Bidirectionally pumped Cr4+:YAG crystal fiber light source for optical coherence tomography

A broadband Cr4+:YAG double-clad crystal fiber light source with a collimated output power of 3.15 mW was demonstrated by using a bidirectional pump scheme. The bidirectional pump scheme increased the pumping efficiency and reduced the thermal problem along the fiber. Good agreement on the output power of the broadband fluorescence was achieved between experiment and theory, which showed a peak net gain coefficient of 0.03 cm(-1) at the center wavelength near 1380 nm. The 3 dB bandwidth of 222 nm with a Gaussian-like spectrum makes it eminently suitable for broadband interferometric technique to have low image cross talk. The calculated interference signal shows a 3 dB width of 3.62 mu m with a cross talk smaller than -24 dB for adjacent axial image pixels. (C) 2011 Optical Society of America