Stable Q-switched Pulses Research Articles

SESAM Q-switched Dy-doped fluoride fiber laser at 3.1 µm

We report on a passive Q-switching laser operation of an in-band pumped Dy-doped zirconium fluoride fiber using a commercially available semiconductor saturable absorber mirror (SESAM). Stable Q-switching pulse trains with minimum pulse duration of 460 ns, highest repetition frequency of 206 kHz, and pulse energy up to 1.7 µJ are demonstrated.

Generation of dual-wavelength Q-switched pulses and bright-dark pulses pairs in an erbium-doped fiber laser with NbS2 as saturable absorber

In this experiment, stable dual-wavelength Q-switched pulses and bright-dark pulses pairs are achieved in an erbium-doped fiber laser based on NbS2 under saturable absorber. At pump powers of 172 mW–322 mW, stable dual-wavelength Q-switched pulses with center wavelengths of 1531.9 nm and 1557.05 nm were obtained with a signal-to-noise ratio (SNR) as high as 43 dB. The repetition frequency was increased from 14.3 kHz to 22.7 kHz as the pump power was increased. When the pump power was increased to 340 mW, we found stable bright-dark pulses with center wavelengths of 1559.7 nm and 1560.12 nm, respectively, and a repetition frequency of 3.44 MHz with an SNR of 52 dB. The experimental results show that NbS2 can be used as an excellent SA for fiber lasers and demonstrate that NbS2 can be used to study dual-wave Q-switched pulses and bright-dark soliton pairs.

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

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

Exploring the potential of a bismuth-erbium-vanadium co-doped optical fiber as a stable Q-switcher in the 1550 nm region

This paper experimentally demonstrates the ability of a bismuth-erbium-vanadium co-doped optical fiber as a saturable absorber (BEV-FSA) to generate stable Q-switched pulses in the 1550 nm region. The laser cavity delivered passively Q-switched pulses exploiting an erbium-ytterbium co-doped double-clad fiber (DC-EYDF) as the laser gain medium while maintaining an all-fiber cavity configuration. The output parameters of the laser such as output power, repetition rate, pulse duration, and pulse energy have been studied in detail with the variation of pump power. The output spectrum centered at 1550.86 nm throughout the experiment. The system produced stable pulses with a minimum pulse width of 1.83 µs with a pulse energy≈0.4µJ at the highest pump power of 2.31 W. The highest achievable repetition rate was 47.5 kHz with an of SNR≈53dB.

Q-switched pulse generation in L-band region with polyacrylonitrile saturable absorber

In this study, we assess the practicality of using Polyacrylonitrile (PAN) as a saturable absorber (SA) for generating Q-switched pulses within an erbium-doped fibre laser (EDFL) cavity. A successful combination of PAN, a resin material, and polyvinyl alcohol resulted in the formation of a SA film. This film was utilised to generate stable Q-switched pulses operating in a long-wavelength band of 1572 nm. The greatest repetition rate achieved was 66.1 kHz, while the minimum pulse width was 2.43 μs. The maximum pulse energy was achieved at 52 nJ and measured at a pump power of 175.9 mW. To the best of our knowledge, this study is the first report of EDFL passive Q-switching employing a PAN absorber.

Porous nano-grained cuprous selenide (Cu2Se) for mid-infrared photonics

Recently, mid-infrared photonics has attracted tremendous attention for various applications. To address the dilemma of the limited variety of materials for mid-infrared photonics, the mid-infrared optical modulation characteristics of the porous nano-grained cuprous selenide (Cu2Se) were investigated for the first time. The large effective nonlinear absorption coefficient, large modulation depth, and low saturation absorption intensity at 2.3 μm indicate that the porous nano-grained Cu2Se were promising saturable absorbers for the generation of Q-switched pulsed laser in the mid-infrared regime. As an application, the Tm:GdVO4 passively Q-switched laser operating on the 3H4 → 3H5 Tm3+ transition was achieved for the first time by using the prepared porous nano-grained Cu2Se as the saturable absorber. The minimum pulse duration and the maximum repetition rate of the stable Q-switched pulse train were 440 ns and 76.9 kHz, respectively. Our results demonstrated that the porous nano-grained Cu2Se was a promising candidate for the mid-infrared photonic applications.

