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

1283-1460 nm continuously tunable, watt-level bismuth-doped phosphosilicate fiber laser and its frequency doubling to a visible laser

We report, to the best of our knowledge, the first demonstration of an O + E-band tunable watt-level bismuth-doped phosphosilicate fiber laser and its frequency doubling to tunable red laser. Benefiting from the two types of bismuth active centers associated with silicon and phosphorus introduced in one fiber, an ultrabroad gain is available in the designed low-water-peak bismuth-doped phosphosilicate fiber (Bi-PSF) pumped by a self-made 1239 nm Raman fiber laser. The high-efficiency tunable lasing is achieved with a maximum output power of 1.705 W around 1320 nm and a slope efficiency of 33.0%. The wavelength can be continuously tuned from 1283 to 1460 nm over a 177 nm spectral range, almost covering the whole O+E-bands. We further employ a polarization beam splitter in the cavity to output an O + E-band linear-polarization laser for second-harmonic generation by a designed multi-period MgO2:PPLN crystal, and a 650-690-nm tunable visible laser is correspondingly obtained. Such an O+E-wideband tunable high-power laser and the SHG red laser may have great potential in the all-band optical communications, biophotonics, and spectroscopy.

CrPS4 Nanoflakes as Stable Direct-Band-Gap 2D Materials for Ultrafast Pulse Laser Applications

Two-dimensional (2D) materials have attracted considerable attention due to their potential for generating ultrafast pulsed lasers. Unfortunately, the poor stability of most layered 2D materials under air exposure leads to increased fabrication costs; this has limited their development for practical applications. In this paper, we describe the successful preparation of a novel, air-stable, and broadband saturable absorber (SA), the metal thiophosphate CrPS₄, using a simple and cost-effective liquid exfoliation method. The van der Waals crystal structure of CrPS₄ consists of chains of CrS₆ units interconnected by phosphorus. In this study, we calculated the electronic band structures of CrPS₄, revealing a direct band gap. The nonlinear saturable absorption properties, which were investigated using the P-scan technique at 1550 nm, revealed that CrPS₄-SA had a modulation depth of 12.2% and a saturation intensity of 463 MW/cm². Integration of the CrPS₄-SA into Yb-doped fiber and Er-doped fiber laser cavities led to mode-locking for the first time, resulting in the shortest pulse durations of 298 ps and 500 fs at 1 and 1.5 µm, respectively. These results indicate that CrPS₄ has great potential for broadband ultrafast photonic applications and could be developed into an excellent candidate for SA devices, providing new directions in the search for stable SA materials and for their design.

1.3/1.4 µm dual-wave band dissipative soliton resonance in a passively mode-locked Bi-doped phosphosilicate fiber laser

We report the 1.3/1.4 µm dual-wave band dissipative soliton resonance (DSR) in a passively mode-locked bismuth-doped phosphosilicate fiber (Bi-PSF) laser. The low-water-peak Bi-PSF with two bismuth active centers associated with silicon and phosphorus supports the O+E-band gain. Using a 1239 nm home-made Raman fiber laser as pump source and nonlinear amplifying loop mirror for initiating mode-locking, stable DSR operation at 1343 and 1406 nm is achieved with the spectral bandwidth of 12 and 16 nm. The pulse duration with the pump power increases from 62 to 270 ps with a repetition frequency of 4.069 MHz. The average power is 11.05 mW corresponding to the maximum energy of 2.7 nJ. This is, to the best of our knowledge, the first demonstration of a mode-locked fiber laser in the ∼1.38 µm water absorption band and the O+E dual-wave band operation for applications in all-spectral-band communications, bio-medical imaging, and terahertz difference frequency generation.

GaSb Film is a Saturable Absorber for Dissipative Soliton Generation in a Fiber Laser

Nanotechnology is at the forefront of scientific research and offers great prospects for the development of technology. As a type of III-V semiconductor, GaSb materials exhibit numerous outstanding optical and electrical characteristics that are very promising for nonlinear optical device applications. In this study, the electronic band structures of GaSb are theoretically calculated, and its application in dissipative soliton fiber lasers is validated. A GaSb thin film is deposited on a microfiber using magnetron sputtering deposition, and the morphology, chemical composition, structure, and nonlinear optical characteristics of the proposed microfiber-GaSb device are investigated. After incorporating it into an Er-doped fiber laser, dissipative soliton laser pulses are readily obtained with a fundamental frequency of 43.5 MHz. With increasing pump power, the fiber laser could work in the fundamental frequency mode-locking state. At a pump power of 570 mW, the pulse width and the output power are measured to be 917 fs and 49.75 mW, separately. These results reveal that GaSb can be used as an efficient saturable absorber, which will have potential applications in ultrafast optics.

Frontier and Hot Topics of Pulsed Fiber Lasers via CiteSpace Scientometric Analysis: Passively Mode-Locked Fiber Lasers with Real Saturable Absorbers Based on Two-Dimensional Materials

Pulsed fiber lasers, with high peak power and narrow pulse widths, have been proven to be an important tool for a variety of fields of application. In this work, frontier and hot topics in pulsed fiber lasers were analyzed with 11,064 articles. Benefitting from the scientometric analysis capabilities of CiteSpace, the analysis found that passively mode-locked fiber lasers with saturable absorbers (SAs) based on two-dimensional (2D) materials have become a hot research topic in the field of pulsed fiber lasers due to the advantages of self-starting operation, high stability, and good compatibility. The excellent nonlinear optical properties exhibited by 2D materials at nanometer-scale thicknesses have become a particularly popular research topic; the research has paved the way for exploring its wider applications. We summarize the performance of several typical 2D materials in ultrafast fiber lasers, such as graphene, topological insulators (TIs), transition metal dichalcogenides (TMDs), and black phosphorus (BP). Meanwhile, we review and analyze the direction of the development of 2D SAs for ultrafast fiber lasers.

Mode-locked ytterbium-doped fiber laser with zinc phthalocyanine thin film saturable absorber

A stable mode-locked laser was demonstrated using a newly developed zinc phthalocyanine (ZnPc) thin film as passive saturable absorber (SA) in ytterbium-doped fiber laser (YDFL). The ZnPc thin film was obtained using a casting method and then inserted between the two fiber ferrules of a YDFL ring cavity to generate mode-locked pulses. The resulting pulsed laser operated at a wavelength of 1034.5 nm having a repetition rate of 3.3 MHz. At pump power of 277 mW, the maximum output power and pulse energy are achieved at 4.92 mW and 1.36 nJ, respectively. ZnPc has a high chemical and photochemical stability, and its significance for use as a potential SA in a mode-locked laser is reported in this work.

Broadband saturable absorption in germanene for mode-locked Yb, Er, and Tm fiber lasers

Passively mode-locked lasers have been widely investigated as one of the effective methods to obtain ultrashort pulses. As an important part of passively mode-locked fiber lasers, the exploration of 2D material-based saturable absorber has become one of the hotspots in ultrafast photonics in recent years. Germanene, a novel 2D Dirac material, with ultrafast optical response and broadband optical absorption, is a promising alternative material for saturable absorber in mode-locked fiber lasers. In this paper, germanium nanosheets are prepared via liquid-phase exfoliated method, with the saturable absorption property systematically characterized in three major wavebands of the near-infrared region. The generation of ultrashort pulses based on germanene saturable absorber in fiber lasers is further realized, in a broad waveband (1000 nm) centered at 1061.1, 1559.3 and 1883.5 nm, respectively. In addition, noise-like pulses operation with central wavelength of 1558.6 nm is also obtained, and the formation of rogue waves is further demonstrated via statistical analysis. To the best of our knowledge, this is the first experimental verification of the broadband saturable absorption property of germanene-based devices, covering three major fiber laser wavelengths from 1.0 to 2.0 μm.

Ultrafast photonics applications of emerging 2D-Xenes beyond graphene

Driven by new two-dimensional materials, great changes and progress have taken place in the field of ultrafast photonics in recent years. Among them, the emerging single element two-dimensional materials (Xenes) have also received much attention due to their special physical and photoelectric properties including tunable broadband nonlinear saturable absorption, ultrafast carrier recovery rate, and ultrashort recovery time. In this review, the preparation methods of Xenes and various integration strategies are detailedly introduced at first. Then, we summarize the outcomes achieved by Xenes-based (beyond graphene) fiber lasers and make classifications based on the characteristics of output pulses according to the materials characterization and nonlinear optical absorption properties. Finally, an outlook of the future opportunities and challenges of ultrafast photonics devices based on Xenes and other 2D materials are highlighted, and we hope this review will promote their extensive applications in ultrafast photonics technology.

Liquid-Phase Exfoliation of Ta2NiS5 and Its Application in Near-Infrared Mode-Locked Fiber Lasers with Evanescent Field Interactions and Passively Q-Switched Bulk Laser

We report on the application of a 1 μm solid-state passively Q-switched (PQS) laser and 1, 1.5 μm mode-locked (ML) fiber lasers based on ternary chalcogenide Ta2NiS5 saturable absorber (SA), which were successfully fabricated by liquid-phase exfoliation method (LPE). The nonlinear absorption of the Ta2NiS5-SA was characterized by 0.32 GW/cm2 and 0.25 GW/cm2 saturation intensities with 7.3% and 5.1% modulations depths at 1 μm and 1.5 μm, respectively. A PQS solid-state laser operating at 1.0 μm has been realized with the Ta2NiS5-SA. The maximum average output power, shortest pulse width, pulse energy, and pulse peak power from the PQS laser are 0.257 W, 180 ns, 1.265 μJ, and 7 W. Moreover, highly stable femtosecond laser centered at 1.5 μm, and picosecond centered at 1 μm, ML fiber lasers were obtained using the Ta2NiS5-SA. A 70 dB signal-to-noise ML laser with a pulse duration of 781 fs was observed in the telecommunication window, which is better than the duration of the previously reported lasers based on Ta2NiS5. The corresponding maximum single pulse energy and peak power are 0.977 nJ and 1251 W, respectively. The Ta2NiS5-SA fabricated by the LPE method was applied in near-infrared (NIR) ML fiber lasers (evanescent field interactions) and PQS bulk lasers. The results indicate that Ta2NiS5-SA prepared by the LPE method can be applied in a 1 μm bulk PQS laser and improved by the new combination mode (evanescent field interactions) for better output performance of the fiber laser.

Novel nanomaterials based saturable absorbers for passive mode locked fiber laser at 1.5μm

Compared with continuous wave lasers, ultrafast lasers have the advantages of ultra-short pulse width and ultra-high peak power, and have significant applications in optical communications, medical diagnostics, and precision machining. Saturable absorber (SA) technology is the most effective technique for the generation of ultra-fast lasers, which are based on artificial SAs and natural SAs. Among them, the semiconductor saturable absorber mirror has become the most commonly used form at present. Recently, basic research and application of nanomaterials such as carbon nanotubes (CNTs) and graphene have been developed rapidly. Researchers have found that nanomaterials exhibit extraordinary characteristics in ultrafast photonics, such as the low saturation intensity of CNTs, zero-band gap of graphene, and extremely high modulation depth of the topological insulator nano-films. Since graphene was first reported as an SA in 2009, many other nanomaterials have been successively explored, resulting in the rapid development of novel nanomaterial-based SAs. In this paper, we classified the nanomaterials used in SA mode-locking technology at 1.5μm and reviewed their research progress with a particular focus on nonlinear optical properties, integration strategies, and applications in the field of ultrafast photonics.

Band structure tuning of g-C3N4 via sulfur doping for broadband near-infrared ultrafast photonic applications

Graphitic carbon nitride (g-C3N4) featuring a stable heptazine ring structure and high polymerization degree, was indexed as a high thermochemical stability material, attracting rising research enthusiasm for diverse applications. However, the poor near-infrared (NIR) optical absorption and resulting limited NIR applications were pronounced for g-C3N4 due to its large bandgap of 2.7 eV. In the present work, sulfur-doping was manifested by first-principles calculations to introduce impurity level and result in anisotropic spin splitting in g-C3N4 for enhancing broadband nonlinear optical characteristics in NIR regime. The modified sulfur-doped g-C3N4 (S-C3N4) exhibited the maximum effective nonlinear absorption coefficient to be -0.82 cm/GW. Pulse duration within hundred nanoseconds was realized with high modulation stability employing S-C3N4 as saturable absorber in Q-switching operations. Moreover, broadband ultrafast photonics properties were successfully demonstrated in constructed ytterbium-doped and erbium-doped fiber lasers, generating highly stable dissipative soliton and traditional soliton mode-locking pulses. The presented S-C3N4 nanomaterial with remarkable nonlinear optical performances might explicitly boost the development and application of g-C3N4 materials in advanced optoelectronic and ultrafast photonic devices.

