Q-switched Ytterbium-doped Fiber Laser Research Articles

Preparation, characterization of violet phosphorus and its application in fiber laser

Violet phosphorus (VP) is a new type of two-dimensional nanomaterial that has unique electronic and optoelectronic properties, and has gained wide attention in the fields of physics, chemistry, and materials science. However, only a few instances of the use of VP in fiber lasers have been demonstrated. For instance, VP films have been utilized as saturable absorbers in Q-switched ytterbium-doped fiber lasers (YDFL) and erbium-doped fiber lasers (EDFL), operating at central wavelengths of 1033 nm and 1560 nm, respectively. Herein, VP films are prepared using a liquid phase exfoliation method and introduced in the ring cavity of a YDFL. Increasing the pump power from 113 mW to 245 mW, and repetition rates from 32.33 kHz to 107.12 kHz, resulted in a stable sequence of Q-switched pulses. A pulse width of 2.9 µs is obtained at a pump power of 245 mW. At a pump power of 230 mW, the pulse energy is 31.02 nJ. In the case of EDFL, stable Q-switched pulses are obtained at a maximum pump power of 150 mW, with the repetition rate, pulse width and pulse energy being 63.51 kHz, 6.4 µs, and 102.19 nJ, respectively. These results indicate that VP may be a promising broadband SA suitable for fiber lasers with wavelengths of 1 µm and 1.5 µm.

Wide tuning range q-switched ytterbium doped fiber laser based on V2AlC saturable absorber

Wide tuning range q-switched ytterbium doped fiber laser based on V2AlC saturable absorber

A Linearly Polarized Wavelength-Tunable Q-Switched Fiber Laser with a Narrow Spectral Bandwidth of 112 MHz.

A tunable and narrow-bandwidth Q-switched ytterbium-doped fiber (YDF) laser is investigated in this paper. The non-pumped YDF acts as a saturable absorber and, together with a Sagnac loop mirror, provides a dynamic spectral-filtering grating to achieve a narrow-linewidth Q-switched output. By adjusting an etalon-based tunable fiber filter, a tunable wavelength from 1027 nm to 1033 nm is obtained. When the pump power is 1.75 W, the Q-switched laser pulses with a pulse energy of 10.45 nJ, and a repetition frequency of 11.98 kHz and spectral linewidth of 112 MHz are obtained. This work paves the way for the generation narrow-linewidth Q-switched lasers with tunable wavelengths in conventional ytterbium, erbium, and thulium fiber bands to address critical applications such as coherent detection, biomedicine, and nonlinear frequency conversion.

Passively Q-switched ytterbium doped fiber laser based on a weak-photothermal saturable absorber

Recently, plasmonic nanocrystals (NCs) have attracted much attention due to their wide applications in bioimaging, photothermal therapy and photonics devices. Compared to other metal NCs, copper NCs show a weak photo-thermal effect, which shows that the copper NCs are a good candidate for nonlinear optical materials. In this paper, we demonstrated a Q-switched fiber laser at 1 μm wavelength by using Cu1.8S NCs as a saturable absorber (SA). By incorporating the Cu1.8S SA into an ytterbium doped fiber laser cavity pumped by a 980 nm laser diode, stable passive Q-switching at 1038 nm was obtained for a threshold pump power of 63 mW. On gradually increasing the pump power from 64 mW to 160 mW, the repetition rate of a Q-switched laser increases from 25.7 kHz to 54.5 kHz and the pulse duration decreases from 6.7 μs to 2.33 μs. Our results showed that Cu1.8S NCs is an effective SA for constructing pulsed lasers with a broadband operating wavelength.

Spatiotemporal pulses from a Q-switched multimode fiber laser

We have demonstrated spatiotemporal pulses from a Q-switched ytterbium-doped multimode fiber laser, with a pulse energy of up to 16.5 μJ, a pulse repetition rate of 108.7 kHz, and an average output power of 1.80 W. Benefiting from the weakened spectral filtering effect, there is high pulse energy that can be produced from multimode fiber oscillators. We have observed and analyzed the evolution of multimode Q-switching with spatiotemporal correlation. Furthermore, we find that the polarization control in the saturable absorber has a modulation and selective effect on the transverse modes of the multimode fiber laser. Our results help to understand the spatiotemporal characteristics of pulsed fiber lasers and contribute to developing high-pulse energy lasers.

