Acousto-optic Q-switched cladding-pumped ytterbium-doped fiber laser

A diode-pumped, acousto-optic Q-switched fiber laser is presented based on multimode ytterbium-doped fiber. The fiber with core diameter of 30 μm is used to increase the laser gain volume and the pulse energy efficiently. The average power in excess of 9 W is obtained at the repetition rate of 20 kHz with 66% slope efficiency. The pulse width is 198 ns with no evident amplified spontaneous emission between pulses, thus the pulse energy and peak power are 465 μJ and 2.36 kW, respectively.     

High-energy, high-power ytterbium-doped Q-switched fiber laser

We report on a Q -switched, cladding-pumped, ytterbium-doped large-mode-area fiber laser operating at 1090 nm that is capable of generating 2.3 mJ of output pulse energy at a 500-Hz repetition rate and more than 5 W of average output power at higher repetition rates in a high-brightness beam (M(2) = 3) . Using a similar fiber with a smaller core, we generated >0.5-mJ pulses in a diffraction-limited beam. Our results represent a threefold increase in pulse energy over previously published values for Q-switched fiber lasers and firmly establish fiber lasers as compact, multiwatt, multimillijoule pulse sources with large scope for both industrial and scientific applications.     

Tunable passively Q-switched ytterbium-doped fiber laser using MoWS2/rGO nanocomposite saturable absorber

We demonstrated a tunable Q-switched ytterbium-doped fiber laser (YDFL) using MoWS₂/rGO nanocomposite as passive saturable absorber. Further, the Mo_1?xW_xS₂/rGO nanosheets, with x proportion of 0.2, are synthesized using hydrothermal exfoliation technique. The proposed nanocomposite-PVA based thin film is fabricated by mixing the MoWS₂/rGO nanosheets with polyvinyl alcohol (PVA). The fabricated thin film is sandwiched between two fiber ferrules to realize the proposed saturable absorber (SA). Further, the proposed MoWS₂/rGO-PVA based thin film SA exhibits a fast relaxation time and a high damage threshold which are suitable to realize a Q-switched pulsed laser with a tunable wavelength range of 10?nm that extends from 1028?nm to 1038?nm. For the highest pump power of 267.4?mW, the generated Q-switched pulses exhibit a narrow pulse width of 1.22 μs, the pulse repetition rate of 90.4?kHz, the highest pulse energy of 2.13?nJ and its corresponding average power of 0.193?mW. To the best of author’s knowledge, this is the first realization of a tunable Q-switching fiber laser in a 1?μm wavelength using MoWS₂/rGO nanocomposite saturable absorber.     

Graphene-assisted all-fiber multiwavelength erbium-doped fiber laser functionalized with evanescent field interaction

An all-fiber multiwavelength erbium-doped fiber laser (MEDFL) functionalized with evanescent-field-interacting graphene is proposed and experimentally demonstrated. Graphene-polymer nanocomposites were deposited around the waist region of a fiber taper fabricated by flame-stretching method. Using the graphene-deposited fiber taper (GDFT) to induce four-wave mixing (FWM) as a power-equalizing device for suppressing the unstable mode competition in MEDFL, stable multiwavelength lasing around 1530 nm was obtained with a wavelength spacing of 0.56 nm, an extinction ratio of 33 dB, and a narrow linewidth per channel of <0.01 nm. The output spectrum of the multiwavelength laser has a good flatness, and the power fluctuation of each wavelength is less than 1.5 dB. Comparing with the traditional methods, such evanescent-field-interaction based graphene stabilizing mechanism for multiwavelength generation possesses unique advantages: (1) it can avoid the graphene thermal damage, (2) it’s a real all-fiber integrated structure, and (3) it provides a longer interaction length for exciting FWM more efficiently.     

Passively Q-switched Er-doped fiber laser using a semiconductor saturable absorber mirror

A passively Q-switched Er-doped fiber laser using a semiconductor saturable absorber mirror (SESAM) is demonstrated. Q-switching is observed with the output power produced at a slope efficiency of 29.4% with respect to the absorbed pump power. The maximum average output power of 8.37 mW is achieved. The pulse repetition frequency obtained can be turned from 1.72 to 7.95 kHz. The pulse energy of 17.2 nJ has been obtained at the pump power of 46.75 mW, and the pulse width is 30 μs.     

