Quantitative and Material-specific Nanoscale imaging with Table-top High Harmonic Sources

Passive modelocking (PML) of lasers is pivotal in modern science and industry. Here, solving a half-century-long challenge, we present the first master equation (ME) describing PML on all time scales, from Q-switched to fundamental and harmonic modelocking, valid for both slow and fast saturable absorption and short and long cavities. The proposed ME should become the workhorse for analytical and numerical studies of ultrafast lasers in both the photonics engineering and laser physics communities.

We present here an experimental demonstration of a new method to access the multi-pulse regime in mode-locked fibre laser. This method allows us to drastically reduce the pumping power, while having a stable train of multiple pulses.

Predicting complex nonlinear dynamical systems has been even more urgent because of the emergence of extreme events such as earthquakes, volcanic eruptions, extreme weather events (lightning, hurricanes/cyclones, blizzards, tornadoes), and giant oceanic rogue waves, to mention a few. The recent milestones in the machine learning framework offer a new prospect in this area. For a high dimensional chaotic system, increasing the system’s size causes an augmentation of the complexity and, finally, the size of the artificial neural network. Here, we propose a new supervised machine learning strategy to locally forecast bursts occurring in the turbulent regime of a fiber ring cavity.

The targeted generation of fs pulses is essential for a variety of applications and it is routinely carried out by 4f pulse shapers. However, this seemingly simple task is complicated by hidden experimental limitations, such as modulator crosstalk or pixelation. We present an approach to overcome this issue by using a high-precision phase plate with a phase change characterized with /500 precision. We generated pseudorandom pulses using a 4f pulse shaper by using a structured PMMA plate with the high-precision predefined shape made by the SPDT machine. We study the accuracy, reproducibility, as well as the sufficiency, and limits of the method. The generated pulses are characterized using the FROG method. The reconstructed pulses’ shapes and their spectral phases are compared to the results of simulations.

The impact of the amount of nonlinearity per focal pass on the beam quality in gas-filled Herriott-type multipass cells (MPCs) is investigated. Through the variation of the gas pressure, the peak nonlinear phase shifts per focal pass was varied from 0.8 rad up to 5.9 rad, which is the highest value demonstrated in a MPC. Simultaneous monitoring of the effective homogeneity [1] and M² revealed no degradation of either. Supported by numeric simulations the findings suggest that the nonlinearity per focal pass in gas-filled MPCs below the self-focusing limit is not limited by spatio-spectral couplings. The presented findings become especially important for challenging regimes such as high compression factors and few-cycle pulses. Here the reduction of passes can significantly boost the transmission and optimized designs may enable the technology to move towards the single-cycle regime.