An actively Q-switched multi-wavelength ytterbium fiber laser with cascaded polarization-maintaining Bragg gratings

In this paper, we investigate the multi-wavelength lasing characteristics of an actively Q-switched ytterbium-doped fiber laser with two cascaded polarization maintaining fiber Bragg gratings (PM-FBGs). By properly adjusting the polarization states in the cavity, a total of 15 wavelength combinations, including single-, dual-, tri-, and quad-wavelength emission states, have been achieved. Stable Q-switched pulses with repetition rates ranging from 10 to 28 kHz are obtained. The influence of repetition rate and pump power upon the pulse width are also investigated. The high spectral stability in lasing operation indicates effectiveness of the proposed cascaded PM-FBGs in actively Q-switched multi-wavelength fiber laser configurations.

Controlled generation of mode-switchable nanosecond pulsed vector vortex beams from a Q-switched fiber laser.

We reported and demonstrated a ring Q-switched Ytterbium-doped fiber laser that can generate mode-switchable nanosecond pulsed vector vortex beams between two different orders. In the spatial optical path of the fiber laser, several cascaded Q-plates, divided into two Q-plate groups, are applied for intracavity mode conversion between LP01 mode and vector vortex beams. In one Q-plate group, two quarter-wave plates are inserted to achieve the addition and subtraction of the order of Q-plates. By tuning the polarization state in the cavity, mode-switchable vector vortex beams (VVBs), including cylindrical vector beams (CVBs), elliptically polarized cylindrical vector beams (EPCVBs), and vortex beams, of two different orders can be generated on demand. The experimental results show that by using the group of 1st and 3rd orders Q-plates, the 2nd and 4th orders mode-switchable VVBs (vortex beams with topological charges of ±2, ±4, CVBs and EPCVBs of 2nd- and 4th-order) can be obtained from the fiber laser. The slope efficiency, pulse width, and repetition rate are 33.4%, 360 ns, and 241kHz respectively. To the best of our knowledge, this is the first time to realize the direct generation of mode-switchable VVBs on the arbitrary position of the higher-order Poincaré sphere between two different orders from a fiber laser. This work lays the foundation for the flexible generation of arbitrary modes of VVBs with multiple different orders in the laser cavity.

Q-switched Ytterbium-doped fibre laser using an 8 cm long Hafnium bismuth erbium co-doped fibre saturable absorber

In this paper, we present a Q-switched fibre laser at 1069 nm which is induced by an 8 cm long Hafnium bismuth erbium co-doped fibre (HBEDF) saturable absorber (SA). The pulsating laser has a maximum repetition rate of 67 kHz at 175 mW pump power. We obtained the narrowest pulse width of 3.48 μs, the maximum pulse energy of 70.2 nJ, the maximum output power of 4.7 mW and the maximum peak power of 20.1 mW. The Q-switched laser is simple and may found practical applications in medicine and remote sensing.

Passively Q-switched Ytterbium-doped fiber laser using zinc phthalocyanine thin film as saturable absorber

This paper presents a ZnPc: PVA film as saturable absorber (SA) for Q-switched pulse generation at 1-micron region. The SA film was obtained by embedding the ZnPc into polyvinyl alcohol (PVA). It was inserted into an Ytterbium-doped fiber laser (YDFL) cavity to act as a Q-switcher. The Q-switching operation was realized at the center of wavelength of 1036 nm with the minimum pulse width of 2.2 μs. The highest repetition rate and the maximum pulse energy were obtained at 63 kHz and 91 nJ, respectively. A signal to noise ratio (SNR) as high as 49 dB was observed, which indicates a stable operation of Q-switching in the YDFL cavity. This is the first demonstration of the use of ZnPc as Q-switcher in 1-micron wavelength region. A stable and high energy Q-switched pulse was realized with the proposed SA, which was obtained with a low-cost fabrication process.

Passively Q-switched ytterbium-doped fiber laser based on a SWCNT@AFI saturable absorber

An all-fiber passively Q-switched ytterbium-doped fiber laser (YDFL) was successfully achieved by using a single-walled carbon nanotube (SWCNT) as a saturable absorber (SA). The SWCNT was fabricated by pyrolyzing tripropylamine in the one-dimensional channel of zeolite single crystal (ZnAPO-5, framework type code: AFI). Zn2+ metal cations were doped to promote the filling density and quality of the SWCNT. Subsequently, by incorporating the SA into an YDFL ring cavity, a stable Q-switched pulse train at 1039.4 nm with a repetition rate of 54.28 kHz was obtained when the pump power elevated to the starting threshold of 245 mW. It proved that this SWCNT@AFI SA can be used as an effective passively Q-switched for operation at 1.0 µm region.

