High-sensitivity line-field spectral-domain OCT driven by a power-scaled gain-managed nonlinear fiber source

Line-field spectral-domain optical coherence tomography (LF-SD-OCT) enables rapid, parallel cross-sectional imaging through line-field illumination. However, the simultaneous acquisition of multiple spatial channels reduces the photon budget available to each individual channel, thereby limiting further improvement in system sensitivity. To address this limitation, we present a high-sensitivity LF-SD-OCT system driven by a home-built, high-power gain-managed nonlinear (GMN) fiber source. The source delivers a broadband and relatively flat optical spectrum, with an average output power of approximately 838 mW and a 3-dB spectral bandwidth of 71.8 nm. During 120 min of continuous operation, the root-mean-square power fluctuation was only 0.311%. In addition, single-shot dispersive Fourier transform (DFT) measurements confirmed excellent pulse-to-pulse spectral repeatability. By combining line-field illumination with a custom-developed spectrometer based on a two-dimensional CMOS camera, the proposed system enables the parallel acquisition of spectral interferograms from multiple lateral positions. The resulting LF-SD-OCT system achieves an axial resolution of 7.22 μm in air, a 6 dB sensitivity roll-off depth of approximately 3.2 mm, a central-channel sensitivity of 108.42 dB, and a lateral resolution of approximately 8.77 μm. Furthermore, ex vivo imaging of porcine myocardial tissue demonstrates the capability of the system to noninvasively visualize tissue morphology and laser-induced ablation structures. These results provide an effective approach for alleviating the photon-budget limitation inherent in LF-SD-OCT and may facilitate its broader application in biomedical imaging and the evaluation of laser-processing outcomes.