Maximum Single Pulse Energy Research Articles

Passively mode-locking fiber laser based on Cr2Si2Te6 saturable absorber

This paper reports on the generation of third-order harmonic mode-locking, double-pulse phenomena, and conventional solitons in an erbium-doped fiber laser using Cr2Si2Te6 as a saturable absorber (SA). The double-balance probing method was employed to examine the nonlinear characteristics of Cr2Si2Te6-SA. Its modulation depth is 2.35 %, and its saturation intensity is 29.74 MW/cm2. We discovered conventional soliton functioning with a center wavelength of 1561.8 nm at a pump power of 34.76 mW. It has a repetition frequency of 6.76 MHz and a signal-to-noise ratio of 45 dB. As the pump power increased, the traditional soliton was able to maintain its existence in the range of 34.76 mW to 80.96 mW. The maximum output power reaches 1.1 mW when the pump power is 80.96 mW, and the maximum single-pulse energy of the conventional soliton is 0.16 nJ. Furthermore, we observed third-order harmonic mode-locking and double-pulse phenomena at pump outputs of 53.65 mW and 71.16 mW. The experimental findings demonstrate the excellent nonlinear effect of the SA based on Cr2Si2Te6. In ultrashort-pulse fiber lasers, Cr2Si2Te6 nanosheets can be employed as an efficient saturable absorption material.

1 kHz, 5.3 kW peak power pulse generation from a LiNbO3 acousto-optically Q-switched Er:YAP laser

In this paper, we present, for the first time, a bulk LiNbO3 (LN) acousto-optic (AO) Q-switched Er:YAP laser operating at a pulse repetition frequency (PRF) of 1 kHz. At this frequency, the laser achieves a maximum single pulse energy of 0.34 mJ, with a corresponding pulse duration of 64.5 ns and a peak power of 5.3 kW. Additionally, we characterize the laser beam quality factors, Mx2 = 2.7 and My2 = 2.5, and its central wavelength at 2730.7 nm, all at 1 kHz. These results highlight the significant potential of LN AO Q-switched Er:YAP lasers for enhancing mid-infrared laser applications.

Large-energy operation of an Er-doped fiber laser with ZrGeTe4 saturable absorber

ZrGeTe4 as a layered semiconductor material with good stability and optoelectronic properties, and excellent saturable absorption characteristics, but its application in fiber lasers is still insufficient. In order to explore its application in fiber lasers, we prepared ZrGeTe4-PVA thin film by liquid phase exfoliation and performed a series of characterizations. A modulation depth of 13.15 %, a non-saturated loss of 6.4 %, and a saturation intensity of 5.5 MW/cm2 were obtained. Then used the ZrGeTe4-PVA thin film as the saturable absorber (SA) in an Er-doped fiber laser (EDFL), the large-energy operation could be realized. In the case of a cavity length of 234 m, when the pump power was increased to 1229 mW, a maximum single pulse energy of about 32.72 nJ was achieved, with a repetition frequency of 859 kHz. To the best of our knowledge, this is the highest single-pulse energy achieved in an EDFL based on ZrGeTe4-SA. This experiment shows that the ZrGeTe4 is a promising two-dimensional (2D) material with good nonlinear absorption properties, proving that it is a promising pulse modulation of SA and laying a foundation for its subsequent study in fiber lasers.

Generation of high-energy self-mode-locked pulses in a Tm-doped fiber laser

The incorporation of a material-based or artificial saturable absorber into a fiber laser cavity imposes a limitation on energy enhancement owing to its low damage threshold and high environmental sensitivity. To address this issue, one promising alternative approach is the utilization of the self-mode-locking technique. Here, we present a robust self-mode-locked Tm-doped fiber laser with high pulse energy emission. A simple and compact fiber laser structure is realized by utilizing a section of a Tm-doped fiber, serving both as a gain medium and a saturable absorber. Thus, the operational stability is enhanced, especially under high-energy conditions. Furthermore, the realization of high-energy pulses is accomplished through the integration of dispersion management technique. Experimental results reveal that the maximum single-pulse energy increases from 34.8 pJ to 120.2 nJ as the round-trip group delay dispersion decreases from −0.43 to −12.40 ps2. The proposed self-mode-locked Tm-doped fiber laser under high-energy operation exhibits remarkable performance. Our results provide a simple approach to obtaining a mid-infrared laser source with high pulse energy and hold significant potential for advancing high-energy laser systems.

