Search

Pulsed solid‐state lasers comprise 2D materials as saturable absorbers that contain transparent windows of the atmosphere and characteristic fingerprint spectra of several vital molecules that are significant in various applications and research. Over the past few decades, significant progress has been made in the development of narrow pulse width, high energy, high average output power, high efficiency, and simple construction of passively Q‐switched and mode‐locked lasers with 2D materials as saturable absorbers. This review summarizes the development of 2D materials, including graphene, transition metal dichalcogenides, black phosphorus, topological insulators, and MXenes, as modulator devices for solid‐state lasers owing to their broadband operation, excellent nonlinear optical response, low recovery time, ultrafast dynamic processing, and easy fabrication. Then, some new emerging and representative applications of pulsed solid‐state lasers are introduced and illustrated such as laser surgery, material processing, and lidar. Finally, future challenges and perspectives of pulsed solid‐state lasers with 2D materials‐based saturable absorbers are analyzed and addressed. The rapid development of pulsed solid‐state lasers with the continuous improvement of modulation technology is expected to expand opportunities for application in industry, scientific, medical, and other areas. [ABSTRACT FROM AUTHOR]

Q-switched fiber lasers have become reliable light sources for generating high-energy pulses, which can be passively modulated by saturable absorbers with excellent nonlinear optical properties. The composite combining Ag and MXene exhibits a broadband nonlinear response and high modulation depth, making it a promising candidate for saturable absorbers in pulsed lasers. Herein, we demonstrate a Q-switched Tm:Ho co-doped fiber laser centered at 2 µm, where the Ag/MXene composite serves as a saturable absorber to generate pulses. The typical spectrum, pulse train, and radio frequency spectrum of Q-switched pulses were observed, in which the 60 dB signal-to-noise ratio was higher than that of 2 µm Q-switched fiber lasers based on other materials, demonstrating the stability of the output pulses. Additionally, the long-term stability of the laser was evaluated over 2 h, where the well-maintained central wavelength and output power also indicated the robustness of the Q-switched laser. Furthermore, the influence of the pump power on the parameters of Q-switched pulses was also investigated, which is conducive to control the output characteristics of lasers. Specifically, the pulse width of the Q-switched pulse decreased, while the repetition rate, output power, and single pulse energy all increased with the increase in pump power. These experimental results demonstrate the ability of Ag/MXene as a saturable absorber and show its potential for generating high-performance pulses in ultrafast lasers. [ABSTRACT FROM AUTHOR]

The utilization of boron carbide nanoparticles (B4C) as a saturable absorber (SA) for generating pulses by a fiber laser operating in Q-switched mode is the subject of our investigation, the findings of which are presented. This was accomplished by combining boron carbide nanoparticles (B4C-NPs) with polyvinyl alcohol (PVA) to form a thin-film-based SA. This SA was then placed within an erbium-doped fiber laser (EDFL) in a ring cavity configuration to enable passive Q-switching operation. The modulation depth of the B4C-SA was 2.3%. Stable Q-switching laser operation was accomplished with a pump power of 180 mW and central wavelength of 1561 nm by producing laser pulses with a pulse duration of 15.27 µs and pulse repetition rate of 31.6 kHz. A comparable pulse energy, which was attained at the maximum pump power of 275 mW, was approximately 2.61 nJ. The radio-frequency spectrum was examined to verify the pulse stability. The study showed a signal-to-noise ratio of 35 dB. These results expand the potential of B4C-based saturable absorbers, making them strong contenders for innovative photonic devices. [ABSTRACT FROM AUTHOR]

In this work, we proposed a mechanical exfoliation technique to compose a saturable absorber (SA) from MAX phase chromium aluminum carbide (Cr2AlC). The performance of a passive Q‐switched erbium‐doped fiber laser (EDFL) based on Cr2AlC‐SA was experimentally demonstrated. The optical properties of SA showed appropriate nonlinear absorption, with a non‐saturable absorption of 92.5%, and saturable absorption of 1.2%. The proposed EDFL was investigated using 50:50 and 80:20 output couplers (OCs). At 167 mW pumping power and 3 dB OC, the EDFL produced pulses with 2 μs width, and 163 kHz repetition rate. Moreover, with 80:20 OC, the EDFL produced shorter laser pulses with 1.46 μs width, and 135.2 kHz pulsing rate. The results reveal that the higher repetition rate with high energy can be obtained with a 3 dB coupler, while narrower pulse width is achieved with an 80:20 OC. [ABSTRACT FROM AUTHOR]

A novel inorganic material of Magnesium Nitrate (Mg(NO3)2) thin film is successfully investigated in the C-band region. The Q-switcher is (Mg(NO3)2) thin film. The solvent casting method has been applied to prepare (Mg(NO3)2) thin film before being positioned within the fiber ferrule duo to act as a Q-switcher. Thereby, the modulation depth and the saturation intensity of the (Mg(NO3)2) thin film exhibit at 32.40% and 0.07 MW/cm², respectively. It is possible to produce a steady Q-switched pulse fiber laser with a maximum pump power of 403.00 mW, a repetition rate of 72.56 kHz, and a pulse width of 3.00 µs. In addition, the tunable Q-switched pulse fiber laser is also examined using a figure-of-eight cavity design incorporating a tunable bandpass filter (TBF). Consequently, the operating wavelength is changed in the range of 1528 nm to 1552 nm, even while the pump power remains the same at 403.00 mW. During this time, the pulse width and repetition rate shifted from 2.10 µs to 4.10 µs and altered from 67.90 kHz to 35.80 kHz, respectively. Consequently, the (Mg(NO3)2) thin film has the opportunity to be an effective saturable absorber for generating pulsed fiber lasers and can be applied in optical communications applications. [ABSTRACT FROM AUTHOR]

This paper presents the investigations toward the direct use of bentonite clay (Al2H2O6Si) nanoparticles to act like a saturable absorber (SA) for the Q-switched pulse operation of an erbium-doped fiber laser (EDFL). The measured results reveal that with the incorporation of bentonite clay nanopowder as a SA, an EDFL is realized with a Q-switching mechanism starting at a pump power of 30.8 mW, and a Q-switched emission wavelength was noticed at 1562.94 nm at 142 mW pump power. With an increased pump from 30.8 mW to 278.96 mW, the temporal pulse parameters including minimum pulse duration and maximum pulse repetition rates were reported as 2.6 µs and 103.6 kHz, respectively. The highest peak power, signal-to-noise ratio, output power and pulse energy were noticed to be 16.56 mW, 51 dB, 4.6 mW, and 47 nJ, respectively, at a highest pump power of 278.96 mW. This study highlights the significance of bentonite clay (Al2H2O6Si) nanoparticles as a potential candidate for a saturable absorber for achieving nonlinear photonics applications. [ABSTRACT FROM AUTHOR]

