Doped Silica Fiber Laser Research Articles

Simulation of solar-pumped multicore Nd3+-doped silica fiber lasers

Simulation of solar-pumped multicore Nd3+-doped silica fiber lasers

Amplification at 2.3-µm in 1.9-µm thulium-doped silica fiber laser

A high-power 1.9-µm Tm3+-doped silica fiber laser generates 7.3-dB of gain at 2.3 µm when cladding- pumped with 207 W of power at 793 nm. We attribute the 2.3-µm gain to the transition 3H4 → 3H5 of Tm3+.

Monolithic ultrashort-cavity DBR gain-switched thulium doped fiber laser made by high-precision femtosecond laser direct-writing

We demonstrate a novel monolithic ultrashort-cavity distributed Bragg reflector (DBR) gain-switched thulium doped silica fiber laser. Commercial heavily thulium doped non-polarization-maintaining silica fiber was selected as the gain medium. Monolithic linear laser resonator, which includes a pair of uniform fiber Bragg gratings (FBGs) with a space of 1.0-mm inbetween, was inscribed in the thulium fiber by femtosecond-laser point-by-point (PbP) writing method. The reflectivity of either FBG is close to 100 % and the effective cavity length is calculated to be 3.5 mm. Such an ultrashort-DBR-cavity fiber laser exhibited high Q factor and low cavity loss, allowing the efficient utilization of pump power within the millimeter-long cavity. Single-longitudinal, linearly polarized, gain-switched TDFL at 2003 nm, with a recorded shortest pulse duration of 4.3 ns, a repetition rate of 50 kHz, a maximum peak power of 500 W, and single pulse energy of 2.14 μJ, has been realized, benefitted from the ultrashort cavity length.

Monolithic 2-µm single-frequency linearly-polarized gain-switched distributed feedback fiber laser by femtosecond laser direct-writing.

We report a single-frequency, linearly polarized gain-switched, distributed feedback (DFB), 2-µm thulium doped silica fiber laser (TDFL), with an effective cavity length of 2.5 mm. The cavity is based on a heavily thulium doped non-polarization-maintaining silica fiber and composed of a π-phase-shifted fiber Bragg grating (FBG) with a total FBG length of 35 mm. The DFB FBG was written by femtosecond-laser point-by-point (PbP) method. In-band pumping scheme is chosen with a 1550 nm nanosecond pulsed erbium-doped silica fiber laser pump. Single-longitudinal, linearly polarized, gain-switched TDFL at 2002 nm, with a recorded shortest pulse duration of 4.7 ns, a repetition rate of 20 kHz, a maximum peak power of 170 W, and single pulse energy of 0.8 µJ, has been obtained, benefitting from the ultrashort DFB cavity made by the femtosecond laser direct-writing method.

Волоконные лазеры с солнечной накачкой без первичного концентратора.

We studied solar pumped fiber lasers without primary concentrator. A model of solar sidepumped Nd3+ doped silica fiber lasers was developed using photon tracing method. Theabsorbed power distribution, possible losses and the pumping efficiency are estimated using the model. We analyzed the estimated paramters and drawed conclutions which have many suggests for improved design of solar pumped fiber lasers. The absorption efficiency of a fiber solar laser without a primary concentrator or sun tracker was calculated to be 0.2% for a 190 m fiber. The output power of the fiber laser is 40 mW, and the conversion efficiency from sunlight to laser light is calculated to be 0.06%. The developed model allows one to estimate the overall efficiency, output power and absorption distribution of Nd3+ fiber lasers without focusing optics, enabling various investigative comparisons.

Ultrathin gold nanowires as broadband saturable absorbers for ultrashort pulsed lasers

Ultrathin gold nanowires (UGNWs) with a diameter of ⩽2 nm have attracted much attention because of their high aspect ratios, unusual physical properties and potential applications in nanoelectronics, sensors and photonics. Despite recent advances on UGNWs and the related devices, nonlinear optical properties of UGNWs and their application on photonic devices (e.g. ultrashort pulsed lasers) remain largely unexplored. Here we show that UGNWs can be used as broadband saturable absorbers (SAs) for constructing ultrashort pulsed lasers with an operating wavelength range from near-infrared to mid-infrared (MIR). UGNWs are prepared by using a silane-mediated approach, and then mixed with polyvinyl alcohol to form the UGNWs film. The UGNWs film not only show strong absorption from visible to MIR spectral region (over 25 μm), but also possess the nonlinear saturable absorption properties in the spectral region. As the UGNWs film SA is inserted into an erbium or thulium doped silica fiber laser cavity, stable passively mode-locked lasers at 1562.2 or 1970 nm with a pulse width of a few hundreds of femtoseconds is obtained, respectively. Especially, by inserting the UGNWs film SA into a holmium/praseodymium codoped fluoride fiber laser cavity, stable passively mode-locked laser at 2864 nm is achieved. Our results show that the UGNWs film are promising SAs for constructing broadband ultrashort pulsed lasers.

