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A compact and robust all-solid-state mid-infrared (MIR) laser at 6.45 µm with high average output power and near-Gaussian beam quality is demonstrated. A maximum output power of 1.53 W with a pulse width of approximately 42 ns at 10 kHz is achieved using a ZnGeP2 (ZGP) optical parametric oscillator (OPO). This is the highest average power at 6.45 µm of any all-solid-state laser to the best of our knowledge. The average beam quality factor is measured to be M2 = 1.19. Moreover, high output power stability is confirmed, with a power fluctuation of less than 1.35% rms over 2 h, and the laser can run efficiently for more than 500 h in total. Using this 6.45 µm pulse as a radiation source, ablation of animal brain tissue is tested. Furthermore, the collateral damage effect is theoretically analyzed for the first time, to the best of our knowledge, and the results indicate that this MIR laser has excellent ablation ability, making it a potential replacement for free electron lasers.

A sub-pm linewidth high beam quality microsecond (μs) Ti:sapphire laser was reported, which was end-pumped by a frequency-doubled 1064 nm Nd:YAG laser. By inserting three birefringent plates tuner and one etalon into the cavity of the Ti:sapphire laser, a ∼ 0.8 pm linewidth at 819.710 nm was achieved with a maximum output power of 3 W operating at a high repetition rate of 500 Hz with pulse width of ∼25 μs. The beam quality factor M2 was measured to be ∼1.14. The wavelength could be finely tuned from 819.699 to 819.718 nm with tuning resolution of 0.76 pm. To the best of our knowledge, this is the first demonstration on the μs pulse Ti:sapphire laser at 819.710 nm with narrow linewidth and high beam quality simultaneously. Such μs 819.710 nm laser could be used to efficiently generate a polychromatic laser guide star together with a 589 nm laser for the tip-tilt correction of ground-based telescopes.

We present a kilowatt-level quasi-continuous-wave (QCW) cryogenically cooled 946-nm slab laser oscillator for the first time, to the best of our knowledge. The laser system is based on a double-face-pumped large-size single-slab Nd:YAG design, delivering a record-high average power of 1.06 kW without additional amplification. This laser oscillator operates at repetition rate of 400 Hz with a pulse duration of 175 µs, resulting in a single pulse energy of 2.65 J. To the best of our knowledge, these results represent the highest output power and pulse energy for any all-solid-state 946-nm laser ever reported to date. Our scheme paves a new path for the development of the compact high-power solid-state 946-nm laser.

We demonstrated a high brightness narrow-linewidth microsecond (μs) pulse green laser from second harmonic generation (SHG) of a master oscillator power amplifier (MOPA) laser system. The oscillator was a quasi-continuous wave pulsed diode-side-pumped 1064 nm Nd:YAG laser with an average output power of 45.2 W and a beam quality factor of M2 = 1.21, operating at a pulse repetition frequency of 500 Hz with a ∼160 μs of pulse duration. After a two-stage amplifier, the fundamental output power of MOPA system was increased up to 198 W. Using a type-I lithium triborate nonlinear crystal, the maximum SHG output power of 78.4 W at 532 nm was obtained with a linewidth of 0.54 pm and a beam quality factor M2 less than 1.61. The brightness of the green light was as high as 1.08 × 1010 W/cm2 sr. This is, to the best of our knowledge, the highest brightness solid state light source for the narrow-linewidth μs pulse green lasers at 532 nm.

Because of the significant nonlinearity of fast steering mirror (FSM), which is actuated by lead zirconate titanate (PZT) stacks, designing a high-performance laser beam pointing stabilization system is always a difficult work. This paper reports an active disturbance rejection control (ADRC) based feedback control system for laser beam pointing stabilization of a high-power quasi-continuous-wave (QCW) Nd:YAG slab laser with a repetition frequency of 160 Hz and an average output power of 1.5 kW. The simulation and experiment show that the ADRC is faster and smoother than traditional proportional-integral-differential (PID) control, and the ADRC can effectively reduce overshoot in the laser beam pointing stabilization process.

We demonstrated a compact high-efficiency 100-W-level, narrow-linewidth, quasi-continuous-wave (QCW) diode-side-pumped Nd:YAG laser with a linearly polarized TEM00 mode. Spatial hole-burning elimination and narrow-linewidth laser output were realized by a twisted-mode cavity and an etalon, respectively. The resonator was based on a thermally near-unstable cavity design with dual-rod birefringence compensation convex–convex structure. A 100.4-W linear polarized 1064-nm laser was achieved with a 340-W pump power, corresponding to an optical-to-optical conversion efficiency of 29.5%. The wavelength of the laser was tunable from 1064.22634 to 1064.68071 nm while stably maintaining a beam quality of M2 = 1.22 and a linewidth of ~240 MHz. The laser was operated at a repetition rate of 500 Hz with 160- $\mu \text{s}$ pulse duration. To the best of our knowledge, this represents the highest average-power and the highest brightness for narrow-linewidth QCW microsecond pulse 1064-nm lasers.

We propose and demonstrate a new approach to scale the average output power with narrow linewidth and good beam quality simultaneously for a 1319 nm laser. A polarization and sequence pulsed beam combining technology is developed to add two lasers. Each laser is based on a quasi-continuous-wave diode-pumped Nd:YAG master-oscillator power-amplifier system. One provides output power of 81 W with s-polarization, M 2 = 1.49, and a repetition rate of 500 Hz. Another also operates at 500 Hz, but delivers power of 78 W with M 2 = 1.47 and p-polarization. After combination, a maximum average power of 156 W with beam quality of M 2 = 1.5 is achieved, corresponding to a combining efficiency of 98.1%. The combined beam has a 1 kHz repetition rate with 120 μs pulse duration and ~0.3 GHz linewidth. To the best of our knowledge, this is a record-high output power for the solid-state 1.3 μm lasers. All results indicate the technique of polarization beam in conjunction with sequence pulsed beam combining not only allows the scaling of the laser power while maintaining narrow linewidth and good beam quality, but also is an effective approach for increasing the pulse repetition rate.

We demonstrated a high-average-power, narrow-linewidth, quasi-continuous-wave diode-side-pumped 1319 nm Nd:YAG twisted-mode laser oscillator with a linearly polarized TEM00 mode. The resonator is based on a symmetrical convex–convex structure with a two-rod configuration for birefringence compensation, working in a thermally near-unstable cavity. With an optimum cavity length of 940 mm, a 39.4 W linear polarized 1319 nm laser is obtained with a good beam quality of M 2 = 1.21 and a linewidth of ~250 MHz, and the corresponding brightness is as high as 1.55 GW cm−2. The laser is operated at a repetition rate of 500 Hz and pulse duration of 150 µs. To the best of our knowledge, this is the highest output power 1319 nm laser with narrow-linewidth from diode-pumped Nd:YAG lasers, and is the first report on the twisted-mode laser operation at the 1.3 µm region.