Extended SWIR Single Photon Avalanche Photo Detector Technology for Bioimaging

There are two principal technical limitations and challenges associated with bioimaging. First, depth imaging is limited by light scattering and diffraction in biological tissue. Second, classical high flux multiphoton optical imaging causes photo-damage to cellular viability and perturbations to molecular biological processes. This renders the sample unusable for repeated in situ imaging and prohibits measurements of dynamic biological processes within the same biological system over different time intervals. Technologies utilizing single photon detection, with the promise of very low photon fluxes, single photon sensing, time gated photon sensing and ghost imaging using entangled photon pairs capabilities, promise to directly address the above challenges and limitations. While there is considerable activity towards the development of quantum photon sources (e.g., solid state lasers and systems for generation of entangled photons), there is significantly less research and development devoted to quantum photon detectors, i.e., single photon avalanche photodetectors (SPADs). Further, efforts on SPADs have been solely limited to those operating in the visible and telecommunications bands, and not in the biologically important 2080-2340 nm band which is a local minimum in the optical absorption of H2O. SPADS operating at 2080-2340 nm are required for development of the next generation of quantum bioimaging system technology. In this DoE SBIR program, Amethyst Research will develop a technology that will be able to deliver a new class of photo detectors directly addressing the current ‘technology gap’ of SPADs operating in the 2080-2340 nm window. These detectors will be designed to be suitable for integration into avalanche photodiode arrays (for direct imaging) or linear arrays for laser photon scanning imaging systems, or as single detectors for sensing. The overall Phase I Objectives will be to design and demonstrate the operation of a Single Photon Detector Technology operating in the 2080 – 2340 nm band for the quantum biosensing and bioimaging community: • Design and modeling of novel 2080-2340 nm GaSb-based SPAD device architectures • Epitaxial growth of GaSb -based SPAD devices • DC electro-optical characterization of GaSb -based SPAD devices • Demonstration of superior performance of GaSb materials for SPAD devices These detectors will provide a critically needed technology for integration into systems for bioimaging, chemical sensing, quantum sensing and imaging when delivered as avalanche photodiode arrays (for direct imaging) or linear arrays for laser photon scanning imaging systems, or as single detectors for sensing.