Maximum Average Output Power Research Articles

Broadband few-layer niobium carbide MXene as saturable absorber for solid-state lasers

Recently, niobium-carbide (Nb2C) nanosheets, a member of MXene family, have gained significant attention because of their unique physical and chemical properties. Here, the few-layer Nb2C nanosheets were synthesized by a combination of selective etching and liquid cascade centrifugation. The broadband absorption properties of the few-layer Nb2C nanosheets were systematically investigated by the open-aperture Z-scan technique. The results indicate the excellent saturable absorption responses of Nb2C nanosheets, revealing the promising optical modulate application of Nb2C in solid-state lasers. Using the Nb2C saturable absorber (SA), passively Q-switched solid-state lasers from visible to near-infrared range were realized, which presented a promising alternative for a broadband optical modulator. Furthermore, a passively mode-locked laser at 1.06 μm was successfully achieved based on the Nb2C SA. A pulse duration of 13.5 ps was produced with the maximum average output power of 426 mW and a repetition rate of 99.1 MHz. To the best of our knowledge, this is the first time to use Nb2C nanosheets as a broadband SA for the solid-state lasers. The results may promote further applications of 2D optoelectronic materials from visible to near-infrared range.

Efficient continuous wave and acousto-optical Q-switched Tm:Lu2O3 laser pumped by the laser diode at 1.7 μm

A resonantly-pumped continuous wave and acousto-optical (AO) Q-switched Tm:Lu2O3 laser was demonstrated in this paper. In the continuous-wave regime, with absorbed pump power of 15.4 W, the Tm:Lu2O3 laser delivered a maximum output power of 6.1 W and a slope efficiency of 66.4% with respect to the absorbed pump power. With a pulse repetition frequency of 10 kHz, the AO Q-switched Tm:Lu2O3 laser produced maximum average output power of 3.87 W. At the pulse repetition frequency of 5 kHz, the AO Q-switched Tm:Lu2O3 laser reached the maximum pulse energy of 0.74 mJ and the minimum pulse width of 46 ns, resulting in a peak power of 16.1 kW.

Magnetically coupled piezoelectric galloping-based energy harvester using a tandem configuration

Herein, we propose a piezoelectric galloping-based energy harvester that uses a magnetic coupling effect to improve its energetic performance. This proposed structure includes two elastic structures with bluff bodies arranged in a tandem configuration and a pair of repulsive magnets installed between the two bluff bodies to enable the use of their mutual interaction. A nonlinear coupled aero-electro-mechanical model is established using the extended Hamilton principle to gain a comprehensive understanding of the nonlinear dynamic behaviors of the proposed system. The mechanism of the magnetic interaction between the outer and inner bluff bodies was thoroughly investigated through time histories, phase portrait, and frequency spectrum analysis. The experimental results exhibited good agreement with the analytic results, highlighting that the present model is considerably accurate and reliable. Compared with the conventional system without the engagement of the magnetic coupling effect, a maximum overall average output power of 8.09 mW and power improvement rate of 65% could be obtained for the proposed energy harvesting system with the optimal magnetic gap distance. The proposed energy harvesting system is expected to be a promising alternative for the convenient and practical development of efficient wind energy harvesters.

Generation of a 59 fs pulse with a 550 nm spectral range in a mode-locked Er-doped single-mode fiber laser system

We demonstrated a compact broad spectrum ultrashort fiber laser system that employed a similariton laser as a seed and fiber-optic nonlinearities in an erbium-doped fiber amplifier to broaden the optical spectrum. The system generated a stable 59 fs ultrashort pulse with a spectral bandwidth beyond 550 nm (i.e. 1490–2030 nm). The mode-locked oscillator produced an 85.9 fs similariton pulse at the wavelength of 1553 nm. The maximum average output power of the laser system was 251 mW. This new type of standard single-mode fiber-format energetic ultrashort system was suitable as a source for biological tissue imaging, broad-band spectroscopy, and optical frequency combs.

An in-band diode-end-pumped high-power and high-efficiency ultrashort pulse Nd:YVO4 bulk laser mode-locked by a frequency doubling LBO crystal

Nonlinear mirror (NLM) mode locking has also been verified to be an efficient technology for high-power ultrashort pulse laser generation. In this paper, we report on high-power and high-efficiency NLM mode-locked Nd:YVO4 laser with a 880-nm diode laser for in-band pumping, which has very rarely been investigated in the past. The achieved maximum average output power reached 6.76 W at an absorbed power of 13.82 W corresponding to a slope efficiency of 54.5%. Thanks to the used type I LBO crystal with small group velocity mismatch, the achieved pulse duration was as short as 6.5 ps. The results represent one of the best performances that ever achieved for NLM mode-locked Nd:YVO4 laser. NLM mode locking could be very promising for high-power ultrashort pulse generation in visible and middle infrared wavelengths, at which SESAMs are still not mature and the average output powers of ultrafast laser oscillators are also still limited to great extent.

