Demonstration of PECVD SiC thermal delay lines for optical coherence tomography in the visible

Abstract

Optical Coherence Tomography (OCT) has found applications in many fields of medicine and has a large potential for the optical biopsy of tumors. One of the technological challenges impairing faster adoption of OCT is the relative complexity of the optical instrumentation required, which translates into expensive and bulky setups. In this paper we report an implementation of Time-Domain Optical Coherence Tomography based on Plasma Enhanced Chemical Vapor Deposition (PECVD) Silicon Carbide (SiC). The devices, with a footprint of 0.3 cm 2 , are fabricated using rib waveguides defined in a SiC layer. While most of the components needed are known when using this material [1], a fast delay line with sufficient scanning range is a specific requirement of Time Domain (TD)-OCT. In the system reported here this is obtained making use of the thermo-optical effect. Though the current implementation still requires external sources and detectors to be coupled to the planar waveguide circuit, future work will include three-dimensional integration of these components onto the substrate to achieve a fully autonomous and compact OCT chip. With the potential to include the read-out and driving electronics on the same die, the reported approach can yield extremely compact and low-cost TD-OCT systems in the visible, enabling a broad range of new applications, including OCT devices for harsh environment.