Enhancing roll-off performance in SD-OCT with a frequency comb

A strong roll-off performance in Optical Coherence Tomography (OCT) is essential for imaging the inner ear, as it enables better depth resolution and penetration into the delicate structures within the temporal bone. This ensures higher-quality images and improved visualization of inner ear pathologies, thereby rendering OCT a valuable non-invasive tool for accurate diagnosis and assessment of inner ear conditions. In this work, we propose a spectral-domain OCT design that incorporates a frequency comb light source to enhance the penetration depth through improved roll-off performance. A broadband (~87nm at 3dB) comb source was developed centered near 1300nm, producing ~1000 lines spaced by a constant dk (~0.83cm^-1), which were coupled into a Mach-Zehnder interferometer and then detected by a spectrometer. Our initial results demonstrate an >80% improvement in 3-dB roll-off compared to the same system without the comb, i.e., with a broadband light source as used in the classical SD-OCT design.