Ultra Low Noise Fourier Domain Mode Locked Laser for high quality Megahertz Optical Coherence Tomography

We investigate the origin of high frequency noise in Fourier Domain Mode Locked (FDML) lasers and present an extremely well dispersion compensated setup which virtually eliminates intensity noise and dramatically improves coherence properties. We show optical coherence tomography (OCT) imaging at 3.2 MHz A-scan rate and demonstrate the positive impact of the described improvements on the image quality. Especially in highly scattering samples, at specular reflections and for strong signals at large delays the noise in optical coherence tomography images reduces significantly. We also suggest a simple model for as explanation, a passive physical stabilizing mechanism that leads to an automatic compensation of remaining cavity dispersion in FDML lasers.