Passively Q-switched pulses from ytterbium-doped fiber laser (YDFL) using copper oxide (CuO) nanoparticles as a saturable absorber

A high pulse energy Q-switched ytterbium-doped fiber laser (YDFL) based on copper oxide (CuO) nanoparticles as a saturable absorber (SA) is demonstrated. The CuO nanoparticles have been fabricated into a thin film using a liquid-phase exfoliation method then it was integrated into a laser cavity to act as Q-switcher. The proposed Q-switched YDFL operates at a central wavelength of 1035.4 nm with a 3-dB bandwidth of 0.26 nm. The Q-switched laser has a repetition rate range from 57 kHz to 104 kHz by varying the pump power from 179 mW to 226.5 mW, while the pulse width was tuned from 4.5 µs to 2.2 µs. Relatively, high pulse energy around 0.192 µJ was achieved at an average output power of 20 mW. This laser with high pulse energy can be seen as a very promising pulsed laser source in many industrial and optical sensing applications. To the best of our knowledge, this is the first demonstration of a Q-switched fiber laser using CuO-SA in YDF.

Generation of widely wavelength tunable Q-switched pulses in an ytterbium doped all-fiber laser

We report an all-fiber, broadband wavelength-tunable, acousto-optic Q-switched ytterbium-doped fiber laser. The tunable lasing operation was achieved by fiber-based acousto-optic tunable filter with a wavelength range spanning to more than 70 nm from 1008.6–1080.3 nm. Pulse shortening is achieved by spectral filtering and reducing the duty cycle of the acousto-optic modulator (AOM) used for Q-switching. At a 345 mW pump power and 1030 nm laser operation, the duration of Q-switched pulses is reduced from 110 ns (without spectral filtering) to 65 ns with 2.2 μJ pulse energy at a 10 kHz repetition rate and 10% duty cycle of AOM. The Q-switched pulse duration is further shortened to ∼10 ns by reducing the duty cycle of AOM to 0.12%. We believe that this all-fiber integrated Q-switched laser system with wide wavelength tunability and shorter duration pulses will be useful in many scientific applications.

Numerical investigation into the impact of Q-switch rise time on the output pulse characteristics in an actively Q-switched ytterbium-doped fiber laser

We report the results of our theoretical investigation into the impact of the Q-switch rise time on three key parameters of the output pulses in an actively Q-switched fiber laser, namely the multipeak phenomenon, pulse energy, and pulse peak power. Our investigation is conducted over a Q-switch time range of up to 12 times the cavity round-trip time (τround). We show that when a longer Q-switch rise time is applied to the cavity, a trade-off exists between multipeak phenomenon suppression and pulse energy maintenance. The results show that the Q-switch rise time (τrise) for the efficient suppression of multipeak phenomenon without loss of pulse energy varies, depending on the cavity parameters. In an exemplary, actively Q-switched fiber laser operating under the condition of a repetition rate of 15 kHz, τrise is estimated to be approximately five times larger than τround.

Mechanical exfoliation of indium tin oxide as saturable absorber for Q-switched Ytterbium-doped and Erbium-doped fiber lasers

This work reports mechanically exfoliated indium tin oxide (ITO) as saturable absorber (SA) for Q-switched operation in fiber lasers. The ITO is mechanically exfoliated from 99.99% pure In2O3/SnO2. As ITO has a broad operational wavelength from visible to infrared, indium tin oxide saturable absorber (ITO-SA) is incorporated into ytterbium-doped fiber laser (YDFL) and erbium-doped fiber laser (EDFL) cavity for Q-switched operation. The Q-switched spectrum was observed to be centered at 1038.25 nm for ytterbium-doped fiber and 1557.8 nm for erbium doped fiber. The ITO-SA has a linear absorption of 2.25 dB and 2.5 dB at 1μm and 1.5μm respectively. A narrow pulse width was observed in the EDFL operating at 0.95 μs. For the first time, ITO-SA is incorporated to YDFL cavity.

Q-Switched YDFL generation by a MAX phase saturable absorber

A stable Q -switching pulse train in a ytterbium-doped fiber laser (YDFL) cavity was generated using MAX-polyvinyl alcohol (PVA) thin film, which is composed of layered ternary metal carbide ( T i 3 A l C 2 ) as a passive saturable absorber (SA) and incorporates it in the laser cavity. MAX-PVA SA was fabricated using a solution-casting method. A self-started pulse train with a maximum repetition rate of 92 kHz and a decreasing pulse width (from 3.5 to 1.92 µs) with increasing pump power (from 214 to 260 mW) was produced. The laser’s stability was notable, with a high signal-to-noise ratio of 52 dB obtained at the highest repetition rate of 92 kHz. This finding suggests that MAX-SA could be used as an alternative to other SAs in Q -switched fiber lasers.