Effects of P co-doping on X-ray/450 nm LD induced photodarkening in Dy3+ doped silica glass and fiber laser

Effects of P-codoping on X-ray/450 nm LD induced photodarkening in Dy3+ doped silica glass and fiber were investigated to develop a visible fiber laser. P and Dy concentrations in Dy-P-doped silica glass were optimized to reduce Rayleigh scattering. It was found in optimized glass that X-ray-induced photodarkening can be well suppressed by P co-doping. 450 nm LD pumped laser oscillation was firstly observed in the fiber using optimized glass. The slope efficiency is 4.2% which is lower than those in Dy–Al-and Dy–Al–Ge-doped fibers previously reported. Contrary to the results of X-ray-induced PD, 450 nm LD-induced photodarkening easily occurred.

Flexible chalcogenide glass large-core multimode fibers for hundred-watt-level mid-infrared 2-5 µm laser transmission

The rapidly-developed high-power mid-infrared 2-5 µm laser technology requires a compact, flexible low-loss glass fiber for power delivery or laser generation. With the broadest bandwidth of low-loss transmission window in mid-infrared region amongst all mid-infrared glass fibers, chalcogenide glass fiber is the best candidate covering the whole 2-5 µm range. Multi-hundred-watt high-power delivery for 5.4-µm CO laser was previously demonstrated in a multimode chalcogenide fiber with a 1-mm-diameter large core, at the cost of giving up one of the most desirable fiber advantages, the flexibility. Indeed, chalcogenide glass fibers with decent flexibility have never exhibited hundred-watt-level power transmitting capability in the 2-5 µm range. In this paper, we have experimentally demonstrated 100-watt-level power transmission in multimode As2S3 chalcogenide fibers, using a customized high-power 2-µm thulium doped silica fiber laser source. With effective forced cooling, the multimode As2S3 fiber with 200 µm core diameter can resist incident laser power of 120 W and deliver transmitted power of 63 W. Nano-sized scattering center related laser damage mechanism and the cylindrical heat transfer model have been proposed to explain the high-power damage process of chalcogenide glass fibers. The calculation is in good agreement with the experiments. It is promising to further enhance the transmitted power above 100 W in flexible chalcogenide glass large-core fibers.

Radiation‐induced darkening and its suppression methods in Yb3+‐doped silica fiber core glasses

AbstractYb3+‐doped silica fiber (YDF) laser has important applications in space. However, the darkening effect caused by space ionizing radiation (called RD effect), which is due to the generation of color centers at the microscopic scale, can significantly deteriorate the performance of the YDF laser. This review mainly includes three aspects. First, we briefly introduce space radiation environment and challenges that optical fibers encounter in space. Second, we review the nature and generation mechanism of color centers responsible for RD in YDFs. Finally, we systematically introduce five methods to inhibit RD and their inhibition mechanisms.

Diode pumped visible Dy3+-doped silica fiber laser: Ge-co-doping effects on lasing efficiency and photodarkening

We present the first demonstration of visible laser oscillation in the Dy3+-doped silica fiber pumped by a 451 nm InGaN laser diode. It was found that Ge-co-doping plays the following important roles of laser oscillation: (1) to reduce the Rayleigh scattering loss, (2) to suppress the X-ray-induced and pump-induced photodarkening (PD), and (3) to increase lasing slope efficiency. In a fiber with 0.46 wt% Dy, 1.8 wt% Ge, and 0.54 wt% Al, the slope efficiency is 22.0% at 582.5 nm, and the maximum output power is 18.4 mW.

