{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,16]],"date-time":"2026-02-16T20:33:46Z","timestamp":1771274026072,"version":"3.50.1"},"reference-count":36,"publisher":"MDPI AG","issue":"3","license":[{"start":{"date-parts":[[2015,9,7]],"date-time":"2015-09-07T00:00:00Z","timestamp":1441584000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Applied Sciences"],"abstract":"<jats:p>By crossing two intense ultrashort laser pulses with different colors in a transparent medium, like a simple piece of glass, a fan of multicolored broadband light pulses can be simultaneously generated. These newly generated pulses are emitted in several well-defined directions and can cover a broad spectral range, from the infrared to the ultraviolet and beyond. This beautiful phenomenon, first observed and described 15 years ago, is due to highly-nondegenerate cascaded four-wave mixing (cascaded FWM, or CFWM). Here, we present a review of our work on the generation and measurement of multicolored light pulses based on third-order nonlinearities in transparent solids, from the discovery and first demonstration of highly-nondegenerate CFWM, to the coherent synthesis of single-cycle pulses by superposition of the multicolored light pulses produced by CFWM. We will also present the development and main results of a dedicated 2.5-D nonlinear propagation model, i.e., with propagation occurring along a two-dimensional plane while assuming cylindrically symmetric pump beam profiles, capable of adequately describing noncollinear FWM and CFWM processes. A new method for the generation of femtosecond pulses in the deep-ultraviolet (DUV) based on FWM and CFWM will also be described. These experimental and theoretical results show that highly-nondegenerate third-order nonlinear optical processes are formally well understood and provide broader bandwidths than other nonlinear optical processes for the generation of ultrashort light pulses with wavelengths extending from the near-infrared to the deep-ultraviolet, which have many applications in science and technology.<\/jats:p>","DOI":"10.3390\/app5030485","type":"journal-article","created":{"date-parts":[[2015,9,8]],"date-time":"2015-09-08T11:59:54Z","timestamp":1441713594000},"page":"485-515","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":13,"title":["Fundamentals of Highly Non-Degenerate Cascaded Four-Wave Mixing"],"prefix":"10.3390","volume":"5","author":[{"given":"Rosa","family":"Weigand","sequence":"first","affiliation":[{"name":"Departamento de \u00d3ptica, Facultad de Ciencias F\u00edsicas, Universidad Complutense de Madrid, Avda. Complutense s\/n, Madrid 28040, Spain"}]},{"given":"Helder","family":"Crespo","sequence":"additional","affiliation":[{"name":"Departamento de F\u00edsica e Astronomia e IFIMUP-IN, Faculdade de Ci\u00eancias, Universidade do Porto, R. do Campo Alegre 687, Porto 4169-007, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2015,9,7]]},"reference":[{"key":"ref_1","unstructured":"Shen, Y.R. (2003). The Principles of Nonlinear Optics, John Wiley & Sons."},{"key":"ref_2","unstructured":"Tamir, T. (1986). Laser-Induced Dynamic Gratings, Springer."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"697","DOI":"10.1364\/OL.24.000697","article-title":"Intense 8-fs pulse generation in the deep ultraviolet","volume":"24","author":"Durfee","year":"1999","journal-title":"Opt. 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