A two‐dimensional titanium disulfide (TiS2) nanosheet film is prepared on a YAG crystal substrate. The saturated absorption behavior of TiS2 on the YAG substrate is investigated. Then, TiS2 is successfully employed as a modulation element to develop a Tm:YAG ceramic eye‐safe pulsed laser. With a 7.04 W absorbed pump light and a 3% transmission of output coupler, the greatest average optical power, and the least pulse width (PD) are 233 mW and 524 ns, separately. The pulse repeated frequency of 69 kHz is generated, while the single pulse energy (SPE) is 3.38 µJ. Based on the experimental results, TiS2 nanosheet films possess the practical value as saturable absorbers for 2.0 μm eye‐safe pulsed lasers. [ABSTRACT FROM AUTHOR]

In this work, we demonstrate a Q-switched erbium-doped fiber laser (EDFL), which is passively produced by using a saturable absorber (SA), which is fabricated by mechanical exfoliation of MAX phase molybdenum titanium aluminum carbide (Mo2Ti2AlC3). Physical and optical properties of the SA are experimentally studied. The optical properties showed a good nonlinear absorption where the saturation intensity is 0.65 MW/cm2, with 40% of non-saturable absorption and 17% of modulation depth. The proposed EDFL is investigated using two output couplers (OCs) with split ratios of 50:50 and 80:20, respectively. For pumping power of 142 mW and coupling ratio of 50%, the proposed EDFL produced pulses with a pulse energy of 69.60 nJ, pulse width of 2.97 μs and repetition rate of 90.09 kHz. Besides, with coupling ratio of 20%, the EDFL can generate a pulse train with a pulse width of 1.91 μs, repetition rate of 77.64 kHz, and pulse energy of 89.52 nJ. [ABSTRACT FROM AUTHOR]

The proposed titanium aluminum carbide (Ti3AlC2) film‐based saturable absorber (SA) for Q‐switching in thulium‐doped fiber laser (TDFL) cavity offers a cost‐effective and practical alternative to conventional SA materials such as graphene or semiconductor. The Ti3AlC2 film was produced using a simple and low‐cost casting approach with polyvinyl alcohol as a binder. The SA was devised from the film using a sandwich‐structured fiber‐ferrule platform and integrated into a TDFL ring cavity. The generated Q‐switched pulses were stable and had a repetition rate of up to 20.82 kHz with a minimum pulse width of 3.167 µs and a maximum pulse energy of 58.12 nJ. The Q‐switched laser produced the bright‐dark pulse pair. These results demonstrate the potential of Ti3AlC2 as a promising SA material for practical applications in the field of fiber lasers. [ABSTRACT FROM AUTHOR]

Polystyrene (PS) possesses numerous remarkable properties like high transparency, impressive mechanical strength, and a large specific surface area, making it an excellent mask plate or template for the preparation of anti-opal structures. Moreover, it should be noted that PS also exhibits exceptional nonlinear properties due to the subwavelength periodic configuration. In this paper, a self-assembled PS microsphere photonic crystal saturable absorber (PSM-SA) has been proposed and fabricated. It exhibits impressive properties including high stability, high damage threshold, high refractive index, and large specific surface area. It is suggested that the periodic structure of PS in the film has a significant impact on the photonic band gap, resulting in excellent adjustable optical nonlinear characteristics. By integrating PSM-SA into a self-built ring fiber laser system, a Q-switched laser with a pulse width of approximately 2 μs and a repetition rate of 40 kHz at a wavelength of 1562 nm is obtained. These findings demonstrate its potential for enabling efficient and adjustable nonlinear optical functionalities in various optical devices, contributing to the expanding realm of PS microsphere photonic crystals and their significant impact on advancing nonlinear optics technology. [ABSTRACT FROM AUTHOR]

The pulse laser using a saturable absorber as a passive device has the advantages of narrow pulse width, high repetition rate, and high pulse energy. Low‐dimensional materials have attracted research interest in recent years due to their excellent saturable absorption properties, ultra‐fast carrier response speed, high damage threshold, and so on. This paper gives a brief review of the state‐of‐the‐at 2 µm solid‐state lasers using saturable absorbers. The output performance of lasers in repetition rate, pulse energy, pulse width, and wavelength are summarized. The paper is expected to provide a development direction of novel materials as saturable absorbers in 2 µm solid‐state lasers. [ABSTRACT FROM AUTHOR]

We use a graphene/WS2 heterojunction as a saturable absorber (SA) in a 2 μm wavelength Thulium-doped Yttrium Aluminum perovskite (Tm:YAP) crystal-based solid-state laser and realize effective modulation performance efficiency in passive Q-switching experiments. At a pump power of 18.80 W, the measured output power is 1.293 W, with a corresponding optical–optical conversion efficiency of 6.9%. Additionally, at a pump power of 11.50 W, we achieve a pulse time of 1.16 μs at a repetition frequency of 90.36 kHz. To the best of our knowledge, this is the first demonstration of the use of graphene/WS2 heterojunctions as SA structures for 2 μm solid-state lasers based on Tm:YAP crystals. [ABSTRACT FROM AUTHOR]

The Au ion implantation process has emerged as an effective and simple method to be utilized for the fabrication of opto-electronic materials and devices due to numerous fascinating features of Au nanoparticles such as surface plasmon resonance (SPR), large third-order nonlinearity and a fast response time. In this paper, we describe the fabrication of a novel Au nanoparticle saturable absorber (Au NP-SA) by embedding the Au NPs into a SiO2 thin film using the ion implantation process, which shows excellent saturable absorption features due to the localized surface plasmon resonance (LSPR) effect of Au NPs. A stable and high-quality pulsed laser with a repetition rate of 33.3 kHz and a single pulse energy of 11.7 nJ was successfully constructed with the Au NP-SA. Both the stable operation characteristic of the obtained Q-switched pulsed laser and the high repeatability of the fabrication process of the Au NP-SA were demonstrated. In addition, the simple feasibility and maturity of the ion implantation process allow for the plasmonic nanoparticles to be easily integrated into other types of opto-electronic materials and devices to further improve their performance, and shows immense potential for the production of wafer-level products. [ABSTRACT FROM AUTHOR]

