Dual-modal all-fiber OCT needle probe integrated with FBG for simultaneous imaging and temperature sensing

We designed and fabricated a single-fiber needle probe integrated with a fiber Bragg grating (FBG) capable of simultaneously performing optical coherence tomography (OCT) imaging and temperature sensing. The Bragg wavelength of the FBG is designed to fall within the spectral bandwidth of the OCT light source, enabling dual-mode functionality with a single OCT source. The probe exhibits a lateral resolution of approximately 30 μm, operates at a working distance of about 0.9 mm in air, and features a temperature sensitivity of 10.14 pm/℃. Grating reflectance has a significant influence on OCT imaging performance; hence, multiple fiber probes with varying grating parameters were investigated. Results indicate that limiting grating reflectance to ≤24% serves as a reference threshold for balancing high-quality imaging with precise temperature sensing. Finally, experiments conducted on ex vivo mouse brains and porcine backfat further demonstrate the potential applications of this dual modal OCT needle probe.