Multi-directions pure even harmonic simultaneous generation from planarmolecules in linearly polarized laser fields

• Published in: Applied physics letters 2021-10, Vol.119 (15)
• Main Authors: Yin Haifeng, Liu, Dandan, Zeng Fanju
• Format: Article
• Language: English
• Subjects: Applied physics; Density functional theory; Harmonic generations; Lasers; Linear polarization; Symmetry
• ISSN: 0003-6951; 1077-3118

Previous studies have found that pure even harmonics are generated from oriented COmolecules in linearly polarized laser fields. In this work, we demonstratemulti-directions pure even harmonic simultaneous generation from planar molecules inlinearly polarized laser fields using the time-dependent density-functional theory. Theanalysis reveals that pure even harmonic generation depends on the special symmetry of theplanar molecule. In the linearly polarized laser field, it is found that only when theplanar molecules have reflective symmetry direction and the molecules perpendicular to thereflective symmetry direction do not have reflection symmetry can the planar moleculesgenerate pure even harmonics along such reflective symmetry direction. When the laserpolarization is perpendicular to the planar molecule, if the molecule has several thesedirections of such reflection symmetry, pure even harmonics will be simultaneouslygenerated along these symmetrical directions. Moreover, when the laser polarization isalong the molecular plane and perpendicular to the direction of one such reflectionsymmetry, even harmonic is also generated along this reflection symmetry direction,whereas odd harmonic is generated along the direction of laser polarization. Thephenomenon exists in all polyatomic planar molecules with such reflection symmetry.