Yb3+ doped single-mode silica fibre laser system for high peak power applications

We present ytterbium doped silica single-mode fibre components for high power and high energy laser applications. We developed in-house the fibre laser with high efficiency of 65% according to the launched power, the threshold of 1.16W and the fibre length of 20 m. We also elaborated the fibre with 20 µm in diameter core suitable for amplifying the beam generated in oscillator. We implemented made in-house endcaps to prove the utility of the fibre towards high peak power applications. Full Text: PDF ReferencesStrategies Unlimited, The Worldwide Market for Lasers: Market Review and Forecast, 2020 DirectLink J. Zhu, P. Zhou, Y. Ma, X. Xu, and Z. Liu, "Power scaling analysis of tandem-pumped Yb-doped fiber lasers and amplifiers", Opt. Express 19, 18645 (2011) CrossRef IPG Photonics, Product information, accessed: October, 2020. DirectLink J.W. Dawson, M. J. Messerly, R. J. Beach, M. Y. Shverdin, E. A. Stappaerts, A. K. Sridharan, P. H. Pax, J. E. Heebner, C. W. Siders, and C. P. J. Barty, "Analysis of the scalability of diffraction-limited fiber lasers and amplifiers to high average power", Opt. Express 16, 13240 (2008) CrossRef W. Koechner, "Solid-State Laser Engineering", Springer Series in Optical Science, Berlin 1999 CrossRef A. V. Smith, and B. T. Do, "Bulk and surface laser damage of silica by picosecond and nanosecond pulses at 1064 nm", Appl. Opt. 47, 4812 (2008), CrossRef M. N. Zervas, C. Codemard, "High Power Fiber Lasers: A Review", IEEE J. Sel. Top. Quantum Electron. 20, 1, 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, 63, 2010, CrossRef M. Li, X. Chen, A. Liu, S. Gray, J. Wang, D. T. Walton; L. A. Zenteno, "Limit of Effective Area for Single-Mode Operation in Step-Index Large Mode Area Laser Fibers", J. Lightw. Technol., 27, 3010, 2009, CrossRef J. Limpert, S. Hofer, A. Liem, H. Zellmer, A. Tunnermann., S. Knoke, and H. Voelckel, "100-W average-power, high-energy nanosecond fiber amplifier", App.Phys.B 75, 477, 2002, CrossRef

Temperature Effect on Yb-Doped Silica Fiber Laser Performance

The operation of the Ytterbium (Yb)-doped silica fiber laser is investigated under high temperature gradients generated by various cryogenic materials. A continuous-wave (CW) double-clad single-mode fiber laser working at 1082.51 nm with a linewidth (FWHM) of 0.16 nm and an average power of 10 W was used to study the effect of cooling rate on its output characteristics such as signal power, efficiency, central wavelength and spectral bandwidth. The cooling process is performed along the gain fiber using a cryogenic bath, while the cryo-coolants don't touch other laser components such as fiber Bragg gratings (FBGs), combiners and optical couplers. A series of rigorous experiments are carried out at room temperature - RT (22.5 °C) and cryo-states when the gain fiber is immersed in different coolants i.e., dry-ice ethylene-glycol - DIEG slurry (-29 °C), dry-ice debris (-58 °C) and liquid nitrogen - LN2 (-189.2 °C) with various pump powers ranging 2.9 - 16.5 W. The gain fiber of 10 m long demonstrates a 36 % power efficiency at LN2 against 66.4 % at RT. The signal power as well as the laser efficiency linearly reduces with temperature drop as to the linewidth undergoes a lucid spectral narrowing accompanying blue shift, mainly owing to the notable temperature response of the absorption / emission cross-section, broadening mechanisms and thermal population as well as energy level schemes, including sublevel and hyperfine structures of the transition accordingly.

High power, 100 W-class, thulium-doped all-fiber lasers

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 ReferencesZ. 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. Karásek, 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 ZnGeP2 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 Tm3+-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

L-Band Wavelength-Tunable Er3+-Doped Tellurite Fiber Lasers

The spectroscopic properties of Er3+-doped tellurite glasses were investigated and a 1 wt.% Er3+-doped tellurite fiber was fabricated for L-band lasers. Wavelength-tunable fiber lasers in a linear cavity based on Littrow configuration were developed and studied with different gain fiber lengths as well as output coupling ratios. Wavelength tunable range of 38 nm from 1589–1627 nm was achieved in the experiment with a 3-m Er3+-doped tellurite fiber laser pumped at 1570 nm. A maximum output power of 52.4 mW was obtained at 1614 nm. Compared to L-band Er3+-doped silica fiber lasers, the demonstrated Er3+-doped tellurite fiber lasers exhibit much higher optical signal-to-noise ratio (>30 dB), even at the longest operating wavelength of 1627 nm. Our simulation shows that the laser wavelength can be further extended to 1634 nm if the tellurite fiber loss is improved and the fiber cavity is optimized.

