Diode Pump Power Research Articles

Watt-Level Dual-Wavelength Q-Switched Mode-Locked All-Solid-State Tm:CYA Laser

A passively Q-switched mode-locked all-solid-state Tm:CaYAIO4 (Tm:CYA) laser with a MoS2 saturable absorber is demonstrated for the first time. Employing a typical X-type cavity and output coupling mirror of 9%, when the laser diode (LD) pump power is higher than 8.5W, the laser enters into a stable Q-switched mode-locked operation, further increasing the pump power into a dual-wavelength operating state, the corresponding typical center wavelengths are 1863nm and 1877nm. When the pump power reaches 20W, the maximum output power is 1.15W, the frequency of mode-locked pulse is 103.7MHz, and the modulation depth of mode-locked pulses in the Q envelope is close to 100%. The results prove that MoS2 SA is suitable for 2 μm high power mode locking.

Enhancement of Intracavity-Pumped Terahertz Parametric Oscillator Power by Adopting Diode-Side Pumped Configuration Based on KTiOPO4 Crystal

In this paper, a KTiOPO4 (KTP) crystal is used as the nonlinear medium in an intracavity-pumped terahertz parametric oscillator (TPO) based on stimulated polariton scattering (SPS). Almost all the reported intracavity SPS sources adopt the diode-end pumped configuration, and the THz output power is limited by the serious thermal effect and small fundamental beam size. For improving the THz output power, we propose diode-side pumping for the laser medium to get a higher fundamental power and a larger fundamental beam size. A convex–plane fundamental laser resonator is used to further offset the thermal effect and increase the fundamental beam size. The THz frequency of the intracavity-pumped KTP terahertz parametric oscillator can be discontinuously tuned from 3.19 THz to 5.94 THz with three gaps. The fundamental beam diameter in the KTP crystal is about 1.3 mm. The maximum average THz power is 166 μW at 5.74 THz under a pulse repetition frequency (PRF) of 6 kHz and a diode pump power of 98 W. By means of the diode-side pumped configuration, the maximum THz output power is more than two-fold higher compared to the diode-end pumped configuration reported using the KTP crystal.

Nickel nanoparticles‐based saturable absorber: Toward compact multiwavelength Yb‐doped fiber pulsed lasers near 1 μm region

AbstractWe experimentally demonstrate a compact pulsed dual‐wavelength Ytterbium‐doped fiber laser (YDF) based on Nickel nanoparticles (Ni‐NPs) as a Q‐switcher and optical stabilizer. By integrating the Ni‐NPs saturable absorber (SA) in the cavity, and adjust the 975 nm diode pump power to 185 mW, a self‐starting passively Q‐switched was generated at a central wavelength of 1038.5 nm. By exploiting the extra high nonlinearity of Ni‐NPs, the homogenous gain broadening of the YDF oscillator can be suppressed. Consequently, at a pump power of 195 mW, a stable dual‐wavelength passively Q‐switching laser has been generated at room temperature without any intracavity spectral filters or modulation elements. As increases the pump power up to the maximum value of 288 mW, the Ytterbium‐doped fiber laser observed that the smallest pulse width, the maximum repetition rate, and the maximum pulse energy of 1.44 μs, 100.1 kHz, and 4.45 nJ, respectively. The Ni‐NPs SA proof its potential in generating multiwavelength pulsed laser in the 1 μm region for different photonic applications.

Ni-NPs doped PVA: An efficient saturable absorber for generation multiwavelength Q-switched fiber laser system near 1.5 μm

We report on the use of Nickel nanoparticles (Ni-NPs) as saturable absorber (SA) to generate Q-switched fiber laser pulses in C-band. The Ni-NPs were incorporated in polyvinyl alcohol (PVA) to produce thin film-based saturable absorber (SA) and integrated into an erbium-doped fiber laser (EDFL) ring cavity to generate passively Q-switching. The Ni-doped PVA SA reveals modulation depth of 15% and a saturation intensity of 200 MW/cm2. Lasing in CW region begins at 77 mW pump power, whereas stable self-starting Q-switching with a central wavelength of 1563.1 nm begins at 85 mW. By fine adjustment of the laser diode pump power up to 236.4 mW dual-, and triple- lasing lines have been observed at 1563.1, 1563.3 and 1563.4 with side mode suppression ratio (SMSR) of more than 49 dB. The proposed laser is useful for generating pulse laser with a minimum pulse width of 1.5 μs and a maximum repetition rate of 56.79 kHz with a pulse energy of about 4.33 nJ at the maximum pump power of 275 mW. The stability of the pulse is verified from the radio-frequency (RF) spectrum with a measured signal-to-noise ratio (SNR) of 44 dB. The ability of Ni-PVA as an effective SA may lead to further development of pulsed fiber laser in the field of photonics.