氧化石墨烯被动调Q掺铒光纤激光器

报道了基于氧化石墨烯的被动调Q掺铒光纤激光器。激光器采用环形腔结构,调Q器件为自制的氧化石墨烯可饱和吸收镜。泵浦功率在81~505 mW范围内时,得到了重复频率68~124 kHz的稳定的调Q脉冲输出,脉宽为0.47~1.60 s。由于泵浦功率限制,激光器最大输出功率为10 mW, 相应单脉冲能量为80.6 nJ。此种基于氧化石墨烯可饱和吸收体的被动调Q光纤激光器体积小、成本低廉、结构简单、稳定性高、光束质量高,具有广阔的应用前景。     

Passively Q-switched mode-locking Erbium-doped fiber laser with net-normal dispersion using nonlinear polarization rotation technique

We experimentally demonstrate a passively Q-switched mode-locking (QML) operation in an Erbium-doped fiber ring laser with net normal dispersion by using nonlinear polarization rotation technique. A 2 m long section of dispersion compensating fiber (DCF) with extra large positive dispersion was inserted into the cavity to ensure the fiber laser working in the region of net positive dispersion. By carefully adjusting the polarization controller, both uniform dissipative mode-locking pulses with fundamental repetition rate and QML pulse trains with tunable repetition rate from 71.58 to 98.83 kHz are achieved. It is found that the QML operation is caused by the interaction between the polarization state of the pulse and the intracavity polarizer.     

Passively Q-switched fiber laser that uses saturable Raman gain

Operation of a short all-fiber passively Q-switched Raman laser pumped by a continuous-wave laser diode is experimentally demonstrated. The passively switched fiber laser consists simply of a double-clad ytterbium-doped silica fiber that is spliced directly to a moderately germanium-doped silica fiber. The placement of the Ge-doped silica fiber within the fundamental (Raman pump) cavity allows interplay between fundamental and Stokes fields to take place, which leads to saturation of the Raman gain as a result of pump depletion. Pulse widths of 70 and 60 ns at the first and second Stokes wavelengths of 1168 and 1232 nm, respectively, are produced at a stable 588 kHz repetition rate.     

Passively Q-switched fiber laser based on graphene saturable absorber

A passively graphene Q-switched Erbium doped fiber laser around 1.5 μm is demonstrated in this paper. The graphene saturable absorber was fabricated by sandwiching a thin graphene film produced via chemical vapor deposition between two FC fiber connectors. Stable pulse trains were obtained with the pulse repetition rate varying between 34.72 and 53.2 kHz and the average output power ranging from 0.504 mW to 0.926 mW. The achieved shortest pulse duration and highest pulse energy were 3.2 μs and 17.41 nJ, respectively.     

A study of a Q-switched double-clad ytterbium-doped fiber laser with amplifying effect

A high repetition rate ytterbium-doped double-clad (YDDC) fiber laser with amplifying effect is described by using acousto-optic modulator. The characteristic of Q-switched pulses are studied with accurate control of opening gate time of modulator. The stable Q-switched pulses with tens of nanoseconds width can be observed at high repetition rate varied from 50 kHz to 500 kHz using this laser. The stable operation area of the Q-switched fiber laser is discussed and the analysis results agree well with that of the experiment.     

Passively Q-switched erbium-doped fiber laser based on gold nanorods

We have demonstrated that the gold nanorods (GNRs) can be used as effective saturable absorbers for passively Q-switched erbium-doped fiber laser (EDFL). Two types of GNRs were synthesized by a seed-mediated growth method. The longitudinal surface plasmon resonance wavelengths of the GNRs with different aspect ratios were around 1068 and 1442 nm, respectively. The GNRs were mixed with sodium carboxymethylcellulose (NaCMC) to form GNRs-NaCMC films with different absorption wavelengths. Using these GNRs-NaCMC films, 9.6-μs pulses with a repetition rate of ∼22.9 kHz and 10.4-μs pulses with a repetition rate of ∼22.4 kHz were obtained from the passively Q-switched EDFLs at a pump power of ∼120 mW, respectively.     

Tunable passively Q-switched ytterbium-doped fiber laser with mechanically exfoliated GaSe saturable absorber

A tunable passively Q-switched ytterbium-doped fiber laser using few-layer gallium selenide(GaSe) as a saturable absorber(SA) is demonstrated.The few-layer GaSe SA,which is fabricated by the mechanical exfoliation method,is able to generate a Q-switched fiber laser that has a maximum repetition rate of 92.6 kHz and a minimum pulsed width of 2.3 μs.The highest pulse energy exhibited by the generated pulse is 18.8 nJ with a signal to noise ratio of ~40 dB.The tunability of the proposed laser covers from 1042 to 1082 nm,giving a tuning range of 40 nm.     

Passively Q-switched 0.1-mJ fiber laser system at 1.53 mum

We demonstrate a passively Q-switched fiber laser system generating pulses with as much as 0.1 mJ of pulse energy at 1.53 mum and a >1-kHz repetition rate. These results were achieved with a simple master oscillator-power amplifier scheme with a single pump source, realized with large-mode-area fiber and multiple reflections upon a semiconductor saturable-absorber mirror.     

