Q-switched Pulses Research Articles

Ti3C2Tx thin film as a saturable absorber for passively generating Q-switched pulses in thulium-doped fiber laser cavity

Ti3C2Tx thin film as a saturable absorber for passively generating Q-switched pulses in thulium-doped fiber laser cavity

Q-switching bifurcation dynamics of passively mode-locked lasers.

We model Q-switched pulses in passively mode-locked lasers using the cubic-quintic complex Ginzburg-Landau equation (CGLE). We show that a wide set of parameters of this equation leads to Q-switched pulses of triangular shape that consist of a periodic sequence of evolving dissipative solitons. Bifurcation diagrams demonstrating various transformations of these pulses are calculated in terms of five major parameters of the CGLE. The diagrams show period doubling transformations as well as the transition to a chaotic evolution of the Q-switched pulses.

Lanthanum hexaboride for Q-switching and mode-locking applications

In this paper, a new saturable absorber (SA) based on Lanthanum Hexaboride (LaB6) is used to produce Q-switched and mode-locked laser pulses. In constructing the SA, the prepared LaB6 powder is dispersed in polyvinyl alcohol (PVA) 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 LaB6 PVA SA and added to a laser cavity of an erbium-doped fiber laser (EDFL) to produce Q-switched and mode-locked pulses. The Q-switched laser operates at 1531 nm. The pulse width of the pulses can be varied between 4.32 to 2.46 μs with a corresponding repetition rate of 62.0 to 89.6 kHz when the pump power is increased from 45.4 to 97.6 mW. At the maximum output power of 4.31 mW, the highest pulse energy of 48.1 nJ was obtained. A passively mode locked EDFL was also successfully realized with LaB6 SA by adding 100 m long single mode fiber inside the cavity. A stable mode-locked laser operating at 1559.1 nm was achieved at the threshold pump power of 102.8 mW with a pulse rate of 1.88 MHz. The pulse energy of 5.6 nJ and output power of 10.54 mW were obtained at a maximum pump power of 144.6 mW. To the best of our knowledge, this is the first demonstration of utilizing LaB6 material as SA to produce pulses in the 1.5 μm region.

Q-Switched 1064/532 nm Laser with Picosecond Pulse to Treat Benign Hyperpigmentations: A Single-Center Retrospective Study

(1) Benign melanoses are a frequent issue in aesthetic dermatology. Solar lentigo, ephelides, café au lait spots, and other melanoses represent a cosmetic issue for a growing number of subjects. The Q-switched 1064/532-nanometer (nm) laser may be considered the gold standard for management of these aesthetic issues. A new generation of Q-switched lasers, capable of concentrating the energy pulse in the spectrum of hundreds of picoseconds, is emerging, promising better results than previous ones. In this paper, we report the use of a Q-switched laser with a picosecond pulse to manage hypermelanoses. (2) Methods: 36 patients seeking melanosis removal were retrospectively enrolled at Magna Graecia University of Catanzaro. Treatment parameters, although variable, were the following: 1064 nm with a pulse duration of 450 picoseconds (ps) for dermic lesions and 532 nm with 370 ps for epidermal lesions. Up to four treatments, with a minimum interval between laser treatments of 30 days, were performed. After the last session, patients’ satisfaction was assessed at a three-month follow up with a Visual Analogue Scale (VAS). Two blinded dermatologists measured the aesthetic outcome using a five-point scale comparing pictures before laser sessions and during follow-up. (3) Results: 36 patients were enrolled; 23 were females (63.9%) and 13 males (36.1%). The mean reported age was 49.2 ± 18.9 years. All participants were assessed with a complete/almost complete melanosis removal at the dermatological evaluation, with a mean VAS score of 9.39 ± 0.90. (4) Conclusions: The Q-switched 1064/532 nm laser may be considered the main weapon in treating benign hypermelanosis. The picosecond pulse seems to guarantee better results than other devices. However, a clinical trial comparing Q-switched nanosecond pulse with picosecond pulse is necessary to confirm this study’s findings.

