7580, 1 (2010) DirectLink M. Michalska et al., "Highly stable, efficient Tm-doped fiber laser—a potential scalpel for low invasive surgery", Laser Phys. Lett. 13, 115101 (2016). CrossRef

An all-fiber thulium-doped fiber laser operating at a wavelength of 1940 nm is reported. A maximum output continuous-wave power of 70.7 W with a slope efficiency of 59%, determined with respect to the absorbed pump power, was demonstrated. The laser delivered almost a single-mode beam with a beam quality factor of < 1.3. Full Text: PDF References M. N. Zervas and C. A. Codemard, "High Power Fiber Lasers: A Review", IEEE J. Sel. Top. Quantum Electron. 20, 0904123 (2014). CrossRef D. J. Richardson, J. Nilsson, and W. A. Clarkson. "High power fiber lasers: current status and future perspectives [Invited]", J. Opt. Soc. Am. B 27, B63 (2010). CrossRef J. Swiderski, A. Zajac, and M. Skorczakowski, "Pulsed ytterbium-doped large mode area double-clad fiber amplifier in MOFPA configuration", Opto-Electron. Rev. 15, 98 (2007). CrossRef M. Eckerle et al. "High-average-power actively-modelocked Tm3+ fiber lasers", Proc. SPIE 8237, 823740 (2012). CrossRef J. Swiderski, D. Dorosz, M. Skorczakowski, and W. Pichola, "Ytterbium-doped fiber amplifier with tunable repetition rate and pulse duration", Laser Phys. 20, 1738 (2010). CrossRef P. Grzes and J. Swiderski, "Gain-Switched 2-μm Fiber Laser System Providing Kilowatt Peak-Power Mode-Locked Resembling Pulses and Its Application to Supercontinuum Generation in Fluoride Fibers", IEEE Phot. J. 10, 1 (2018). CrossRef S. Liang et al. "Transmission of wireless signals using space division multiplexing in few mode fibers", Opt. Express 26, 6490 (2018). CrossRef J. Swiderski, M. Michalska, and P. Grzes, "Broadband and top-flat mid-infrared supercontinuum generation with 3.52 W time-averaged power in a ZBLAN fiber directly pumped by a 2-µm mode-locked fiber laser and amplifier", Appl. Phys. B 124, 152 (2018). CrossRef F. Zhao et al. "Electromagnetically induced polarization grating", Sci. Rep. 8, 16369 (2018). CrossRef J. Sotor et al. "Ultrafast thulium-doped fiber laser mode locked with black phosphorus", Opt. Lett. 40, 3885 (2015). CrossRef M. Olivier et al. "Femtosecond fiber Mamyshev oscillator at 1550 nm", Opt. Lett. 44, 851 (2019). CrossRef J. Swiderski and M. Michalska, "Over three-octave spanning supercontinuum generated in a fluoride fiber pumped by Er & Er:Yb-doped and Tm-doped fiber amplifiers", Opt. Laser Technol. 52, 75 (2013). CrossRef C.Yao et al. "High-power mid-infrared supercontinuum laser source using fluorotellurite fiber", Optica 5, 1264 (2018). CrossRef J. Swiderski and M. Maciejewska, "Watt-level, all-fiber supercontinuum source based on telecom-grade fiber components", Appl. Phys. B 109, 177 (2012). CrossRef O. Traxer and E. X. Keller, "Thulium fiber laser: the new player for kidney stone treatment? A comparison with Holmium:YAG laser", World J. Urol., 1-12 (2019). CrossRef M. Michalska, et al. "Highly stable, efficient Tm-doped fiber laser—a potential scalpel for low invasive surgery", Laser Phys. Lett. 13, 115101 (2016). CrossRef R. L. Blackmon et al. "Thulium fiber laser ablation of kidney stones using a 50-μm-core silica optical fiber", Opt. Eng., 54, 011004 (2015). CrossRef A. Zajac et al. "Fibre lasers – conditioning constructional and technological", Bull. Pol. Ac.: Tech. 58, 491 (2010). CrossRef C. Guo, D. Shen, J. Long, and F. Wang, "High-power and widely tunable Tm-doped fiber laser at 2 \mu m", Chin. Opt. Lett. 10, 091406 (2012). CrossRef F. Liu et al. "Tandem-pumped, tunable thulium-doped fiber laser in 2.1 μm wavelength region", Opt. Express 27, 8283 (2019). CrossRef H. Ahmad, M. Z. Samion, K. Thambiratnam, and M. Yasin, "Widely Tunable Dual-Wavelength Thulium-doped fiber laser Operating in 1.8-2.0 mm Region", Optik 179, 76 (2019). CrossRef N. M. Fried, "Thulium fiber laser lithotripsy: An in vitro analysis of stone fragmentation using a modulated 110‐watt Thulium fiber laser at 1.94 µm", Lasers Surg. Med. 37, 53 (2005). CrossRef N. M. Fried, "High‐power laser vaporization of the canine prostate using a 110 W Thulium fiber laser at 1.91 μm", Lasers Surg. Med. 36, 52 (2005). CrossRef E. Lippert et al. "Polymers Designed for Laser Applications-Fundamentals and Applications", Proc. SPIE 6397, P639704 (2006). CrossRef N. Dalloz et al. "High power Q-switched Tm 3+ , Ho 3+ -codoped 2μm fiber laser and application for direct OPO pumping", Proc. SPIE 10897, 108970J (2019). CrossRef N. J. Ramirez-Martinez, M. Nunez-Velazquez, A. A. Umnikov, and J. K. Sahu, "Highly efficient thulium-doped high-power laser fibers fabricated by MCVD", Opt. Express 27, 196 (2019). CrossRef T. Ehrenreich et al. "1-kW, All-Glass Tm:fiber Laser", Proc. SPIE 7580, 758016 (2010). DirectLink L. Shah et al. "Integrated Tm:fiber MOPA with polarized output and narrow linewidth with 100 W average power", Opt. Express 20, 20558 (2012). CrossRef H. Zhen-Yue, Y. Ping, X. Qi-Rong, L. Qiang, and G. Ma-Li, "227-W output all-fiberized Tm-doped fiber laser at 1908 nm", Chin. Phys. B 23, 104206 (2014). CrossRef

