YAlO3 Laser Research Articles

Mo2TiAlC2 as a Saturable Absorber for a Passively Q-Switched Tm:YAlO3 Laser.

Owing to their remarkable characteristics, two-dimensional (2D) layered, MAX phase materials have garnered significant attention in the field of optoelectronics in recent years. Herein, a novel MAX phase ceramic material (Mo2TiAlC2) was prepared into a saturable absorber (SA) by the spin-coating method for passively Q-switching (PQS), and its nonlinear optical absorption properties were characterized with a Tm:YAlO3 (Tm:YAP) nanosecond laser. The structure characteristics and composition analysis revealed that the Mo2TiAlC2 material exhibits a well-defined and stable structure, with a uniform thin film successfully obtained through spin coating. In this study of a PQS laser by employing a Mo2TiAlC2-based SA, an average output power of 292 mW was achieved when the absorbed pump power was approximately 4.59 W, corresponding to a central output wavelength of 1931.2 nm. Meanwhile, a stable pulse with a duration down to 242.9 ns was observed at a repetition frequency of 47.07 kHz, which is the narrowest pulse width recorded among PQS solid-state lasers using MAX phase materials as SAs. Our findings indicate that the Mo2TiAlC2 MAX phase ceramic material is an excellent modulator and has promising potential for ultrafast nonlinear photonic applications.

Self-frequency-doubling Yb:GdCOB laser intracavity-pumped Pr:YAP laser

Abstract We present for the first time a Pr:YAlO3 (Pr:YAP) laser emitting at 547 nm intracavity-pumped by a self-frequency-doubling Yb3+:Ca4GdO (BO3)3 (Yb:GdCOB) blue laser at 488 nm. We carried out a model to design the system properly, and the laser performance was experimentally investigated. Intracavity sum-frequency mixing at 547 and 488 nm was then realized in a CsLiB6O10 (CLBO) nonlinear crystal to reach the ultraviolet laser at 258 nm. We obtained a continuous wave output power of 575 mW at 258 nm with a pump source, which is a diode-pumped quasi-three-level Sr1-x La x -y Nd y Mg x Al12-x O19 (Nd:ASL) laser emitting 11.2 W at 902 nm.

Application of a UV nanosecond laser to the rapid and direct photothermal activation of Cu-BTC metal–organic frameworks

Activating metal–organic frameworks (MOFs) to create open coordination sites is crucial for exploiting the functions of MOFs. This study successfully demonstrates the direct activation of Cu-BTC crystals using rapid and efficient heat treatment assisted by a nanosecond pulse laser. Localized thermal energy was irradiated to the surfaces of the MOFs through a photothermal process, which rapidly and effectively removed solvent residues within the structures of the MOFs. The Cu-BTC crystals synthesized through the solvothermal method were activated through a photothermal process, without inducing any structural damage, by irradiating with the second harmonic of a Nd3+:Y3Al5O12 laser with a wavelength of 355 nm. This process occurred most efficiently without any structural collapse at 30 mJ/cm2, and the residues within the MOFs were removed through the photothermal process within approximately 5 min. Thus, the study offers a novel design strategy involving the rapid activation of MOFs.

Diode-end-pumped self-Q-switched Tm:YAlO3 laser at 2362 nm

A diode-end-pumped self-Q-switched Tm:YAlO3 laser at 2362 nm based on 3H4→3H5 transition is proposed for the first time according to the references. The max mean output power of 0.41 W with a slope efficiency of 14.1% was obtained under the absorbed pump power of 6.7 W, corresponding pulse width and pulse repetition frequency were 7.82 μs and 45.09 kHz respectively. By analyzing the laser beam spatial distribution, the self-Q-switched Tm:YAlO3 laser at 2362 nm was originated from the time-dependent lens mechanism. The present research provides an approach for generating Q-switched lasers in the 2.3 μm spectral region.

Polarization switching in a mid-infrared Er:YAlO3 laser.