Dual-wavelength intracavity Raman laser driven by a coaxially pumped dual-crystal fundamental laser.

An actively Q-switched dual-wavelength intracavity Raman laser based on a coaxially pumped dual-crystal (Nd:YAG and b-cut Nd:YAP) fundamental configuration was theoretically and experimentally investigated. Stable dual-wavelength Stokes output at 1176 nm and 1195 nm was subsequently obtained by the Raman conversion from an a-cut YVO4 crystal. A total average power of 1.8 W was produced at 10 kHz pulse repetition frequency under an incident diode pump power of 15.8 W, in which the power levels at the two Stokes wavelengths were nearly equivalent. The power proportion and the interval between the dual-wavelength Stokes pulses could be manipulated actively by changing the pump focal position or pump wavelength.

Stable L-band multiwavelength erbium-doped fiber laser based on four-wave mixing using nickel nanofluid.

A simple continuous-wave multiwavelength erbium-doped fiber laser based on four-wave mixing has been successfully demonstrated utilizing nickel nanofluid (Ni-NF) for the first time, to the best of our knowledge. By fine adjustment of the laser diode pump power up to 196mW and without any intracavity filtering, stable dual-, triple-, and quadruple-lasing lines in the L-band have been observed at 1595.6nm, 1596.8nm, 1598nm, and 1599.2nm, respectively, with a signal-to-noise ratio ∼43 dB. The induced L-band wavelengths showed high stability with wavelength shifts <0.07 nm and power fluctuation of <3 dB by monitoring the output spectra for a duration of 30min at room temperature. Taking into account the superiority of Ni-NF in terms of compactness, low cost, and easy fabrication, this design can be practically used in a variety of nonlinear photonic applications.

Effects of nonlinear phase in cascaded mode-locked Nd:YVO4 laser.

A diode-pumped mode-locked Nd:YVO4 laser via positive cascaded second-order Kerr lens using periodically poled MgO:LN at 1064 nm was reported. Mode-locking performances including output power, bandwidth, pulse duration, and time-bandwidth product were studied under different phase-mismatched conditions. The induced nonlinear phase combined with soft aperture effect yield a stable mode-locked operation in a wide phase-mismatched range (-8π < ∆kL < -π). Additionally, the mode-locking bandwidth was broadened by self-phase modulation and the time-bandwidth product was increased to be more than twice the ideal product for a sech2 pulse shape. Under 11 W diode pump power, the measured average power, pulse repetition rate and pulse duration are 1.3 W, 186 MHz and 2.8 ps, respectively.

ИССЛЕДОВАНИЕ ОСОБЕННОСТЕЙ ТЕПЛОВОЙ ЛИНЗЫ В АКТИВНОМ ЭЛЕМЕНТЕ ЛАЗЕРНОГО УСИЛИТЕЛЯ ПРИ МОЩНОЙ ДИОДНОЙ НАКАЧКЕ

A femtosecond laser system with a pulse repetition rate up to 1 kHz is being developed at the Institute of Laser Physics of the SB RAS. The key component of the system is the channel of laser amplification based on media doped with Yb3+ ions. The designed average output power of the channel is 300 W. Thermal effects in high-power laser amplifiers are decisive for the parameters of the radiation at the output of system. In this paper the results of experimental measurements of thermal lens focal distance dependence in Yb:YAG active element on diode pump power using geometric method are given. Calculation of the dependence thermal lens focal distance on the power of pump power and a comparison with experimental data are given.

Tunable 3–6 THz Polariton Laser Exceeding 0.1 mW Average Output Power Based on Crystalline RbTiOPO 4

We report a diode-pumped, intracavity THz laser source based on stimulated polariton scattering in crystalline RbTiOPO4 using a surface-emitting configuration. The system was continuously tunable in four regions, from 3.05 to 3.16 THz, from 3.50 to 4.25 THz, from 4.57 to 4.75 THz, and from 5.40 to 5.98 THz. The laser delivered 124.7 μW average output power at 4.10 THz for only 6.0 W diode pump power at 808 nm, corresponding to a diode-to-THz conversion efficiency of 2.1 × 10−5. The horizontal and vertical beam quality parameters were $M_H^2 and $M_V^2 and the linewidth of the terahertz field was 28 GHz at 4.10 THz. The results demonstrate that the surface-emitting configuration is a very efficient technique to produce high-power THz laser sources with frequency-tunable output suitable for real-world applications.

