Low-spatial-coherence broadband fiber source for speckle free imaging

TL;DR

This paper presents a high-power, broadband fiber-based ASE source with low spatial and temporal coherence, enabling speckle-free imaging and potential applications in full-field imaging and ranging.

Contribution

The authors design and demonstrate a novel fiber ASE source with low coherence and high power per mode, suitable for speckle-free imaging.

Findings

Achieved 270 mW continuous emission at 1055 nm with 74 nm bandwidth.

Distributed emission among ~70 spatial modes for speckle suppression.

Successfully demonstrated speckle-free full field imaging.

Abstract

We designed and demonstrate a fiber-based amplified spontaneous emission (ASE) source with low spatial coherence, low temporal coherence, and high power per mode. ASE is produced by optically pumping a large gain core multimode fiber while minimizing optical feedback to avoid lasing. The fiber ASE source provides 270 mW of continuous wave emission, centered at {\lambda}=1055 nm with a full-width half-maximum bandwidth of 74 nm. The emission is distributed among as many as ~70 spatial modes, enabling efficient speckle suppression when combined with spectral compounding. Finally, we demonstrate speckle-free full field imaging using the fiber ASE source. The fiber ASE source provides a unique combination of high power per mode with both low spatial and low temporal coherence, making it an ideal source for full-field imaging and ranging applications.