Local nonlinearity engineering of evanescent-field-interaction fiber devices embedding in black phosphorus quantum dots

Tapered fiber (TF) and D-shaped fiber (DF) are two types of widely investigated devices in facilitating evanescent-field interactions with external materials. Although they have been found to be particularly useful in various ultrafast regimes, to date there is still no clear or systematic investigation on their local nonlinearities as well as the exerted influences on ultrafast behaviors. Herein, we present such thorough investigation through local nonlinearity engineering on TF and then in contrast with a DF as a reference. Optically deposited black phosphorus quantum dots (BPQDs) are used for saturable absorption. The nanometer-scale extremely small sizes of the BPQDs helpfully eliminate size-induced uncertainties or distortions during both device fabrication and the latter light-matter interaction. For the TF, in the experiment, it is found that the local nonlinear effect starts to be rather appreciable as the TF shrinks to a moderate thickness. Remarkably in comparison, the local nonlinearity of the DF itself can even be neglected reasonably, but after coating with BPQDs, it possesses a much larger modulation depth than any of the used BPQDs-coated TFs with different thicknesses/lengths. Further, we theoretically analyze the related locally nonlinear effects and reveal, for the first time, the direct origin of saturable absorption with evanescent-field-based general structures.

TiN nanoparticles deposited onto a D-shaped fiber as an optical modulator for ultrafast photonics and temperature sensing

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.

A Review on Rhenium Disulfide: Synthesis Approaches, Optical Properties, and Applications in Pulsed Lasers

Rhenium Disulfide (ReS₂) has evolved as a novel 2D transition-metal dichalcogenide (TMD) material which has promising applications in optoelectronics and photonics because of its distinctive anisotropic optical properties. Saturable absorption property of ReS₂ has been utilized to fabricate saturable absorber (SA) devices to generate short pulses in lasers systems. The results were outstanding, including high-repetition-rate pulses, large modulation depth, multi-wavelength pulses, broadband operation and low saturation intensity. In this review, we emphasize on formulating SAs based on ReS₂ to produce pulsed lasers in the visible, near-infrared and mid-infrared wavelength regions with pulse durations down to femtosecond using mode-locking or Q-switching technique. We outline ReS₂ synthesis techniques and integration platforms concerning solid-state and fiber-type lasers. We discuss the laser performance based on SAs attributes. Lastly, we draw conclusions and discuss challenges and future directions that will help to advance the domain of ultrafast photonic technology.

Three-dimensional Ag2S cubes for switchable multi-wavelength ultrashort pulse application

Three-dimensional (3D) materials are widely used in optoelectronics, thermodynamics and ultrafast fiber lasers because of their excellent nonlinear optical properties. Silver sulfide (Ag₂S) is a kind of 3D material with a unique cubic structure and large absorption coefficient. In this paper, a double-balance detection system is used to measure the saturation absorption intensity of Ag₂S as 226.6 MW cm^-2and the modulation depth as 13.9%. In the ring fiber laser, Ag₂S is used as a saturable absorber (SA) to obtain a stable dual-wavelength mode locking. The center wavelengths of the mode locking are 1536.9 and 1544.5 nm, and the corresponding 3 dB bandwidths are 1.3 and 1.5. nm. By adjusting the polarization controller, a tuning process from two wavelengths to multiple wavelengths is realized, and the tunable width is 13.1 nm. This phenomenon is due to the combined effect of birefringence and nonlinear effects in the cavity. To our knowledge, this is the first report of a multiplexed fiber laser with Ag₂S as a SA. The emergence of this result provides a valuable reference information for the multifunctional compact fiber laser, and the formed system can be applied in the fields of fiber sensing, telecommunications and optical communication.

Ultrafast Fiber Lasers with Low-Dimensional Saturable Absorbers: Status and Prospects

Wide-spectral saturable absorption (SA) in low-dimensional (LD) nanomaterials such as zero-, one-, and two-dimensional materials has been proven experimentally with outstanding results, including low saturation intensity, deep modulation depth, and fast carrier recovery time. LD nanomaterials can therefore be used as SAs for mode-locking or Q-switching to generate ultrafast fiber laser pulses with a high repetition rate and short duration in the visible, near-infrared, and mid-infrared wavelength regions. Here, we review the recent development of emerging LD nanomaterials as SAs for ultrafast mode-locked fiber laser applications in different dispersion regimes such as anomalous and normal dispersion regimes of the laser cavity operating in the near-infrared region, especially at ~1550 nm. The preparation methods, nonlinear optical properties of LD SAs, and various integration schemes for incorporating LD SAs into fiber laser systems are introduced. In addition to these, externally (electrically or optically) controlled pulsed fiber laser behavior and other characteristics of various LD SAs are summarized. Finally, the perspectives and challenges facing LD SA-based mode-locked ultrafast fiber lasers are highlighted.

Nonlinear optical property measurements of rhenium diselenide used for ultrafast fiber laser mode-locking at 1.9 μm

An experimental investigation into the nonlinear optical properties of rhenium diselenide (ReSe2) was conducted at a wavelength of 1.9 μm using the open-aperture and closed-aperture Z-scan techniques for the nonlinear optical coefficient (β) and nonlinear refractive index (n2) of ReSe2, respectively. β and n2 measured at 1.9 μm were ~ - 11.3 × 103 cm/GW and ~ - 6.2 × 10-2 cm2/GW, respectively, which to the best of our knowledge, are the first reported measurements for ReSe2 in the 1.9-μm spectral region. The electronic band structures of both ReSe2 and its defective structures were also calculated via the Perdew-Becke-Erzenhof functional to better understand their absorption properties. A saturable absorber (SA) was subsequently fabricated to demonstrate the usefulness of ReSe2 for implementing a practical nonlinear optical device at 1.9 μm. The 1.9-μm SA exhibited a modulation depth of ~ 8% and saturation intensity of ~ 11.4 MW/cm2. The successful use of the ReSe2-based SA for mode-locking of a thulium-holmium (Tm-Ho) co-doped fiber ring cavity was achieved with output pulses of ~ 840 fs at 1927 nm. We believe that the mode-locking was achieved through a hybrid mechanism of saturable absorption and nonlinear polarization rotation.