Raman scattering provides a convenient mechanism to generate or amplify light at wavelengths where gain is not otherwise available. When combined with recent advancements in high power fiber lasers that operate at wavelengths ~2 μm, great opportunities exist for Raman systems that extend operation further into the mid-infrared (IR) regime for applications such as gas sensing, spectroscopy, and biomedical analyses. Here, a thulium-doped fiber laser is used to demonstrate Raman emission and amplification from a highly nonlinear silicon core fiber (SCF) platform at wavelengths beyond 2 μm . The SCF has been tapered to obtain a micrometer sized core diameter (~1.6 μm) over a length of 6 cm, with losses as low as 0.2 dB/cm. A maximum on-off peak gain of 30.4 dB was obtained with a modest average pump power of 12.4 mW, with simulations indicating that the gain could be increased to up to ~50 dB by extending the SCF length. Simulations also show that by exploiting the large Raman gain and extended mid-infrared transparency of the SCF, cascaded Raman processes could yield tunable systems with practical output powers across the 2-5 μm range.

We report high-energy 2 μm dissipative soliton generation from a passively mode-locked thulium-doped fiber laser with a semiconductor saturable absorber mirror. Self-starting stable mode-locking has been achieved with pulse energy of 12.07 nJ, pulse width of 43 ps and average power of 263 mW at a repetition rate of 21.79 MHz. The laser spectral width is ~2.65 nm with a center wavelength of 1928.2 nm. To the best of our knowledge, this is the highest single pulse energy reported to date directly from a passively mode-locked thulium-doped fiber laser.