Generation of Q-switched and mode-locked pulses in erbium-doped fiber ring laser using saturable absorption of Ti2SnC

MAX phase materials have garnered significant attention due to their corrosion resistance, impressive antioxidation and high electrical and optical conductivity. One such material, Titanium Tin Carbide (Ti2SnC), has demonstrated notable nonlinear optical properties. The saturable absorption of Ti2SnC, embedded into a polyvinyl (PVA) film, was measured to assess its potential. The Ti2SnC -PVA film exhibited a calculated modulation depth of 7.8%. In the context of practical applications, the Ti2SnC-PVA film was employed as a saturable absorber (SA) in an Erbium-doped fiber laser (EDFL) cavity. This configuration enabled the generation of stable Q-switched and mode-locked pulse trains. Q-switched operation occurred in a pump power range of 51.67 mW–83.83 mW, reaching a peak pulse energy of 110.94 nJ. Transitioning to mode-locking operation, the laser cavity demonstrated efficiency in the pump power range of 105.27 mW–196.39 mW. At a pump power of 196.39 mW, the fiber laser cavity achieved its highest pulse energy of 5.42 nJ, characterized by a pulse width of 2.32 ps and a pulse repetition rate of 1.825 MHz. These results highlight the promising potential of Ti2SnC-PVA thin film as a cutting-edge material for applications in pulsed laser systems. The material's excellent nonlinear optical properties make it a compelling candidate for advancing the field of pulsed laser technology.

120 nm wide band tunable pulsed laser generation employing vanadium carbide MXene/polyvinyl alcohol (V2C-PVA) film

MXene, a group of 2D materials, has garnered significant attention from researchers due to its impressive characteristics, such as large surface area, high metallic conductivity, and strong nonlinear saturable absorption. These properties make MXene an excellent material for exploring new possibilities in ultrafast photonics technology. The present study has demonstrated that vanadium carbide (V2C) MXene can function as a saturable absorber (SA) and effectively generate Q-switching pulses in the 1.9 μm wavelength region. The molten salt synthesis method was used to synthesize V2C MXene, which involved the selective etching of aluminum (Al) layers from the V2AlC MAX Phase precursor. The V2C MXene was transformed into a thin film by mixing it with polyvinyl alcohol (PVA) using a solution casting technique. The resulting V2C-PVA film was found to have saturable absorption properties, with a modulation depth of 8% and saturation intensity of 1.6 MW cm −2. Upon integrating the V2C-PVA film into the Thulium/Holmium-doped fiber laser (THDFL) cavity, stable Q-switching pulses were realized at a central wavelength of 1896.9 nm with 13.9 nm of 3-dB spectral bandwidth. At the maximum pump power of 448.7 mW, the 2.2 μs of pulse duration, 58.26 kHz of repetition rate, and 31 nJ of pulse energy were achieved. By adjusting the tunable bandpass filter (TBPF) integrated within the THDFL cavity, the system has a tunable spectral range of approximately 120.75 nm, from 1889.75 nm to 2010.5 nm. The exceptional performance of V2C-based SA for Q-switching operation showcases the immense potential of other MXene materials in the future of photonics applications.