CH3NH3PbBr3 as a saturable absorber for infrared passively Q-switched solid-state laser

Perovskite materials are used in the field of lasers and can achieved good results. In this paper, we prepared an organic–inorganic hybridized CH3NH3PbBr3 saturable absorber (SA). Continuous wave (CW) Tm:YAP solid-state lasers with CH3NH3PbBr3-SA successfully obtained pulsed lasing at 1987.5 nm after continuous tuning. In CW mode, the maximum absorbed pump power by the laser was 19.42 W, which corresponds to 0.68 W output power. The central output wavelength of the continuous wave laser was 1989.9 nm. In PQS mode, the output power of laser was 203 mW. Under the condition of maximum repetition frequency of 45 kHz, the narrowest pulse width of the PQS laser were 1.16 μs. Meanwhile, the laser produced a maximum single-pulse energy (4.5 μJ) and a maximum peak power (3.9 W). The beam quality factors (the horizontal/vertical directions) were M2 x = 1.1 and M2 y = 1.39. The CH3NH3PbBr3 was an excellent SA for infrared PQS solid-state lasers, which had a large potential for development applications in the field of lasers.

High energy and high repetition rate QCW-LD end-pumped electro-optical Q-switched Yb:YAG laser

The quasi-continuous wave laser diode (QCW-LD) pumping is considered as the most efficient way for generating high energy nanosecond pulsed laser with repetition rate ranging from 50 to 1000 Hz. Here, a high efficiency, high repetition rate and high energy QCW-LD end-pumped electro-optical (EO) Q-switched Yb:YAG laser was demonstrated. The shortest pulse duration of 17.4 ns with a maximum single pulse energy of 5.1 mJ was obtained at the repetition rate of 100 Hz. As the repetition rate increases up to 500 Hz, the maximum output single pulse energy was obtained to be 5.38 mJ with the pulse width of 18.7 ns, corresponding to the slope efficiency of 21.6% and beam quality factor of M x 2=1.04, and M y 2=1.01. In addition, a theoretical study was carried by numerical simulation of the rate equations, and the results were agreed well with the experimental ones. The results show that QCW-LD pumping with Yb-doped crystals is a promising way for highly efficient, high-energy and high repetition rate nanosecond pulsed laser generation.

High-performance 1.06 μm continuous-wave and passive Q-switched laser with a novel Nd: CTGAS crystal

This paper reported continuous-wave and passive Q-switched laser at 1.06 μm with a novel langasite Nd3+: Ca3TaGa2.1Al0.9Si2O14 crystal. A high-efficiency continuous-wave laser with an output power of 1.71 W was obtained at an absorbed pump power of 3.92 W; the corresponding slope efficiency was 46.5 %, and optical conversion efficiency was 43.6 %. A high-performance passive Q-switched laser was realized with Cr4+: Y3Al5O12 as a saturable absorber. The shortest pulse width was 8.2 ns, and the maximum single pulse energy and peak power were 75.5 μJ and 3.83 kW, respectively.

Watt-level output power and near-diffraction-limit beam quality mid-infrared Ho:GdVO4 self-Raman laser at 2.5 µm.

We demonstrate an efficient active Q-switched Ho:GdVO4 self-Raman laser at 2500 nm for the first time, to our knowledge. Using Ho:GdVO4 crystal as the gain medium for both the 2048nm fundamental laser and the 2500 nm Raman laser, the output performances of a new mid-infrared self-Raman laser were investigated. The maximum average output power of 1.45 W was achieved at an incident pump power of 22.5 W, with a slope efficiency of 25.8%, for an output transmittance of 30% and a pulse repetition frequency of 15 kHz. The maximum single pulse energy of 96.7 µJ with a pulse width of 11.35 ns was obtained, corresponding to the peak power of 8.5 kW. The beam quality was near diffraction limited with the M2 factors of 1.15 and 1.06 along the x and y directions. Moreover, adopting the two-end output way of the fundamental laser and the Raman laser, the Raman gain coefficient of Ho:GdVO4 crystal was estimated to be 1.14 cm/GW at 2048nm. This work shows that Ho:GdVO4 is an excellent self-Raman laser crystal for the generation of high power Raman laser at 2.5 µm.