In this work, we present ultrashort pulse generation from passively mode-locked Cr:ZnS laser with a monolayer graphene-coated ZnSe substrate exhibiting high nonlinearity. The femtosecond Cr:ZnS laser produces output power up to 330 mW at a 233 MHz repetition rate. Even in the presence of an uneven negative dispersion profile, the enhanced self-phase modulation by the ZnSe substrate of the graphene saturable absorber enables the polycrystalline Cr:ZnS laser to produce slightly chirped 99 fs pulses at 2373 nm. With extracavity dispersion compensation using a mixture of 3 mm and 2 mm thick ZnSe plates, the pulse width was compressed from 99 fs to 73 fs, resulting in an improved time–bandwidth product from 0.431 to 0.318. Assuming a sech2 pulse shape (0.315), the pulses were almost transform-limited. These results indicate that utilizing a graphene saturable absorber on a substrate with high nonlinearity presents an effective method for developing sub-100 fs solid-state lasers within the mid-IR spectral range. [ABSTRACT FROM AUTHOR]

We demonstrate the utilization of iron oxide (Fe2O3) as light-absorbing material in an erbium-doped fiber laser (EDFL) for the generation of Q-switched pulses. A sandwich-type saturable absorber (SA) with Fe2O3 nanoparticles between fiber ferrules is proposed. A fiber ferrule tip is tapped onto a cap of index-matching gel, which is then dipped into Fe2O3 nanoparticle powder to allow its deposition through the adhesion effect. By incorporating Fe2O3–SA in an EDFL, self-started and stable Q-switched pulses are attained at a threshold power of 50.1 mW. The pulse repetition rate is tunable from 9.92 kHz to 22.47 kHz, whereas the pulse duration reduces from 38.4 µs to 13.8 µs with the pump power increment. The maximum pulse energy achieved is 36.9 nJ. This work offers a simple integration method of Fe2O3 nanoparticles as potential SAs for the generation of Q-switched pulses. [ABSTRACT FROM AUTHOR]

All-solid-state Tm lasers have a wider wavelength range and higher output power compared to other types of lasers. In this work, we demonstrate an all-solid-state, high repetition, Tm:YAP laser Q-switched by a graphdiyne (GDY) saturable absorber. The high-quality optical nonlinear material GDY, synthesized by a cross-coupling method, exhibits a strong nonlinear optical response. The application of GDY as a saturable absorber in the passively Q-switched (PQS) Tm:YAP of an all-solid-state laser has been realized with the shortest pulse duration of ~785 ns and repetition frequency of ~199.6 kHz at a central wavelength of 1985.8 nm. This represents the shortest pulse duration and the highest repetition frequency achieved from GDY in a solid-state Tm laser to date. Our work demonstrates the remarkable nonlinear optical properties of GDY, which holds promising potential in the field of optoelectronics. [ABSTRACT FROM AUTHOR]

In this work, we have demonstrated passive Q-switched and mode-locked erbium-doped fiber lasers (EDFLs) by using metal salt of cadmium chloride hydrate (CdCl2.xH2O) as a saturable absorber (SA). The mechanical exfoliation method was utilized to fabricate the CdCl2.xH2O-SA. The fabricated SA showed a modulation depth of 20% with a saturation intensity of 80 mW/cm2. At a pump power of 167 mW, the proposed Q-switched laser operated at 1542 nm with a maximum repetition rate of 127 kHz and a narrowest pulse width of 1.76 µs. The maximum output power was 23 mW with a signal to noise ratio (SNR) of 76 dB. On the other hand, the mode-locked pulses were generated within a pump power range of 91–167 mW, achieving a repetition rate of 990 kHz. The maximum pulse energy and output power were 7.3 nJ and 7.2 mW, respectively. The SA film demonstrated reliability and simplicity in the fabrication process. [ABSTRACT FROM AUTHOR]

MXene materials have shown numerous useful mechanical and electronic properties, and have been found to possess nice potential in the field of optical modulation. Here, we fabricated a MXene Cr2C saturable absorber by the liquid-phase exfoliation method, and systemically analyzed the surface morphology and nonlinear properties of the Cr2C sample. Applying the Cr2C saturable absorber as a Q-switch in a thulium-doped yttrium aluminum perovskite (Tm: YAP) laser, the shortest single pulse was obtained with a width of 602 ns under an absorbed pump power of 3.3 W at a repetition rate of 55 kHz with a T = 1% output coupler. The maximum output power was obtained with a T = 5% output coupler at a repetition rate of 58 kHz. The obtained maximum pulse energy and peak power were 3.96 μJ and 4.36 W, separately, which reveal that the MXene Cr2C can be applied as a promising modulation material in the near-infrared pulsed lasers. [ABSTRACT FROM AUTHOR]

Emerging 3D photonic circuits would greatly benefit from the ability to integrate skimming waveguides with low loss and controllable inscription depth into photonic circuits. These waveguides allow for the interaction of guiding light directly with external modulation signals and enable programmable photonic circuits. Here, we report the fabrication of a novel photonic-lattice-like skimming waveguide (PLLSW) using femtosecond laser writing. Our method enables fine control of cross-sectional symmetry and writing depth of waveguides, achieving a minimum depth of 1 μm and a low insertion loss of 1 dB. Based on the PLLSW, we demonstrate on-chip light modulation by designing an evanescent-field-type saturable absorber through the coupling of a carbon nanotube film with the PLLSW, which exhibits saturation intensity from 20 to 200 MW/cm2 through the balanced twin-detector measurement. The strong nonlinear optical response of the PLLSW-based saturable absorber is further exploited to drive a Q-switched pulse laser at 1550 nm based on a fiber laser cavity. Our work demonstrates an effective method to integrate nonlinear optical materials into a glass chip for all-optical switching based on 3D waveguides, which holds great potential for the construction of large-scale programmable photonic circuits in the future. [ABSTRACT FROM AUTHOR]

In this paper, a passively Q‐switched (PQS) Tm:YAP laser was experimentally demonstrated by using a Ti3AlC2‐based saturable absorber (SA). In the PQS regime, an average output power of 2010/1575 mW with a pulse width of 266/859 ns at 130/155 kHz was achieved from a Tm:YAP laser under an output couple mirror with a transmittance (T) of 1.5%/2.5%, corresponding to an optical conversion efficiency of 9.2%/11.6%. Also, a single pulse energy of 15.5/10.2 μJ and a peak power of 58.1/11.8 W were acquired from the PQS Tm:YAP laser. As far as we know, this is the first time that a Ti3AlC2‐based SA was used for a PQS Tm:YAP laser. [ABSTRACT FROM AUTHOR]