Background: The role of liver surgery is increasing for primary and secondary liver tumors. One of the most feared complications of liver surgery is Post-Hepatectomy Liver Failure (PHLF). The authors would like to present their experience in a year for liver surgery with morbidity and mortality, including PHLF as evaluation parameters.Methods: This is a prospective study from July 2019-2020 in a single-center, in which patients with pre-existing liver pathology were assigned to receive liver resection. Types and duration of liver resection, duration of Pringle maneuver, and blood loss were measured. PHLF was evaluated using the ISGLS classification, and morbidity was evaluated using Clavien-Dindo and FABIB classification. The energy device used varies from the harmonic scalpel, ligature, and Thulium-doped fiber laser (TDFL). Data were processed descriptively with IBM SPSS 25 (SPSS Inc., Chicago, USA). Data are presented in descriptive frequency tables as medians and means.Results: A total of 17 procedures were performed, including minor hepatectomies (58.82 %) and major hepatectomies (41.18%). The mean duration of operation 5.3 hours, the duration of parenchymal transection 91.5 minutes, and the estimated blood loss 1638.2 cc. Vascular occlusion method using Pringle maneuver with mean duration of 31.67 minutes. PHLF incidence found were grade B (5.88 %) and grade C (11.7%), while morbidities by Clavien-Dindo mostly are grade 2 (38.2%) and FABIB classification mostly are Bleeding (45%). The mean postoperative ICU is 3.06days, and the mortality rate is as high as 23.52%.Conclusion: Liver resection in our center is quite fair judging from the low incidence of PHLF, although the mortality rate is at 23.52%. Due to that, surgical technique and teamwork between units involved need to be improved even further.

We report the generation of harmonic noise-like mode-locked pulses in a thulium-doped fiber laser. In this laser, mode-locking can be realized through the nonlinear polarization rotation (NPR) technique. The ring cavity configuration uses 5 m of a Tm-doped dual-cladding fiber, as a gain medium, pumped by a 793 nm diode laser. The cavity uses a couple of polarization controllers (PCs) and polarization-dependent isolator to form a nonlinear polarization-rotating saturable absorber. By carefully adjusting of the PCs, the laser generates noise-like mode-locked pulses at the 2.04 µm band. With the increase of the pump power, the laser generates harmonics of the mode-locking fundamental repetition frequency of 6.88 MHz, from which we can obtain the second harmonic in a controlled mode. The obtained results may be useful for enhancing the understanding of the mechanism and characteristics of noise-like pulse at the 2 µm band.

Ultrafast fiber lasers with a wide spectral range have huge demands for many applications. In this article, magnetron sputtering deposition (MSD) technique was utilized to prepare a new broadband microfiber based Sb thin film saturable absorber (SA), and ultrafast pulses in both 1.5 and 2 μm wavebands were generated with the integrated microfiber-based Sb thin film SA in erbium-doped fiber laser (EDFL) and thulium-doped fiber laser (TDFL), respectively. Pulse duration of 544 fs/972 fs and output power of 21.76 mW/36.1 mW centered at 1557 nm/1892 nm were respectively produced from stable mode-locked EDFL and TDFL. To the best our knowledge, this is the first time that ultrafast fiber lasers including both 1.5 μm and 2 μm wavebands were mode locked by a single microfiber-based Sb thin film SA.