Passively mode-locked fiber lasers with broadband FeOOH saturable absorber

In this contribution, we synthesized iron oxide hydroxide (FeOOH) nanomaterials and successfully demonstrated the application of FeOOH-based saturable absorbers in ultrafast photonics at 1 μm and 1.5 μm. Various characterizations were conducted to analyze the morphological and structural features of FeOOH nanomaterials. Subsequently, a tapered fiber coated with FeOOH was integrated into the resonator as a saturable absorber, exhibiting the significant saturable absorption effect with modulation depths of 1.26 % at 1 μm and 2.61 % at 1.5 μm, respectively. In an Yb-doped fiber laser, stable noise-like mode-locking pulses were achieved with a pulse duration of 519 fs at the operating wavelength of 1037.2 nm with a full-width at half-maximum (FWHM) spectral bandwidth of 4.7 nm, yielding a maximum single pulse energy of 1.23 nJ with a high signal-to-noise ratio (SNR) of 47.8 dB. Meanwhile, the conventional soliton pulses were produced in the passively mode-locked Er-doped fiber laser, featuring a pulse duration of 1.02 ps, and an SNR of 42.5 dB at a peak wavelength of 1559.25 nm with a FWHM bandwidth of 2.8 nm. This work demonstrates the considerable nonlinear optical properties of FeOOH nanomaterials in the near-infrared range, proposing a promising saturable absorber for ultrafast photonics applications.

WSe2/BN heterostructure as saturable absorber for a diode-pumped passively Q-switched 2 µm solid-state laser.

We have successfully achieved the synthesis of heterojunction consisting of WSe2 and BN, by using a liquid phase exfoliation method, and characterization of the prepared materials under the microstructure. The WSe2/BN heterojunction was used as a saturable absorber in the Tm:YAP laser for passively Q-switched operation, and a pulsed laser with an output wavelength around 2 µm range was successfully obtained. After comparing the effects of resonators composed of different cavity mirrors, it is concluded that when the curvature radius of the input mirror is 250 mm and the transmittance of the output coupler is 2.5%, the best output performance was obtained. The maximum average output power of 834 mW was achieved, with a pulsed repetition frequency of 43.51 kHz and a minimum pulse duration of 1.28 µs, corresponding to a peak power of 14.97 W and a maximum single pulse energy of 19.17 µJ.

High-power and high-energy coherent sources at 1.1-μm based on compact diode-end-pumped Nd:YAG crystal fiber lasers

In this work, we have reported the first Nd:YAG single crystal fiber lasers at 1.1 μm spectral region operating in continuous-wave and passively Q-switched modes. A maximum continuous-wave output power of 34.52 W is achieved and the corresponding slope efficiency with respect to pump power is 39.9 %. Using Cr4+:YAG as saturable absorber, a maximum average output power of 10.37 W is obtained during passively Q-switched laser operation. The maximum pulse peak power and single pulse energy reach approximately 103.7 kW and 1.1 mJ, respectively. In terms of diode end pumping geometry, these reported results represent the best achievements of 1.1-μm lasers, which indicate that crystal fiber has great potential in improving laser power and energy.

High Repetition Frequency Solid-State Green Laser with Large Stable Area for Water Jet Guided.

