A 1060 nm stretched-pulse mode-locked wavelength-swept laser source providing an A-scan rate of 20 MHz

Abstract

The laser source is the deciding factor in improving the rapid imaging of swept-source optical coherence tomography (OCT) systems. We introduce an intrinsically stable stretched-pulse mode-locking (SPML) laser operating a tuning range of over 92 nm at a center wavelength of 1060 nm. The laser provides variable A-line rates up to ~20 MHz as a function of the duty cycle. The cavity comprises a unidirectional ring cavity with matched positive and negative continuously chirped fiber Bragg gratings generating ± 556 ps/nm dispersion. We demonstrate the ability of the stretched-pulse mode-locking laser to provide rapid optical signals for optical coherence tomography. Finally, we highlight performance by displaying the 3D datasets acquired at > 19,487 × 103 A-lines/s as cross-sectional images, averaging the complex A-scan signals of the voxel, and examining the inter-frame phase variance without the need for trigger signals and a phase calibration method. By integrating three-dimensional coherence-based optical imaging into a video-rate, camera-like deployment using a high-speed digitizer, this laser may potentially leverage the use of optical coherence tomography of complex tissue dynamics in pre-clinical studies