We report on a polarization-resolved study of mid-infrared emission properties of Er3+-doped orthorhombic yttrium aluminum perovskite YAlO3 single crystal. For the 4I11/2 → 4I13/2 Er3+ transition, the stimulated emission cross section is 0.20 × 10-20 cm2 at 2919 nm for light polarization E ‖ c. Pumped by an Yb-fiber laser at 976 nm, the 10 at.% Er:YAlO3 laser delivered 1.36 W at 2919 nm with a slope efficiency of 31.4%, very close to the Stokes limit, a laser threshold as low as 33 mW and a linear polarization. Pump-induced polarization switching between E || b and E || c eigen states was observed and explained by excited-state absorption from the terminal laser level.

High peak power passively Q-switched Tm:YAP solid-state laser with Cr2+:ZnSe and Cr2+:ZnS saturable absorber

We experimentally demonstrate a passively Q-switched thulium-doped YAlO3 (Tm:YAP) laser based on the Cr2+:ZnSe (Chromium, Zinc Selenide) and Cr2+:ZnS (Zinc Sulfide) crystals. Wavelength tuning for 1.87 μm, 1.90 μm, and 1.94 μm operations was achieved by employing a birefringent plate. The impact of varying doping concentrations of Cr2+:ZnS crystals and a Cr2+:ZnSe crystal on the laser output was investigated. During the analysis, the passively Q-switched Tm:YAP laser achieved a pulse with the highest peak power of 107.5 kW and the narrowest pulse width of ∼6 ns, utilizing a Cr2+:ZnSe crystal as the saturable absorber (SA) with a modulation depth (ΔR) of 14 %.

Pulsed Optical Vortex Array Generation in a Self-Q-Switched Tm:YALO3 Laser.

Optical vortex arrays are characterized by specific orbital angular momentums, and they have important applications in optical trapping and manipulation, optical communications, secure communications, and high-security information processing. Despite widespread research on optical vortex arrays, the 2 μm wavelength range remains underexplored. Pulsed lasers at 2 μm are vital in laser medicine, sensing, communications, and nonlinear optic applications. The need for 2 μm-pulsed structured optical vortices, combining the advantages of this wavelength range and optical vortex arrays, is evident. Therefore, using just three elements in the cavity, we demonstrate a compact self-Q-switched Tm:YALO3 vortex laser by utilizing the self-modulation effect of a laser crystal and a defect spot mirror. By tuning the position of the defect spot and the output coupler, the resonator delivers optical vortex arrays with phase singularities ranging from 1 to 4. The narrowest pulse widths of the TEM00 LG0,-1, two-, three-, and four-vortex arrays are 543, 1266, 1281, 2379, and 1615 ns, respectively. All the vortex arrays in our study have relatively high-power outputs, slope efficiencies, and single-pulse energies. This work paves the way for a 2 μm-pulsed structured light source that has potential applications in optical trapping and manipulation, free-space optical communications, and laser medicine.

Doubly Q-switched Tm:YAP laser based on the Cr2+:ZnS crystal and electro-optical modulator

A doubly Q-switched Tm3+:YAlO3 (Tm:YAP) laser based on the Cr2+:ZnS saturable absorber (SA) and electro-optical modulator (EOM) is presented. The pulse duration of the doubly Q-switched lasers is shorter as compared to single actively and passively Q-switched operations. The shortest pulse duration of 17.3 ns with a repetition rate of 100 Hz was measured at the pump power of 12 W in the doubly Q-switched laser. The corresponding pulse peak power of 184.8 kW and the pulse energy of 3.2 mJ was obtained. The center wavelength of the doubly Q-switched operation was 1.94 μm. The results demonstrate that Cr2+:ZnS is an excellent saturable absorber for 2 μm Tm:YAP laser, and the doubly Q-switched operation can greatly narrow the Q-switched pulse width.