8.08 W holmium doped fluorotellurite fiber laser at 2067 nm

We reported a multi-watt ~2.1 µm laser output from a 30 cm long Ho3+-doped fluorotellurite microstructured fiber (FTMF) pumped by a homemade 1980 nm Tm3+-doped silica fiber laser. When the pump power was increased to 61.8 mW, lasing at 2067 nm was achieved from the Ho3+-doped FTMT, and an unsaturated maximum output power of ~8.08 W was obtained for a pump power of ~10.56 W. The corresponding slope efficiency was about 77.21%. During our experiments, no obvious damage was observed on the end face of the Ho3+-doped FTMF. Our results indicated that Ho3+-doped fluorotellurite fibers had the potential for constructing high power fiber lasers at 2.1 µm.

Gain-switched dysprosium fiber laser tunable from 2.8 to 3.1 μm.

We demonstrate a tunable gain-switched Dy3+-doped ZBLAN fiber laser around 3 μm, for the first time, to the best of our knowledge. The pump source is a homemade actively Q-switched Yb3+-doped silica fiber laser at 1.1 μm, yielding a repetition rate of 80 kHz and a pulse width of 300 ns. A plane-ruled grating in a Littrow configuration functions as the tuning element. At the launched pump power of 2.78 W, stable gain-switched pulses tunable within a ~300 nm range of 2800~3095 nm are achieved. When tuning the wavelength to 2946.5 nm, a maximum output power of 218.6 mW with a repetition rate of 80 kHz is obtained. The corresponding pulse width and energy are 530 ns and 2.73 μJ, respectively. The results imply that gain-switching of Dy3+-doped ZBLAN fiber laser is an alternative way for mid-infrared nanosecond pulse generation around 3 μm.

Numerical Modeling of in-Band Pumped Ho-Doped Silica Fiber Lasers

A theoretical model to describe in-band pumped holmium doped silica fiber lasers is presented. The model is established based upon theory and parameters obtained from published research works. Both core-pumped system and cladding-pumped system are simulated with the model. The simulation results agree well with most experimental results, and for the cases in which the simulation results show discrepancy with the experimental results the disagreement can be reasonably explained. Through numerical analysis it is found that besides common negative factors such as non-radiative decay, fiber loss, and non-optimized resonator configuration, energy transfer upconversion plays a deleterious role in the performance of in-band pumped holmium doped silica fiber lasers. In particular, inhomogeneous upconversion associated with ion clustering is found to cause significant degradation of slope efficiencies of lasers, a fact that is useful to understand the unsolved problem regarding the lower-than-expected slope efficiencies observed in previous studies of in-band pumped holmium doped fiber lasers.

高功率掺铥石英光纤激光器研究进展

高功率掺铥石英光纤激光器研究进展

Impact of cerium and lanthanum on the photo-darkening and photo-bleaching mechanisms in thulium-doped fibre

Photo-darkening prevents developing of new applications of rare-earth doped silica fibre lasers or amplifiers operating at wavelengths shorter than 1μm or at any wavelength at high power. The photo-darkening is characterized by a decrease of the laser intensity during amplification. In this article, we are interested in Tm-doped fibres. This ion offers many potential optical transitions spanning from 0.45 to 1.9μm. Several interesting transitions can be excited via up-conversion, using one pump around 1μm. However, this scheme induces a particularly fast and intense photo-darkening, enough to prevent amplification in the short wavelengths region (0.45–0.9μm). To mitigate this effect, we co-dope the fibres with cerium or lanthanum ions. By characterizing the steady state values of photo-darkening and its characteristic times, we demonstrate the beneficial role of Ce and La on the bleaching mechanisms.

Single-frequency distributed Bragg reflector Nd doped silica fiber laser at 930 nm.

We report a single-frequency distributed Bragg reflector (DBR) fiber laser at 930 nm for the first time, to the best of our knowledge. A ∼2.5 cm long commercial highly neodymium-doped silica fiber was utilized as the gain medium to achieve ∼1.9 mW laser output. The single longitudinal mode operation of this laser was verified by a scanning Fabry-Perot interferometer. This fiber laser is suited for seeding high-power 930 nm narrow-linewidth laser amplifiers, which can be used to generate coherent single-frequency pure blue light through frequency doubling.