Abstract
A swept source with both high repetition-rate and broad bandwidth is indispensable to enable optical coherence tomography (OCT) with high imaging rate and high axial resolution. However, available swept sources are commonly either limited in speed (sub-MHz) by inertial or kinetic component, or limited in bandwidth (<100 nm) by the gain medium. Here we report an ultrafast broadband (over 100 nm centered at 1.55-µm) all-fiber inertial-free swept source built upon a high-power dispersion-managed fiber laser in conjunction with an optical time-stretch module which bypasses complex optical amplification scheme, which result in a portable and compact implementation of time-stretch OCT (TS-OCT) at A-scan rate of 44.5-MHz, axial resolution of 14 µm in air (or 10 µm in tissue), and flat sensitivity roll-off within 4.3 mm imaging range. Together with the demonstration of two- and three-dimensional OCT imaging of a mud-fish eye anterior segment, we also perform comprehensive studies on the imaging depth, receiver bandwidth, and group velocity dispersion condition. This all-fiber inertia-free swept source could provide a promising source solution for SS-OCT system to realize high-performance volumetric OCT imaging in real time.
Highlights
Optical coherence tomography (OCT) is a well-recognized non-contact and non-invasive cross-sectional imaging modality for two-dimensional (2D) and three-dimensional (3D) tissue architecture visualization [1]
The erbium-doped fiber (EDF) laser has 102-nm 10-dB optical bandwidth centered at 1.55-μm, 22-mW direct output average power, and 1.6-ps pulse width at 44.5-MHz repetition rate
The >100 nm optical bandwidth is comparable with conventional inertial-based swept source with semiconductor optical amplifiers (SOA), e.g. Fourier Domain Mode Locking (FDML) laser, but the repetition rate is more than two orders of magnitude higher without buffering stages
Summary
Optical coherence tomography (OCT) is a well-recognized non-contact and non-invasive cross-sectional imaging modality for two-dimensional (2D) and three-dimensional (3D) tissue architecture visualization [1]. The erbium-doped fiber (EDF) laser has 102-nm 10-dB optical bandwidth centered at 1.55-μm, 22-mW direct output average power, and 1.6-ps pulse width at 44.5-MHz repetition rate This source considerably outperforms the work presented in [29,30,31]. It is worthy to note that, a dispersion-managed fiber lasers with bandwidth of 80 nm center at 1.55-μm was successfully applied in TD-OCT [41], and it is the first time that an EDF laser with larger than 100 nm bandwidth was realized and used in SSOCT, to the best of our knowledge This all-fiber inertia-free swept source provides a promising solution for SS-OCT system to realize high-performance volumetric OCT imaging in real time. The signal detection, signal processing, and light beam scanning parts were synchronized through the real-time oscilloscope, while the swept source was free running for the limited signal processing speed and synchronization bandwidth for the swept source
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