All-optical system for acquiring and transmitting image over very long distances

As the amount of data grows exponentially around the world, there is an increasing need to quickly acquire and transmit multidimensional data over long distances. Online video surveillance in sectors such as industrial manufacturing has significantly increased productivity while reducing security risks. Real-time global video calling has revolutionized people’s daily lives.

Existing systems can use high-performance detectors, image sensors and other technologies to collect information about media such as light, sound and microwaves. This data is then transmitted back to the operator via various media such as cables, networks, wireless communications and fiber optics.

However, in scenarios where observation requires narrow or hard-to-reach areas, data acquisition equipment and electronic circuits (for tasks such as compressing, encoding, and modulating information) are needed to process the data before transmission. This imposes special requirements on timeliness and system resistance to disruptions.

In recent years, optical fiber has gained wide application in data transmission due to its low transmission losses and high bandwidth. Although technologies such as wavelength division multiplexing (WDM) and space division multiplexing (SDM) using multi-core optical fibers have significantly increased the system’s transmission capacity and efficiency, the transmission process still requires multiple signal conversions.

All-optical acquisition and transmission allows image information to be sent from one end to the other at the speed of light, without the need for additional electronic components.

Fiber optic bundles can directly convert and transmit two-dimensional light fields end-to-end, making them essential in extreme environments such as inaccessible and obscured areas such as aerospace, industrial manufacturing, and healthcare. However, fiber optic bundles are typically limited in length, expensive, and pose quality assurance issues when transmitting data over long distances due to manufacturing constraints.

Scientists have developed various all-optical networks for tasks such as information gathering, encrypted transmission and image classification, which are expected to form the basis of next-generation communications.

However, these systems face practical implementation obstacles and are generally only compatible with coherent light sources such as lasers. Therefore, there is an urgent need for an efficient, efficient and interference-resistant image acquisition and transmission system.

In a new study published in Optoelectronic advancesresearchers proposed an all-fiber multiplexed parallel single-piece acquisition and transmission system called multi-core fiber image acquisition and transmission (MFAT) system to address the challenges mentioned above.

The front-end design without electronic circuitry eliminates the need for complex signal conversion processes, making it suitable for use in a variety of environments and resistant to noise from inconsistent light sources. The image data is encoded in the optical domain via a fiber optic connection.

The multi-channel characteristics of multi-core optical fibers enable high-bandwidth and high-quality transmission. Furthermore, digital aperture technology enables image recovery and reconstruction from an end-plane image that completely hides the original information, thus enabling real-time scene reconstruction from a distance of up to one kilometer.

The process of image acquisition and transmission consists of two main stages: encoding and decoding. The encoding phase is based on the principle of excitation of the optical fiber propagation mode, where different angles of light reaching the end surfaces of different fiber cores excite different propagation modes.

In most natural settings, the pattern in each fiber core channel can be viewed as a composite of all the object points exciting a variety of modes. As a result, information from the incident light field is encoded into the spatial and mode components of the multicore optical fiber for transmission. However, accurately determining the occupancy of each mode is usually difficult and requires significant computational resources.

To address this problem, this study introduces a cost-effective digital aperture decoding technique based on image processing methodologies to facilitate rapid reconstruction. By extracting and calculating the feature values ​​for different areas of the fiber core, the decoding of various spatial information in the dimension of fiber transmission modes can be achieved.

This study presents the system performance in both direct and encoded image transmission modes. Direct image transmission mode allows direct observation of the scene at the other end, while encoded image transmission can be integrated with digital coding techniques to enable encrypted transmission of multidimensional data.

Simultaneous multiplexing of time and space channels significantly increases transmission efficiency. Moreover, the combination of polarization, wavelength and other channel multiplexing techniques further enhances the transmission efficiency of the system.

The study also paid attention to factors affecting the effectiveness of system reconstruction, such as temperature changes, bending and algorithm robustness. The proposed solution has significant application value in image acquisition and transmission over long distances, especially in extreme conditions.

The interference-resistant, compact design is the basis for the transmission of global, fast multimedia streams in real time. The exploration and use of more multidimensional information combined with advanced algorithms creates the potential to develop next-generation all-optical parallel transmission systems.