Systems and methods for performing RF ablation while monitoring the procedure using low coherence interferometry (LCI) data are described. A catheter includes a distal section, a proximal section, a multiplexer, and a sheath coupled between the distal section and the proximal section. The distal section includes several interconnected optical ports configured to transmit exposure radiation toward a sample and receive radiation that have been reflected or scattered from the sample. The interconnected optical ports are formed on a substrate having rigid sections and flexible sections arranged around the distal section. A holder maintains the interconnected optical elements in a fixed spatial relationship.