We propose and demonstrate a new Q-switched thulium-doped fiber laser (TDFL) by utilizing a passive saturable absorber (SA) based on Molybdenum–Aluminium boride (MoAlB). The MoAlB is a metal–ceramic-based material; it is embedded in polyvinyl-alcohol (PVA) material to operate as the SA. The laser successfully generates stable Q-switched pulses operating at 1974.7 nm with a maximum repetition rate of 57.7 kHz and a minimum pulse width of 1.79 μs. A maximum pulse energy of 90.2 nJ is recorded at 436 mW pump power. Our experiment is the first demonstration on the use of MoAlB for the pulse laser generation in the 2 μm wavelength region. [ABSTRACT FROM AUTHOR]

The regions of stability of homogeneous generation regimes in a wide-aperture laser with a saturable absorber, including a semiconductor laser with a vertical output of radiation, are determined depending on the relative relaxation rate of carriers in active and passive media and on the frequency detunings of working transitions in these media with a resonant frequency of radiation, taking into account its polarization state. The excitation thresholds for relaxation and polarization oscillations are determined within the four-level model. [ABSTRACT FROM AUTHOR]

A silver sulfide saturable absorber (SA) was successfully employed in an Erbium‐doped fiber laser (EDFL) cavity for short and ultrashort pulse generations. The Q‐switched laser was obtained with an operation wavelength of 1566 nm, pulse rate of 93.81 kHz, and pulse duration of 1.68 μs at a 187.04 mW pump. As the EDFL cavity was optimized for mode‐locking operation by adding 100 m long single mode fiber, a stable soliton pulse train operating at 1564 nm was realized with a constant repetition rate of 1.88 MHz and pulse duration of 3.01 ps. The good nonlinear characteristics of the SA make synergetic contributions to the generation of high‐performance Q‐switched and mode‐locked lasers. [ABSTRACT FROM AUTHOR]

In this paper, we propose a new and efficient ferroelectric nanostructure metal oxide lithium niobate [(Li 1.075 Nb 0.625 Ti 0.45 O 3), (LNTO)] solid film as a saturable absorber (SA) for modulating passive Q-switched erbium-doped fiber laser (EDFL). The SA is fabricated as a nanocomposite solid film by the drop-casting process in which the LNTO is planted within polyvinylidene fluoride-trifluoroethylene [P(VDF-TrFE)] as host copolymer. The optical and physical characteristics of the solid film are experimentally established. The SA is incorporated within the cavity of EDFL to examine its capability for producing multi-wavelength laser. The experimental results proved that a multi-wavelength laser is produced, where stable four lines with central wavelengths at 1529.5, 1530.5, 1531.5, and 1532 nm are observed on the laser spectrum at 157 mW pumped power. Furthermore, at maximum available pumped power (157 mW), laser pulses are running with a rate of 178 kHz and pulse width of 2.64 μs. The output power of 3.7 mW is attained at pumped power of 157 mW. The result proved that the LNTO-SA could be a potential candidate for generating multi-wavelength passive Q-switched fiber laser pulses. • Nanostructure metal oxide lithium niobate (LNTO) is utilized to form saturable absorber (SA). • A new and efficient SA based LNTO is proposed. • LNTO film is one of an excellent promising material for a various photonic applications. • The proposed Q-switched EDFL can generate multi-wavelength laser pulses. [ABSTRACT FROM AUTHOR]

Interlayer engineering offers a promising approach to modifying the structure of layered vanadium-based oxides, enhancing their saturable absorption effect and making them a desirable choice for developing infrared wavelength-range photonics devices. This experimental work synthesizes interlayer vanadium pentoxide (V 2 O 5) using hydrothermal techniques to produce an excellent saturable absorber (SA). The interlayer engineering strategy enhances strong saturable absorption and self-defocusing effects in V 2 O 5 -based SA, enabling the generation of ultrashort pulses in the infrared region. Their superior nonlinear optical characteristics are demonstrated by a modulation depth of 13.9 % and saturation intensity of 0.42 GW cm−1, respectively. By utilizing a transmission coupling fiber-based V 2 O 5 -SA inside an Er-doped fiber laser cavity, a passively Q-switched (PQS) laser with a narrow pulse width of 2.78 μs and signal-to-noise ratio (SNR) ∼50 dB is realized for the first time. Furthermore, we explore a V 2 O 5 NPs-SA long-term stability and high damage threshold. The results not only offer additional proof of the capable potential of interlayer V 2 O 5 as a photo-bleaching absorber for realizing pulsed lasers in the NIR band but also cover the method for advancing their probable applications in optoelectronic devices. • In this work, interlayer vanadium pentoxide (V 2 O 5) is synthesized using hydrothermal techniques to produce a high-quality photo-bleaching device (SA). • The saturable absorption property of V 2 O 5 NPs-SA was measured by a balanced twin-detector system with a modulation depth of 13.9 % and a saturation optical intensity of 0.42 GW/cm2. • Furthermore, by inserting the V 2 O 5 NPs-based saturable absorber, a passively Q-switched (PQS) laser operating at 1562.0 nm was obtained with a short pulse duration of 2.78 μs and maximum average output power of 5.6 mW. • TMO V 2 O 5 NPs-SA provides better long-term stability with a high damage threshold and a better tolerance were examined. [ABSTRACT FROM AUTHOR]

• Application of cerium oxide as saturable absorber for Q-switched pulse laser. • Low Q-switch threshold (33.33 mW) despite relatively long fiber cavity. • High Q-switch pulse energy in L-band (410 nJ). • High Q-switch pulse energy compared to other rare-earth oxide saturable absorbers. • Cerium oxide nanopowder used as-is on fiber ferrule to fabricate saturable absorber. Cerium oxide (CeO 2), a rare earth metal oxide belonging to the lanthanide group is a mature engineered nanoparticle that has been developed for various industry applications. The nanoparticle features defects in its lattice structure, which is highly advantageous for bandgap tuning, and is acclaimed for its least cytotoxicity among other metal oxides. In this work, CeO 2 is employed as a saturable absorber (CeO 2 -SA) in the generation of an L-band Q-switched erbium-doped fiber laser. Q-switching was attained at 33.33 mW pump power threshold with a central wavelength of 1600.512 nm. Within 33.33 mW to 153.20 mW pump power range, the Q-switched laser obtained pulse repetition rates between 11.00 to 34.48 kHz, and pulse widths between 39.0 to 12.0 µs, with a high maximum pulse energy of 410 nJ. The Q-switched fiber laser remained stable over a 45-minute observation time at 153.20 mW pump power. The room temperature and direct mechanical deposition fabrication technique of the CeO 2 -SA in this work demonstrates the extreme simplicity and low cost of the device, which would reduce the overall cost and facilitate a wider technology adoption of pulse laser systems. [ABSTRACT FROM AUTHOR]