Carbon nanomaterials as nonlinear optical modulators for pulsed laser generation at near-infrared region

In this study, carbon nanoparticles (CNPs) were experimentally investigated as novel saturable absorbers (SAs) capable of delivering strong ultrashort pulses in a passively Q-switched fiber laser. Carbon nanoparticles produced by candle burning and laser ablation can act as saturable absorbers (SAs). In addition, the nonlinear saturable absorption properties of the two synthetic CNPs in telecommunication region (1.5 μm) are investigated. Nonlinear optical measurements show that both SAs have good saturable absorption properties with average modulation depths of about ∼1 and 5 % at 1560 nm. These candle soot carbon nanoparticles (CSC-np) and laser ablation carbon nanoparticles (LAC-np) based SAs, can be used as a building blocker for the generating of stable Q-switched pulses in the near-infrared region. The shortest pulse duration measured with CSC-np and LAC-np are 5.62 and 3.87 μm, respectively. The pulse energy, peak power and SNR were also compared with both SA types at the highest pump power. The damage threshold and long-term stability of the CSC-cn SA and LAC-np were also explored. To the best of the author's knowledge, it is the first comparison of performance and long-term stability of EDFL based on two experimental techniques CSC-np and LAC-np based SAs. These results indicate that LAC-np SA provide have several advantages, including a high damage threshold, good saturable absorption, and optimum stability over a long time compared to CSC-np SA.

Conversion from Q-switched to bright-dark soliton pair mode-locked operation in an InSb based erbium-doped fiber laser

In this experiment, stable Q-switched pulses and bright-dark soliton pairs were realized in an InSb based erbium-doped fiber laser. Firstly, when the pump power was between 70 and 115 mW, a stable passive Q-switched operation with a central wavelength of 1565.38 nm was achieved, and the signal-to-noise ratio (SNR) was about 37 dB. As the pump power increased, the repetition frequency of the Q-switched pulse can be increased from 4.0145 to 10.623 kHz. When the pump power was increased to the range of 185 to 450 mW, stable bright-dark soliton pairs mode-locked operation was realized, and the two peaks of the spectrum were located at 1568.67 and 1569.34 nm, respectively. The pulse repetition rate was 3.419 MHz, and the SNR was about 59 dB. This research will broaden the application of InSb in ultrafast optics and nonlinear optics.

Fe2O3 Nanoparticle-Based Q-Switched Pulse Fiber Laser

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.

Passively Q-switched Er3+-doped fiber laser based on double-transition metal MAX phase TiNbAlC saturable absorber

We demonstrated a stable passively Q-switched fiber laser operation at 1531.57 nm using a double-transition metal MAX phase TiNbAlC saturable absorber. The prepared saturable absorber’s modulation depth, saturation intensity, and non-saturation loss are 1.75%, 0.089 MW/cm2, and 32.81%, respectively. Using the TiNbAlC saturable absorber within an erbium-doped fiber laser ring cavity, stable Q-switched pulses with a central wavelength of 1531.57 nm, and a 3-dB bandwidth of 1.43 nm are acquired. The minimum pulse duration and the maximum single pulse energy are 3.18 μs and 51.56 nJ, respectively. Furthermore, the maximum repetition rate is 37.9 kHz with a signal-to-noise ratio of 50 dB. Our results indicate that double-transition metal MAX phase TiNbAlC can be an excellent saturable absorber candidate for an ultrashort pulse fiber laser.

Zinc Oxide Nanoparticles-Poly(vinyl) Alcohol Thin Film for Generation Q-Switched Erbium-Doped Fiber Laser

The nonlinear optical property of Zinc oxide (ZnO) nanoparticles thin film synthesized by the solution casting method was investigated from the continuous wave to the Q-switching using an erbium-doped fiber laser cavity. Our laser experiment shows that ZnO nanoparticles embedded with polyvinyl alcohol (PVA) allow for the generation of a stable Q-switching laser pulse, centered at 1560.08nm with a 3-dB spectral bandwidth of 0.941 nm, a pulse duration of 3.53 µs and a high pulse energy of 171 nJ. Our finding suggests that ZnO nanoparticles thin film can be a useful nonlinear optical material for laser photonics devices such as passive q-switching for applications involving high energy.

