A high-power potassium yttrium tungstate (KYW) Raman laser based on an extra-cavity configuration is demonstrated at the first-Stokes wavelength of 1178 nm for the first time. The KYW crystal is pumped by a 1064 nm Q-switched Nd:YAG laser with a repetition frequency of 9 kHz. With an incident pump power of 29 W, the maximum Stokes output power of 4.7 W is obtained with a pulse width of 55.5 ns, and the corresponding slope efficiency is 40.5%. This work provides a good candidate for the generation of 589 nm sodium yellow laser by frequency doubling technology.

In the field of femtosecond laser physics, a phenomenon has been discovered wherein silicon plasma appears earlier than air filaments in tightly focused femtosecond laser fields. This phenomenon exhibits an advance time of several picoseconds. Analysis of the results reveals that the disparity in ionization thresholds between silicon and the surrounding air is the primary cause of this phenomenon. Moreover, the temporal contrast of the femtosecond laser pulses influences the extent of the advance time. The findings provide valuable insights into the complex interactions between laser-plasma and laser-material interactions, and have implications for advancements in the laser precision machining, laser remote sensing, and related applications.

A temperature-sensing scheme is realized by a passively mode-locked Yb-doped fiber laser based on the nonlinear optical loop mirror (NOLM). The ambient temperature can be measured by detecting the pulse repetition frequency of the mode-locked fiber laser by an oscilloscope. When the ambient temperature increases from −40 °C to 6 °C, the pulse repetition frequency decreases linearly with a temperature sensitivity of 72.548 Hz/°C. The experimental results prove the feasibility of the mode-locked laser sensor operating in a low-temperature environment.

The sequencing of laser-induced plasma formation in multi-material systems is fundamentally governed by the interplay between material ionization thresholds and laser temporal characteristics. This study uncovers a counterintuitive phenomenon where silicon plasma precedes air filamentation at air–silicon interfaces under tight femtosecond laser focusing, which can be attributed to the significant difference in their ionization thresholds. Through time-resolved shadowgraphy with 550 fs resolution, we demonstrate that silicon plasma precedes air filamentation by approximately 3 ps, a temporal discrepancy that can be quantitatively attributed to the 137.5-fold lower ionization threshold of silicon compared to air. The combined influence of the laser temporal contrast and tight focusing geometry modulates this lead time from femtosecond to picosecond scales. This threshold-governed plasma chronology mechanism provides a new paradigm for controlling laser–material interactions, with direct implications for precision manufacturing of layered composites, depth-resolved optical diagnostics, phase-change material characterization, and 3D material architectures.

We report on a high-power acoustic-optical (AO) Q-switched Tm:YLF laser operating at ~1.83 μm by controlling the transmittance of the output coupler. Under the continuous-wave (CW) operation, the maximum output power of 13 W is achieved, and the slope efficiency is up to 32.7%. With a YAG etalon inserted into the cavity, the linewidth is compressed below 0.5 nm with a maximum output power of 12.2 W. In the Q-switched state, the maximum pulsed output power of 10.32 W is achieved with a pulse duration of 150 ns when the repetition rate is 15 kHz. And the maximum pulsed energy of 1.13 mJ is generated with a duration of 131 ns at 5 kHz. As far as we know, this is the highest output power reported for the CW and pulsed 1.83 μm laser. In addition, the relationship between the output wavelength and crystal length is theoretically analyzed, which shows that increasing the loss of 1880 nm is the key to high-power 1.83 μm laser output.