• Gallium-Doped Zinc Oxide (Ga:ZnO) was fabricated by sonochemical and embedding approaches for generating passively Q-switched in an Er-doped fiber laser. • Dual-wavelength Er-doped fiber laser operating at 1.55 μm. • The Q-switched fiber laser based on Ga:ZnO SA has high energy and damage threshold. We demonstrated a new type of metal-oxide heterostructures, Gallium-Doped Zinc Oxide (Ga:ZnO) as a saturable absorber (SA) for the generation of a Q-switched laser operating in the 1.55 μm region. The Ga:ZnO was fabricated by a sonochemical approach and then it used the embedding method to combine it with polyvinyl alcohol (PVA) to form a thin film. The Ga:ZnO PVA film was effectively incorporated into a ring cavity to produce a Q-switched pulse laser. The Ga:ZnO PVA film has a modulation depth of ∼13 % with a saturation intensity of 0.09 MW/cm2. The high pulse energy and maximum average output power of 315.76 nJ and 16.12 mW were achieved. The SA film has a repetition rate within a range of 25.94 to 51.05 kHz, while the pulse width decreased from 10.93 µs to 2.215 µs, respectively. This is the first time that Ga:ZnO PVA has been used in fiber laser applications. [ABSTRACT FROM AUTHOR]

• In our work, we report the use of ZrS 2 solution-deposited micro-nano fiber as a saturable absorber to achieve stable Q-switched and mode-locked fiber lasers. • When the pump power increases from 100.4 to 260.4 mW, the laser works at the Q-switched operation. • Stable mode-locked operation is acquired at 310 mW without changing the states of single-mode fiber and polarization controller. • ZrS 2 devices show excellent saturable absorption performance, with saturation intensity and modulation depth of approximately 5.9 MW/cm2 and 3.42 %, respectively. We demonstrate the use of ZrS 2 solution-deposited micro-nano fiber as a saturable absorber to achieve stable Q-switched and mode-locked fiber lasers. When the pump power increases from 100.4 to 260.4 mW, the laser works at the Q-switched operation. The repetition rate of the laser pulse added 16 to 41.9 kHz and the pulse width reduces from 9.5 to 5.9 μs. Stable mode-locked operation is acquired at 310 mW without changing the states of single-mode fiber and polarization controller. At the pump power of 310 mW, the mode-locked erbium doped fiber laser generates pulse centered at wavelength of 1558.9 nm with a fundamental repetition rate of 10.47 MHz and a 3-dB bandwidth of 0.45 nm. The results prove that ZrS 2 material has great potential in many fields such as ultrafast fiber laser and good nonlinear saturable absorption characteristics. [ABSTRACT FROM AUTHOR]

• It is of great significance to demonstrate the nonlinear optical properties of VP and apply them to the Q-switched pulse fiber laser. • For the first time, a broadband few-layer VP saturable absorber was used as a passive Q-switcher for fiber lasers. • VP saturable absorber was used as a passive Q-switcher for Yb- and Er-doped fiber lasers operating at wavelengths of 1.06 and 1.56 nm, respectively, covering a broadband range of approximately 500 nm. 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. [ABSTRACT FROM AUTHOR]

The growing field of photonics has seen significant developments in optical pulse fiber-based sensing technologies. In this research, a novel fiber Bragg grating using a Q-switched erbium-doped fiber laser source and innovative spider silk as a base material is presented, specifically designed for the detection of adulteration in pure kelulut honey. Kelulut honey has attracted much attention from Malaysian researchers as it is a highly prized, versatile local health remedy. During the experimental setup, concentrations of the adulterant isoglucose ranging from 0 % to 8 % and 10–50 % were intentionally added to the pure kelulut honey. The sensor showed remarkable sensitivity and detected subtle shifts in both the wavelength and radio frequency spectrum. The experimental results obtained emphasize the effectiveness of the proposed sensor and demonstrate its exceptional sensitivity in detecting adulteration in pure kelulut honey. This inherent property makes the derived pulse fiber laser sensor a promising tool for various applications in clinical detection and diagnosis as well as in the food industry. The results presented here not only contribute to the field of photonics but also have the potential to advance the quality control and authenticity assessment of kelulut honey in various fields. [Display omitted] • Developed a highly sensitive FBG sensor using a spider silk saturable absorber for adulteration detection in kelulut honey. • Demonstrated the effectiveness of a Q-switched pulse erbium-doped fiber laser in enhancing the detection sensitivity. • The sensor shows exceptional sensitivity in detecting kelulut honey adulteration, promising for clinical, diagnostic, and food industry applications. [ABSTRACT FROM AUTHOR]

Two-dimensional transition metal dichalcogenides (TMDs) with remarkable nonlinear properties, like MoS 2 /WS 2 and the ternary compound Mo 0.5 W 0.5 S 2 , have attracted a lot of attention. The field has made use of the nonlinear characteristics of all-solid-state lasers. The liquid-phase exfoliation method was used in this work to create Mo 0.5 W 0.5 S 2 nanosheets. At 2 μm, the nonlinear absorption characteristics of Mo 0.5 W 0.5 S 2 were examined and the results showed a saturation intensity of 1.56 MW/cm2 and a modulation depth of 5.2%. A high-power passively Q-switched Tm:YAP laser with an average output power of 3.20 W and a brief pulse width of 633 ns was produced using the Mo 0.5 W 0.5 S 2 nanosheet as a saturable absorber. According to the results, Mo 0.5 W 0.5 S 2 has the potential to produce pulsed lasers with high peak and average powers that operate at about 2 μm. • The Mo 0.5 W 0.5 S 2 -based SA showed a modulation depth of 5.2 % and a saturation intensity of 1.56 MW/cm2. • When T oc = 2 %, the laser with the highest average power of 3.55 W and the central wavelength of 1936 nm were obtained. • The passively Q-switched laser with maximum peak power of 34.43 W and pulse width of 633 ns were achieved. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) ternary transition-metal dichalcogenides (TMDCs) are of great research interest because their superior layer-dependent optical modulation properties. In this work, three different kinds of TMDC nanosheets, including hafnium diselenide (HfSe2), titanium diselenide (TiSe2) and zirconium diselenide (ZrSe2), are prepared by liquid phase exfoliation (LPE) technique. The high-quality material properties of these TMDC nanosheets are confirmed by Raman spectroscopy and X-ray diffraction analysis. Furthermore, the bandgap information of five-layer MSe2 has been investigated via utilizing density functional theory. The calculation results exhibit ultra-narrow bandgap structure (lower than 1.1 eV) for all these three materials, indicating that MSe2 is suitable for broadband photonic applications. By applying the fabricated MSe2 as saturable absorbers, high-performance Q-switched mode-locked laser operation has been realized. The laser gain media are Nd:GdVO4 cladding waveguides fabricated by femtosecond laser direct writing. As a result, the pulsed waveguide lasers are able to deliver approximately 6-GHz laser pulses with a signal-to-noise ratio of over 45 dB. The minimum pulse width is determined to be as short as 26 ps. The results demonstrated in this work exhibit the great potential of TMDCs and waveguide structures in applications of pulsed lasers with compact footprints. [ABSTRACT FROM AUTHOR]

