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Transition metal dichalcogenides have been widely utilized as nonlinear optical materials for laser pulse generation applications. Herein, we study the nonlinear optical properties of a VS2-based optical device and its application as a new saturable absorber (SA) for high-power pulse generation. Few-layer VS2 nanosheets are deposited on the tapered region of a microfiber to form an SA device, which shows a modulation depth of 40.52%. After incorporating the microfiber-VS2 SA into an Er-doped fiber laser cavity, passively Q-switched pulse trains could be obtained with repetition rates varying from 95 to 233 kHz. Under the pump power of 890 mW, the largest output power and shortest pulse duration are measured to be 43 mW and 854 ns, respectively. The high signal-to-noise ratio of 60 dB confirms the excellent stability of the Q-switching state. To the best of our knolowdge, this is the first illustration of using VS2 as an SA. Our experimental results demonstrate that VS2 nanomaterials have a large potential for nonlinear optics applications.

Transition metal dichalcogenides have been widely utilized as nonlinear optical materials for laser pulse generation applications. Herein, we study the nonlinear optical properties of a VS2-based optical device and its application as a new saturable absorber (SA) for high-power pulse generation. Few-layer VS2 nanosheets are deposited on the tapered region of a microfiber to form an SA device, which shows a modulation depth of 40.52%. After incorporating the microfiber-VS2 SA into an Er-doped fiber laser cavity, passively Q-switched pulse trains could be obtained with repetition rates varying from 95 to 233 kHz. Under the pump power of 890 mW, the largest output power and shortest pulse duration are measured to be 43 mW and 854 ns, respectively. The high signal-to-noise ratio of 60 dB confirms the excellent stability of the Q-switching state. To the best of our knolowdge, this is the first illustration of using VS2 as an SA. Our experimental results demonstrate that VS2 nanomaterials have a large potential for nonlinear optics applications. [ABSTRACT FROM AUTHOR]

• MnFe 2 O 4 nanoparticles are used as saturable absorbers for the first time. • The shortest pulse width is 622 ns. • The maximum output power is 29.75 mW. Low-dimensional (LD) materials show the extraordinary properties and have led to applications in the fields of photonics, optoelectronics and energy. As a kind of zero-dimensional (0D) transition metal oxides, MnFe 2 O 4 nanoparticles possess various magneto-optical properties. However, the nonlinear optical characteristics as well as the applications in pulsed lasers have never been studied so far. Herein, the MnFe 2 O 4 nanoparticles with diameter of 10 nm were synthesized by the thermal decomposition method. The MnFe 2 O 4 -microfiber device was prepared by depositing MnFe 2 O 4 nanoparticles on a microfiber, whose saturation intensity/modulation depth was measured to be 16.68 MW/cm2/19.64%. Furthermore, this MnFe 2 O 4 -microfiber device was used to generate passively Q-switching laser pulses in Er-doped fiber (EDF) laser. Under the pump power of 80–780 mW, the pulse duration/repetition rate varies from 4.76 μs/73.1 kHz to 622 ns/230.9 kHz. The largest output power is 29.75 mW. The 70 dB signal-to-noise ratio (SNR) verifies the stability of Q-switching operation. This work is the first demonstration of using MnFe 2 O 4 nanoparticles as saturable absorber (SA) in designing Q-switching laser. Compared to recent reported Q-switching EDF lasers with LD materials, our work shows some improvements. These experimental results demonstrate that MnFe 2 O 4 nanoparticles can be developed as an efficient SA materials and have potential photonics applications. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) transition metal dichalcogenides (TMDs) have been extensively researched as nonlinear optical absorption materials for pulse fiber lasers applications. Herein, the liquid phase exfoliation method is employed to obtain HfSe 2 nanosheets, and HfSe 2 /polyvinyl alcohol (PVA) film is prepared, whose modulation depth (ΔT) is measured to be 12.37 %. When inserting HfSe 2 -based saturable absorber (SA) into the compact fiber cavity, stable Q-switching pulse train is established at 1558.8 nm. Setting pump power at 559 mW, the narrowest pulse width/largest single pulse energy is determined to be 1.883 μs/292.67 nJ. In comparison to the reported results recently, our laser performance is superior to other works. Our experimental results prove that HfSe 2 can be developed as a valid saturable absorption material for pulse laser generation. [ABSTRACT FROM AUTHOR]

Tungsten disulfide (WS 2 ), as one of typical transition metal dichalcogenides with the characteristics of strong nonlinear polarization and wide bandgap, has been widely used in such fields as biology and optoelectronics. With the magnetron sputtering technique, the saturable absorber (SA) is prepared by depositing WS 2 and Au film on the tapered fiber. The heat elimination and damage threshold can be improved for the WS 2 SA with evanescent field interaction. Besides, the Au film is deposited on the surface of the WS 2 film to improve their reliability and avoid being oxidized. The fabricated SA has a modulation depth of 14.79%. With this SA, we obtain a relatively stable mode-locked fiber laser with the pulse duration of 288 fs, the repetition rate of 41.4 MHz and the signal to noise ratio of 58 dB. [ABSTRACT FROM AUTHOR]

• The Mo x Ta (1-x) Se 2 nanosheets are used as saturable absorbers for the first time. • The mode-locking pulse width is 377 fs. • The maximum output power is 10.52 mW. Ternary transition metal chalcogenides (TTMCs) are emerging as a promising branch of two-dimensional (2D) materials due to their special layered structure as well as wide-range tunable bandgap properties, which permit the implementation of novel optoelectronic characteristics. The manifestation of nonlinear optical properties of Mo x Ta (1-x) Se 2 nanosheets and their application in ultrafast erbium-doped fiber (EDF) laser is reported in this work. The Mo x Ta (1-x) Se 2 nanosheets were fabricated by employing the liquid phase exfoliation technology. In addition, the saturable absorption property of Mo x Ta (1-x) Se 2 -based saturable absorber (SA) is illustrated by obtaining a large optical modulation depth of 32.01 (0.76)%. Furthermore, an operational ultrashort pulse fiber laser was demonstrated. The laser has the ability to emit ultrashort pulses of 377 (0.3) fs at 1532 nm while a maximum output power of 10.52 mW was delivered by the employed within the EDF cavity Mo x Ta (1-x) Se 2 -based SA. Our experimental results provide concrete pieces of evidence that the Mo x Ta (1-x) Se 2 nanosheets exhibit third-order optical nonlinearity and the significant potential in nonlinear optoelectronic devices. [ABSTRACT FROM AUTHOR]