Ytterbium-doped Fiber Laser Research Articles

Tunable dual-wavelength ytterbium-doped fiber laser using a strain technique on microfiber Mach-Zehnder interferometer.

In this paper, stable dual-wavelength generation using a strain technique for a ytterbium-doped fiber laser is successfully demonstrated. A microfiber-based Mach-Zehnder interferometer is inserted into the laser ring cavity and stretched using the xyz translation stage. Four sets of dual-wavelength output lasing are obtained when the strain is applied onto a microfiber. The dual-wavelength output possesses spacing between 7.12 and 11.59nm, with displacement from 2 to 190μm from the central wavelength. The obtained side-mode suppression ratio is ∼48 dBm, while the maximum power fluctuation and wavelength shift are less than 0.6dB and 0.01nm, respectively. The results demonstrate that this setup generates a stable dual-wavelength laser in the 1μm region.

Nanosecond pulse generation in a MoS2 mode-locked ytterbium-doped fiber laser

We demonstrate a mode locked nanosecond ytterbium-doped fiber laser using a multilayer MoS2 saturable absorber. The MoS2 is prepared by a simple hydrothermal method and made into a film structure by spin-coating. The laser directly produces nanosecond pulses with stable mode locking at a pump threshold of 110 mW with a slope efficiency of 41 %. Resultant output pulses have central wavelength, pulse duration, and repetition rate of 1063.25, 0.1 nm, 22.88 ns and 2.17 MHz, respectively. The average output power was measured to be 9.84 mW under the pump power of 220 mW, corresponding to single pulse energy of 4.53 nJ. The experimental results show that multilayer MoS2 is a promising material for ultrafast laser systems.

Generation of more than 40 W of average output power from a passively Q-switched Yb-doped fiber laser.

We report on the generation of 41.6 W of average output power from a passively Q-switched ytterbium-doped fiber laser using Cr4+:YAG crystal as a saturable absorber (SA). This is the highest average power from passively Q-switched fiber lasers reported so far in the literature, to our knowledge, and it has been achieved by using a specially designed T-type double-end pumping configuration. Variation in average output power, pulse energy, pulse duration, pulse frequency, and pulse-to-pulse stability has also been studied using SAs of different linear transmissions. The effect of an intracavity SA on self-pulsing dynamics was also investigated and it was observed that, at lower input pump power near threshold, the presence of an SA enhances the peak power of relaxation oscillations to trigger the generation of stimulated Raman scattering in the gain fiber. With an increase in pump power, when the passive Q-switching threshold is reached, high peak power random self-pulses regenerate into low amplitude regular Q-switched pulses. The effect of the length of the gain medium on dual-wavelength generation at very low input pump power and broadband generation at sufficiently higher pump power has also been explored.

Ultra-wide wavelength tuning of a cascaded Raman random fiber laser.

An ultra-broadband tunable cascaded Raman random fiber laser pumped by a tunable (1020-1080 nm) ytterbium-doped fiber laser is investigated. By continuously adjusting the pump laser wavelength, the Raman random laser tunes accordingly due to the Raman gain competition. By increasing the pump power, up to the 5th order Raman random laser is achieved. As a result, 300 nm of continuous wavelength tuning from 1070 to 1370 nm is achieved by adjusting the pump wavelength and power altogether. The highest output power is 1.8 W at 1360 nm with an optical efficiency of 15% from 1080 nm. To the best of our knowledge, this is the widest wavelength tuning range reported for a random fiber laser so far.

PMMA-doped CdSe quantum dots as saturable absorber in a Q-switched all-fiber laser

We demonstrate the generation of Q-switched pulses from an ytterbium-doped fiber laser (YDFL) using quantum dot (QD) CdSe as a passive saturable absorber (SA). The CdSe QD is fabricated by the synthesis of CdO, Se, and manganese acetate and paraffin oil and oleic acid as the solvent and surfactant, respectively. The CdSe QD is then doped into poly-methyl-methacrylate (PMMA) via an emulsion polymerization process. A PMMA-hosted CdSe QD thin flake with a homogeneous end surface is then formed and placed between two ferrules and assembled in a YDFL cavity to achieve the Q-switching operation with a repetition rate of 24.45 to 40.50 kHz while varying the pump power from 975 to 1196 mW. The pulse width changes from 6.78 to 3.65 μs with a maximum calculated pulse energy at 0.77 μJ at a pump power of 1101 mW. This work may be the first demonstration of CdSe QD-based Q-switching in an all-fiber configuration that should give proportional insight into semiconductor QD materials in photonics applications.

