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Optical amplification of the signal and sensitivity of the ultrafast spectral domain optical coherence tomography at an A-scan rate of 10MHz in a wavelength region of 1300nm

We report on detailed characterization of a newly developed ultra-high speed optical coherence tomography (OCT) system using arrayed wave guide at 1.3 μm. An axial resolution of 27 μm, a depth range of 3.98 mm, and a detection speed of 2.5 or 10 MHz axial scan per second have been achieved. We also discuss the effectiveness of a semiconductor optical amplifier (SOA) in the system. The system sensitivity without SOA was about 78 dB, which is far less than the shot-noise-limited sensitivity because of relative intensity noise and loss of optical intensity in the system. To improve the low sensitivity, we used the SOA in the system and achieved a sensitivity of 94 dB with a probe power of 10 mW, which allowed us good imaging quality in biomedical applications. The OCT system is also capable to display a volumetric tomography continuously in real time by using field programmable gate arrays (FPGA) and general purpose graphical processing unit (GPGPU) for high-speed parallel data processing. We present several tissue images such as human finger skin, finger near nail and extracted trachea of a pig.