Mode-locked fiber laser with MoSe_2 saturable absorber based on evanescent field

An all-fiber mode-locked fiber laser was achieved with a saturable absorber based on a tapered fiber deposited with layered molybdenum selenide(MoSe_2). The laser was operated at a central wavelength of 1558.35 nm with an output spectral width of 2.9 nm, and a pulse repetition rate of 16.33 MHz. To the best of our knowledge, this is the first report on mode-locked fiber lasers using MoSe_2 saturable absorbers based on tapered fibers.     

Tunable Q-switched ytterbium-doped fibre laser by using zinc oxide as saturable absorber

This paper demonstrates the use of a zinc oxide (ZnO) thin film in a 1-μm ring laser cavity as a saturable absorber to successfully generate Q-switching pulses. The tunability of the laser pulses is achieved by integrating a tunable bandpass filter (TBPF) in an ytterbium-doped laser cavity that results in 9.4 nm of tuning range, which wavelength is from 1040.70 nm to 1050.1 nm. The peak energy in the pulse which is 1.47 nJ was measured together with a minimum pulse width of 2.4 μs. In addition, the repetition rate increases from 25.77 to 45.94 kHz as the pump power level being increased from 103.1 to 175.1 mW. The results obtained in this experiment demonstrated consistent results and stable throughout the experiment. Therefore, ZnO thin film is considered as a good candidate in 1-μm pulsed laser applications.     

Passively Q-switched green laser operation using CdTe/CdS quantum dots

The direct generation of passively Q-switched lasers at a green wavelength has rarely been investigated in the past. In this Letter, we demonstrate a passively Q-switched praseodymium-doped yttrium lithium fluoride green laser at 522 nm using CdTe/CdS quantum dots as a saturable absorber. A maximum average output power of 33.6 m W is achieved with the shortest pulse width of 840 ns. The corresponding pulse energy and peak power reached 0.18 μJ and 0.21 W, respectively. To the best of our knowledge, this is the first demonstration in regard to a quantum dots saturable absorber operating in the green spectral region.     

An acousto-optic Q-switched fiber laser using China-made double-cladding fiber

A simple laser-diode pumped acoustic-optic Q-switched fiber laser is reported by using China-made largemode-area ytterbium-doped fiber. Q-switched pulses with a beam quality factor of M2 ≈ 2 and several hundred nanoseconds pulse duration are achieved at the repetition rate of 1 - 50 kHz. When the repetition rate is 1 kHz, the pulse energy is 0.93 mJ with the pulse duration of 132 ns. Meanwhile, the profile of laser pulses shows some mode-locking phenomena, the mechanism of the phenomena is discussed.     

Passively Q-switched mode-locked Tm:LLF laser with a MoS_2 saturable absorber

A passively Q-switched mode-locked(QML) Tm:Li Lu F4(LLF) laser with a Mo S2 saturable absorber(SA) is demonstrated for the first time, to our best knowledge. For the Q-switching mode, the maximum average output power and Q-switched pulse energy are 583 m W and 41.5 μJ, respectively. When the absorbed power is greater than 7.4 W, the passively QML pulse is formed, corresponding to an 83.3-MHz frequency. The modulation depth in Q-switching envelopes is approximately 50%. Results prove that Mo S2 is a promising SA for Q-switched and QML solid-state lasers.     

Passively Q-switched Self-frequency Doubling NYAB laser with GaAs Saturable Absorber

1　Ｉｎｔｒｏｄｕｃｔｉｏｎ　　Ｉｎｒｅｃｅｎｔｙｅａｒｓ ,ｉｎｃｒｅａｓｉｎｇａｔｔｅｎｔｉｏｎｈａｓｂｅｅｎ ｐａｉｄｔｏｈｉｇｈ ｐｅａｋ ｐｏｗｅｒａｌｌ ｓｏｌｉｄ ｓｔａｔｅｐｕｌｓｅｄｂｌｕｅ ｇｒｅｅｎｌａｓｅｒｓｆｏｒｓｏｍｅａｐｐｌｉｃａｔｉｏｎｓｓｕｃｈａｓｓｐｅｃｔｒｏｓｃｏｐｙ ,ｄｉｓｐｌａｙ ,ｏｐｔｉｃａｌｄａｔａｓｔｏｒａｇｅ ,ｕｎｄｅｒｓｅａｃｏｍｍｕｎｉｃａｔｉｏｎｓａｎｄｓｏｏｎ .Ｓｕｃｈｌａｓｅｒｓｃａｎｂｅｒｅａｌｉｚｅｄｂｙｉｎｔｒａｃａｖｉｔｙｏｒｅｘｔｅｒ…