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High-speed wide tuning range wavelength swept laser around 1310 nm for frequency domain OCT

Optical coherence tomography (OCT) is an emerging cross-sectional imaging technology. It uses broadband light sources to achieve axial image resolutions on a few microns scale. In this paper, the principle of Fourier domain mode-locked (FDML) wavelength swept laser for swept source optical coherence tomography (SS-OCT) is presented and crucial parameters of the laser system are discussed. On analysis of different methods and system configurations, a new configuration of swept laser system is put forward. We theoretically demonstrate a high-speed, broad bandwidth, Fourier domain mode-locked (FDML) wavelength swept laser around 1310 nm for high-resolution frequency domain optical coherence tomography (FD-OCT). The laser has a fiber ring cavity with a semiconductor optical amplifier gain medium. Intra-cavity mode selection is achieved with an in-fiber tunable fiber Fabry-Perot filter. The laser is designed to generate 32 kHz sweeping rate with a tuning range of 165 nm full width, 3 dB sweep range of 91 nm. In SS-OCT applications the swept laser will achieve about 8.3 μm axial resolution in air and 5.9 μm axial resolution in biological tissue. The instantaneous linewidth is 0.103 nm corresponding to a coherence length of several mm, enabling OCT imaging over a large axial range. The swept laser implemented in the FD-OCT system can provide information of biological tissue imaging in real time.