Q-„switched tunable ytterbium-doped fiber laser with molybdenum ditelluride-based saturable absorber

A Q-switched ytterbium-doped fiber laser incorporating a molybdenum ditelluride saturable absorber for operation at 1046 nm is demonstrated. The laser cavity has a low Q-switching threshold of ∼48 mW. At the maximum pump power, the laser is able to generate pulses with a duration, repetition rate, and output power of 4.88 μs, 39.6 kHz, and 0.76 mW, respectively, as well as a pulse energy of 18.9 nJ. The output of the laser can be tuned from 1064 to 1099 nm, giving a tuning range of 35 nm. The generated pulses have a signal-to-noise ratio of around 60 dB. No interference frequency components or spectral modulation is observed, indicating that the proposed system is highly stable and suitable for use as a fiber laser source in the 1.0-μm region.

Few Layer Molybdenum Selenide Saturable Absorber using Optical Deposition Technique for Q-switched Ytterbium Pulses Laser Generation

We have successfully generated a Q-switched ytterbium-doped fiber laser pulses using few layers of Molybdenum Selenide (MoSe2) as saturable absorber (SA). The setup was a ring fiber laser cavity with few-layer MoSe2, deposited onto a fiber ferrule using an optical deposition technique. A stable pulses started at input power of 68.8 mW with repetition rate ranging from 14.2 kHz to 34.0 kHz was achieved with highest pulse energy, shortest pulse width and highest output power of 3.6 nJ, 4.4 µs and 0.12 mW were observed, respectively.

Tunable Q-switched ytterbium-doped fibre laser with Nickel Oxide saturable absorber

A passively Q-switched ytterbium-doped fibre laser (YDFL) using a nickel oxide-based saturable absorber is proposed and demonstrated. The Q-switched YDFL is capable of generating a stable output with a minimum pulse width of 6.9 µs and maximum repetition rate of 57.01 kHz. The generated pulses are highly stable, with an observed signal-to-noise ratio of ~ 33 dB. The output of the laser can be tuned over a wavelength range of 18 nm from 1035 to 1053 nm. The Q-switched YDFL would find use in multiple applications ranging from medicine to manufacturing.

Passively Q-switched mode-locked ytterbium-doped fiber laser based on an Fe3O4-nanoparticle saturable absorber

A passively Q-switched mode-locked ytterbium-doped fiber laser (QMYDFL) at 1084.4 nm using ferroferric-oxide (Fe3O4) nanoparticles (FONPs) as the saturable absorber (SA) is reported. The FONPs SA exhibits a large nonlinear saturable absorption property with the modulation depth of 6.6% at the laser wavelength of 1µm band. Stable passively Q-switched pulse train with the repetition rate increasing from 5.43 kHz to 59 kHz, the corresponding pulse duration reducing from 18 µs to 2.68 µs are achieved when the input pump power increases from 100 mW to 330 mW. The maximum single pulse energy can reach 181.6 nJ. Q-switched mode-locked (QM) phenomenon is also observed by adjusting the state of the polarization controller (PC). When the input pump power is 150 mW, stable QM pulse train occurs. By continuous increasing the pump power to 320 mW, the QM pulse trains with the repetition rate increasing from 17.1 kHz to 34.3 kHz, mode-locked pulse repetition rate of 11.1 MHz and pulse duration of 880 ps are achieved. The observed phenomenon is interpreted as a mutual interaction of dispersion, non-linear effect and insertion loss. This work provides a new mechanism for fabricating cheap QMYDFL with FONPs SA.

1030-nm passively Q-switched ytterbium-doped fiber laser using excited-state absorption of thulium fiber

We demonstrated a pulsed ytterbium all-fiber laser passively Q -switched using excited-state absorption of thulium fiber and a mode-field-area mismatch. The absorption cross section of the excited state 3 F 4 was measured and determined to be the key factor inducing pulsing, and it was much higher than that of the ground state 3 H 6 over 0.95–1.15 µm. By successfully realizing the pulsed laser at 1030 nm, which is the most critical wavelength for Q -switching, we verified that the excite state 3 F 4 of T m 3 + could be a full-range saturable-absorber Q -switch for a Yb fiber laser over 1.0–1.15 µm.