3.46 μm Q-switched Er3+:ZBLAN fiber laser based on a semiconductor saturable absorber mirror

By adopting a InAs based semiconductor saturable absorber mirror (SESAM), we have demonstrated a 3.46 μm passively Q-switched Er3+:ZBLAN fiber laser. An amplified spontaneous emission (ASE) seeded 1973 nm pump source is introduced to enhance the temporal stability. Stable 3.46 μm Q-switched pulse trains are obtained with a maximum repetition rate of 58.71 kHz and corresponding pulse width of 2.47 μs. The maximum average output power and single pulse energy are 63 mW and 1.4 μJ, respectively. The pulse characteristics with respect to the two pump powers are also evaluated. The results prove that the commercial SESAMs in stock have the capacity to extend the operation wavelength to the mid-infrared (mid-IR) wavelength region beyond 3.0 μm.

Characterisation of passively Q-switched Yb:Lu2O3 ceramic laser based on graphdiyne absorber

A stable pulsed Yb:Lu2O3 ceramic laser using graphdiyne (GDY) as a saturable absorber has been successfully demonstrated for the first time. The nonlinear optical absorption of GDY was obtained by a homemade picosecond pulsed solid-state laser at ~1064 nm as the source, which indicate the feasibility of GDY in laser modulation. The passively Q-switched Yb:Lu2O3/GDY laser was carried out. A 288 mW maximum average output power was achieved. The obtained repetition rate, pulse energy and peak power were 46.20 kHz, 6.23 μJ and 3.85 W, respectively, when the absorbed pump power of Yb:Lu2O3 ceramics was 2.3 W. These results indicate that GDY is a promising saturable absorption material and is expected to be widely used in ceramic laser.

Continuous wave and rhenium disulphide-based Nd:GdTaO4 laser under direct pumping

In this paper, a continuous wave (CW) and rhenium disulphide (ReS2) passively Q-switched Nd:GdTaO4 laser under the pump at 879 nm was firstly reported. CW output characteristics under indirect 808 nm pumping and direct 879 nm pumping were investigated, respectively. By comparison with indirect pumping, the direct pump at 879 nm effectively relieved thermal lenses effect. Under direct pumping, the maximum CW output power was 5.1 W with slope efficiencies (ηs) of 48.6%. In the indirect pumping a maximum CW output power of 4.3 W was obtained, corresponding to ηs of 41.2%. A ReS2 nanosheet was utilized to achieve the pulsed laser output. At absorbed pump power of 7.1 W, the highest repetition rate, narrowest pulse width, maximum average output power, single pulse energy, and peak power reached 67 kHz, 230 ns, 1 W, 14.93 μJ, and 64.9 W, respectively.

Passively Q-switched Nd:GdNbO4 laser using platinum diselenide under direct pumping

A pulsed Nd:GdNbO4 laser using two-dimensional (2D) platinum diselenide (PtSe2) nanosheet as a saturable absorber (SA) is reported for the first time. The optical characteristics and microstructure of PtSe2 nanosheet were investigated at first. The passively Q-switched 1.06 μm Nd:GdNbO4/PtSe2 laser was carried out under direct pumping. A 426 mW maximum average output power was achieved. The obtained pulse duration, repetition rate, pulse energy and peak power were 300 ns, 210 kHz, 2 μJ and 6.8 W, respectively, when the absorbed pump power of Nd:GdNbO4 crystal was 3.8 W.

Bistable energy harvester using easy snap-through performance to increase output power

This paper describes a novel bistable piezoelectric energy harvester that collects kinetic energy from ambient vibrations for a sustainable powering of microelectronics. The host structure is a beam pre-deformed into a sinusoidal form, with piezoelectric layers on its upper and lower surfaces. A U-shaped torsion device is integrated into the middle of the beam to facilitate a more efficient break through the potential barrier. The harvester is tested under different conditions by a vibration test system. Experimentally, the peak open-circuit output voltage is 1377 mV (when the pre-deformation height is 10 mm and the mass of the block is 40 g, with a frequency range of 6.4–11.5Hz.). At this point, snap-through occurs in the generating beam. As the load resistance of the harvester’s external circuit increases, the output voltage increases sharply and then flattens; the output power first increases and then decreases. At a load of 47 kΩ the harvester reaches its optimal output state with a maximum average output power is 0.179 mW.

10 µJ noise-like pulse generated from all fiberized Tm-doped fiber oscillator and amplifier.