This paper presents the design and experimental results of a long cavity length Nd:YAG laser with a large stable zone for water jet-guided laser (WJGL) applications. The design is based on the light transmission matrix and resonator stability conditions, aiming to achieve a large stable zone and a short cut-off thermal focal length (CTFL). A folded concave resonator is researched to enhance the cavity length, and the influence of the tunable cavity arm length on the oscillating beam in the resonator and in the YAG crystal is theoretically studied. Moreover, the effects of the output mirror curvature and the cavity arm length on the range of the stable area and the cut-off thermal focal length are also investigated. Experimental results show that a stable green laser output is obtained after second harmonic generation (SHG) with a pulse width ranging from 43 to 143 ns within the laser operating frequency range of 5-20 kHz. At an operation frequency of 10 kHz, the output power is 21.33 W, and the instability of the output power within 400 min is 0.88%. The laser source achieves a maximum power of 25.7 W at 20 kHz, and the maximum single pulse energy reaches 2.7 mJ at 6 kHz. Finally, this is used as the laser source to couple with a water jet with a diameter of 100 microns, achieving a lossless water conductivity transmission over 60 mm length. These results demonstrate the suitability of the designed laser source for WJGL technology research. In precision machining applications, this technology exhibits processing advantages of low thermal damage (~2 μm) and large depth (>10 mm), for 7075 aluminum alloy.

High-Quality Acousto-Optic Modulators with High Diffraction Efficiency, Polarization Extinction Ratio, and Small Insertion Loss Based on a Novel BaO-TeO2 -WO3 Glass.

The Q-switched material and device have attracted extensive attention due to their irreplaceable role in pulsed lasers. In this paper, BaO-TeO2 -WO3 glass (BTW glass) with sound velocity and sound attenuation coefficient of 3422 m-1 s and 0.653dB cm-1 is successfully selected and fabricated as acousto-optic material. Both free-spaced and fiber-coupled acousto-optic modulation devices based on BTW glass are designed and fabricated. The primary parameters such as diffraction efficiency, polarization extinction ratio, and insertion loss are comparable to or even surpassed that of commercial devices. A 1064nm pulsed laser is successfully realized with a BTW glass free-spaced acousto-optic modulator. The maximum optical conversion efficiency, the narrowest pulse width, and the maximum single pulse energy of the 1064nm pulsed laser are 32%, 54ns, and 242.6 µJ, respectively. Both the device and laser performance indicate that the BTW glass is a remarkable acousto-optic material.

Monolithic tapered Yb-doped fiber chirped pulse amplifier delivering 126 μJ and 207 MW femtosecond laser with near diffraction-limited beam quality

In this work, a high-energy and high peak power chirped pulse amplification system with near diffraction-limited beam quality based on tapered confined-doped fiber (TCF) is experimentally demonstrated. The TCF has a core numerical aperture of 0.07 with core/cladding diameter of 35/250 µm at the thin end and 56/400 μm at the thick end. With a backward-pumping configuration, a maximum single pulse energy of 177.9 μJ at a repetition rate of 504 kHz is realized, corresponding to an average power of 89.7 W. Through partially compensating for the accumulated nonlinear phase during the amplification process via adjusting the high order dispersion of the stretching chirped fiber Bragg grating, the duration of the amplified pulse is compressed to 401 fs with a pulse energy of 126.3 μJ and a peak power of 207 MW, which to the best of our knowledge represents the highest peak power ever reported from a monolithic ultrafast fiber laser. At the highest energy, the polarization extinction ratio and the M2 factor were respectively measured to be ~ 19 dB and 1.20. In addition, the corresponding intensity noise properties as well as the short- and long-term stability were also examined, verifying a stable operation of the system. It is believed that the demonstrated laser source could find important applications in, for example, advanced manufacturing and photomedicine.Graphical

1178 nm self-Q-switched Raman laser generation enabled by BaTeW2O9 crystal

Multifunctional composite crystals have received great attention as an effective way to simplify the laser cavity. In this work, a self-Q-switched Raman laser operating at 1178 nm is demonstrated by using a multifunctional composite crystal BaTeW2O9 (BTW). An acousto-optic modulator (AOM) with a diffraction efficiency of 74% is designed and fabricated based on the Raman crystal BTW. A 1064 nm pulsed laser with a maximum single pulse energy of 260.6 μJ corresponding to a pulse width of 42 ns is obtained by inserting the BTW AOM into the laser cavity with Nd: YAG as the laser gain medium. Then an 1178 nm self-Q-switched Raman laser with the maximum single pulse energy of 22.8 μJ corresponding to a pulse width of 10 ns is successfully obtained. This work not only provides a competitive multifunctional composite device that can simplify the Raman laser cavity design but also has guiding significance for the design and development of multifunctional composite crystals.