espanolEn este trabajo se presenta un laser de fibra dopada con tulio en cavidad de anillo, operando en modo continuo. El bombeo se realiza en la zona de 1600 nm mediante laseres de fibra dopada con erbio. Se ha estudiado el comportamiento con bombeo en modo continuo y en modo pulsado, obteniendo unas eficiencias del 35% y del 38%, respectivamente. Estas eficiencias son superiores a las tipicas que se consiguen bombeando en 1600 nm. El laser emite en dos longitudes de onda separadas unos pocos nanometros, situadas entre 1910 nm y 1920 nm. Al mismo tiempo, se presentan tambien medidas de ganancia espectral de la fibra dopada con tulio. A modo de ejemplo, se ha realizado un amplificador de fibra dopada con tulio y se ha demostrado su viabilidad amplificando un espectro supercontinuo en la region comprendida entre 1800 nm y 2000 nm, el cual podria utilizarse para bombear fibras no lineales cuya longitud de onda de dispersion cero este situada en dicha region espectral. EnglishWe present in this work a thulium-doped fiber laser with ring cavity in continuous wave operation. The pumping is based on Erbium-doped fiber lasers at 1600 nm. The operation with continuous wave pumping and pulsed pumping has been studied, obtaining efficiencies of 35% and 38 % respectively. These efficiencies are higher than the known efficiencies pumping at 1600 nm. The emission spectrum has two peaks located between 1910 nm and 1920 nm. As the same time, we present measurements of the spectral gain of the thulium-doped fiber. As an example, we have implemented a thulium-doped fiber amplifier, demonstrating to be able to amplify a supercontinuum spectrum in the interval between 1800 nm and 2000 nm, which could be used to pump highly nonlinear fibers with a zero-dispersion wavelength in this region.

We demonstrate the data transmission characteristics of a 1.96 µm laser in an indoor simulated smoke channel. An active mode-locked thulium-doped fiber laser at 1961.63 nm can be generated, and the repetition rate is 2.11 GHz corresponding pulse duration of 12.47 ps. Therefore, the pulse can be modulated by a 2.11 Gb/s digital sequence to act as a carrier light source. The transmission characteristics of signal light under different visibility conditions of 0.5, 0.05, and 0.005 km are studied. Compared with the back-to-back conditions, the signal-to-noise ratios of the carrier can decrease after passing through the smoke channels, which are 3.93, 7.1, and 9.08 dB, respectively. At the same time, the received power jitter can increase from ± 0.16 to ± 1.14 d B . The sensitivity can be − 19.52 d B m at the visibility of 0.005 km. The experimental results show that thulium-doped mode-locked laser has an excellent performance in a smoke channel.

We report an all-fiber 2.8-µm ultra-short pulse master oscillator power amplifier (MOPA) system seeded by a soliton self-frequency shift from a mode-locked thulium-doped fiber laser. This all-fiber laser source delivers 2.8-µm pulses with an average power of 3.42 W, a pulse width of 115 fs, and a pulse energy of 45.4 nJ. We demonstrate, to the best of our knowledge, the first femtosecond watt-level all-fiber 2.8-µm laser system. A 2.8-µm pulse seed was obtained via the soliton self-frequency shift of 2-µm ultra-short pulses in a cascaded silica and passive fluoride fiber. A novel, to the best of our knowledge, high-efficiency and compact home-made end-pump silica-fluoride fiber combiner was fabricated and used in this MOPA system. Nonlinear amplification of the 2.8-µm pulse was realized, and soliton self-compression was observed accompanied by spectral broadening.

We report the fabrication and characterization of a five-tube nested hollow-core anti-resonant fiber (Nested HC-ARF), which exhibits outstanding optical performance in terms of a record attenuation value of 0.85 dB/km at 2 µm wavelength range with a 200 nm bandwidth below 2 dB/km and excellent modal purity. The power handling capability of the Nested HC-ARF is also demonstrated in this work. Pulses of 75 W, 160 ps from the thulium-doped fiber laser are delivered using a 6-m-long fabricated Nested HC-ARF. The tested fiber is coiled into a 20 cm bending radius and achieves a coupling efficiency of 86.7%. The maximum average power of 60.5 W is transmitted through our Nested HC-ARF in a robust single-mode fashion without introducing any damage to the input and output fiber end-faces, which demonstrates the superior ability of such a fiber for high-power laser delivery.