Herein, we presented a high energy noise-like (NL) pulse Tm-doped fiber laser (TDFL) system. Relying on the nonlinear amplifying loop mirror (NALM), stable noise-like pulses with coherence spike width of ∼317 fs and envelope width of ∼4.2 ns were obtained from an all polarization-maintaining fiberized oscillator at central wavelength of ∼1946.4 nm with 3 dB bandwidth of ∼24.9 nm. After the amplification in an all-fiberized TDF amplifier system, the maximum average output power of ∼32.8 W and pulse energy of ∼10.1 µJ were obtained, which represents the highest pulse energy of NL pulse at ∼2 µm, to the best of our knowledge. We believe that the high energy NL pulse source has the potential application in mid-infrared supercontinuum generation.

Hybridized Triboelectric‐Electromagnetic Nanogenerator for Wind Energy Harvesting to Realize Real‐Time Power Supply of Sensor Nodes

AbstractAs the power consumption of various electronic devices is gradually reduced to milliwatt or even microwatt level, it is possible to achieve self‐powered electronic devices by obtaining weak energy from the environment. In this article, a hybrid nanogenerator that contains two working parts, —the triboelectric nanogenerator (TENG) in sliding independent layer mode and the electromagnetic generator (EMG) in rotating mode, is reported. The hybrid generator can effectively broaden the output voltage range while shortening the voltage boost time. After polishing the surface of nylon film with different mesh sandpaper, the maximum increase of output voltage and current can reach 60% and 80%, respectively. When the wind speed is 9 m s–1, the maximum average output power values of TENG and EMG are 0.33 and 32.87 mW, respectively. Also the hybrid nanogenerator can stably power 200 light‐emitting diodes (LEDs) and hygro‐thermograph after working for 2 s. Compared with the method of supplying power to electronic devices after a long period of energy storage, the triboelectric‐electromagnetic hybrid nanogenerator that is designed can realize real‐time power supply for wireless sensor nodes and Bluetooth modules at a wind speed of 10.5 m s–1, and the voltage at both ends is always maintained dynamic equilibrium.

Sub-nanosecond, high peak power Yb:YAG/Cr4+:YAG/YVO4 passively Q-switched Raman micro-laser operating at 1134 nm

We demonstrate a sub-nanosecond, high peak power Yb:YAG/Cr4+:YAG/YVO4 passively Q-switched Raman micro-laser (PQSRML) operating at 1134 nm. The effect of transmission of the output coupler (TOC) and Cr4+:YAG initial transmission (T0) on the Raman laser performance have been investigated. Stable Raman laser pulse trains have been observed for Yb:YAG/Cr4+:YAG/YVO4 PQSRMLs with different combinations of output couplers and Cr4+:YAG crystals. Maximum average output power of Raman laser was 142.8 mW with TOC = 11% output coupler and T0 = 90% Cr4+:YAG. Enhanced Stokes pulse performance of 24.1 μJ, 45.1 kW, 535 ps was achieved with TOC = 16% and T0 = 85% Cr4+:YAG. A modified Raman laser rate equation model is established and the theoretically calculated results are in fairly good agreement with experimental results.

Traditional soliton erbium-doped fiber laser with InSe as saturable absorber

Indium selenide (InSe) is a typical layered metal-chalcogenide semiconductor that has potential for developing ultrafast optoelectronic devices. In this work, InSe-polyvinyl alcohol (InSe-PVA) film is employed as saturable absorber and prepared by mixing InSe nanosheets solution and polyvinyl alcohol solution. The nonlinear absorption properties of the InSe saturable absorber (InSe-SA) are investigated, showing that the nonsaturable absorption and modulation depth are 37.5% and 9.55%, respectively. Traditional soliton lasers are generated in erbium-doped fiber (EDF) laser-employed InSe as a mode-locker. The central wavelength and pulse duration of the traditional soliton pulse are 1568.73 nm and 2.06 ps, respectively, under a repetition rate of 1.731 MHz. The maximum average output power is 16.4 mW at the pump power of 413 mW. To the best of our knowledge, this is the first demonstration of a traditional soliton pulse with InSe as a mode-locker. The experimental results further demonstrate that InSe is an outstanding nonlinear absorption material in ultrafast fiber laser.

Passively mode-locked laser at 1μm region based on tungsten trioxide (WO3) saturable absorber

Stable and efficient mode-locked operation at 1065 nm was demonstrated using tungsten trioxide (WO3) thin film as a saturable absorber (SA). The WO3 thin film composite was prepared by a low cost and simple method and it has a modulation depth of 20 %. As the SA film was inserted into a Ytterbium-doped fiber laser (YDFL) cavity. The mode-locked laser operated in normal dispersion regime and generated pulses at 1065 nm with 3-dB bandwidth of 1 nm. The YDFL operated at fixed repetition rate of 10 MHz with pulse width of 1.67 ps. The maximum average output power of 21.64 mW and pulse energy of 2.16 nJ were recorded at a pump power of 162 mW.

