Femtosecond third-harmonic generation: self-phase matching through a transient Kerr grating and the way to ultrafast computing

• Published in: Applied physics. B, Lasers and optics Lasers and optics, 2002-05, Vol.74 (7-8), p.745-748
• Main Authors: REIF, J, SCHMID, R. P, SCHNEIDER, T
• Format: Article
• Language: English
• Subjects: Beams (radiation); Diffraction gratings; Dynamics of nonlinear optical systems; optical instabilities, optical chaos and complexity, and optical spatio-temporal dynamics; Exact sciences and technology; Femtosecond; Frequency conversion; harmonic generation, including high-order harmonic generation; Fundamental areas of phenomenology (including applications); Gratings (spectra); Harmonic generation, frequency conversion; Harmonics; Lasers; Matching; Nonlinear optics; Optics; Phase conjugation, optical mixing, and photorefractive effect; Phase conjugation, optical mixing; photorefractive and kerr effects; Photons; Physics
• ISSN: 0946-2171; 1432-0649
• DOI: 10.1007/s003400200847

The third harmonic of 810-nm 100-fs pulses at 130 *mJ is generated very efficiently when ultrashort pulses from two noncollinear beams interfere in an optical medium to create an instantaneous transient grating via the optical Kerr effect. The grating couples two pathways for third-harmonic generation, each taking two photons from one beam and one photon from the other beam, respectively. The coupling enables self-phase matching in the complete process, resulting in a conversion efficiency of #~3%. Scattering an independent beam at the transient grating confirms a lifetime limited by the pulse duration, with a reaction on the order of one optical cycle. Using the second harmonic of a Ti-sapphire laser at 405 nm, it is shown that the generation of the transient Kerr grating is a general feature, requiring less than 20 *mJ/pulse. By introducing a third femtosecond beam we are able to emulate various digital logic units with femtosecond response.