V-Waves: Spatio-temporally induced group-velocity dispersion in free space

Abstract

Introducing precise spatio-temporal structure into a pulsed optical field can lead to remarkable changes with its free propagation. `Space-time' (ST) wave packets, for example, propagate rigidly at a tunable group velocity in free space by inculcating a one-to-one relationship between the axial wave numbers and the temporal frequencies. Here we introduce a new class of ST wave packets that we call V-waves (so named because of their characteristically V-shaped spatio-temporal spectrum) in which a linear one-to-one relationship is introduced between the temporal frequencies and the transverse wave numbers (or spatial frequencies). We confirm experimentally that V-waves experience anomalous group velocity dispersion in free space, all the while maintaining the group velocity fixed at the speed of light in vacuum. Extremely large values of group velocity dispersion can be easily realized, which are not accessible with traditional optical materials or photonic structures. Moreover, V-waves are the unique optical wave packets whose diffraction and dispersion lengths are intrinsically equal by virtue of the spatio-temporal structure of the field itself. These results are of interest for optical signal processing and nonlinear optics.

References in corpus (8)

• Diffraction-free space-time beams
• Ultrashort Tilted-Pulse-Front Pulses and Nonparaxial Tilted-Phase-Front Beams
• Self-healing of space-time light sheets
• Gaussian beams diffracting in time
• Sub-luminal wave bullets: Exact Localized subluminal Solutions to the Wave Equations
• The space-time Talbot effect
• Axial spectral encoding of space-time wave packets
• Classical entanglement underpins the propagation invariance of space-time wave packets

Cited by in corpus (7)

• Arbitrarily accelerating space-time wave packets
• The consequences of non-differentiable angular dispersion in optics: Tilted pulse fronts versus space-time wave packets
• Non-Dispersive Space-Time Wave Packets Propagating in Dispersive Media
• Transverse spin angular momentum of space-time surface plasmon polariton wave packet
• Exciting space-time surface plasmon polaritons by irradiating a nanoslit structure
• Realizing normal group-velocity dispersion in free space via angular dispersion
• Flying focus with arbitrary directionality for spatiotemporal control of laser pulses