High efficiency cryogenic CW Nd:YAlO3 laser with dual wavelengths at 1072 and 1079 nm

High efficiency cryogenic CW Nd:YAlO3 laser with dual wavelengths at 1072 and 1079 nm

Polarization-anisotropy of mid-infrared emission properties of Er3+ ions in YAlO3 crystal – INVITED

We report on a polarization-resolved study of mid-infrared emission properties of Er3+ ions in the orthorhombic YAlO3 crystal. For the 4I11/2 → 4I13/2 transition, σSE reaches 0.20×10-20 cm2 at 2919 nm (for light polarization E || c). Pump-induced polarization switching between the E || b and E || c eigen-states is observed in an 10 at.% Er:YAlO3 laser. Pumped by an Yb-fiber laser at 976 nm, this laser delivers 0.77 W at 2919 nm with a slope efficiency of 31.4% being close to the Stokes limit and a laser threshold of 33 mW.

All-solid-state far-UVC pulse laser at 222 nm wavelength for UVC disinfection

A 222 nm all-solid-state far-ultraviolet C (UVC) pulse laser system based on an optical parametric oscillator (OPO) and second-harmonic generation (SHG) using β-Ba2BO4 (BBO) crystals was demonstrated. Pumped by a Nd:Y3Al5O12 laser with a repetition rate of 100 Hz at 355 nm, the maximum signal laser pulse energy of 1.22 mJ at 444 nm wavelength was obtained from the BBO-OPO system, corresponding to a conversion efficiency of 27.9%. The maximum output pulse energy of 164.9 µJ at the 222 nm wavelength was successfully achieved, corresponding to an SHG conversion efficiency of 16.2%. Moreover, the tunable output wavelength of UVC light from 210 nm to 252.5 nm was achieved.

Kerr-lens mode-locked Yb:YAlO3 laser generating 24-fs pulses at 1085 nm.

We report on a Kerr-lens mode-locked Yb:YAlO3 laser generating soliton pulses as short as 24 fs at 1085 nm with an average output power of 186 mW and a pulse repetition rate of 87.5 MHz, representing the shortest pulses ever achieved from any mode-locked laser based on Yb3+-doped structurally ordered crystal. Optimized for power-scalable operation, the Yb:YAlO3 laser delivers 1.9 W at 1060 nm at the expense of a longer pulse duration of 44 fs, corresponding to a peak power of 462 kW and an optical efficiency of 43.2%.

Application of nanosecond laser to a direct and rapid growth of Cu-BTC metal-organic framework thin films on copper substrate

Significant research efforts are being devoted to achieve metal-organic framework (MOF) thin films with tailored film thickness and high stability on solid substrates. We demonstrate the successful synthesis of uniform Cu-BTC films directly on a copper metal substrate, using rapid and efficient heat treatment assisted by a nanosecond laser. An oxidized copper substrate with an organic ligand is irradiated by the second harmonic of Nd3+:Y3Al5O12 laser (532 nm), thereby forming Cu-BTC thin films through the photothermal process. The temperature of the laser-irradiated surface was estimated using COMSOL Multiphysics, aiding the optimization of the laser energy density for Cu-BTC crystal growth. The prepared Cu-BTC films exhibit a high surface area (985 m2/g) at 30 mJ/cm2, with a peak surface temperature of ∼364 K. Notably, 3000 laser shots generate Cu-BTC films with a thickness of 10 µm. Thus, the study offers a novel fabrication method for a design strategy, involving the rapid growth (∼ 2 min) of MOF thin films on metal substrates.

1.15 W Passively Q-Switched Operation Of Tm:YAlO3 Laser with MoS2-Based Saturable Absorber

1.15 W Passively Q-Switched Operation Of Tm:YAlO3 Laser with MoS2-Based Saturable Absorber

High Efficiency Cryogenic Cw Nd:Yalo3 Laser with Three Wavelengths at 1064, 1072 and 1079 Nm

High Efficiency Cryogenic Cw Nd:Yalo3 Laser with Three Wavelengths at 1064, 1072 and 1079 Nm

