Ultrahigh-Resolution Optical Coherence Tomography in 1.7 µm Region with Fiber Laser Supercontinuum in Low-Water-Absorption Samples

Ultrahigh-resolution, high-penetration-depth optical coherence tomography (OCT) by use of an all-fiber supercontinuum source at 1.7 µm was demonstrated. A Gaussian-like supercontinuum with 358 nm bandwidth at a center wavelength of 1.7 µm was generated by an ultrashort-pulse Er-doped fiber laser system. A longitudinal resolution of 3.3 µm in tissue, with a sensitivity of 95 dB, was achieved. In vitro ultrahigh-resolution imaging of biological tissues was also demonstrated. To the best of our knowledge, this is the first demonstration of ultrahigh-resolution OCT in the 1.7 µm-wavelength region.