Defective States of Structured Light for High-Capacity Information Transmission

Structured light brings a breakthrough in information capacity carried by the laser field, finding an ideal utility in optical information transmission. Advancements in optical intensity-based imaging have facilitated the use of structured light for simple information decoding. However, the practicality of available structured-light-based encoding methods is limited by the scarcity of easily distinguishable beam structures. What’s more, currently the structured light is confined to digital bits encoding or channel distinguishing that needs the decoding process, due to a single structured pattern still lacking of effective information. Here, in response to these limitations, we propose a method for extremely high-capacity information encoding, as well as image direct transmission, by modulating the structured light to defective states. Hermite-Gaussian (HG) eigenmode in defect states are designed and generated to achieve a large quantity of easily distinguishable patterns. With well-designed two-dimensional binary hologram gratings to generate different defects in a single HG mode, we achieve over 10 ⁿ ( n  > 10) of varying laser states for encoding, corresponding to information capacity being tens of bits. These defect states are recognized by image processing method for quick decoding. What’s more, various image patterns can also be generated and are possible to achieve long-distance transmission with high fidelity. It means that the images can be directly transmitted without Fourier lens imaging, which paves a new way for information transmission. Free propagation and atmospheric turbulence performance of the defective mode are investigated to prove the defective mode has a similar performance to the standard eigenmode and is practical for information transmission.