Generation of Mode-locked Ytterbium doped fiber ring laser using few-layer black phosphorus as a saturable absorber

We demonstrate the generation of mode-locked pulses from a double-clad ytterbium-doped fiber laser (YDFL) employing a saturable absorber (SA) made of a few layers of black phosphorus (BP). The BP SA was prepared by mechanically exfoliating BP crystal and spreading the acquired BP flakes on a piece of scotch tape. The tape was then sandwiched between two ferrules and incorporated in a YDFL cavity to achieve a stable mode-locked operation at 1085.58 nm with a repetition rate of 13.5 MHz. A maximum pulse energy of 5.93 nJ was obtained at pump power of 1322 mW with the output power of 80 mW. Our study may well be the first demonstration of the BP-based mode-locked fiber laser that should shed some new insights into two-dimensional layer materials related photonics.

Titanium dioxide-based Q-switched dual wavelength in the 1 micron region

In this work a passively Q-switched dual-wavelength ytterbium-doped fiber laser using a titanium dioxide-based saturable absorber is proposed and proven. The system also utilizes a side-polished fiber in a ring cavity configuration to obtain the desired pulse train. A stable dual-wavelength pulse output is obtained at 1034.7 and 1039.0 nm, with a maximum pulse energy of 2.0 nJ, and a shortest pulse width of 3.2 μs. The generated pulse train is stable, and has a pulse repetition rate from 31.2 to 64.5 kHz.

Automated 3D bone ablation with 1,070 nm ytterbium-doped fiber laser enabled by inline coherent imaging.

Laser osteotomy bears well-identified advantages over conventional techniques. However, lack of depth control and collateral thermal damage are barriers to wide clinical implementation. Flexible fiber delivery and economical benefits of ytterbium-doped fiber lasers make them desirable for laser osteotomy. In this work, we demonstrate automated bone ablation with a 1,070 nm industrial-scale fiber laser to create 3D target structures with minimal thermal side-effects. Fresh and dry ex vivo cortical bone samples are ablated using 50-100 µs laser pulses of 15-30 mJ. In situ inline coherent imaging monitors ablation dynamics with micron precision and on microsecond timescales. Ablation depth is extracted by on-the-fly processing of ICI data, enabling feedback control of depth (via laser pulse number). Final ablated morphology, measured by an ex situ stylus profiler, is compared to the target shape. Histological examination is performed to quantify the thermal side-effects of laser ablation. Percussion drilled hole depth is highly variable for fixed laser parameters (880 ± 151 µm on fresh bone and 1038 ± 148 µm on dry bone) due to nondeterministic ablation. ICI-enabled depth control is implemented to achieve precise ablation of complex 3D features. The RMS deviation between target and ablated morphology is 12.6 µm. The heat-affected zone is found to be 5-10 µm on fresh and dry bone. An ytterbium-doped fiber laser is utilized for cortical bone ablation with limited thermal side-effects. In situ real-time ICI measurement enables characterization of bone ablation dynamics. Furthermore, ICI closed-loop feedback realizes depth-controlled ablation on heterogeneous bone. This proof-of-principle study shows great promise for ICI-guided laser osteotomy.

Generation of an ultra-stable dual-wavelength ytterbium-doped fiber laser using a photonic crystal fiber

This paper describes the demonstration of a simple ytterbium-doped fiber (YDF) laser that utilized a short length of photonic crystal fiber (PCF) in a ring cavity and adjustments to the polarization state of an incorporated polarization controller (PC) to achieve a stable dual-wavelength output. The dual-wavelength lasing operation exploited the Mach–Zehnder interferometer effect, and the laser output consistently achieved high power stability with a 0.8 dB fluctuation over a period of 30 min. This proposed setup has the capability for adjustable spacing of two lasing wavelengths from a minimum of 0.40 nm to a maximum of 3.40 nm, allowing for flexibility in dual-wavelength laser generation in addition to stable and reliable system features.

Ambient Molecular Analysis of Biological Tissue Using Low-Energy, Femtosecond Laser Vaporization and Nanospray Postionization Mass Spectrometry.