Efficient Ho:CaF2 laser intracavity-pumped by a Tm:LuAG laser in-band pumped at 1.6 µm

In this paper we demonstrate an efficient intra-cavity pumped Ho:CaF2 laser based on a tandem in-band pumping scheme for the first time. The laser diode at 1.6 µm was employed to pump a Tm:LuAG crystal. At an incident laser diode pump power of 9.5 W, the in-band pumped Tm:LuAG laser realizes a maximum output power of 2.3 W and a slope efficiency of 33.4%. With the same incident pump power, a maximum output power of 1.5 W at 2085 nm was achieved with a slope efficiency of 24.2% in the Ho:CaF2 laser intra-cavity pumped by the Tm:LuAG laser. The beam quality factor of the Ho:CaF2 laser at the maximum output level was measured to be 1.3 and 1.2 in the horizontal and vertical directions, respectively.

Potassium titanyl arsenate based cascaded optical parametric oscillator emit at 2.5 µm derived by neodymium-doped yttrium lithium fluoride laser

We reported a potassium titanyl arsenate (KTA) based cascaded optical parametric oscillator (OPO). The secondary OPO signal light at 2.5 µm was obtained with two OPO processes in one non-critical phase matching cut KTA crystal. This cascaded OPO was driven by a Q-switched neodymium-doped yttrium lithium fluoride (Nd:YLF) laser at 1047 nm. Making full use of the negative thermal lens effect and long upper level fluorescence lifetime of Nd:YLF, signal power of 605 mW at 2503 nm was achieved with a pulse repetition frequency of 15 kHz and an incident diode pump power of 9.7 W. Therefore, the cascaded OPO derived by Q-switched Nd:YLF laser could provide high peak power pulsed laser emission in mid-infrared band.

Laser-induced nonlinear crystalline waveguide on glass fiber format and diode-pumped second harmonic generation

Abstract We report a diode pumped self-frequency-doubled nonlinear crystalline waveguide on glass fiber. A ribbon fiber has been drawn on the glass composition of 50GeO 2 -25B 2 O 3 -25(La,Yb) 2 O 3 . Surface channel waveguides have been written on the surface of the ribbon fiber, using space-selective laser heating method with the assistance of a 244 nm CW UV laser. The Raman spectrum of the written area indicates that the waveguide is composed of structure-deformed nonlinear (La,Yb)BGeO 5 crystal. The laser-induced surface wavy cracks have also been observed and the forming mechanism of the wavy cracks has been discussed. Efficient second harmonic generation has been observed from the laser-induced crystalline waveguide, using a 976 nm diode pump. 13 μW of 488 nm output has been observed from a 17 mm long waveguide with 26.0 mW of launched diode pump power, corresponding to a normalized conversion efficiency of 4.4%W −1 .

Diode-pumped power scalable Kerr-lens mode-locked Yb:CYA laser

Stable 68 fs pulses with the average power of 1.5 W is directly generated from a multimode diode-pumped Kerr-lens mode-locked Yb:CYA laser by separating the gain medium and Kerr medium. The repetition rate is about 50 MHz, resulting in a single pulse energy of 30 nJ and a peak power of 0.44 MW. To the best of our knowledge, this is the highest single pulse energy ever produced from a mode-locked Yb:CYA oscillator. Our experimental results show that Yb:CYA crystal is an excellent candidate for multiwatt, sub-100 fs pulse generation in diode-pumped all-solid-state lasers. It is believed that the output power can be scalable to multi-W while the pulse duration is maintained with this simple method.

Diode-pumped mid-infrared YVO4 Raman laser at 2418 nm

A mid-infrared YVO4 Raman laser intracavity-pumped by a diode-pumped actively Q-switched Tm:YAP laser at 1990 nm is demonstrated for the first time. An a-cut 30-mm-long YVO4 crystal is utilized in the Raman laser as a gain medium. With an incident diode pump power of 10.9 W, an average output power of 272 mW at the first Stokes wavelength of 2418 nm is obtained at a pulse repetition rate (PRR) of 1 kHz. The optical conversion efficiency from the diode pump to the first Stokes is about 2.5%. The corresponding pulse width and single pulse energy of the first Stokes are 15 ns and 0.27 mJ, respectively. Compared with the spectrum of the fundamental laser at 1990 nm, the output spectrum of the first Stokes at 2418 nm has a broader linewidth of approximately 10 nm.

1.4 µm continuous-wave diamond Raman laser.