Passively Mode-Locked Fiber Laser with WS2/SiO2 Saturable Absorber Fabricated by Sol-Gel Technique

High-performance ultrafast fiber lasers require saturable absorbers (SAs) of high optical damage threshold and high operation stability. Here, the optical properties and application of the WS₂/SiO₂ SA prepared by the sol-gel method are reported. SiO₂ prepared by sol-gel technique has similar properties to fiber in ultrafast fiber lasers, such as mechanical strength, refractive index, optical transmission, and absorption. For the SA device by the sol-gel method combined with WS₂ material, not only will the additional scattering loss not be introduced, but also, the damage threshold of the SA device can be effectively increased. Furthermore, SA material is wrapped by SiO₂, which insulates the influence of the external environment. Based on the first preparation of the WS₂/SiO₂ glass SA, stable soliton pulses are obtained in ytterbium-doped fiber lasers (YDFLs) with a pulse width of 58 ps, an average output power of 56.8 mW, and a repetition rate of 19.03 MHz. In addition, a stable mode-locked operation with a pulse width of 325 fs and an output power of 39.6 mW is also achieved in an erbium-doped fiber laser (EDFL). These results demonstrate that the WS₂/SiO₂ glass prepared by the sol-gel method can significantly increase laser output power and shorten pulse width in the fiber laser, which provides a new opportunity for the traditional preparation method of the SA device.

Engineering Mono-Chalcogen Nanomaterials for Omnipotent Anticancer Applications: Progress and Challenges

Belonging to the chalcogen group, the elements selenium (Se) and tellurium (Te) are located in Group VI-A of the periodic table. Zero-valent nanodimensioned Se (nano-Se) and Te (nano-Te) have displayed important biomedical applications in recent years. The past two decades have witnessed an explosion in novel cancer treatment strategies using nano-Se and nano-Te as aggressive weapons against tumors. Indeed, they are both inorganic nanomedicines that suppress tumor cell proliferation, diffusion, and metastasis. Abundant synthesis strategies for rational and precise surface decoration of nano-Se and nano-Te make them significant players in resisting cancers by means of powerful multi-modal treatment methods. This review focuses on the design and engineering of nano-Se- and nano-Te-based nanodelivery systems and their precise uses in cancer treatment. The corresponding anticancer molecular mechanisms of nano-Se and nano-Te are discussed in detail. Given their different photo-induced behaviors, the presence or absence of near infrared illumination is used as a defining characteristic when describing the anticancer applications of nano-Se and nano-Te. Finally, the challenges and future prospects of nano-Se and nano-Te are summarized and highlighted.

High-efficiency second-order nonlinear processes in an optical microfibre assisted by few-layer GaSe

The centrosymmetric nature of silica fibre precludes the realisation of second-order nonlinear processes in optical fibre systems. Recently, the integration of 2D materials with optical fibres has opened up a great opportunity to develop all-fibre active devices. Here, we demonstrate high-efficiency second-order nonlinear frequency conversions in an optical microfibre assisted with few-layer gallium selenide (GaSe) nanoflakes. Attributed to the strong evanescent field of the microfibre and ultrahigh second-order nonlinearity of the GaSe nanoflakes, second harmonic generation (SHG) and sum-frequency generation (SFG) are effectively achieved with only sub-milliwatt continuous-wave (CW) lasers in the wavelength range of 1500-1620 nm, covering the C and L telecom bands. The SHG intensity from the microfibre is enhanced by more than four orders of magnitude with the assistance of the GaSe nanoflakes on fibre nonlinear processes. Moreover, in the SFG process, the intensity transfer between different frequencies can be effectively manipulated by changing the wavelengths and powers of two pump lasers. The realised strong second-order nonlinearity in the GaSe-integrated microfibre might expand the applications of all-fibre devices in all-optical signal processing and new light source generation at awkward wavelengths.

Wideband saturable absorption in metal-organic frameworks (MOFs) for mode-locking Er- and Tm-doped fiber lasers

We fabricate a metal-organic framework (MOF) saturable absorber (SA) based on a microfiber. Nonlinear optical absorption of the MOF SA is characterized systematically. The modulation depth is found to be 6.57% and 14.25% at 1.5 and 2 μm spectral ranges, respectively. We report ultrashort pulse generation in both Er- and Tm-doped fiber lasers by using the same microfiber-based MOF SA, operating at 384 fs and 1.3 ps pulse duration at 1563 nm and 1882 nm, respectively. To the best of our knowledge, this is the first report of a MOF-based fiber laser at near infrared spectral ranges. Our findings validate the applicability of MOFs as a broadband SA in ultrafast photonics.

Stationary and pulsating vector dissipative solitons in nonlinear multimode interference based fiber lasers

Rapid progress in real-time spectroscopy uncovers the spatio-spectral scenarios of ultrashort pulses in dissipative systems. Varieties of transient soliton dynamics on different timescales have been revealed. Here, we report on an experimental observation of stationary and pulsating vector dissipative solitons in a nonlinear multimode interference (NL-MMI) based fiber laser with net normal dispersion. Polarization non-discrimination of the NL-MMI mode-locking facilitates the dissipative soliton trapping process. Two orthogonally polarized components are coupled together through oppositely shifting their central frequencies to form the group-velocity-locked vector dissipative solitons (GVLVDSs). Dispersive Fourier transform (DFT) based polarization resolved measurement enables insights into the transient polarization dynamics and the long-term evolution. Particularly, both stationary and pulsating GVLVDSs are obtained with appropriate parameter settings. It is found that the quasi-stationary pulsating manner is accompanied with recurrent spectral breathing and energy oscillation; the two orthogonally polarized components possess synchronous pulsating manners due to the cross-phase modulation induced trapping mechanism and the similar formation process. Additionally, chaotic pulsation is also captured in sense that the spectra cannot recover to their original profiles despite of the harmonic energy oscillation. All these findings can enhance our understanding towards soliton pulsation with the freedom of vectorial degree.