Direct analysis of plant and animal tissue samples by laser electrospray mass spectrometry (LEMS) was investigated using low-energy, femtosecond duration laser vaporization at wavelengths of 800 and 1042 nm followed by nanospray postionization. Low-energy (<50 μJ), fiber-based 1042 nm LEMS (F-LEMS) allowed interrogation of the molecular species in fresh flower petal and leaf samples using 435 fs, 10 Hz bursts of 20 pulses from a Ytterbium-doped fiber laser and revealed comparable results to high energy (75-1120 μJ), 45 fs, 800 nm Ti:Sapphire-based LEMS (Ti:Sapphire-LEMS) measurements. Anthocyanins, sugars, and other metabolites were successfully detected and revealed the anticipated metabolite profile for the petal and leaf samples. Phospholipids, especially phosphatidylcholine, were identified from a fresh mouse brain section sample using Ti:Sapphire-LEMS without the application of matrix. These lipid features were suppressed in both the fiber-based and Ti:Sapphire-based LEMS measurements when the brain sample was prepared using the optimal cutting temperature compounds that are commonly used in animal tissue cryosections.

Generation of stable and narrow spacing dual-wavelength ytterbium-doped fiber laser using a photonic crystal fiber

We demonstrate the design and operation of novel narrow spacing and stable dual-wavelength fiber laser (DWFL). A 70-cm ytterbium-doped fiber has been chosen as the gain medium in a ring cavity arrangement. Our design includes a short length photonic crystal fiber, acting as a dual-wavelength stabilizer based on its birefringence coefficient and nonlinear behavior and tunable band pass filter (TBPF) to achieve narrow spacing spectrum lasing. Our laser output is considered to be highly stable, with power fluctuation less than 0.8 dB over a period of 15 min. The flexibility and tunability of TBPF, together with polarization controller enable the spacing tuning of the DWFL from 0.03 nm up to 0.07 nm for 1040 nm region, and 0.10 nm up to 0.40 nm for 1060 nm region. The tunable wavelength spacing shows the flexibility of the DWFL in addition to stable and reliable properties of fiber laser in 1-μm region.

Broadband high-power mid-IR femtosecond pulse generation from an ytterbium-doped fiber laser pumped optical parametric amplifier.

We report on a high-power periodically poled MgO-doped lithium niobate (MgO:PPLN)-based femtosecond optical parametric amplifier (OPA), featuring a spectral seamless broadband mid-infrared (MIR) output. By modifying the initial chirp and spectrum of the mode-locked seed laser, the Yb fiber pump laser exhibits a final output power of 14 W with sub-200-fs pulse duration after power amplification and compression. When the OPA was seeded with a broadband amplified spontaneous emission (ASE) source, a damage-limited 0.6 W broadband MIR radiation was experimentally obtained under the pump power of 10.15 W at 82 MHz repetition rate, corresponding to an overall OPA conversion efficiency of 32.7%. The 3 dB bandwidth of the mid-IR idler was 291.9 nm, centering at 3.34 μm.

Mode-locked ytterbium-doped fiber laser based on tungsten disulphide

We demonstrated an all-normal-dispersion Yb-doped mode-locked fiber laser based on tungsten disulphide (WS2). The saturable absorbers (SA) were made by mixing WS2 solution with polyvinyl alcohol (PVA), and then evaporated on a substrate. The modulation depth of the WS2 film was 2.06% and the saturable optical intensity was 71.6 MW cm−2. When the WS2 film was inserted into the fiber laser, the mode-locked pulses with pulse width of 2.5 ns and repetition rate of 2.84 MHz were obtained. As the pump power increased to 350 mW, the maximum output power was measured to be 8.02 mW. To the best of our knowledge, this is the first time to realize mode-locked pulses based on WS2-SA at 1 μm waveband.

Single-mode monolithic fiber laser with 200 W output power at a wavelength of 1018 nm.

We report on an ytterbium-doped monolithic fiber laser at a wavelength of 1018 nm with an output power of 200 W in continuous wave operation. The optimal parameters for setting up such a high-power fiber laser with an ytterbium-doped fiber are investigated and discussed in detail. An in-house-developed pump light stripper and a single-mode fused fiber coupler were applied to use the fiber laser for core-pumping of ytterbium-doped high-power fiber amplifiers in a monolithic setup.

WS₂ saturable absorber for dissipative soliton mode locking at 1.06 and 1.55 µm.

