Ultra-Degree-of-Freedom Structured Light for Ultracapacity Information Carriers

Abstract

Structured light recently highlighted the higher-dimensional control with many tailored degrees of freedom (DoFs) such as amplitude, wavelength, polarization, and orbital angular momentum (OAM), spurring the extension of fundamental science and advanced applications, especially as the novel information carrier to meet the requirement of everlastingly increasing communication bandwidth and security. In addition to the basic DoFs in light, there are also several complex DoFs hidden in spin−orbital coupled vector beams, ray-wave geometric modes, spatiotemporal vortex rings, etc., extending the structured light manipulation. In this Review, we summarize a systematic technical roadmap on how to extend multiple DoFs step-by-step beyond the conventional OAM beams, creating new forms of ultra-DoF structured light, and present a tutorial on how to exploit multiple DoFs of light as advanced information carriers, especially with the recent assistance of artificial intelligence or deep learning method, enhancing the capacity, security, and dimension for the next-generation information technologies.

Three-dimensionally programmable soft crystals toward geometric phase photonics

“…In the context of modern photonics, light has been endowed with a structure in the spatiotemporal field, having multiple degrees-of-freedom. 1,2 For a multiplexed optical modulation, a 3D tunable optical element shows the possibility of multichannel information processing, which is significant for realizing ultra-compact optical systems. Blue phase liquid crystals (BPLCs), as chiral mesophases with highly ordered 3D order, have attracted considerable interest for application in advanced photonics for their selective reflection, sensitive stimuli responsiveness, adaptive attributes and multiple degrees-of-freedom control.…”

Direct space–time manipulation mechanism for spatio-temporal coupling of ultrafast light field

“…To validate the proposed mechanism, an exemplary experiment to generate a single-coil LS is designed and conducted. Measurements show that the single-coil LS possesses a tunable topological charge (TC) with a broad TC bandwidth, leveraging great potential applications in laser-plasma dynamics 30 – 32 , information encoding 33 and laser-driven electron acceleration applications 34 , 35 . Notably, the unique angular delay of the single-coil LS can serve as the light source for annular on-chip dielectric laser-based accelerators.…”

Correlating Space, Wavelength, and Polarization of Light: Spatiospectral Vector Beams

“…Increasing the complexity of a light field and the control of different degrees of freedom (DoFs) is beneficial for advancing research and technology. Increasingly complex structures realized by combining several DoF’s have been studied in a myriad of experiments over the last decades, and the enhanced understanding of the interplay of the DoFs has already enabled novel photonic technologies. − Initially, many experiments have studied structuring transverse light fields and shaping the temporal profile of pulses, both in their scalar forms, i.e., with a uniform polarization structure. , The complexity of the light field’s structure was further increased by including the polarization domain, leading to beams with spatially nonuniform polarization distributions, i.e., spatial vector beams, as well as a temporally varying polarization vector across the pulse duration. Over the last years, this approach has been extended to combine all DoFs, e.g., the study of advanced spatiotemporal pulses of vectorial light fields, or the adaptation of established concepts such as complex transverse spatial fields to the spatiotemporal domain. , Interestingly, the focus in most of the research efforts has been to generate complex polarization and spatial patterns over the temporal domain of light with much less attention to studying structured light fields in the time’s complementary DoF, i.e., the spectral domain.…”