The longest wavelength (~1.4 µm) emitted by a diamond Raman laser pumped by a semiconductor disk laser (SDL) is reported. The output power of the intracavity-pumped Raman laser reached a maximum of 2.3 W with an optical conversion efficiency of 3.4% with respect to the absorbed diode pump power. Narrow Stokes emission (FWHM <0.1 nm) was attained using etalons to limit the fundamental spectrum to a single etalon peak. Tuning of the Raman laser over >40 nm was achieved via rotation of an intracavity birefringent filter that tuned the SDL oscillation wavelength.

A 7.08-kW YAG/Nd:YAG/YAG Composite Ceramic Slab Laser with Dual Concentration Doping

The theoretical design and experiment research on the YAG/Nd:YAG/YAG composite ceramic slab laser amplifier were conducted. The numerical analysis was used to obtain the design of YAG/Nd:YAG/YAG composite ceramic slab. A high optical quality composite ceramic slab with two different doping concentrations was fabricated successfully. The double-pass extracted power in composite ceramic slab laser amplifier reached 7.08 kW, and the optical-to-optical conversion efficiency increased to 39.2% under the total diode pump power of 18.06 kW. The depolarization of single-pass transmission was about 3.2% and the peak and valley of the transmission wave-front distortion among the center 26.1-mm region in the width direction of the laser slab was less than 0.5 μm at the double-pass extracted power of 7.08 kW.

Aluminum oxide nanoparticles as saturable absorber for C-band passively Q-switched fiber laser.

We report on aluminum oxide nanoparticles (Al2O3 NPs) as a saturable absorber (SA) for passively Q-switched erbium-doped fiber laser (EDFL) operating at a wavelength of 1560.6nm within the C-band region. A thin film of Al2O3-SA was prepared using polyvinyl alcohol (PVA) as a host polymer. Very stable pulses with a 57.8KHz repetition rate and 5.6 μs pulse width at a threshold pump power of 158mW were obtained. A 2.8μs pulse width, 81kHz pulse repetition rate, with maximum pulse energy of 56.7nJ at a diode pump power of 330mW were recorded. To the best of the authors' knowledge, this is the first time that a Al2O3-based SA has been used to generate a Q-switched EDFL.

Passively Q-switched laser based on gold nanobipyramids as saturable absorbers in the 1.3 [formula omitted]m region

We demonstrate a passively Q-switched solid-state laser operating at the central wavelength of 1342 nm based on gold nanobipyramids (Au-NBPs) as saturable absorber (SA) for the first time. Au-NBPs are fabricated through a seed-mediated growth method, and placed in a simple linear cavity. Under an absorbed diode-pumped power of 5.339 W, an average power of 175 mW was generated with a minimum pulse width of 342 ns and a repetition rate of 141.8 kHz, corresponding to a pulse energy of 1.23 μJ.

THz polariton laser using an intracavity Mg:LiNbO3 crystal with protective Teflon coating.

An enhancement in the performance of a THz polariton laser based on an intracavity magnesium-doped lithium niobate crystal (Mg:LiNbO3) in surface-emitted (SE) configuration is demonstrated resulting from the deposition of a protective Teflon coating on the total internal reflection surface of the crystal. In this cavity geometry the resonating fields undergo total internal reflection (TIR) inside the lithium niobate, and laser damage to that surface can be a limiting factor in performance. The protective layer prevents laser damage to the crystal surface, enabling higher pump power, yielding higher THz output power and wider frequency tuning range. With the unprotected crystal, narrow-band THz output tunable from 1.50 to 2.81 THz was produced, with maximum average output power of 20.1 µW at 1.76 THz for 4 W diode pump power (limited by laser damage to the crystal). With the Teflon coating, no laser damage to the crystal was observed, and the system produced narrow-band THz output tunable from 1.46 to 3.84 THz, with maximum average output power of 56.8 µW at 1.76 THz for 6.5 W diode pump power. This is the highest average output power and the highest diode-to-terahertz conversion efficiency ever reported for an intracavity terahertz polariton laser.

Highly stable self-pulsed operation of an Er:Lu2O3 ceramic laser at 2.7 µm

We report on the highly stable self-pulsed operation of a 2.74 µm Er:Lu2O3 ceramic laser pumped by a wavelength locked narrow bandwidth 976 nm laser diode. The operating pulse repetition rate is continuously tunable from 126 kHz to 270 kHz depending on the pump power level. For 12.3 W of absorbed diode pump power, the Er:Lu2O3 ceramic laser generates 820 mW of average output power at a 270 kHz repetition rate and with a pulse duration of 183 ns. The corresponding pulse-to-pulse amplitude fluctuation is estimated to be less than 0.7%. In the continues-wave (CW) mode of operation, the laser yields over 1.3 W of output power with a slope efficiency of 11.9% with respect to the 976 nm pump power.