In recent years, optical crystals for 1.3 μm all-solid-state passively Q-switched lasers have been widely studied due to their eye-safe band, atmospheric transmission characteristics, compactness, and low cost. They are widely used in the fields of high-precision laser radar, biomedical applications, and fine processing. In this review, we focus on three types of optical crystals used as the 1.3 μm laser gain media: neodymium-doped vanadate (Nd:YVO4, Nd:GdVO4, Nd:LuVO4, neodymium-doped aluminum-containing garnet (Nd:YAG, Nd:LuAG), and neodymium-doped gallium-containing garnet (Nd:GGG, Nd:GAGG, Nd:LGGG). In addition, other crystals such as Nd:KGW, Nd:YAP, Nd:YLF, and Nd:LLF are also discussed. First, we introduce the properties of the abovementioned 1.3 μm laser crystals. Then, the recent advances in domestic and foreign research on these optical crystals are summarized. Finally, the future challenges and development trend of 1.3 μm laser crystals are proposed. We believe this review will provide a comprehensive understanding of the optical crystals for 1.3 μm all-solid-state passively Q-switched lasers. [ABSTRACT FROM AUTHOR]

We experimentally demonstrate a passively Q -switched thulium-doped YAlO 3 (Tm:YAP) laser based on the Cr2+:ZnSe (Chromium, Zinc Selenide) and Cr2+:ZnS (Zinc Sulfide) crystals. Wavelength tuning for 1.87 μm, 1.90 μm, and 1.94 μm operations was achieved by employing a birefringent plate. The impact of varying doping concentrations of Cr2+:ZnS crystals and a Cr2+:ZnSe crystal on the laser output was investigated. During the analysis, the passively Q -switched Tm:YAP laser achieved a pulse with the highest peak power of 107.5 kW and the narrowest pulse width of ∼6 ns, utilizing a Cr2+:ZnSe crystal as the saturable absorber (SA) with a modulation depth (ΔR) of 14 %. [ABSTRACT FROM AUTHOR]

• Fabrication of perovskite materials explained briefly. • Crystal structure and nonlinear optical properties of perovskite materials. • A brief description of some current applications of perovskite from near-infrared to mid-infrared lasers. • Research progress of Q-switched lasers, and mode-locked lasers by employing perovskite materials. • Future prospects of perovskite materials are discussed and analyzed. 2D perovskite materials have merged as a novel addition to the family of saturable absorbers, offering the capability to generate high-energy and ultrashort pulses due to their distinct optoelectronic properties, as well as their structure and chemical versatility. In recent times, numerous reports have highlighted the progress of ultrafast pulsed lasers utilizing perovskite materials, which indicates a positive and promising outlook for advancements in this area. This review provides a summary of the crystal structure and nonlinear optical properties of perovskite materials. Fabrication methods of perovskites are divided into hybrid organic–inorganic, all-inorganic perovskite materials, and Ruddlesden-Popper perovskite materials based on their components. Subsequently, we provided a systematic introduction to ultrafast lasers that utilized perovskite materials across different spectral bands. Finally, an analysis of present challenges and perspectives for the advancement of ultrafast lasers facilitated by perovskite materials is presented. [ABSTRACT FROM AUTHOR]

As a member of the MXene family, tungsten carbide (WC), with its unique physical structure and excellent optical properties, possesses enormous development potentials in ultrafast optoelectronics. In this letter, A WC film saturable absorber (SA) is successfully demonstrated to induce passive Q-switching in an erbium-doped fiber laser (EDFL). The WC nanoparticles (NPs) are synthesized by a hydrothermal method. Stable Q-switched pulses are generated at 1558 nm with a threshold pump power of 141 mW, after inserting the prepared WC film into the EDFL ring cavity. As the pump power ranges from 141 mW to 193 mW, the repetition rate increases from 32.34 kHz to 35.8 kHz, while the pulse duration decreases from $5.5~\mu \text{s}$ to $4.16~\mu \text{s}$. When the pump power reaches a maximum power of 193 mW, the corresponding maximum pulse energy and output power are 81 nJ and 2.9 mW, respectively. To our best knowledge, this is the first report of utilizing WC as SA to achieve Q-switched pulses. Our research results provide a new reference for the realization of pulsed laser using MXene materials and reveal that WC has immense applications in nonlinear optics and ultrafast laser technology, which greatly broadens the frontier of materials for optoelectronic techniques. [ABSTRACT FROM AUTHOR]

We have experimentally demonstrated dual-wavelength Q-switching operation by using a newly developed organic material, hybrid organic small molecules (HOSM), as saturable absorber (SA). The HOSM SA was fabricated by the drop-casting method in which the martial compound was deposited onto polyvinyl alcohol (PVA) to form a thin-film. The thin film was then incorporated between two FC/PC to form a SA device. On the other hand, a microfiber with 8 µm diameter was used to induce a dual-wavelength operation. The output spectrum has two peaks at 1557 nm and 1559.7 nm. The laser produced a repetition rate in the range between 18 kHz to 78 kHz and the pulse width between 17.6 µs to 4.25 µs. The laser has a very high signal-to-noise ratio of 57 dB. This is the first time, to the best of author knowledge, that dual-wavelength operation is produced by using HOSM as SA in fiber laser technology. [ABSTRACT FROM AUTHOR]

