Mode Division Multiplexing (MDM) is a communication technique that involves transmitting multiple data streams simultaneously over different spatial modes of a multimode optical fiber or waveguide. Each spatial mode represents a distinct path that can carry independent data. MDM is often used in optical communication systems to increase data transmission capacity by utilizing the multiple modes supported by the optical medium.


The Resilience of Hermite- and Laguerre-Gaussian Modes in Turbulence

Vast geographical distances in Africa are a leading cause for the so-called digital divide due to the high cost of installing fiber. Free-space optical (FSO) communications offer a convenient and higher bandwidth alternative to point-to-point radio microwave links, with the possibility of repurposing existing infrastructure. Unfortunately, the range of high-bandwidth FSO remains limited. While there has been extensive research into an optimal mode set for FSO to achieve maximum data throughput by mode division multiplexing, there has been relatively little work investigating optical modes to improve the resilience of FSO links. Here, we experimentally show that a carefully chosen subset of Hermite-Gaussian modes is more resilient to atmospheric turbulence than similar Laguerre-Gauss beams, with a predicted upper bound increase in propagation distance of 167% at a mode-dependent loss of 50%.