Q-switched ytterbium-doped fiber laser based on evanescent field interaction with lutetium oxide

We demonstrated lutetium oxide (${\textrm{Lu}_2}{\textrm{O}_3}$Lu₂O₃) deposited onto D-shaped fiber producing Q-switched ytterbium-doped fiber laser (YDFL) with an operating wavelength of 1037 nm. D-shaped fiber ${\textrm{Lu}_2}{\textrm{O}_3}$Lu₂O₃ as a saturable absorber (SA) was prepared using a polishing-wheel technique by polishing 2 times to establish an excellent evanescent field interaction between material and light on the surface of the polished region. The SA was deployed into a YDFL to generate Q-switching. The proposed D-shaped fiber ${\textrm{Lu}_2}{\textrm{O}_3}$Lu₂O₃ initiated pulses as short as 3.6 µs, with the highest repetition rate of 65.8 kHz. Stability of the SA is proven, as it produced stable pulses within the pump power of 99 to 133 mW with an SNR of 62.13 dB. Q-switched YDFL generates pulses with an output power of 0.93 to 1.99 mW and pulse energy of 17 to 30 nJ. We obtained a laser cavity with the optical-to-optical efficiency of 3.33%, which was the highest among D-shaped fiber-deposited SA materials in YDFL. Therefore, ${\textrm{Lu}_2}{\textrm{O}_3}$Lu₂O₃ deposited onto D-shaped fiber can be deployed as an SA in YDFL for a portable Q-switched laser source.

In2Se3 nanosheets with broadband saturable absorption used for near-infrared femtosecond laser mode locking

Indium selenide (In₂Se₃) has attracted tremendous attention due to its favorable electronic features, broad tunable bandgap, high stability and other attractive properties. However, its further applications for nonlinear optics have not yet been fully explored. In this work, we demonstrate that few-layer α-In₂Se₃ nanosheets exhibit strong saturable absorption properties over a wide wavelength range covering 800, 1064 and 1550 nm. The few-layer α-In₂Se₃ nanosheets used for this experiment are fabricated via a simple ultrasonic exfoliation in liquid. Stable ultrafast mode-locking laser pulses are obtained from both ytterbium-doped and erbium-doped fiber laser systems operating at 1064 and 1550 nm, respectively. A pulse duration as short as 215 fs was achieved in the Er-doped fiber laser system. Stable output pulses over 6 h of operation were obtained in both laser systems. The pulse energy and peak power of the laser output pulses were increased by reducing the In₂Se₃ thickness. These results indicate that α-In₂Se₃ nanosheets with low layer numbers are promising candidates for broad ultrafast photonics devices, such as optical switchers, Q-switchers and mode lockers.

Nonlinear Optical Properties of Zirconium Diselenide and Its Ultra-Fast Modulator Application

Recently, two-dimensional (2D) materials have been widely studied by researchers due to their exceptional 2D structure and excellent optical characteristics. As one of the typically-layered 2D transition metal dichalcogenide (TMD) semiconductors from group IVB with a bandgap value of 0.9–1.2 eV (bulk to monolayer), the characteristics of zirconium diselenide (ZrSe₂) have already been extensively investigated in many fields. However, the nonlinear absorption properties of ZrSe₂ in ultra-fast lasers have not been previously demonstrated. In this work, we measured various parameters in order to investigate the characteristics of the nonlinear saturable absorption of ZrSe₂. A ZrSe₂–polyvinyl alcohol (PVA) film was successfully prepared, which was employed as a saturable absorber (SA) to demonstrate, for the first time, an erbium (Er)-doped passive mode-locking fiber laser with a ring cavity. The saturation intensity of the ZrSe₂–PVA film-type SA is 12.72 MW/cm², while its modulation depth is 2.3%. The stable soliton state with a maximum output power of 11.37 mW and a narrowest monopulse duration of 12.5 ps at a repetition frequency of 21.22 MHz was detected. The experimental results conclusively proved that ZrSe₂, with its suitable bandgap value and excellent nonlinear absorption properties, as well as its high damage threshold, should have extensive potential applications within the field of ultra-fast pulse lasers.

Broadband Nonlinear Optical Response of Single-Crystalline Bismuth Thin Film

Bismuth (Bi), a topological material, where many interesting condensed matter phenomena have been observed, possesses unique physical properties when its thickness is reduced to thin film. Here, we prepared the highly stable, single-crystalline, continuous Bi thin film via the vapor deposition (VD) method and found that the Bi thin film can exhibit broadband, ultrafast nonlinear optical response with low saturable intensity ranging from the near-infrared to mid-infrared spectral range under strong excitation. Moreover, we demonstrated that the Bi thin film was favorable to act as a nonlinear pulse modulator toward a high performance pulsed laser operating in optical communication and mid-infrared wavelengths. The experimental results highlight the prospects of Bi thin film as broadband pulsed modulators and may open new avenues toward advanced Bi-based broadband photonic devices.

WS2 Nanotubes, 2D Nanomeshes, and 2D In-Plane Films through One Single Chemical Vapor Deposition Route

We demonstrate a versatile, catalyst free chemical vapor deposition process on insulating substrates capable of producing in one single stream one-dimensional (1D) WO_{3- x} suboxides leading to a wide range of substrate-supported 2H-WS₂ polymorphs: a tunable class of out-of-plane (of the substrate) nanophases, with 1D nanotubes and a pure WS₂, two-dimensional (2D) nanomesh (defined as a network of webbed, micron-size, few-layer 2D sheets) at its extremes; and in-plane (parallel to the substrate) mono- and few-layer 2D domains. This entails a two-stage approach in which the 2WO₃ + 7S → 2WS₂ + 3SO₂ reaction is intentionally decoupled. First, various morphologies of nanowires or nanorods of high stoichiometry, WO_2.92/WO_2.9 suboxides (belonging to the class of Magnéli phases) were formed, followed by their sulfurization to undergo reduction to the aforementioned WS₂ polymorphs. The continuous transition of WS₂ from nanotubes to the out-of-plane 2D nanomesh, via intermediary, mixed 1D-2D phases, delivers tunable functional properties, for example, linear and nonlinear optical properties, such as reflectivity (linked to optical excitations in the material), and second harmonic generation (SHG) and onset of saturable absorption. The SHG effect is very strong across the entire tunable class of WS₂ nanomaterials, weakest in nanotubes, and strongest in the 2D nanomesh. Furthermore, a mechanism via suboxide (WO_{3- x}) intermediate as a possible path to 2D domain growth is demonstrated. 2D, in-plane WS₂ domains grow via "self-seeding and feeding" where short WO_2.92/WO_2.9 nanorods provide both the nucleation sites and the precursor feedstock. Understanding the reaction path (here, in the W-O-S space) is an emerging approach toward controlling the nucleation, growth, and morphology of 2D domains and films of transition-metal dichalcogenides.

