Ultrafast adiabatic frequency conversion

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.

Detuning modulated composite segments for robust optical frequency conversion

“…In the past two decades, several methods have been proposed for the creation of efficient, broadband and robust frequency conversion processes. Among them are the random designs [10], the multi-periodic phase-matching [11,12] and chirped designs [1,[13][14][15][16], which exhibit broadband conversion capabilities that were shown also to be suitable for ultrashort pulse conversion and manipulation. Yet, these methods fail to offer a robust, broadband and efficient conversion process while maintaining short nonlinear crystal length and low pump intensity.…”

“…For example, it was shown that a nonlinear crystal based on a gradual adiabatic variation of the phase mismatch parameter exhibits an efficient conversion for ultra-broadband or tunable quasi-continuouswave (quasi-CW) signals. Moreover, the adiabatic conversion scheme was implemented for sum and difference frequency conversion of ultrashort pulses [13,15], taking it to an extreme generation of octave spanning single cycle mid-infrared pulses [17]. In addition, the adiabatic scheme was extended to cascaded processes and also for depleted nonlinear processes [15].…”