High-power low spatial coherence random fiber laser

A high-power multi-transverse modes random fiber laser (RFL) is investigated by combining a master oscillator power-amplifier (MOPA) configuration with a segment of extra-large mode area step-index multimode fiber (MMF). Spatial coherence of the high power multi-transverse modes RFL has been analyzed, which shows that speckle contrast is reduced dramatically with the output power increasing. In this way. considerably low speckle contrast of similar to 0.01 is achieved under high laser power of similar to 56 W. which are the records for multi-transverse modes RFLs in both spatial coherence and output power. This work paves a way to develop high-power RFLs with Very low spatial coherence for NA/ide-range speckle-free imaging and free-space communication applications. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement