Photonic orbital angular momentum with controllable orientation

Abstract

Vortices are whirling disturbances commonly found in nature ranging from tremendously small scales in Bose-Einstein condensates to cosmologically colossal scales in spiral galaxies. An optical vortex, generally associated with a spiral phase, can carry orbital angular momentum (OAM). The optical OAM can either be in the longitudinal direction if the spiral phase twists in the spatial domain or in the transverse direction if the phase rotates in the spatiotemporal domain. In this article, we demonstrate the intersection of spatiotemporal vortices and spatial vortices in a wave packet. As a result of this intersection, the wave packet hosts a tilted OAM that provides an additional degree of freedom to the applications that harness the OAM of photons.

Spatiotemporal Differentiators Generating Optical Vortices with Transverse Orbital Angular Momentum and Detecting Sharp Change of Pulse Envelope

“…Recently, such STOVs with transverse OAM have been theoretically DOI: 10.1002/lpor.202100357 proposed and experimentally demonstrated, based on the spatiotemporal control methods with adjustable resolution and applications. [19][20][21][22][23][24][25][26] As a new degree of freedom for optical manipulation, transverse OAM unique in the spatiotemporal domain strongly inspires potential advances to generate STOVs in a novel way.…”

Quadrics for Structuring Invariant Space–Time Wavepackets

“…11 Besides the intense research activities on optical vortex beams carrying longitudinal OAM (i.e., the spiral phase twists in the spatial domain), the recent studies on spatiotemporal optical vortices (STOVs) carrying transverse or tilted OAM (here the phase rotates in the spatiotemporal domain) have opened up new opportunities for structuring light. [12][13][14][15][16][17] More generally, structured light, particle beams, and invariant wavepackets are nowadays indispensable tools in numerous fields of science and technology, [18][19][20][21][22][23][24] and a new step forward in the advanced control of wave propagation would facilitate the emergence of new functionalities. While most of the above examples have been deeply studied in the monochromatic regime, strong interest is currently shown for space-time (ST) invariant wavepackets.…”

Topologically protected generation of spatiotemporal optical vortices with nonlocal spatial-mirror-symmetry-breaking metasurface

“…Our studies not only provide a new topological perspective for STOV generation but also lay a solid foundation for potential applications of STOV metasurfaces integrated with other optoelectronic devices, because of their robust immunity to fabrication defects.Since the intriguing recognition that optical phase singularity [1] can lead to longitudinal orbital angular momentum (OAM) [2][3][4], the studies of optical field singularities have been broadly extended over spatial dimensions. Recently, intense interest has been attracted to explore the optical vortices in the spatiotemporal domain [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22]. In particular, spatiotemporal optical vortices (STOVs), as an optical pulse, can be tilted with respect to the propagation direction and exhibit transverse components of OAM unique in the spatiotemporal domain [6][7][8].…”

“…With such transverse OAM, all the family members of optical angular momentum are united from both spin and orbital perspectives and with both transverse and longitudinal components.Although transverse OAM offers a new degree of freedom and potential advances, it is a challenge to generate STOVs due to the requirement of neat optical manipulations associated with both spatial and temporal domains, simultaneously. By using pulse shapers, the spatiotemporal control method was firstly experimentally demonstrated to generate STOVs in free space with bulk optical systems [9][10][11][12][13][14][15]. Alternatively, much more compact than pulse shapers, nonlocal metasurfaces were proposed to create phase singularities in the spatiotemporal domain by breaking spatial mirror symmetry [16,17].…”