In this paper, a new thin‐film saturable absorber (SA) that belongs to the MXene family is used to generate Q‐switched laser pulses. In constructing the SA, titanium carbide (Ti3C2Tx) powder obtained through a selective etching process is dispersed in polyvinyl alcohol solution before the mixture is dried to form a thin film. A small piece of the film is placed between two fiber ferrules to form a SA device and added to a laser cavity of an erbium‐doped fiber laser to produce Q‐switched pulses in the region of 1561 nm. The repetition rate of the pulses can be varied between 45.25 and 65.59 kHz with the corresponding pulse width of 5.04–3.11 μs when the pump power is increased from 29.8 to 66.3 mW. At the maximum output power of 8.17 mW, the highest pulse energy of 125 nJ is obtained. [ABSTRACT FROM AUTHOR]

We have experimentally demonstrated the mode-locked and Q-switched fibre lasers based on MXene Ti3C2Tx as a saturable absorber (SA). MXene Ti3C2Tx was obtained using selective etching and then embedded into polyvinyl alcohol (PVA) to form the thin film. A stable soliton mode-locked laser was achieved when the Ti3C2Tx film was added in the Erbium-doped fibre laser cavity, and the pump power was adjusted between 55 and 144 mW. The pulse width of mode-locked laser was obtained to be 3.68 ps, while the repetition rate was 1.89 MHz. The maximum average output power and pulse energy were measured to be 24.42 mW and 12.92 nJ. After we decreased the cavity length by removing 100 m of SMF, the same SA could produce Q-switched laser instead of mode-locked laser. The Q-switched laser operated within the pump power of 19–66 mW, having the shortest pulse width and operating wavelength of 2.6 µs and 1557 nm, respectively. [ABSTRACT FROM AUTHOR]

Dual-wavelength Q-switched Erbium-doped fiber laser (EDFL) was shown by using tungsten disulfide (WS2), which was deposited onto a micro-sphere resonator (MSR) as a saturable absorber (SA). WS2 functions to modulate the cavity loss for Q-switching while the dual-wavelength operation was realized due to MSR, which allows only two wavelengths to oscillate in the resonator. MSR with the sphere diameter of 200 μm was fabricated at the tip of a standard single mode-fiber by employing a fiber fusion splicer machine. The SA was obtained by repeatedly dropping and drying of WS2 solution onto the MSR structure to form an active thin layer. The SA was incorporated into an EDFL cavity to realize a dual-wavelength Q-switched laser operating at 1554.0 nm and 1560.7 nm. The repetition rate of the pulse train is tunable from 72.4 kHz to 85.1 kHz as the pump power is increased from 104.6 mW to 145.8 mW. At 145.8 mW pump, the minimum pulse width and maximum pulse energy were obtained at 3.47 µs and 131.4 nJ, respectively. The dual-wavelength Q-switched laser was stable and thus it is suitable for use in airborne Lidar, environmental sensing, and terahertz applications. [ABSTRACT FROM AUTHOR]

In this study, we have experimentally demonstrated the sodium carbonate (Na₂CO₃) thin-film as a saturable absorber (SA) for Q-switched laser generation in erbium-doped fiber laser (EDFL) cavity. The Na₂CO₃ powder was embedded in polyvinyl alcohol (PVA) to fabricate the thin film. The Na2CO3 was then employed in an EDFL cavity for passively generating Q-switched pulses with a minimum pulse width of 1.2 µs and maximum repetition rate of 94.7 kHz. The fundamental frequency of 94.7 kHz had the signal to noise ratio of 73.51 dB, which indicates the pulses were stable. The Q-switched laser operated at center wavelength of 1560 nm. [ABSTRACT FROM AUTHOR]

In this work, we have experimentally reported the generation of Q-switched pulses by using Indium Tin Oxide (ITO) as a saturable absorbing thin film. First, the slide of glass was kept in an e-beam chamber for deposition, and the ITO layer was coated over the glass slide. Then the ITO was exfoliated from the glass slide, over the fiber ferrules in the Erbium-Doped Fiber (EDF) laser cavity. The Q-switched laser operated on the central wavelength of 1562.6 nm. The pulse width and pulse repetition rate were obtained to be 5.65-4.23 µs and 48.31-64.52 kHz, respectively. [ABSTRACT FROM AUTHOR]

• A 1.5-μm Q-switched fiber laser was built up based on MXene. • The generation pulses were amplified to ablate self-made thrombus. • The thrombolysis effects of continuous wave laser and pulsed laser were compared, proving that pulsed laser shows better performance in thrombus ablation. Near-infrared band fiber lasers exhibit strong water absorption capabilities, and their photothermal effects are often harnessed in the field of laser medical surgery. In this work, a 1.5-μm Q-switched fiber laser was realized by incorporating MXene, demonstrating its excellent performance as a saturable absorber. The output pulsed laser was amplified to achieve a maximum power of 500 mW, after which a self-made thrombus model was ablated to observe the experimental phenomenon. The obtained pulsed laser was compared with continuous wave laser thrombolysis under the same conditions. The results indicated that the 1.5-μm Q-switched fiber laser possesses thrombolytic capabilities, and the surface ablation depth and damage area of the thrombus were determined at various time and power levels. The pulsed laser thrombolysis has a smaller damage area and a greater penetration depth compared with continuous wave laser. [ABSTRACT FROM AUTHOR]

• The localization of gray losses during chemical etching has been determined. • A comparison is made of the effect of the type of Q-switch mode. • SA was created based on Bi2Te3 nanopowder - polymer. • The pulse duration in this case was 5 ns with a repetition rate of 4 MHz. • Taper-based Q-switch fiber laser has a pulse energy of more than 1000 nJ. The presented work shows an influence of geometry passive Q-switch based on a nanopowder-polymer on the characteristics of an erbium ring fiber laser. The saturable absorber Bi 2 Te 3 was applied to two types of specially prepared samples of thinned sections of optical fiber, and the resulting structures were built into the ring circuit of an erbium fiber laser. In the first case, the surface of the light guide segment was thinned by chemical etching, and in the second, by mechanical grinding. For the first time, the time-domain optical reflectometry technique was used to control the quality of the resulting sample surface and the resulting losses. For a more complete comparison, a set of different optical splitters was used, providing a change in the feedback coefficient in the resonator from 5 to 95 %. A study in the mode of passive Q-switching using polarized light showed that for both types of modulators there are optimal ratios of the amount of energy output from the resonator to obtain the highest values of the average generation power. The d-shape fiber modulator allows mode-locking to be observed without any additional changes to the laser circuit. The pulse duration in this case was 5 ns with a repetition rate of 4 MHz. A Q-switch based on a chemically thinned fiber segment made it possible to obtain narrower pulses in Q-switching mode (up to 700 ns at 38 kHz), a stable peak position in the transmission spectrum, and an average power of 34 mW. [ABSTRACT FROM AUTHOR]

