Image information transfer with petal-like beam lattices encoding/decoding

Abstract

Orbital angular momentum (OAM) presents an additional degree of freedom for enhancing the information capacity in optical communications. To make full use of the OAM states, mode-division multiplexing (MDM) technology based on multiplexing multiple OAM modes has been adopted. However, numerous recent studies indicate that the recognition of multiplexed optical vortices is sensitive to the misalignment and requires complicated calculations, which severely restricts the decoding efficiency of a communication system. In this paper, a novel optical lattice that contains spatial positions and modes information is specially-designed and applied for short-haul free-space optical communications. Specifically, at the transmitter, the lattices with four different superposition modes (±1, ±2, ±3, ±4) and positions information are obtained and utilized to code the 8-bit length sequences into each 256-ary symbol. And at the receiver side, the initial information sequences can be decoded by directly identifying the captured intensity patterns (i.e., incoherent detection method). In the proof-of-concept experiment, a 64 × 64 pixel Lena gray image is successfully transmitted over a 3 m indoor optical communication link. The bit error among all received symbol sequences is evaluated, and zero bit error rate (BER) is observed, showing favorable link communication performance. Due to the mode and spatial paralleling, this work exhibits great potential in the future high-dimensional large capacity optical communications.