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Abstract Motivated by the profound impact of laser technology on science, arising from an increase in focused light intensity by seven orders of magnitude and flashes so short electron motion is visible, this roadmap outlines the paths forward in laser technology to enable the next generation of science and applications. Despite remarkable progress, the field confronts challenges in developing compact, high-power sources, enhancing scalability and efficiency, and ensuring safety standards. Future research endeavors aim to revolutionize laser power, energy, repetition rate and precision control; to transform mid-infrared sources; to revolutionize approaches to field control and frequency conversion. These require reinvention of materials and optics to enable intense laser science and interdisciplinary collaboration. The roadmap underscores the dynamic nature of laser technology and its potential to address global challenges, propelling progress and fostering sustainable development. Ultimately, advancements in laser technology hold promise to revolutionize myriad applications, heralding a future defined by innovation, efficiency, and sustainability. 

We introduce a concept for efficient optical parametric amplification (OPA) based on simultaneously phase-matched idler second harmonic generation (SHG), which together exhibits the dynamical behavior of parametric amplification but with damped conversion-back-conversion cycles. This enables amplification efficiency exceeding that of conventional OPA by several-fold for femtosecond and picosecond signal pulses with bell-shaped intensity profiles by allowing a near-uniform spatiotemporal depletion of the pump wave. We develop a Duffing oscillator model that unifies the description of conventional OPA and amplification accompanied by idler photon displacement by either linear absorption or SHG. A spatiotemporal analysis of devices based on birefringent or superlattice quasi-phase matching in common bulk media predicts energy conversion up to 55%. 

We demonstrate dramatic parametric amplifier conversion efficiency enhancement simply by arranging for simultaneously phase-matched idler second-harmonic generation, with 44% pump-to-signal energy conversion (68% pump depletion) in a 48-dB-gain bulk-crystal mid-IR amplifier stage with Gaussian beams. 

We illustrate that a Hermitian nonlinear optical system consisting of hybridized parametric amplification and second harmonic generation mimics non-Hermitian evolution dynamics. Oscillation damping, evolution to a static steady state, and exceptional points arise from the use of second harmonic generation as an irreversible loss mechanism. The investigated system can be used to solve problems of inefficiency in parametric amplifier systems used widely in laser science and industrial applications. More generally, these findings suggest a new paradigm for the engineering of system dynamics where energy recovery and system sustainability are of importance. 

Abstract Ultrafast adiabatic frequency conversion is a powerful method, capable of efficiently and coherently transfering ultrashort pulses between different spectral ranges, e.g. from near-infrared to mid-infrared, visible or ultra-violet. This is highly desirable in research fields that are currently limited by available ultrafast laser sources, e.g. attosecond science, strong-field physics, high-harmonic generation spectroscopy and multidimensional mid-infrared spectroscopy. Over the past decade, adiabatic frequency conversion has substantially evolved. Initially applied to quasi-monochromatic, undepleted pump interactions, it has been generalized to include ultrashort, broadband, fully-nonlinear dynamics. Through significant theoretical development and experimental demonstrations, it has delivered new capabilities and superior performance in terms of bandwidth, efficiency and robustness, as compared to other frequency conversion techniques. This article introduces the concept of adiabatic nonlinear frequency conversion, reviews its theoretical foundations, presents significant milestones and highlights contemporary ultrafast applications that may, or already do, benefit from utilizing this method.