Large-energy mode-locked ytterbium-doped linear-cavity fiber laser based on chemical vapor deposition-Bi2Se3 as a saturable absorber

We reported on the generation of pulse bunch and large-energy dark pulses in a mode-locked ytterbium-doped linear-cavity fiber laser based on Bi₂Se₃ as a saturable absorber (SA). Bi₂Se₃ nanosheets were successfully synthesized by the chemical vapor deposition (CVD) method and transferred to the end facet of a fiber connector for the proposed SA. Its saturation intensity and modulation depth were measured to be 52  MW/cm² and 14.5%, respectively. By inserting the Bi₂Se₃-based SA into the Yb-doped all-fiber linear cavity, stable pulse bunches were observed. In addition, dark soliton operation with a maximum average output power of 32.6 mW and a pulse energy of 61.8 nJ were also achieved. To the best of our knowledge, this is the first demonstration of a dark soliton within a linear cavity with much larger pulse energy than previous works. Our study fully indicated that CVD-Bi₂Se₃ could be an excellent SA for achieving large-energy pulse operations.

Optical properties and applications of molybdenum disulfide/SiO2 saturable absorber fabricated by sol-gel technique

We investigate a new type of molybdenum disulfide (MoS₂)-doped sol-gel glass saturable absorber (SA) fabricated by sol-gel technique. The reagents used for the sol-gel glass contain Tetraethyl orthosilicate (TEOS), ethanol, water, and hydrochloric acid. Different from the traditional ways of fabricating SAs, the MoS₂ in our method is encapsulated by inorganic sol-gel glass instead of polymer compound with low laser damage resistance, which greatly increases the optical damage threshold of MoS₂ SA. The MoS₂-doped sol-gel glass as an SA is experimentally demonstrated in a passively mode-locked ytterbium-doped fiber laser (YDFL). Stable mode-locked pulse trains are successfully generated in the normal dispersion regime with a pulse width of 13.8 ps and the average output power of 34.6 mW. The fluctuation of the central wavelength and spectral bandwidth is as low as 0.9% in one week, which indicates that the mode-locking state has good environmental stability. To the best of our knowledge, it is the first example of sol-gel glass SA for ultrafast pulses generated in YDFL, which potentially gives a new approach to improve optical damage threshold and long-term working stability for broadband absorbers.

Nonlinear optical properties of MoS2-WS2 heterostructure in fiber lasers

As a saturable absorption material, the heterostructure with the van der Waals structure has been paid much attention in material science. In general, the heterogeneous combination is able to neutralize, or even exceed, the individual material's advantages in some aspects. In this paper, which describes the magnetron sputtering deposition method, the tapered fiber is coated by the MoS₂-WS₂ heterostructure, and the MoS₂-WS₂ heterostructure saturable absorber (SA) is fabricated. The modulation depth of the prepared MoS₂-WS₂ heterostructure SA is measured to be 19.12%. Besides, the theoretical calculations for the band gap and carrier mobility of the MoS₂-WS₂ heterostructure are provided. By employing the prepared SA, a stable and passively erbium-doped fiber laser is implemented. The generated pulse duration of 154 fs is certified to be the shortest among all fiber lasers based on transition mental dichalcogenides. Results in this paper provide the new direction for the fabrication of ultrafast photon modulation devices.

Emerging 2D materials beyond graphene for ultrashort pulse generation in fiber lasers

Ultrafast fiber lasers have significant applications in ultra-precision manufacturing, medical diagnostics, medical treatment, precision measurement and astronomical detection, owing to their ultra-short pulse width and ultra-high peak-power. Since graphene was first explored as an optical saturable absorber for passively mode-locked lasers in 2009, many other 2D materials beyond graphene, including phosphorene, antimonene, bismuthene, transition metal dichalcogenides (TMDs), topological insulators (TIs), metal-organic frameworks (MOFs) and MXenes, have been successively explored, resulting in rapid development of novel 2D materials-based saturable absorbers. Herein, we review the latest progress of the emerging 2D materials beyond graphene for passively mode-locked fiber laser application. These 2D materials are classified into mono-elemental, dual-elemental and multi-elemental 2D materials. The atomic structure, band structure, nonlinear optical properties, and preparation methods of 2D materials are summarized. Diverse integration strategies for applying 2D materials into fiber laser systems are introduced, and the mode-locking performance of the 2D materials-based fiber lasers working at 1-3 μm are discussed. Finally, the perspectives and challenges facing 2D materials-based mode-locked fiber lasers are highlighted.

Broadband polarization-insensitive saturable absorption of Fe2O3 nanoparticles

The synthesis and functionalization of transition-metal oxides are one of the most active research areas in advanced materials. As a typical transition-metal oxide, iron oxide has been widely used in lithium-ion batteries, gas sensors, and for water treatment. Herein, we synthesized Fe₂O₃ nanoparticles by a co-precipitation method that is inexpensive and non-toxic. The Fe₂O₃ nanoparticles exhibited broadband saturable absorption. Furthermore, thin Fe₂O₃ polyvinyl alcohol films were prepared to realize Q-switched operations in a ytterbium-doped fibre laser, an erbium-doped fibre laser, and a thulium-doped fibre laser. Attributed to the polarization-insensitive feature of the saturable absorber, Q-switched cylindrical vector beams were also generated based on mode coupling and selection in two-mode fibre lasers. Such Fe₂O₃ nanoparticles show great promise for use in Q-switching applications of infrared fibre lasers and cylindrical vector lasers.

CVD-grown MoSe2 with high modulation depth for ultrafast mode-locked erbium-doped fiber laser

Two-dimensional materials have been widely used as optical modulator materials in mode-locked fiber lasers. In terms of the performance of the fiber laser, one with an ultrashort pulse and high stability has great commercial value. Herein, the MoSe₂ grown by the chemical vapor deposition (CVD) method with high modulation depth, quality lattice structure and uniformity is successfully applied in a mode-locked erbium-doped fiber laser. The pulse duration and signal-to-noise ratio of the laser are 207 fs and 85 dB, respectively. The multifarious performance comparisons indicate that the CVD-based MoSe₂ saturable absorber with the tapered fiber structure has unique advantages not only in the generation of ultrashort pulses, but also in the optimization of laser stability.