New near-infrared optical modulator of Co2+:β-Ga2O3 single crystal

As a binary oxide, β-Ga2O3 is a promising host material with high thermal conductivity compared with the traditional laser materials. In this work, Co2+-doped β-Ga2O3 single crystal was successfully grown by the edge-defined film-fed growth (EFG) method and firstly designed as a near-infrared (NIR) optical modulator by doping with cobalt. The doping concentration of Co2+ ions was determined to be 0.029 at.% by X-ray fluorescence. The thermal conductivity was determined to be 13.0 W·m-1·K-1 along a* direction. There were two typical broadband absorption peaks around 1173 nm and 1588 nm related to the transitions of transitions of 4A2(4F)→4T1(4F). By means of Z-scan technique, the third-order nonlinear refractive index of Co2+:β-Ga2O3 was measured to be 9.14×10−13 (esu), which was much larger than that of Cr4+:YAG crystal. It was further successfully employed as a saturable absorber for passively Q-switched lasers at 1342 nm. In the Q-switched regime, the maximum average output power of 35 mW was obtained with the shortest pulse width of 280 ns and repetition rate of 181 kHz. The results indicated that Co2+:β-Ga2O3 crystals have important potential to be used as optical modulators for passive Q-switching laser generation at the NIR band.

High signal-noise ratio passively mode-locked femtosecond Yb: CaF2 laser at 1034 nm

Stable and self-starting diode-pumped passively mode-locked Yb: CaF2 laser with a high signal-noise ratio is experimentally demonstrated by using a semiconductor saturable absorber mirror (SESAM). By using GTI mirrors to manage the intracavity dispersions, the generated pulses are as short as 573 fs at the central wavelength of 1034 nm with a spectral bandwidth of 2.08 nm. When the fundamental repetition frequency is 51.5 MHz, the single pulse energy is 7.4 nJ, the peak power is 12.9 kW, and the maximum average output power can reach 382 mW, corresponding to an optical-to-optical conversion efficiency of 10.3 %. The recorded RF spectrum shows a signal-noise ratio as high as 70 dB, exhibiting the excellent ability of Yb: CaF2 crystal in generating high-stability femtosecond lasers.

Nanosecond optical parametric oscillator with midinfrared intracavity difference-frequency mixing in orientation-patterned GaAs.

We report on efficient midinfrared difference-frequency generation (DFG) in orientation-patterned GaAs by intracavity mixing the signal and idler pulses of a narrowband nanosecond optical parametric oscillator based on periodically poled LiNbO3. The maximum average DFG output power reached 215 mW at 8.15 µm for a repetition rate of 35 kHz. The temperature tuning range spanned over 8026-8710 nm. The maximum overall conversion efficiency from 1 to 8 µm amounted to ∼1.3%.

Ultra-long-period grating-based multi-wavelength ultrafast fiber laser [Invited

We propose and demonstrate the cascaded multi-wavelength mode-locked erbium-doped fiber laser (EDFL) based on ultra-long-period gratings (ULPGs) for the first time, to the best of our knowledge. Study found that the ULPG can be used as both a mode-locker for pulse shaping and a comb filter for multi-wavelength generation simultaneously. Using the dual-function of ULPG, three-, four-, five-, six-, and seven-wavelength mode-locked pulses are obtained in EDFL, seven of which are the largest number of wavelengths up to now. For the four-wavelength soliton pulses, their pulse width is about 7.8 ps. The maximum average output power and slope efficiency of these pulses are 8.4 mW and 2.03%, respectively. Besides the conventional pulses, hybrid soliton pulses composed of a four-wavelength pulse and single soliton are also observed. Finally, the effect of cavity dispersion on the multi-wavelength mode-locked pulses is also discussed. Our findings indicate that apart from common sensing and filtering, the ULPG may also possess attractive nonlinear pulse-shaping property for ultrafast photonics application.

Short Pulse Width and High Peak Power 457 nm Deep Blue Laser with V-Type Cavity

An intracavity frequency doubling acousto-optically Q-switched Neodymium-doped Yttrium Orthvanadate (Nd:YVO4) 457 nm blue laser by employing a three-mirror folded cavity was demonstrated. With the incident pump power of 40.4 W, the maximum average output power of 439 mW 457 nm laser, and the minimum pulse duration of 86.14 ns and the maximum peak power of 510 W were achieved at 10 kHz. The M2 factors are 1.23 and 1.61 in X and Y directions, respectively. The power stability in two hours is better than 2%.