L-band compact Q-switched fiber laser based on a thulium-doped fiber saturable absorber

In this paper, a compact and stable Q-switched erbium-doped fiber laser operating at around 1600 nm by employing a segment of 1-cm thulium-doped fiber saturable absorber (TDF-SA) is proposed. When the pump power is adjusted between 28 and 71 mW, the Q-switched operation can be maintained stably, and the output power increases from 74 µW to 2.6 mW. Furthermore, the peak power clamping effect is also observed when the pump power exceeds 60 mW. The structure of the cavity is greatly simplified by using all-optical and hybrid fiber components, which contributes to its long-term stability. Our results prove that the TDF can be a promising SA for all-fiber Q-switched pulses generation in the L-band.

Continuous-wave and passively Q-switched pulse 1060 nm Nd:GdPO4 lasers

1060 nm continuous-wave and passively Q-switched pulse lasers were demonstrated in a 3.5-mm-thick X-cut Nd:GdPO4 crystal. At an absorbed pump power of 1.91 W, a 1060 nm continuous-wave laser with a maximum output power of 0.72 W and a slope efficiency of 42% was realized. When a Cr4+:YAG saturable absorber with an initial transmission of 85% was used, a passively Q-switched pulse laser with repetition frequency of 6.7 kHz, pulse energy of about 19 µJ, pulse duration of 58 ns, and peak power of 0.33 kW was obtained in a plano-concave cavity with a length of 95 mm and an absorbed pump power of 1.91 W. For a plano-plano cavity with a length of 9 mm and the same pump power, a pulse laser with repetition frequency of 7.2 kHz, pulse energy of about 14.1 µJ, pulse duration of 4.1 ns and peak power of 3.4 kW was obtained.

Passively Q-switched modulation based on antimonene in erbium-doped fiber laser with a long term stability

Antimonene, as a novel two-dimensional material, has received extensive attention in recent years. It has similar properties to most semiconductor materials and has many other materials unmatched characteristics. Herein, we prepare antimonene nanosheets by the liquid-phase exfoliation method, and fabricate antimonene-based saturable absorbers (SA) according to their saturable absorption characteristics and successfully apply them in fiber lasers to achieve stable passively Q-switched output with a center wavelength of 1558 nm. The saturation intensity of antimonene-based SA is 1.52 MW/cm 2 , and the modulation depth is 11.63% in our experiment. The pulse duration is varied from 5.10 μs to 1.42 μs, and the repetition frequency is changed from 25.6 kHz to 124.1 kHz, with the pump power from 81 mW to 445 mW in the passively Q-switched operation. The experimental results fully reveal the huge potential and nonlinear optical properties of antimonene used in pulsed fiber lasers and expand the scope of new optical applications. • Successfully employed Sb-SA in erbium-doped fiber lasers based on its saturated absorption characteristics. • The Q-switched pulse with a center wavelength of 1558 nm and pulse duration of 1.42 μs was realized. • The Q-switched output pulse has long-term stability without obvious spectral changes and intensity fluctuations.

Remove Skin Deformities by Using CO2 and Nd:Yag Laser

The treatment of some skin damage have been studied influence the laser beam CO2 and the Nd:Yag with wavelengths (10600nm and 1064 nm) respectively as foundation of radiation. The current research aims to verify effect of altered laser dosages of the skin in an attempt to recognize how the laser achieves medicinal effects to treat skin lesions. And the aims to establish the correlation between laser dose and biological influence and so after that calculate its low dose with higher medical influence and minimal harm to. The number of cases included four different diseases, ranging between 18-50 years. Areas of the body were exposed to laser beams and different wavelengths by type laser user. The first case, represent the image of a girl suffering from autoimmune disease, Nd:YAG laser was used with Q-swtich Nd: YAG to treat this condition and the wavelength is 1064 nm, second case, image of a person suffering from the impact. Fractional Co2 Laser and wavelength 10600 nm where used and third case: An image of a person suffering from costs, treatment by using Q-switch Nd-YAG laser short pulse has a wavelength of 1064nm.

Passively Q - Switched Linear Cavity IR Fibre Laser via Nonlinear Polarization Rotation

Abstract: Setup for self-starting passive Q-switch operation of IR fibre laser via nonlinear polarization rotation (NPR) was demonstrated for the first time for linear cavity. A Q-switched pulse duration of ~ 600 ns, a maximum peak power of ~16 W and an average power of 408 mW have been obtained at 223 kHz repetition rate for 5.1 W pump power from 1319 nm CW Nd: YAG laser launched to ~ 2.78 m unidirectional single-clad Tm-doped silica fibre linear cavity using only flat polarizer and feedback mirror to induce NPR. The dependence of the fibre laser output characteristics on the polarization angle of the polarizer is also reported. However, self induced passive Q-switching in linear fibre laser cavities is only observed in fibres with angled cleaved ends and with lengths that are around the optimum length for CW operation. Keywords: IR fibre laser, Passive Q-switching, Nonlinear polarization rotation, Linear cavity, Ring cavity. PACS: Fiber lasers, 42.55.Wd, Q-switching, 42.60.Gd.