Tungsten diselenide for mode-locked erbium-doped fiber lasers with short pulse duration

In this paper, a WSe₂ film prepared by chemical vapor deposition (CVD) is transferred onto a tapered fiber, and a WSe₂ saturable absorber (SA) is fabricated. In order to measure the third-order optical nonlinearity of the WSe₂, the Z-scan technique is applied. The modulation depth of the WSe₂ SA is measured as being 21.89%. Taking advantage of the remarkable nonlinear absorption characteristic of the WSe₂ SA, a mode-locked erbium-doped fiber laser is demonstrated at 1557.4 nm with a bandwidth of 25.8 nm and signal to noise ratio of 96 dB. To the best of our knowledge, the pulse duration of 163.5 fs is confirmed to be the shortest compared with previous mode-locked fiber lasers based on transition-metal dichalcogenides SAs. These results indicate that WSe₂ is a powerful competitor in the application of ultrashort pulse lasers.

Sub-200 femtosecond dispersion-managed soliton ytterbium-doped fiber laser based on carbon nanotubes saturable absorber

Ultrafast fiber laser light sources attract enormous interest due to the booming applications they are enabling, including long-distance communication, optical metrology, detecting technology of infra-biophotons, and novel material processing. In this paper, we demonstrate 175 fs dispersion-managed soliton (DMS) mode-locked ytterbium-doped fiber (YDF) laser based on single-walled carbon nanotubes (SWCNTs) saturable absorber (SA). The output DMSs have been achieved with repetition rate of 21.2 MHz, center wavelength of 1025.5 nm, and a spectral width of 32.7 nm. The operation directly pulse duration of 300 fs for generated pulse is the reported shortest pulse width for broadband SA based YDF lasers. By using an external grating-based compressor, the pulse duration could be compressed down to 175 fs. To the best of our knowledge, it is the shortest pulse duration obtained directly from YDF laser based on broadband SAs. In this paper, SWCNTs-SA has been utilized as the key optical component (mode locker) and the grating pair providing negative dispersion acts as the dispersion controller.

All-fiber radially/azimuthally polarized lasers based on mode coupling of tapered fibers

We demonstrate a mode converter with an insertion loss of 0.36 dB based on mode coupling of tapered single-mode and two-mode fibers, and realize all-fiber flexible cylindrical vector lasers at 1550 nm. Attributing to the continuous distribution of a tangential electric field at taper boundaries, the laser is switchable between the radially and azimuthally polarized states by adjusting the input polarization. In the temporal domain, the operation is controllable among continuous-wave, Q-switched, and mode-locked statuses by changing the saturable absorber or pump strength. The duration of Q-switched radially/azimuthally polarized laser spans from 10.4/10.8 to 6/6.4 μs at the pump range of 38 to 58 mW, while that of the mode-locked pulse varies from 39.2/31.9 to 5.6/5.2 ps by controlling the laser bandwidth. The proposed laser combines the features of a cylindrical vector beam, a fiber laser, and an ultrafast pulse, providing a special and cost-effective source for practical applications.

Transition-metal dichalcogenides heterostructure saturable absorbers for ultrafast photonics

In this Letter, high-quality WS₂ film and MoS₂ film were vertically stacked on the tip of a single-mode fiber in turns to form heterostructure (WS₂-MoS₂-WS₂)-based saturable absorbers with all-fiber integrated features. Their nonlinear saturable absorption properties were remarkable, such as a large modulation depth (∼16.99%) and a small saturable intensity (6.23  MW·cm^-2). Stable pulses at 1.55 μm with duration as short as 296 fs and average power as high as 25 mW were obtained in an erbium-doped fiber laser system. The results demonstrate that the proposed heterostructures own remarkable nonlinear optical properties and offer a platform for adjusting nonlinear optical properties by stacking different transition-metal dichalcogenides or modifying the thickness of each layer, paving the way for engineering functional ultrafast photonics devices with desirable properties.

Investigation on the effect of output mirror transmission in WS2-based red-light passively Q-switched Pr:ZBLAN all-fiber lasers

We report the experimental investigation of visible passively Q-switched Pr³⁺-doped all-fiber lasers with tungsten disulfide (WS₂) saturable absorber, where red-light short-pulse generations from different output mirror transmissions are systemically characterized. The proposed simple and compact all-fiber linear cavity was constructed by a fiber-pigtail-based blue laser-diode pump, a Pr³⁺-doped fluorozirconate glass active fiber, and the fiber end-facet mirrors. Integrating a free-standing layered WS₂ film into the laser cavity initiated the Q-switching operation. Stable microsecond-duration output pulses with kilohertz repetition rates are achieved, corresponding to a few mW/nJ average output power and single-pulse energy. The comparisons on red-light Q-switched output parameters for output transmissions of both ∼40% and ∼80% are performed. This work could provide a useful guideline to manipulate the output performance of visible pulsed all-fiber lasers for various practical applications.

Tungsten disulphide for ultrashort pulse generation in all-fiber lasers

Tungsten disulphide (WS₂), which exhibits excellent saturable absorption properties, has attracted much attention in the applications of photonic devices. In this paper, WS₂ is applied for the preparation of a saturable absorber (SA). Using the pulsed laser deposition (PLD) method, WS₂ is deposited on the side surface of the tapered fiber. In order to obtain larger non-linearity of the SAs with evanescent wave interaction, the tapered fiber had a smaller waist diameter and longer fused zone. Gold film was deposited on the fiber-taper WS₂ SAs to improve their reliability and avoid oxidation and corrosion. Employing the balanced twin-detector method, the modulation depth of the fiber-taper WS₂ SAs was measured to be 17.2%. With the fiber-taper WS₂ SA, a generated pulse with 246 fs duration and a 57 nm bandwidth was obtained at 1561 nm. The electrical signal to noise ratio was better than 92 dB. To our knowledge, the pulse duration was the shortest among the reported all-fiber lasers with transition metal dichalcogenide (TMD) SAs. These results indicate that fiber-taper WS₂ SAs with smaller waist diameter and longer fused zone are promising photonic devices for ultrashort pulse generation in all-fiber lasers.

High-repetition-rate all-fiber femtosecond laser with an optical integrated component

We demonstrate a high-repetition-rate all-fiber soliton pulse laser mode-locked by the nonlinear polarization rotation technique. The laser cavity is effectively shortened by incorporating an optical integrated component possessing the hybrid functions of a polarization-dependent isolator, a wavelength-division multiplexer, and an output coupler. Resultant output soliton pulses have a fundamental repetition rate of 384 MHz, a 3-dB spectral bandwidth of 25.2 nm, and a dechirped pulse duration of 115 fs. By using an external power amplification and pulse recompression system, the average output power of the laser is boosted to 207 mW. The amplified pulses have a 2.33-ps duration, which is recompressed to 340 fs. Numerical simulations reproduce the generation of high-repetition-rate soliton pulses in the fiber laser. Such a simple and low-cost high-repetition-rate fiber laser is a potential laser source for various practical applications.