Generation of dual large energy pulses in Er3+-doped fiber lasers based on ZrTe2 saturable absorber via polarization manipulation

We report on the generation of dual large energy pulses in a passively mode-locked Er-doped fiber laser based on ZrTe2 as saturable absorber. When the pump power is 100.4 mW, dissipative soliton resonance mode-locked operation with an output power of 9.1 mW is generated. With the increase of pump power, its average output power increased from 9.1 to 52 mW, and its corresponding fundamental repetition rate and maximum single-pulse energy are 1.22 MHz and 42.6 nJ, respectively. By properly adjusting the polarization controller, stable large energy mode-locked pulse is obtained at the same pump power. At the maximum pump power of 617.5 mW, the maximum average output power, and single-pulse energy are 55.8 mW and 45.7 nJ, respectively. Our experimental results proved that ZrTe2 has good performance in obtaining large energy pulse operations, which promotes the development of ZrTe2 nanosheets as an effective saturable absorber in the future.

A good beam quality Ho:GdVO4 laser pumped by thulium‐doped fiber laser at 1940 nm

AbstractWe demonstrate a Ho:GdVO4 solid‐state laser pumped by a thulium (Tm)‐doped fiber laser at 1940nm. In continuous wave mode, a maximum output power of 6.1 W was obtained under the absorbed pump power of 31.9 W with the slope efficiency of 24.3% at the temperature of 18°C. The wavelength of output laser was 2048.53 nm with full width at half maximum of 0.2 nm. In Q‐switched mode, a maximum single pulse energy of 0.94 mJ was obtained with a minimum pulse duration of 7.3 ns at the pulse repetition frequency of 5 kHz, corresponding to a peak power of 129 kW and an average output power of 4.7 W. The beam quality factor of M2 was 1.01 under the maximum absorbed pump power. To the best of our knowledge, 0.94 mJ is the highest single pulse energy in single holmium (Ho) doped GdVO4 laser pumped by Tm‐doped fiber laser at 1940 nm, and 1.01 is the best beam quality factor of M2 in Ho:GdVO4 laser pumped by a Tm‐doped fiber laser.

Peak-power of 25 W passively Q-switched [formula omitted]2.8 [formula omitted]m Er:YAP bulk laser based on a reflective TaSe2 saturable absorber mirror

Improving the overall performance of saturable absorber mirrors (SAMs) based on Two-dimensional (2D) narrow-band-gap materials is critically important in their applications of mid-infrared pulse laser sources. Herein, a reflective TaSe2 SAM with laser-induced damage threshold of ∼12 MW/cm2 was successfully fabricated, the saturable absorption properties around 2.8 μm were characterized with a modulation depth of 5.3% and a total unsaturated loss of 2.2%. With the as-prepared SAM, high-peak-power passively Q-switched Er:YAP laser operation at ∼2.8 μm was realized. For the condition of the maximum absorbed pump power of 8.0 W, the maximum average output power of 0.7 W was obtained with a pulse width of 264 ns at a repetition rate of 105.5 kHz, which corresponds to a maximum single pulse energy of 6.6 μ J and a peak power of 25.1 W.

2637.5 nm Mid-infrared SrWO4 Raman laser intracavity-pumped by an actively Q-switched Ho:YAG laser

We first report a 2.6 µm mid-infrared SrWO4 Raman laser, intracavity-pumped by an actively Q-switched Ho:YAG laser. The 2122 nm fundamental laser was generated from the Ho:YAG laser, which was resonantly pumped by a 1908 nm continuous wave Tm:YLF laser. Based on the stimulated Raman scattering effect of SrWO4 crystal, the fundamental wavelength of 2122 nm was converted into the Raman wavelength of 2637.5 nm, corresponding to the Raman shift of 921 cm−1. The output characteristics of SrWO4 Raman laser were investigated at various repetition frequencies. The maximum average output power was 720 mW at the 6.6 W absorbed pump power and 4 kHz repetition frequency. The maximum single pulse energy and peak power were 196 μJ and 10.9 kW at the 5.6 W absorbed pump power and 3 kHz repetition frequency, respectively. The pulse Raman laser near 2.6 µm has potential applications in material processing, spectroscopy, remote sensing, and nonlinear frequency conversion.

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.