Broadband low-repetition-rate mode-locked fiber laser for swept source optical coherence tomography

Abstract

We proposed and demonstrated an all-fiber Nonlinear Polarization rotation (NPR) erbium-doped mode-locked laser, which reduces the laser repetition rate to 5.7 MHz based on a Large Mode Area Fiber (LAMF). In addition, the laser 3 dB bandwidth is extended to 86.4 nm by using extra cavity supercontinuum broadening. To the best of our knowledge, this is the first time to obtain a broadband output using such a low repetition rate mode-locked laser. This broadband low repetition rate mode-locked laser signal is then applied to time-stretched Optical Coherence Tomography (OCT). The swept source can achieve an imaging range of more than 85 mm and a sensitivity roll-off of 3.5 dB in OCT. The all-fiber low repetition rate broadband swept source based on time-stretching technology has a compact structure and high stability, and is very promising in the field of frequency measurement and high-resolution OCT.