High-power and high-efficiency 4.3 µm ZGP-OPO

In this paper, a high-power and high-efficiency 4.3 µm mid-infrared (MIR) optical parametric oscillator (OPO) based on ZnGeP2 (ZGP) crystal is demonstrated. An acousto-optically Q-switched Ho:Y3Al5O12 laser operating at 2.1 µm with a maximum average output power of 35 W and pulse width of 38 ns at a repetition rate of 15 kHz is established and employed as the pump source. A doubly resonant OPO is designed and realized with the total MIR output power of 13.27 W, including the signal and idler output power of 2.65 W at 4.07 µm and 10.62 W at 4.3 µm. The corresponding total optical-to-optical and slope efficiencies are 37.9% and 67.1%, respectively. The shortest pulse width, beam quality factor, and output power instability are measured to be 36 ns, Mx2=1.8, My2=2.0, and RMS<1.9% at 8 h, respectively. Our results pave a way for designing high-power and high-efficiency 4–5 µm MIR laser sources.

Pr:YAlO3 laser performance enhancement by operating the laser close to liquid helium temperatures

Investigation of Pr3+:YAlO3 (Pr:YAP) lasers operating at cryogenic temperatures close to 4 K at fundamental wavelengths covering the visible spectral range is reported. A microchip resonator geometry formed by cavity mirrors directly deposited on the crystal facets was used. This geometry allows to minimize resonator losses and it is also very attractive due to its compact and rugged design. As a pumping sources, blue InGaN laser diode with maximum available pump power of approx. 4 W at 447 nm wavelength was employed. Cooling of the Pr:YAP crystals close to liquid helium temperatures allowed to significantly improve the Pr:YAP laser performances with respect to room temperature, which yielded in Watt-level laser outputs at all studied wavelengths (747 nm, 622 nm, 547 nm, and 493 nm).

Optical study of relaxation dynamics of photo-induced absorption of Cr-doped Bi12SiO20 crystals

The charge carriers tunneling produced in the forbidden band of the Cr doped Bi12SiO20 has been studied using photo-induced absorption (PIA) spectroscopy. These are excited by a green nanosecond neodymium-doped Yttrium Aluminum Garnet; Nd: Y3Al5O12 (ND: YAG) laser at a wavelength of 532 nm. The relaxation dynamics of these charge carriers in this crystal are characterized by a stretched exponential decay with a highly correlated constant of a streched life time τ and a stretched coeffcient α. The charge transport processes of these charge carriers in the forbidden band in this crystal shows nearly temperature independent behavior from the Arrhenius plot. This corresponds to a very weak dependence of the PIA of the charge carriers' dynamics within the forbidden band. The electo-optical descriptions are explained in the framework of the fast and slow time decays of the charge carriers tunneling within the localized states.

Three-nanosecond-equal interval sub-pulse Nd:YAG laser with multi-step active Q-switching

We demonstrate a three-nanosecond equidistant sub-pulse multi-step Q-switched Nd:Y3Al5O12 (Nd:YAG) laser. In the time interval of 100–1000 ns, three pulses with the same nanosecond interval and the same peak power are obtained at the pulse width of 24 ns, 28 ns, and 36.6 ns, respectively. The energy is 32.5 mJ, and the optical efficiency is 10.8%. The multi-step Q-switched method does not require the insertion of other optical elements into the traditional Q-switched laser, and it is very suitable to obtain pulse group output with several nanosecond pulse intervals.

Experimental study on the performances of second-harmonic dispersion interferometers at 10.6 µm and 1064 nm for plasma density measurements.

Two common-path interferometers based on CO2 and Nd:Y3Al5O12 (Nd:YAG) lasers are benchmarked with a two-arm microwave interferometer on a hydrogen plasma produced by an RF discharge and injected into a large magnetic-confinement vessel. The ∼1019m-2 line-integrated electron density is clearly measured in agreement by the interferometers. The frequency spectrum of the measured data is analyzed on the 20 kHz range for all interferometers and up to 600 kHz for the Nd:YAG laser-based interferometer. Mechanical vibration measurements performed on the components of the two common-path interferometers result in a peak-to-peak displacement up to about one and twenty wavelengths for the CO2 and Nd:YAG laser-based interferometers, respectively. Such results set for the first time, to the best of our knowledge, a quantitative limit for the displacement that the two second-harmonic dispersion interferometers can sustain while still providing a high sensitivity for accurate plasma density measurements.