Speckle-free Imaging Using a High-power Multimode Random Fiber Laser

A high-power multimode random fiber laser (MM-RFL) is demonstrated with high spectral density and low spatial coherence by combing random fiber laser (RFL) with a multimode fiber (MMF) incorporated master oscillator power-amplifier (MOPA) configuration. The generated MM-RFL provides a maximum output power of 100.6 W and a 3-dB bandwidth of 0.4 nm. The introduction of MMF can achieve a speckle contrast of as low as 0.037. Furthermore, speckle-free imaging is also demonstrated using the MM-RFL at different output powers. Experimental result shows that the imaging quality can be improved with the increase of output power of the MM-RFL as its spatial coherence decreases with the increasing number of effective transverse modes excited in the MMF. This high-power low spatial coherence MM-RFL provides a suitable laser source for speckle-free imaging applications with high power requirement to realize high-quality imaging.