Characteristics of remote hologram multiplexing with random pattern references from a multimode fiber bundle

We propose and characterize the remote multiplexing of holograms with random pattern references from a multimode fiber bundle. The random pattern reference is modeled by using the superposition and concatenation of propagation modes of multimode fibers and free space. We compare two laser-coupling methods to the fiber bundle, i.e., direct coupling and lens coupling, for angle, shift, and wavelength remote multiplexings. The optimum laser-coupling method for each multiplexing is analyzed based on the theoretical model and experimental results. Retrieved hologram images show that 1-D intensity variation of the image might occur for the 90-deg geometry holograms in relation to the random pattern properties. Environmental variation effects such as vibration and temperature variation are also discussed and examined. These remote multiplexing methods can be applied to general multimode waveguide arrays to construct compact and integrated optical systems, where multiplexing can be performed at remote places.