Mid-infrared nanosecond pulse generation from a graphene modulated Er3+-doped fluoride fiber laser

We demonstrate a 2792.0 nm passively Q-switched Er3+-doped fluoride fiber laser using a graphene saturable absorber mirror (GSAM). Through optimizing the cavity design and the parameters of the GSAM, stable pulses are obtained with a repetition frequency ranging from 60.2 to 221.8 kHz. The shortest pulse duration is 238.2 ns, which, to the best of our knowledge, is the shortest passively Q-switching pulse obtained in 3 μm mid-infrared wavelength region. The maximum average output power is 535 mW, and the single pulse energy is 2.53 μJ. Further improvement of the pulse energy and pulse width is possible by optimizing the bleaching energy of the GSAM.

Q-switched pulse generation in a bidirectionally pumped EDFL utilizing Lu2O3 as saturable absorber

Q-switched pulse generation in a bidirectionally pumped EDFL utilizing Lu2O3 as saturable absorber

Synthesis of silver nanoparticles using chemical reduction techniques for Q-switcher at 1.5 µm region

This research investigated the generation of passively Q-switched erbium (Er)-doped fibre laser using silver nanoparticles/poly (vinyl alcohol) (Ag/PVA) as a saturable absorber (SA). The Ag nanoparticles were synthesised via the chemical reduction technique. The Ag/PVA film based SA was fabricated by blending Ag nanoparticles powder into the PVA suspension, then left to dry at ambient to develop a free-standing SA film. Next, the Ag/PVA film was sandwiched in between two FC/PC fibre ferrules and integrated into the laser cavity for Q-switched pulse generation. The result shows that the Q-switched pulsed laser achieved pulse energy and peak power of 128.04 nJ and 21.34 mW at the maximum pump power of 107.1 mW. A signal-to-noise ratio (SNR) value of 66.23 dB was obtained at a frequency of 66.23 kHz proving that it is an excellent candidate as a SA material for Q-switched generation in future large-scale manufacturing.

Multifunctional all-fiber mode-locked laser based on graphene-integrated polarization-dependent microfiber resonator

A stable pulsed all-fiber laser based on the hybrid graphene microfiber knot resonator device is proposed and demonstrated. Unlike previous pulse generation mechanisms, the operation utilizes saturable absorption as well as the nonlinear-polarization-rotation effect introduced by the polarization-dependent feature of the device to enhance intracavity power for boosting multiple pulsation regimes. 15.5 MHz conventional soliton mode-locking pulse, 140 MHz 9-order-harmonic mode-locking pulse, 27.4 to 48.6 GHz high-repetition-rate dissipative four-wave-mixing pulse, and 50 kHz stable Q-switched pulse were achieved experimentally based on one device. The easily fabricated versatile device acts as a polarizer, comb filter, and nonlinear component simultaneously, thereby introducing a novel application of microfiber resonator devices in ultrafast and nonlinear photonics.

Gold nanoparticles film for Q-switched pulse generation in thulium doped fiber laser cavity

Gold nanoparticles film for Q-switched pulse generation in thulium doped fiber laser cavity

Wavelength-tunable Q-switched erbium-doped fiber laser based on a digital micromirror device.

A wavelength-tunable Q-switched erbium-doped fiber laser based on a digital micromirror device (DMD) is experimentally demonstrated. The Q-switched pulses are generated by incorporating a saturable absorption device made of graphene oxide. Stable Q-switched pulses at 1.5 µm band are obtained at a low threshold of 20 mW, corresponding to the pulse width of 7.1 µs and the repetition rate of 43.3 kHz. The maximum output power and the maximum pulse energy of the Q-switched pulses are 260.1 µW and 3.97 nJ, respectively. By controlling the DMD, the center wavelength of the Q-switched pulses can be tuned from 1528.2 to 1559.3 nm, with a tuning range of about 31 nm. The fine tunable accuracy can reach 0.08 nm by precisely controlling the DMD. Combining the filtering characteristics of the DMD with the saturable absorption characteristics of nanomaterials, the Q-switched laser with tunable wavelength is realized, which, we believe, is reported for the first time and has broad application prospects.

