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Main Authors: Seres, J., Seres, E., Schumm, T.
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2603.12705
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author Seres, J.
Seres, E.
Schumm, T.
author_facet Seres, J.
Seres, E.
Schumm, T.
contents Nonlinear crystals are widely used to efficiently generate second or third harmonics, and also for frequency mixing. Generation of multiple cascaded harmonics simultaneously, however, appears much less studied, although supported by the usually large nonlinearity of these crystals. Here, we demonstrate the generation of multiple harmonics up to 6th order in a \b{eta}-BBO crystal, extending into the vacuum ultraviolet spectral range. Phase matched generation of the second or the third harmonic is directly driven by a single 800 nm Ti:sapphire oscillator beam. Our study reveals that the harmonics are generated by \c{hi}(2):\c{hi}(2) and \c{hi}(2):\c{hi}(3) cascaded processes and intense harmonic signals are obtained even for the 5th and 6th harmonics, where the \b{eta}-BBO crystal is mostly absorbing. While higher order harmonics cannot be phase matched simultaneously, limiting the harmonic amplitudes, even the weakest harmonics are more than three orders of magnitude above the measurement noise limit, making them suitable for many spectroscopic applications.
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id arxiv_https___arxiv_org_abs_2603_12705
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Cascaded multi-harmonic generation in a \b{eta}-BBO crystal reaching 133 nm from a single 800 nm pump beam
Seres, J.
Seres, E.
Schumm, T.
Optics
Nonlinear crystals are widely used to efficiently generate second or third harmonics, and also for frequency mixing. Generation of multiple cascaded harmonics simultaneously, however, appears much less studied, although supported by the usually large nonlinearity of these crystals. Here, we demonstrate the generation of multiple harmonics up to 6th order in a \b{eta}-BBO crystal, extending into the vacuum ultraviolet spectral range. Phase matched generation of the second or the third harmonic is directly driven by a single 800 nm Ti:sapphire oscillator beam. Our study reveals that the harmonics are generated by \c{hi}(2):\c{hi}(2) and \c{hi}(2):\c{hi}(3) cascaded processes and intense harmonic signals are obtained even for the 5th and 6th harmonics, where the \b{eta}-BBO crystal is mostly absorbing. While higher order harmonics cannot be phase matched simultaneously, limiting the harmonic amplitudes, even the weakest harmonics are more than three orders of magnitude above the measurement noise limit, making them suitable for many spectroscopic applications.
title Cascaded multi-harmonic generation in a \b{eta}-BBO crystal reaching 133 nm from a single 800 nm pump beam
topic Optics
url https://arxiv.org/abs/2603.12705