Long-time stable Q-switched bulk laser at 1.34 and 1.94 μm based on antimonene saturable absorber

The low stability of laser pulse production induced by the deterioration of saturable absorber (SA) under long-time laser excitation is a common shortage of passive Q-switched bulk lasers that strongly impedes their general applications. The 2D mono-elemental nanomaterial antimonene has been recently verified as a promising SA for realizing high-stability pulsed fiber laser benefiting from its stable semimetallic bonding and superior thermal conductivity. However, its performance in enhancing the stability of pulsed bulk laser has less been investigated. Here we demonstrated the successful application of multi-layer antimonene for stable passive Q-switching operations in Tm:YAP laser at 1.94 μm and Nd:GdVO4 laser at 1.34 μm. The multi-layer antimonene was characterized to have broadband SA properties with a modulation depth of 3.2 % (12.2 %) and a saturable intensity of 0.19 GW/cm2 (0.17 GW/cm2) at 1.94 μm (1.34 μm). Stable Q-switched pulses were obtained with pulse duration of 238 ns at 1.94 μm and 324 ns at 1.34 μm. The long-time pulse duration instability was only 9.6 % at 1.94 μm and 6.9 % at 1.34 μm within 180-minute measurement. Our work indicates the exceptional potential of antimonene SA in infrared pulsed bulk laser, which may arouse great interest for developing antimonene-based optics and optoelectronics applications with enhanced stability.

Dual Regime Mode-Locked and Q-Switched Erbium-Doped Fiber Laser by Employing Graphene Filament-Chitin Film-Based Passive Saturable Absorber.

We investigate the dynamics of high energy dual regime unidirectional Erbium-doped fiber laser in ring cavity, which is passively Q-switched and mode-locked through the use of an environmentally friendly graphene filament-chitin film-based saturable absorber. The graphene-chitin passive saturable absorber allows the option for different operating regimes of the laser by simple adjustment of the input pump power, yielding, simultaneously, highly stable and high energy Q-switched pulses at 82.08 nJ and 1.08 ps mode-locked pulses. The finding can have applications in a multitude of fields due to its versatility and the regime of operation that is on demand.

Chromium oxide film for Q-switched and mode-locked pulse generation.

Chromium oxide (Cr2O3) is a promising material used in the applications such as photoelectrochemical devices, photocatalysis, magnetic random access memory, and gas sensors. But, its nonlinear optical characteristics and applications in ultrafast optics have not been studied yet. This study prepares a microfiber decorated with a Cr2O3 film via magnetron sputtering deposition and examines its nonlinear optical characteristics. The modulation depth and saturation intensity of this device are determined as 12.52% and 0.0176 MW/cm2. Meanwhile, the Cr2O3-microfiber is applied as a saturable absorber in an Er-doped fiber laser, and stable Q-switching and mode-locking laser pulses are successfully generated. In the Q-switched working state, the highest output power and shortest pulse width are measured as 12.8 mW and 1.385 µs, respectively. The pulse duration of this mode-locked fiber laser is as short as 334 fs, and its signal-to-noise ratio is 65 dB. As far as we know, this is the first illustration of using Cr2O3 in ultrafast photonics. The results confirm that Cr2O3 is a promising saturable absorber material and significantly extend the scope of saturable absorber materials for innovative fiber laser technologies.

Nonlinear optical properties of PVD-grown Cr2Te3 film and its nonlinear switching application

Recently, two-dimensional (2D) nanomaterials have been investigated extensively in the field of nonlinear photonics. Cr2Te3, which is one of the 2D transition metal chalcogenides, has garnered attention in the field of spintronics and optoelectronics because of its fascinating magnetic and optical properties. Despite its potential in optoelectronics, Cr2Te3 has rarely been studied in the field of nonlinear photonics. This study investigates the nonlinear optical responses of nanoscale-layered Cr2Te3 films grown by physical vapor deposition at telecommunication wavelengths. A large nonlinear absorption coefficient of –(1.43 ± 0.06) × 105 cm/GW and a nonlinear refractive index of –1.22 ± 0.04 cm2/GW at 1560 nm obtained through Z-scan measurements indicate that the Cr2Te3 film shows saturable absorption and self-defocusing properties at telecommunication wavelengths. Density functional theory calculation show that Cr2Te3 is suitable for broadband optical device. The potential of the nanoscale-layered Cr2Te3 film as a base medium for a nonlinear optical switch was evaluated by fabricating a saturable absorption mirror (SAM). Stable Q-switched pulses with a maximum repetition rate of 33.35 kHz and minimum temporal width of 2.62 μs were readily achieved from a fiber laser cavity incorporating the SAM.

