High capacity terahertz communication systems based on multiple orbital-angular-momentum beams

Abstract

Structured electromagnetic (EM) waves carrying orbital angular momentum (OAM) have been explored in various frequency regimes to enhance the data capacity of communication systems by multiplexing multiple co-propagating orthogonal OAM beams (i.e., mode-division multiplexing (MDM)). Terahertz (THz) communications in free space have gained interest as THz waves tend to have: (a) larger bandwidth and lower beam divergence than millimeter-waves, and (b) lower interaction with matter conditions than optical waves. In this paper, we review recent experimental demonstrations of OAM-based THz MDM communication systems, including (i) THz MDM system with two multiplexed OAM beams; (ii) THz OAM multiplexing together with frequency-division-multiplexing (FDM) and polarization-division-multiplexing (PDM); (iii) multiplexing a full set of two-dimensional Laguerre-Gaussian (LG_(l,p)) beams; and (iv) THz integrated OAM emitter for OAM mode generation and multiplexing. System performance of THz OAM links with the effect of turbulence, divergence, and multipath is also simulated and analyzed.

Resonant Fully Dielectric Metasurfaces for Ultrafast Terahertz Pulse Generation

“…General research on terahertz light, which occupies the 0.1 to 10 THz band of the electromagnetic spectrum, is fuelled by fundamental and practical ramifications in fields as different as biological imaging, [7][8][9] art restoration, [10][11][12] and telecommunications. [13][14][15] Indeed, the nonlinear generation of terahertz pulses from ultrafast optical sources is indeed standard in the field [16][17][18] and it is historically considered a seminal achievement enabling the modern terahertz research area. However, the lack of efficient largearea thin emitters is certainly a fundamental and practical limit, bringing cumbersome experimental setups with complex geometries as well as several other limitations like the resolution limits of novel near-field imaging systems.…”

Proposal and numerical verification of an ultrasmall terahertz source using integrated photonic crystal waveguides for highly efficient differential frequency generation

“…Terahertz (THz)-wave technologies have been extensively studied for various applications [1][2][3][4] such as spectroscopic sensing, nondestructive imaging, and telecommunications. For these applications, various THz-wave generation methods have been developed.…”