Optical Free Space Focal Plane Interconnect

The increasing array sizes and bits per pixel of focal-plane imaging devices require a reliable, easily assembled and repaired, electrically isolated, high bandwidth (= to or > than 200 Mbps) interconnection between focal plane detectors (operating at cryogenic temperatures) and output electronics (operating at ambient temperatures). This proposal addresses the problem of providing such a connection with free-space optics and smart-pixel optoelectronic devices. Free-space optics is uniquely suited to implementing this connection because it: (1) requires no physical connection between the focal plane and the outside electronics, leading to simple assembly and low heat loss; (2) has the lowest optical losses of any connection technique; (3) minimizes the number of components at cryogenic temperatures; and (4) can be scaled to higher bandwidth applications. Smart-pixel devices combine arrays of optoelectronic modulators with signal processing electronics using monolithic or hybrid integration on a common substrate. The goal is to develop a free-space link to move data from a cooled focal plane to an ambient temperature electronic output will less heat loss than existing electronic or fiber interconnects. In Phase I, we will determine suitable optical components, evaluate transmitter and receiver designs, and determine the best combination of devices to maximize data transfer rate, parallelism and robustness while minimizing cryogenic heat load, alignment and packaging problems. We will develop a thorough preliminary design for a complete link, evaluate its performance, power dissipation and cost, identify technical challenges to implementing the free-space focal plane interconnect to be constructed in prototype form in Phase II.