Transition-metal dichalcogenides, such as tungsten disulfide (WS2) and molybdenium disulfide (MoS2), are highly anisotropic layered materials and have attracted growing interest from basic research to practical applications due to their exotic physical property that may complement graphene and other semiconductor materials. WS2 nanosheets are found to exhibit broadband nonlinear saturable absorption property, and saturable absorbers (SAs) are fabricated by depositing WS2 nanosheets on side-polished fibers. Attributing to the weak evanescent field and long interaction length, the WS2 nanosheets are not exposed to large optical intensity, which allows the SA to work at the high-power regime. The SAs are used to mode lock erbium- and ytterbium-doped fiber lasers with normal dispersion, producing trains of dissipative soliton at 1.55 and 1.06 µm respectively. Simulations show that the bandgap of WS2 nanosheets decreases from 1.18 to 0.02 and 0.65 eV by introducing W and S defects respectively, which may contribute to the broadband saturable absorption property of the WS2.

Fabrication of 16 W all-normal-dispersion mode-locked Yb-doped rod-type fiber laser with large-mode area**Project supported by the National Key Technology R&D Program of the Ministry of Science and Technology, China (Grant No. 2012BAC23B03), the National Basic Research Program of China (Grant No. 2013CB922401), and the National Natural Science Foundation of China (Grant No. 11474002).

A mode-locked ytterbium-doped rod-type fiber laser with 85 μm core diameter is developed based on the nonlinear polarization evolution in an all-normal-dispersion ring cavity, in which a uniaxial birefringent plate is used as the spectral filter. Average power up to 16 W is obtained at the repetition rate of 58 MHz, and the pulse duration is compressed to 182 fs with a grating-pair compressor. The output laser pulses show very good beam quality and power stability.

Temporally Stable Random Fiber Laser Operates at 1070 nm

We experimentally demonstrate a temporally stable random fiber laser (RFL) operating at 1070-nm wavelength. A piece of 25-km passive fiber pumped by a 1018-nm ytterbium-doped fiber laser provides both Raman amplification from stimulated Raman scattering and random distributed feedback via Rayleigh scattering. The laser output of the RFL system shows temporally stable characteristics, despite the high-intensity noise of the pump source. The output power of the 1070-nm RFL reaches the 10-W level. The RFL working in the wavelength range between 1.06 and 1.09 m is reported for the first time, to the best of our knowledge, in this paper. We believe that our result may be fur- ther applied in high-power fiber laser amplifications.

Investigation on chaotic dynamics of ytterbium-doped fiber laser with Mach–Zehnder interferometer

Chaotic dynamics are observed experimentally from an ytterbium-doped fiber laser when the polarization controller is adjusted to an appropriate position and the pump power is increased. But chaotic signals hide the cavity-length signature of ytterbium-doped fiber laser and the cavity-length can be identified by the sidelobes of chaotic autocorrelation. The perturbation of variable optical attenuator inserted to the ytterbium-doped fiber laser and the interference effect induced by the optical path difference (OPD) of a fiber optical Mach–Zehnder interferometer (MZI) are adopted to investigate the chaotic dynamics. The results show that such sidelobes can be completely suppressed by exerting the perturbation and by the interference effect of MZI with optimum OPD which is demonstrated theoretically and experimentally. Moreover, the optimum OPD corresponding to the delay-time of MZI is intimately related to the relaxation oscillation period.

High-power 1018 nm ytterbium-doped fiber laser and its application in tandem pump.

In this paper, we present our experimental results of a high-power 1018 nm fiber laser and its usage in tandem pump. A record output power of 476 W 1018 nm fiber laser is obtained with an efficiency of 78.2%. Utilizing a specially designed gain fiber, a one-stage high-power monolithic fiber amplifier tandem pumped by six 1018 nm fiber lasers is assembled. A 110 W 1090 nm seed is amplified to 2140 W, and the efficiency is as high as 86.9%. The beam quality factor M2 is measured to be 1.9. Limitations and possible solutions for purchasing higher output power are discussed.

Pulsed ytterbium-doped fibre laser with a combined modulator based on single-wall carbon nanotubes

This paper describes an all-normal-dispersion pulsed ytterbium-doped fibre ring laser mode-locked by a nonlinear combined modulator based on single-wall carbon nanotubes. We have demonstrated pulse generation at with a repetition rate of . At the laser output, the pulses were compressed to . We have examined an intracavity nonlinear modulator which utilises nonlinear polarisation ellipse rotation in conjunction with a saturable absorber in the form of a polymer-matrix composite film containing single-wall carbon nanotubes.