We demonstrate a Thulium-doped fiber laser that is Q-switched mode-locked via nonlinear polarization rotation in an As2S3 taper. The laser allows single and multiwavelength pulses, tunable central wavelength and tunable multiwavelength separation.

Titanium nitride (TiN) with outstanding physical and chemical properties has earned considerable attention. However, few studies have been conducted on the ability of TiN in the ultrafast photonics field. In this study, ultrafast fiber lasers operating at 1.5 and 2 μm were realized using TiN nanoparticles (NPs) deposited onto a D-shaped fiber (DF) as the optical modulator. TiN NPs were synthesized via a reduction–nitridation route. As the TiN-DF saturable absorber (SA) was integrated into the erbium-doped fiber laser (EDFL) and thulium-doped fiber laser (TDFL) cavities, femtosecond pulses of 1532 nm and 1960 nm were obtained with high performance. To the best of our knowledge, the mode-locked fiber laser operating around 1530 nm was realized for the first time. Interestingly, TiN-DF SA in the TDFL could be used as a temperature sensitive device, and a novel temperature sensor was proposed with the sensitivity of 88 pm °C−1. Our results verified that TiN-DF modulators are excellent nonlinear optical devices for ultrafast photonic applications.

Semiconducting polymer dots (Pdots) have attracted much attention due to their outstanding optical properties. However, the potential of Pdots in laser technology is rarely studied. Here, we first report the benzobisthiadiazole (BBT)-based Pdot as a single broadband nonlinear saturable absorber (SA) for passively Q-switched fiber lasers at 1, 1.5, and 2 μm. The Pdot-SA possesses a strong saturable absorption, a broadband nonlinear optical response, and a large modulation depth. Once the Pdot-SA is integrated into the ytterbium-, erbium-, and thulium-doped fiber laser cavities, stable Q-switched operations are observed at the central wavelengths of 1036, 1561, and 1951 nm. Our results verify that the Pdots are promising nonlinear media for Q-switched pulse generation, and highlight the potential of Pdots for relevant nonlinear optical applications.

In this paper, we demonstrated an all-fiber bidirectional ultrafast thulium-doped fiber laser at 2 μm with a single-wall carbon nanotube presented as saturable absorber. We successfully obtained bidirectional mode-locking operations with pulse repetition frequency adjustable from 35 to 122 MHz by shortening the cavity length. Meanwhile, with the reduction of the intracavity dispersion, the number of Kelly sidebands was significantly decreased and the output energy was more concentrated on the soliton pulse. Besides, by manipulating the pump power and polarization controller, the two results of bidirectional mode-locked pulses with the same repetition frequency and differential repetition frequency were observed. We found that the repetition rate difference between the clockwise and counterclockwise pulse trains was adjustable by changing the pump power or controlling the intracavity polarization. When the pulse repetition frequency was 35 MHz and 122 MHz, the adjustment range of repetition rate difference was 764–922 Hz and 540–2000 Hz, respectively. It is believed that this novel laser source can support free-running dual optical comb spectroscopy to detect important air gases like H2O or CO2 in the future.

All-solid photonic bandgap fibers (PBGFs) were designed and fabricated to work as low-pass filters in 2-μm region. They were used for manipulating thulium doped fiber laser (TDFL) operating in the 2-μm region via amplified spontaneous emission suppression. A sharp lasing peak at 1915 nm was achieved using a single-stage TDFL with full width at half maximum and optical signal-to-noise ratio of 0.3 nm and 39.5 dB, respectively. This lasing is achieved using the fabricated PBGF low-pass filter with cutoff wavelength at 1945 μm and loss of more than 25 dB. In this respect, the resultant TDFL performed better than the one that did not employ the low-pass filter. In this paper, we present a few representative cases involving the all-solid PBGF. We have shown that by increasing the diameter of the fabricated PBGF from 142 to 189 μm, their cutoffs related to their bandgaps shifted from 1727 nm toward longer wavelengths, 2079 nm. As a result, lasers with different wavelengths were generated within 2-μm region.