Wide-field high-speed space-division multiplexing optical coherence tomography using an integrated photonic device

Faster imaging speed is one of the key driving factors for the improvement of optical coherence tomography (OCT). Space-division multiplexing OCT (SDM-OCT) is a recently developed parallel OCT imaging method in order to achieve multi-fold speed improvement. Our laboratory has previously demonstrated the feasibility of SDM-OCT. However, the assembly of fiber optics components used in our first prototype system was labor-intensive and susceptible to errors which may limits the broad dissemination of the SDM-OCT technology. In this paper, we demonstrate a prototype high-speed SDM-OCT system (~800,000 A-scans/s) using an integrated photonic chip to replace many of the fiber optic components. The chip measures only 2.5×2.0 cm², close to the size of a US quarter coin. A three-layer cascade of 1×2 splitters was integrated in the chip to split the single incident beam into 8 beams. Optical delays (equivalent ~2.5 mm delay length on the chip) were included between each waveguide channel in order to generate multiplexed interference signals that can be detected simultaneously. The chip-based SDM-OCT system was then used to demonstrate the feasibility for high-speed and wide-field imaging applications. Three-dimensional (3D) volumetric images of ex vivo porcine eye and in vivo human fingerprint covering a large imaging area of up to 18.0 × 14.3 mm² were obtained in ~1 second. High-definition 3D OCT images (1500 × 1600 A-scans) of human finger nail were acquired in ~3 seconds. Integrated photonic devices can be reliably manufactured with high precisions and low per-unit cost, facilitating the deployment and adoption of the SDM-OCT technology.