Tunable period-multiplying Q-switched pulse outputs based on birefringence induced multiwavelength tuning in a linear erbium-doped fiber oscillator

A tunable period-multiplying Q-switched erbium-doped fiber laser based on birefringence induced multiwavelength tuning in a linear cavity is demonstrated. By carefully adjusting the polarization controller to control birefringence filter effect under the pump power of 204 mW, period-doubling, period-tripling and period-quadrupling operations corresponding to dual-, quadruple- and triple-wavelength pulses are experimentally demonstrated, respectively. Unlike the traditional period-multiplying pulses operating in the narrow control parameters, they can persistently exist under constantly changing pump power from 204 mW to 117 mW. We attribute them to the intrinsic property of laser system with multiwavelength pulse emissions across 1530- and 1550-nm gain regions. And multiwavelength tuning provides the versatility of period-multiplying pulses. To the best of our knowledge, it is the first demonstration of the persistent and tunable period-multiplying Q-switched pulse outputs. This could offer an attractive alternative seed source integrated with all-optical modulation for applications requiring modulated Q-switched pulse sequences such as multiple-pulse laser-induced breakdown spectroscopy and processing.

Theoretical and experimental investigations on Nb2CT x MXene Q-switched Tm:YAP laser at 2 μm for the nonlinear optical response

In this paper, the Nb2CT x MXene nanosheets were fabricated and the corresponding microstructures were investigated. The nonlinear optical response was illustrated by open aperture Z-scan and I-scan methods. The ground and the excited state absorption cross-sections of 2D Nb2CT x MXene were also investigated. As the saturable absorber (SA), the Nb2CT x MXene was applied in the passively Q-switched Tm:YAP laser. 1.96 μs Q-switched pulses with 3.97 W peak power were achieved at the repetition frequency of 80 kHz. Further theoretical model was built by using the coupled rate equations in simulating the dynamic process of the passively Q-switched Tm:YAP laser. The numerical simulation results are fundamentally in agreement with the experimental results, which proves the Nb2CT x MXene can be a good potential nanomaterial for further optoelectronic applications.

MoTe2-PVA as saturable absorber for passively Q-switched thulium-doped fluoride and erbium-doped fiber laser

Passively Q-switched fiber lasers in the S- and C-band region were demonstrated using molybdenum ditelluride (MoTe2) as the saturable absorber (SA). The MoTe2 was prepared using liquid phase exfoliation method, which was then embedded in the polyvinyl alcohol (PVA) polymer to form a MoTe2 thin film SA. By incorporating the MoTe2 SA in the thulium-doped fluoride fiber laser (TDFFL) and erbium-doped fiber laser (EDFL) cavities, stable Q-switched pulses were observed in the S-band and C-band region with microsecond pulse durations and tens of kilohertz repetition rate. The modulation depth and the saturation intensity of the MoTe2 SA were ∼ 38 % and ∼ 0.314 MWcm−2, respectively. The Q-switched operation can be tuned by employing a tunable bandpass filter (TBPF), covering the S-band and C-band region from 1453 nm to 1572 nm. Thus, the finding validates the feasibility of MoTe2 as a promising SA for a broadband optical applications.

Sodium Carbonate for Generating Q-Switched Pulses in 1550 nm Region

ABSTRACT 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.

Q-Switched and Mode-Locked Er-doped fiber laser based on MAX phase Ti2AlC saturable absorber

MAX phase materials, exhibiting excellent antioxidation, corrosion resistance and high electrical and optical conductivity, attract much attention. The nonlinear optical properties of the MAX phase Ti2AlC was demonstrated by measuring the saturable absorption of Ti2AlC- polyvinyl (PVA) film. The modulation depth of the Ti2AlC-PVA film is calculated to be 2.21%. Stable Q-switched and mode-locked pulses train were achieved in Erbium-doped fiber ring cavity by using Ti2AlC-PVA film as a saturable absorber. The maximum single pulse energy of the Q-switched laser was 92.8 nJ, and the pulse width of the mode-locked laser was 680 fs. This study shows the great potential of MAX phase materials for ultrashort laser pulses generation and provides some valuable design guidelines for the preparation of SAs based on MAX phase materials.