Superior dynamic range roll-off in a MHz Fourier domain mode-locked laser by a high-finesse Fabry--Pérot filter

In intraoperative optical coherence tomography (OCT), the dynamic range (DNR) and its roll-off are critical parameters to simultaneously image weak scattering and highly reflective surfaces and maintain image fidelity across the entire axial imaging range. This study demonstrates improved DNR roll-off performance using a high-finesse Fabry--Pérot tunable filter (FFP-TF) in a Fourier domain mode-locked (FDML) laser. Comparative measurements between high- and low-finesse filters reveal that increased finesse reduces intensity noise and flattens the roll-off of a 60.5-dB dynamic range from 3.71 dB/mm to 1.33 dB/mm, highlighting the critical role of FFP-TF finesse in FDML laser optimization.