J. Eur. Opt. Society-Rapid Publ. 2025, 21, 18 Ó The Author( s), published by EDP Sciences, 2025 https:// doi. org / 10.1051 / jeos / 2025015 Available online at: https:// jeos. edpsciences. org
Journal of the European Optical Society-Rapid Publications
EOSAM 2024 Guest editors: Luca De Stefano and Raffaele Velotta SHORT COMMUNICATION
Phase compensation scheme to achieve clean pulses from a multipass cell post-compression setup
Victor Wilfried Segundo Staels 1, 2,*
, Enrique Conejero Jarque 1, 2, and Julio San Roman 1, 2
1 Grupo de Investigación en Aplicaciones del Láser y Fotónica, Departamento de Física Aplicada, Universidad de Salamanca, E-37008, Salamanca, Spain 2 Unidad de Excelencia en Luz y Materia Estructuradas, Universidad de Salamanca, E-37008, Salamanca, Spain
Received 31 January 2025 / Accepted 28 March 2025
Abstract. An effective post-compression scheme requires a good compression system to generate the desired ultrashort pulse. In this work, we demonstrate that a compressor based on a pair of grisms, with an additional piece of dispersive glass, is able to shorten pulses coming from an all-bulk multipass cell post-compression setup to temporal profiles very close to the transform limited one. This proposal paves the way for the design of compressors, not based on chirped mirrors, with excellent performance.
Keywords: Multipass cells, Nonlinear propagation, Post-compression.
1 Introduction
The fast development of intense ultrashort laser pulses has promoted remarkable scientific fields such as ultrafast optics, attosecond science and microscopy [ 1 – 4 ]. To improve the temporal and spatial resolution of the experiments the scientific community demands even shorter, more intense and better-quality pulses. These ultrashort pulses are usually obtained by means of post-compression schemes in which the pulse spectrum is first broadened, due to Self- Phase Modulation( SPM) and other nonlinear effects, and second, the spectral phase is compensated to obtain an output as close as possible to the transform limited pulse [ 5, 6 ]. The second step can be skipped, if we are able to develop the spectral broadening step in the self-compression regime, in which the pulse shortens its temporal duration while broadening its spectrum [ 7, 8 ].
Among the diverse two-step post-compression schemes used to perform this spectral broadening, multipass cells( MPCs) have emerged as a strong option due to their reliability and versatility [ 8, 9 ]. MPCs are cavities formed by two mirrors in which a laser beam is propagated several round trips, broadening its spectrum by introducing some nonlinear media that could be a gas filling the cell, or one or several solid plates. Solid nonlinear media-based MPCs have some advantages over the gas-filled ones since they have higher nonlinearity and a simpler setup. One way to successfully perform this spectral broadening in a smooth and controlled way is to work in the enhanced frequency
* Corresponding author: vwsstaels @ usal. es chirp regime( EFCR), a regime in which the material dispersion and the nonlinearity act together achieving a broad and relatively smooth spectrum compatible with a very clean and short temporal profile, after passing through an adequate compression system. The EFCR has been already described in MPCs filled with gases [ 10 – 12 ] and with solid plates [ 13 ].
As mentioned above, after the propagation through the MPC, where the spectrum has been broadened, it is necessary to compress the pulse. A good compression stage is essential to obtain the desired short and clean pulses and, therefore, has been largely studied in the literature, where the most common approaches are gratings, chirped mirrors or grisms( diffraction gratings written on a prism) [ 14 – 17 ]. One of the most limiting parts of these compressors, when dealing with pulses with single or few optical cycle durations, are the chirped mirrors, widely used in these cases. Standard chirped mirrors present limited spectral bandwidth and, moreover, they focus on compensating the group delay dispersion( GDD), but here we will be also interested in compensating higher order dispersion terms. We show here, by means of numerical simulations, a new compressor setup, without chirped mirrors, able to obtain short, clean intense pulses for the case of an all-bulk MPC post-compression system. This compressor, based on a pair of grisms and the addition of some material dispersion, compensates very well the phase coming out of the MPC, even in the case of few-cycle pulses. We have been able to find a compressor configuration which allows us to obtain pulses that are very close to their Fourier Limit regarding duration, cleanness and peak intensity.
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