In this work, BiOBr nanoflowers with oxygen vacancies as saturable absorber are prepared using hydrothermal method. Passively Q-switched mode-locked infrared laser is achieved. The output power reaches the maximum 312 mW. The minimum Q-switched envelope is 242 ns with the maximum repetition rate of 180.5 kHz. Meanwhile, the mode-locked pulse duration within the Q-switched envelope is approximately 315 ps with repetition rate of 232 MHz. The results of X-ray diffraction (XRD), Electron paramagnetic resonance (EPR), UV–Vis–NIR diffuse reflectance spectra, and X-ray photoelectron spectroscopy (XPS) demonstrate the oxygen vacancies introduce intermediate energy levels in the energy band of BiOBr, which enhances the optical absorption in the near-infrared region. Therefore, BiOBr saturable absorber exhibits good saturable absorption characteristics in the near-infrared region and is a promising modulation element in Q-switched mode-locked infrared lasers. • The modulation depth and the saturation intensity of BiOBr nanoflowers saturable absorber is 7.5% and 522 MW/cm2 respectively. • The maximum output power of the laser is 312 mW. The pulse duration and repetition rate are 242 ns and 180.5 kHz respectively, corresponding to single pulse energy of 1.73 μJ and peak power of 7.14 W. • The mode-locked pulse duration within the Q-switched envelope is approximately 315 ps with repetition rate of 232 MHz. [ABSTRACT FROM AUTHOR]

• Enhanced nonlinear optical properties were observed in Mo 4/3 B 2 T 2 /TiO 2 vdW heterostructure. • The enhancement is due to the carrier migration in the heterostructure. • Stable conventional soliton and harmonic solitons output are experimentally demonstrated by using Mo 4/3 B 2 T 2 /TiO 2 heterostructure SA. Van der Waals heterostructure have garnered significant interest in ultrafast laser generation because of their attractive saturable absorption properties, holding promise for application in optics, medicine, and optoelectronics. In this study, the saturable absorption properties of TiO 2 , Mo 4/3 B 2 T 2 , and Mo 4/3 B 2 T 2 /TiO 2 vdW heterostructure SAs are investigated. The integration of the SAs into the cavity reveals the observation of fundamentally conventional solitons. The output characteristics of conventional solitons based on three SAs are recorded. These results suggest that the saturable absorption of Mo 4/3 B 2 T 2 /TiO 2 vdW heterostructure is enhanced obviously compared with that of Mo 4/3 B 2 T 2 and TiO 2. Furthermore, 2nd-, 4th-, and 5th-order harmonic solitons are achieved, corresponding to the repetition rate of 20.36 MHz, 42.71 MHz, and 53.39 MHz, respectively. We established a model in order to understand the saturable absorption properties of the Mo 4/3 B 2 T 2 /TiO 2 , which suggests the enhancements of the saturable absorption are attributed to the carrier migration between Mo 4/3 B 2 T 2 and TiO 2. Our results indicate that Mo 4/3 B 2 T 2 /TiO 2 vdW heterostructure can be used as an excellent nonlinear optical material, which can be used as an SA in ultrafast pulse generation. [ABSTRACT FROM AUTHOR]

In this study, we explored a saturable absorber (SA) using a metal oxide-biopolymer film, resulting in the generation of Q-switched fiber lasers at 1.0 µm and 1.5 µm wavelengths. A straightforward sonochemical technique was employed to synthesize a nickel oxide (NiO) film in cooperation with Chitosan as a host polymer. The fabricated NiO-Chitosan film exhibits nonlinear absorption properties with modulation depth of 32.20%, saturation intensity of 0.43 kW/cm2, and non-saturable loss of 7.80%. Upon integrating the NiO-Chitosan film into the cavities of Erbium-Doped Fiber Laser (EDFL) and Ytterbium-Doped Fiber Laser (YDFL), the emergence of stable self-starting Q-switched pulsed lasers were observed at 1040.86 nm and 1557.60 nm central wavelength, respectively. Notably, the shortest pulse widths of 0.73 µs and 2.44 µs were achieved, along with maximum repetition rates of 111.61 kHz and 61.73 kHz, respectively, at these wavelengths. Our investigation identifies an effective SA material with good nonlinear absorption properties for inducing Q-switching in the 1.0 µm and 1.5 µm regions. Significantly, the Chitosan properties, encompassing biocompatibility, non-toxicity, and high thermal resistance, combined with the uncomplicated NiO fabrication process and cost-effectiveness, hold promise for diverse applications. [ABSTRACT FROM AUTHOR]

Authors reported the generation of Q - Switched pulses in an erbium-ytterbium co-doped fiber laser using an aqueous solution of colloidal gold nanorods (GNRs) and Polyvinyl Alcohol (PVA) as a saturable absorber (SA). The effect of the GNRs and PVA concentrations on the pulses has been explored. Passive Q-Switching is achieved at 1.1 W (1.8 A). Pulses with a minimum width of 9.6 µs having a repetition rate of 21.5 kHz and a maximum energy of 0.15 µJ at 1.56 μm are obtained for a pump current of 2.195 W (3.12 A). [ABSTRACT FROM AUTHOR]

2D materials have recently attracted extensive attention in solid‐state laser devices due to the improvement of their beam quality and service life. However, most conventional devices suffer from the fixed saturable absorption properties of certain 2D materials and are confined to the determined operation state. Herein, on‐chip electrically tunable infrared laser signals are realized by introducing a novel 2D nanomesh saturable absorber (SA) interaction layer without other tuning elements based on printable graphene–insulator–semiconductor (GIS) heterostructures. The pulse width can be highly controllable ranging from 1 µs to 360 ns under ultralow electrical modulation power (≈10 pA current and <0.5 nW power), thanks to the high conductivity and tunability of graphene. Furthermore, the precise regulation mechanism of the Fermi level of graphene by the heterostructures is comprehensively explored through opto‐electrical characterization with spectroscopic methods. The GIS device introduces a promising way to achieve actively controlled solid‐state optoelectronic and nonlinear photonic devices in the future. [ABSTRACT FROM AUTHOR]