Seeing at a distance with multicore fibers

Images and videos provide a wealth of information for people in production and life.Although most digital information is transmitted via optical fiber,the image acquisition and transmission processes still rely heavily on electronic circuits.The development of all-optical transmission networks and optical computing frameworks has pointed to the direction for the next generation of data transmission and information processing.Here,we propose a high-speed,low-cost,multiplexed parallel and one-piece all-fiber architecture for image acquisition,encoding,and transmission,called the Multicore Fiber Acquisition and Transmission Image System(MFAT).Based on different spatial and modal channels of the multicore fiber,fiber-coupled self-encoding,and digital aperture decoding technology,scenes can be observed directly from up to 1 km away.The expansion of capacity provides the possibility of parallel coded transmission of multimodal high-quality data.MFAT requires no additional signal transmitting and receiving equipment.The all-fiber processing saves the time traditionally spent on signal conversion and image pre-processing(compression,encoding,and modulation).Additionally,it provides an effective solution for 2D information acquisition and transmission tasks in extreme environments such as high temperatures and electromagnetic interference.

Optical scanning endoscope via a single multimode optical fiber

Optical endoscopy has become an essential diagnostic and therapeutic approach in modern biomedicine for directly observing organs and tissues deep inside the human body,enabling non-invasive,rapid diagnosis and treatment.Optical fiber endoscopy is highly competitive among various endoscopic imaging techniques due to its high flexibility,compact structure,excellent resolution,and resistance to electromagnetic interference.Over the past decade,endoscopes based on a single multimode optical fiber(MMF)have attracted widespread research interest due to their potential to significantly reduce the footprint of optical fiber endoscopes and enhance imaging capabilities.In comparison with other imaging principles of MMF endoscopes,the scanning imaging method based on the wavefront shaping technique is highly developed and provides benefits including excellent imaging contrast,broad applicability to complex imaging scenarios,and good compatibility with various well-established scanning imaging modalities.In this review,various technical routes to achieve light focusing through MMF and procedures to conduct the scanning imaging of MMF endoscopes are introduced.The advancements in imaging performance enhancements,integrations of various imaging modalities with MMF scanning endoscopes,and applications are summarized.Challenges specific to this endoscopic imaging technology are analyzed,and potential remedies and avenues for future developments are discussed.

Bessel-beam-based side-view measurement of seven-core fibre internal core distribution

Accurate knowledge of the internal core distribution of multicore fibres(MCFs)is essential,given their widespread application,including in fibre splicing,bundle fan-in/fan-out,mode coupling,writing gratings,and fibre drawing.However,the extensive use of MCFs is restricted by the limited methods available to precisely measure the fibre core distribution,as the measurement accuracy determines the performance of the product.In this study,a side-view and nondestructive scheme based on Bessel beam illumination was proposed for measuring the internal core distribution of a seven-core fibre.Bessel beams offer a large focal length in a scattering medium,and exhibit a unique pattern when propagating in an off-axis medium with a spatially varying refractive index.The results revealed that a long focal length and unique pattern influence the image contrast in the case of Bessel beams,which differs from a typical Gaussian beam.Further,high-precision measurement of a seven-core fibre core distribution based on a Bessel beam was demonstrated using a digital correlation method.A deep learning approach was used to improve the measurement precision to 0.2°with an accuracy of 96.8%.The proposed side-view Bessel-beam-based method has the potential to handle more complex MCFs and photonic crystal fibres.