A Filmy Black-Phosphorus Polyimide Saturable Absorber for Q-Switched Operation in an Erbium-Doped Fiber Laser

We demonstrate an erbium-doped fiber laser passively Q-switched by a black-phosphorus polyimide film. The multi-layer black-phosphorus (BP) nanosheets were prepared via a liquid exfoliation approach exploiting N-methylpyrrolidone as the dispersion liquid. By mixing the BP nanosheets with polyimide (PI), a piece of BP-PI film was obtained after evaporating the mixture in a petri dish. The BP-PI saturable absorber had a modulation depth of 0.47% and was inserted into an erbium-doped fiber laser to realize passive Q-switched operations. The repetition rate of the Q-switched laser increased from 5.73 kHz to 31.07 kHz when the laser pump was enhanced from 31.78 mW to 231.46 mW. Our results show that PI is an excellent host material to protect BP from oxidation, and the BP-PI film can act as a promising nonlinear optical device for laser applications.

Dual-wavelength passively Q-switched Nd:GYSGG laser by tungsten disulfide saturable absorber

A dual-wavelength passively Q-switched Nd:GYSGG laser using vacuum evaporating tungsten disulfide (WS₂) as a saturable absorber was demonstrated for the first time to the best of our knowledge. The WS₂ saturable absorber was prepared simply by evaporating nanometer WS₂ powders onto a quartz substrate in a vacuum. By inserting the WS₂ saturable absorber into the laser cavity, stable Q-switched laser operation was achieved with a maximum average output power of 367 mW, a pulse repetition rate of 70.7 kHz, the shortest pulse width of 591 ns, and pulse energy of about 1.05 μJ. By vacuum evaporation method, a high-quality WS₂ saturable absorber can be produced, and it seems to be a suitable method for fabrication of 2D transition metal dichalcogenides.

Femtosecond harmonic mode-locking of a fiber laser at 3.27 GHz using a bulk-like, MoSe2-based saturable absorber

We experimentally demonstrate the use of a bulk-like, MoSe₂-based saturable absorber (SA) as a passive harmonic mode-locker for the production of femtosecond pulses from a fiber laser at a repetition rate of 3.27 GHz. By incorporating a bulk-like, MoSe₂/PVA-composite-deposited side-polished fiber as an SA within an erbium-doped-fiber-ring cavity, mode-locked pulses with a temporal width of 737 fs to 798 fs can be readily obtained at various harmonic frequencies. The fundamental resonance frequency and the maximum harmonic-resonance frequency are 15.38 MHz and 3.27 GHz (212th harmonic), respectively. The temporal and spectral characteristics of the output pulses are systematically investigated as a function of the pump power. The output pulses exhibited Gaussian-temporal shapes irrespective of the harmonic order, and even when their spectra possessed hyperbolic-secant shapes. The saturable absorption and harmonic-mode-locking performance of our prepared SA are compared with those of previously demonstrated SAs that are based on other transition metal dichalcogenides (TMDs). To the best of the authors' knowledge, the repetition rate of 3.27 GHz is the highest frequency that has ever been demonstrated regarding the production of femtosecond pulses from a fiber laser that is based on SA-induced passive harmonic mode-locking.

Nonlinear Saturable Absorption of Liquid-Exfoliated Molybdenum/Tungsten Ditelluride Nanosheets

Molybdenum disulfide (MoS2 ) and tungsten disulfide (WS2 ), two representative transition metal dichalcogenide materials, have captured tremendous interest for their unique electronic, optical, and chemical properties. Compared with MoS2 and WS2 , molybdenum ditelluride (MoTe2 ) and tungsten ditelluride (WTe2 ) possess similar lattice structures while having smaller bandgaps (less than 1 eV), which is particularly interesting for applications in the near-infrared wavelength regime. Here, few-layer MoTe2 /WTe2 nanosheets are fabricated by a liquid exfoliation method using sodium deoxycholate bile salt as surfactant, and the nonlinear optical properties of the nanosheets are investigated. The results demonstrate that MoTe2 /WTe2 nanosheets exhibit nonlinear saturable absorption property at 1.55 μm. Soliton mode-locking operations are realized separately in erbium-doped fiber lasers utilizing two types of MoTe2 /WTe2 -based saturable absorbers, one of which is prepared by depositing the nanosheets on side polished fibers, while the other is fabricated by mixing the nanosheets with polyvinyl alcohol and then evaporating them on substrates. Numerous applications may benefit from the nonlinear saturable absorption features of MoTe2 /WTe2 nanosheets, such as visible/near-infrared pulsed laser, materials processing, optical sensors, and modulators.

WS(2)/fluorine mica (FM) saturable absorbers for all-normal-dispersion mode-locked fiber laser

The report firstly propose a new WS(2) absorber based on fluorine mica (FM) substrate. The WS(2) material was fabricated by thermal decomposition method. The FM was stripped into one single layer as thin as 20 μm and deposited WS(2) on it, which can be attached to the fiber flank without causing the laser deviation. Similar to quartz, the transmission rate of FM is as high as 90% at near infrared wavelength from one to two micrometers. Furthermore, FM is a highly elastic material so that it is not easy to break off even its thickness was only 20 μm. On the contrary, quartz is hard to be processed and easy to break off when its thickness is less than 100 μm. Compared to organic matrix such as polyvinyl alcohol (PVA), FM has higher softening temperature, heat dissipation and laser damage threshold than those of organic composites. In our work, the modulation depth (MD) and non-saturable losses (NLs) of this kind of saturable absorber were measured to be 5.8% and 14.8%, respectively. The WS(2)/FM absorber has a high damage threshold of 406 MW/cm(2), two times higher than that of WS(2)/PVA. By incorporating the saturable absorber into Yb-doped fiber laser cavity, a mode-locked fiber laser was achieved with central wavelength of 1052.45 nm. The repetition rate was 23.26 MHz and the maximum average output power was 30 mW. The long term stability of working was proved to be good too. The results indicate that WS(2)/FM film is a practical nonlinear optical material for photonic applications.