Near-Infrared Speckle-Illumination Imaging Based on a Multidimensionally Disordered Fiber Laser

Abstract

Speckle illumination is extensively applied in various imaging scenarios due to its advantages in enhancing the performance of imaging. Generally, the existing speckle-illumination methods are mainly based on external spatial modulation of light through a rotating diffuser or spatial light modulator. Both the lighting efficiency and the system's compactness are limited for these conventional external modulation methods, due to their free-space light coupling and insertion or diffraction loss. Here, a multimode fiber laser with self-reconfigurable speckle illumination is proposed and realized, benefiting from the temporal-spectral randomness of a homemade coherent random-fiber laser and the spectral-sensitive output pattern of an out-coupling multimode fiber. Output characteristics in the spectral and spatial domain of the proposed laser are analyzed and show dynamically varying speckles within a moderate bandwidth. These features pave efficient ways for superresolution imaging through an opaque scattering medium as well as ghost imaging, which is realized and demonstrated based on the lighting of the proposed laser.