We present a study on a watt-level acousto-optically Q-switched Pr:YLF laser at three different repetition rates (10 kHz, 20 kHz, and 50 kHz) for the first time, to the best of our knowledge. The corresponding average output powers and pulse widths were measured to be 1.14 W, 1.2 W, and 1.32 W, and 40 ns, 52 ns, and 80 ns, respectively. A maximum pulse energy of 0.11 mJ was obtained, corresponding to a peak power of up to 2.8 kW at a repetition rate of 10 kHz. The simulated dynamics of a fast Q-switched Pr:YLF laser is in agreement with the experiment. The laser’s ability to generate stable pulses with high peak power and short pulse width makes it highly desirable for various practical applications, such as laser machining and material processing.

Direct generation of visible frequency from a compact all-fiber laser while preserving high output characteristics has been a subject of research in laser technology. We investigated the high output performance of all-fiber lasers based on Ho3+-doped ZBLAN fluoride glass fiber especially operating in the deep-red band by pumping at 640 nm. Remarkably, we achieved a maximum continuous-wave output power of 271 mW at 750 nm with a slope efficiency of 45.1%, which represents, to our knowledge, the highest direct output power recorded in an all-fiber laser with a core diameter of less than 10 μm in the deep-red band. Additionally, we successfully developed a 1.2 μm all-fiber laser pumped by a 640 nm laser. We extensively investigated the correlation between these two-laser generation processes and their performances at 750 nm and 1.2 μm wavelengths. By increasing the pumping rate, we observed an efficient recycling of population through a highly excited state absorption process, which effectively returned the population to the upper laser level of the deep-red transition. Moreover, we determined the optimized conditions for such lasers, identified the processes responsible for populating the excited state energy levels, and established the corresponding spectroscopic parameters.

We demonstrate an all-polarization-maintaining (PM) passively mode-locked Yb3+-doped fiber laser (YDFL) with a fundamental repetition rate of 1.3 GHz. The optical spectra of a linearly polarized soliton exhibit different shapes by rotating the fast axis of the fiber optical pigtail of a dispersive dielectric mirror. The oscillator provides a series of laser performance, such as a threshold pump power for continuous wave laser oscillation of 3.1 mW, an optical-to-optical efficiency for mode-locking of 29%, and an integrated relative intensity noise of 0.08%. To the best of our knowledge, this is the first report of >1GHz ultrafast all-fiber YDFL with PM architecture.

We report continuous-wave deep red lasers at 696.6 and 698.6 nm in a Pr3+:YLF crystal pumped by an InGaN laser diode. A Lyot filter was inserted into the cavity as a birefringent filter to select wavelength; the lasers at 696.6 and 698.6 nm were obtained with a maximum output power of 1.36 and 3.11 W, separately. To the best of our knowledge, the output powers of these two lasers are the highest to date, and this is the first scaling of the output power of the Pr3+:YLF laser to the watt level at around 696 nm. In addition, the corresponding theoretical analysis and simulation were carried out to explain the experimental phenomena.

High-power continuous-wave ultraviolet lasers are useful for many applications. As ultraviolet laser sources, the wavelength switching capability and compact structure are very important to extend the applicability and improve the flexibility in practical applications. In this work, we present two simple and relatively compact schemes by laser diode pumping to obtain a watt-level single-wavelength 348.7-nm laser and discrete wavelength tunable ultraviolet lasers around 349 nm (from 334.7 to 364.5 nm) by intracavity frequency doubling based on Pr³⁺:YLF and $\unicode{x3b2}$ -BBO crystals. The maximum output power of the single-wavelength 348.7-nm laser is 1.033 W. The output powers of the discrete wavelength tunable lasers are at the level of tens of milliwatts, except for two peaks at 348.7 and 360.3 nm with output powers of approximately 500 mW. In addition, simulations are carried out to explain the experimental results and clarify the tuning mechanisms.

可见光激光器在激光彩色显示、激光医疗、量子信息、光通讯等领域有着十分重要的作用。三价镨离子(Pr³⁺)因在可见光波段存在丰富的激光能级跃迁而备受人们关注。特别是近年来，激光二极管(LD)、光泵浦半导体激光器(OPSL)等商业化泵浦源的出现，更是使得掺Pr³⁺固体激光器的研究得到了长足的发展。本文按照掺Pr³⁺固体激光器连续、脉冲和单纵模三种输出类型，介绍了每种输出类型在特定波段处的典型工作，以时间为主线对掺Pr³⁺固体激光器的研究历程与现状进行了概述，以及对未来掺Pr³⁺固体激光器的研究做了展望。

Here we developed a novel wavelength-switchable visible continuous-wave (CW) Pr³⁺:YLF laser around 670 nm. In single-wavelength laser operations, the maximum output powers of 2.60 W, 1.26 W, and 0.21 W, the maximum slope efficiencies of 34.7%, 27.3%, and 12.3% were achieved with good beam qualities (M² < 1.6) at 670.4 nm, 674.2 nm, and 678.9 nm, respectively. Record-high output power (2.6 W) and record-high slope efficiency (34.7%) were achieved for the Pr ³⁺:YLF laser operation at 670.4 nm. This is also the first demonstration of longer-wavelength peaks beyond 670 nm in the ³P₁→³F₃ transition of Pr³⁺:YLF. In multi-wavelength laser operations, the dual-wavelength lasings, including 670.1/674.8 nm, 670.1/679.1 nm, and 675.0/679.4 nm, were obtained by fine adjustment of one/two etalons within the cavity. Furthermore, the triple-wavelength lasings, e.g. 672.2/674.2/678.6 nm and 670.4/674.8/679.4 nm, were successfully demonstrated. Moreover, both the first-order vortex lasers (LG₀⁺¹ and LG₀^-1 modes) at 670.4 nm were obtained by off-axis pumping.

Mid-infrared (MIR) fiber pulsed lasers are of tremendous application interest in eye-safe LIDAR, spectroscopy, chemical detection and medicine. So far, these MIR lasers largely required bulk optical elements, complex free-space light alignment and large footprint, precluding compact all-fiber structure. Here, we proposed and demonstrated an all-fiberized structured gain-switched Ho³⁺-doped ZBLAN fiber laser operating around 2.9 μm. A home-made 1146 nm Raman fiber pulsed laser was utilized to pump highly concentrated single-cladding Ho³⁺-doped ZBLAN fiber with different lengths of 2 m or 0.25 m. A home-made MIR fiber mirror and a perpendicular-polished ZBLAN fiber end construct the all-fiberized MIR cavity. Stable gain-switched multiple states with a sub-pulse number tuned from 1 to 8 were observed. The effects of gain fiber length, pump power, pump repetition rate and output coupling ratio on performance of gain-switched pulses were further investigated in detail. The shortest pulse duration of 283 ns was attained with 10 kHz repetition rate. The pulsed laser, centered at 2.92 μm, had a maximum average output power of 54.2 mW and a slope efficiency of 10.12%. It is, to the best of our knowledge, the first time to demonstrate a mid-infrared gain-switched Ho³⁺:ZBLAN fiber laser with compact all-fiber structure.

We report on the direct generation of passively mode-locked vortex lasers in the visible spectral region, for the first time to the best of our knowledge, using a Pr:LiYF4 (Pr:YLF) crystal as the gain medium. A stable mode-locked TEM00 mode has been achieved with a maximum average output power of 75 mW using a graphene saturable absorber mirror. The mode-locked pulse width is measured to be as short as about 73.4 ps at a repetition rate of about 140 MHz, and the laser wavelength is at about 721 nm with spectral width of about 0.5 nm. By slightly misaligning the laser resonator, a first-order Laguerre-Gaussian mode (LG0,1) has also been obtained with output power reduced to about 22 mW. The achieved LG0,1 mode has been verified via a home made improved Fizeau interferometer. This work provides a simple and universal method for direct generation of an ultrafast vortex laser, which can be readily extended to other spectral regions by using different laser gain mediums.

Raman and Brillouin lasers based on a high-quality (high-Q) whispering gallery mode microresonator (WGMR) are usually achieved by employing a tunable single-frequency laser as a pump source. Here, we experimentally demonstrate visible Raman and Brillouin lasers using a compact microresonator/ZrF4 BaF2 LaF3 AlF3 NaF (ZBLAN)-fiber hybrid system by incorporating a WGMR with a fiber-compatible distributed Bragg reflector/fiber Bragg grating to form a Fabry–Perot (F-P) fiber cavity and using a piece of Pr:ZBLAN fiber as gain medium. The high-Q silica-microsphere not only offers a Rayleigh-scattering-induced backreflection to form the ～635 nm red laser oscillation in the F-P fiber cavity, but also provides a nonlinear gain in the WGMR itself to generate either stimulated Raman scattering or stimulated Brillouin scattering. Up to six-order cascaded Raman lasers at 0.65 μm, 0.67 μm, 0.69 μm, 0.71 μm, 0.73 μm, and 0.76 μm are achieved, respectively. Moreover, a Brillouin laser at 635.54 nm is clearly observed. This is, to the best of our knowledge, the first demonstration of visible microresonator-based lasers created by combining a Pr:ZBLAN fiber. This structure can effectively extend the laser wavelength in the WGMR to the visible waveband and may find potential applications in underwater communication, biomedical diagnosis, microwave generation, and spectroscopy.