Fig. 1. Schematic of light field modulation technology^[21]. (a) Random speckle formed by plane waves passing through strongly scattering media; (b) regulating the incident light field to form a focal point for scattered light

Fig. 2. Lee holography method using binary amplitude grating for complex amplitude modulation. (a) Schematic of DMD and 4f system optical path; (b) phase determined by lateral position of stripes; (c) amplitude determined by duty ratio of stripes

Fig. 3. Schematic of superpixel method^[24]. (a) Off-axis lenses formed by a 4f system; (b) filter aperture on the spectral plane; (c) 4×4 superpixel phase mask, with green indicating the three open pixels; (d) response of the target plane is the phase sum of the three pixels turned on in Fig. 3(c)

Fig. 4. Digital phase conjugation imaging technology in multimode fiber^[4]

Fig. 5. Schematic of off-axis holography^[26]. (a) Hologram recorded by the camera; (b) Fourier transform of the hologram; (c) amplitude and phase of the reconstructed speckle

Fig. 6. Steps for measuring the transmission matrix using the internal reference method^[29]. (a) First group of pixels is modulated and second group is used as a reference; (b) first group of pixels is used as a reference and second group is modulated; (c) reference phase matching process

Fig. 7. Typical optical setup of multimode fiber imaging based on transmission matrix^[12]

Fig. 8. Schematic of multimode fiber imaging device based on speckle scanning ^[46]

Fig. 9. Reconstructing input image from output speckle based on CNN network^[50]

Fig. 10. Multimode fiber bending correction technology. (a) Schematic of generating virtual beacon on holographic plate^[13]; (b) refocus the spot after calibrating the transmission matrix^[14]; (c) graded-index fiber with better bending resistance^[15]; (d) metasurface reflection structure^[16]; (e) schematic of rotation memory effect of multimode fiber^[17]

Fig. 11. Spatial-frequency domain encoding tracking adaptive beacon light-field-encoded method^[12]

Fig. 12. Endoscopic imaging applications based on multimode fiber. (a) Fluorescently stained neuronal cell images obtained by using a multimode fiber endoscope^[4]; (b) multimode fiber confocal imaging^[57]; (c) imaged dendrites at different depths using digital zoom^[59]; (d) continuously acquisition imaging of neuronal cell bodies, inhibitory neuronal processes, and visual cortex at a frame rate of 3.5 frame/s^[7]; (e) 3D image reconstruction of multiple scenes at video rates^[60]; (f) imaging of deep brain neurons and blood flow in mice using a side-view fiber probe^[11]

Fig. 13. Application of STABLE technology^[12]. (a) Schematic of endoscopic imaging in complex environment; (b) sheep small intestine images captured via MMF endoscopy

Fig. 14. MMF nonlinear imaging. (a) Fiber optic probe for two-photon fluorescence imaging^[62]; (b) bright field and Raman imaging of bacterial samples^[63]; (c) CARS imaging of polystyrene spheres^[8]; (d) polarization second harmonic imaging of mouse tail tendons^[64]

Fig. 15. MMF multimodal imaging technology. (a) Composite image of photoacoustic and fluorescence imaging of red blood cells (red) and fluorescent balls (green)^[66]; (b) imaging of the colon using a white light and multimode fiber integrated endoscopic probe^[12]; (c) reflection/fluorescence/phase multimodal imaging^[68]

Fig. 16. Optical tweezers based on multimode fiber. (a) Two silica beads (diameter of 2 μm) are captured and moved in real time by a multimode fiber focusing point^[39]; (b) nine particles are manipulated in three dimensions simultaneously by multimode fiber optical tweezers^[70]

Fig. 17. Application of multimode optical fiber in optical computing. (a) Schematic diagram of a programmable linear optical network based on multimode optical fiber^[71]; (b) illustration of the neuromorphic computing architectures and the experimental setup based on multimode fiber^[72]; (c) optical logic operations through multimode fiber^[73]; (d) training process of the DN₂s for MMF speckle pattern reconstruction^[74]