Influence of thickness on tunability performance of plasma sputtered indium tin oxide as Q-switcher

We successfully investigated the influence of thickness on the tunability performance of plasma-sputtered indium tin oxide (ITO) as a Q-switcher. ITO is coated using direct current magnetron sputtering techniques with sputtering times of 150 s, 250 s, and 350 s to generate excellent quality ITO. Filmetrics measures the thickness, yielding 17.80 nm, 30.70 nm, and 38.90 nm, respectively. A stable Q-switched pulse is achieved at an operating wavelength and peak power of 1562.30 nm and −6.47 dBm for the thickness of 17.80 nm, 1561.40 nm and −3.19 dBm for the thickness of 30.70 nm, and 1560.2 nm and −2.44 dBm for the thickness of 38.90 nm. The thickness of 38.90 nm exhibit a high repetition rate of 43.60 kHz and narrow pulse width of 4.83 µs compared to other thickness. Employing the tunable bandpass filter in the laser ring cavity gives the wide-tuning of the wavelength range of 19.69 nm, 31.86 nm, and 36.59 nm for the thickness of 17.80 nm, 30.70 nm, and 38.90 nm, respectively. The tunability of Q-switched with the thicknesses of 30.70 nm and 38.90 nm is realized in the region of C-band to L-band. Regarding the authors’ expertise, this seems to be the first proposed influence of thickness on the tunability of plasma sputtered ITO that serves as saturable absorber in a Q-switched pulse.

Indium Tin Oxide-based Q-switched pulse fiber laser for sensing application

We demonstrate a novel method of ring cavity Q-switched pulse erbium-doped fiber laser (EDFL) for liquid ammonia sensors. Q-switched pulse is generated using an indium tin oxide (ITO) deposited onto a side-polished fiber (SPF) as a saturable absorber (SA). The generated Q-switched pulses exhibit a repetition rate from 15.22 kHz to 28.28 kHz when the pump power is tuned from 77.2 mW to 211.60 mW. The shortest pulse width retrieved was 6.42 µs with a pulse energy of 11.23 nJ. A stable Q-switched pulse was obtained from the cavity configuration, with the repetition rate of 28.28 kHz. This pulse was then being used as a reference for the ammonia sensing purposes. When the liquid ammonia was injected into the setup, the wavelength and frequency shifts was observed by increasing the ammonia concentrations. From the results, the sensor can achieve good linear responses. To the best of our knowledge, this is the first report of Q-switched pulse EDFL based on side-polished fiber indium tin oxide (SPF-ITO) as a Q-switcher of the pulsed laser and a sensing transducer at the same time. These results indicates that the proposed SA is suitable for generating ultrashort pulse and optical sensors.

Compact nanosecond Yb:YAG/V:YAG solid-state laser generating switchable radially and azimuthally beams.

We demonstrated a compact self-starting nanosecond Yb:YAG/V:YAG solid-state laser with cylindrical vector beams output modulated by the intracavity mode converter S-waveplate experimentally. We can deliver the stable Q-switched pulse with the highest repetition rate 3.61 kHz and minimum pulse width 26 ns at the wavelength of 1030.07 nm with the help of the V:YAG crystal. In addition, the switchable radially and azimuthally polarized beams can be realized with polarization extinction ratios of 92.3% and 89.6%, respectively. The compact laser configuration can provide solutions for generating stable nanosecond structured light, and may benefit the applications like micro/nano material processing.