Expanded-beam Conformal Hermetic Optical-fiber Connector (ECHO-Con)

Conventionally, optical fiber connectors are precision devices that repeatedly constrain two optical fibers in five dimensions [or six in the case of polarization maintaining (PM) fibers].   Via this constraint, the cores of the optical fiber cores are aligned and contacted in as continuous a path as possible, allowing for efficient and unperturbed light coupling from one waveguide to another.  This traditionally necessitates holding the optical fibers straight at the point of contact and this, combined with a limited bend radius before structural failure of the fiber, creates minimum clearance distances for bulkhead type connectors designed for feeding through device housings.  With the goal of making compact devices, this is a difficult position to start from.It has been demonstrated that fiber-optic gyroscopes (FOGs) can be pushed to their limits when housed in a fixed environment.  To transmit an optical signal into such a housing, the bulkhead connector must additionally provide a hermetic seal to prevent atmospheric exchange.  Traditionally this is accomplished by sealing a small section of similar fiber within the connector for each fiber to contact while blocking the flow of atmosphere, potentially extending the connector length and certainly doubling the minimum achievable coupling losses and polarization perturbations from the connection misalignments due to double the optical connections being made.FOGs are being integrated into ever more systems that engineers struggle to continually reduce in size.  In order to recover every available centimeter, it is critical to reduce the size of the hermetic pass-through connectors.  Naval interest implies long term exposure to salt and humidity, which can highly accelerate corrosion of many materials and material interfaces.  Use on FOG implies motion through varying environments, so pressure variations as well as shock and vibe performance will be important while in energized and de-energized states. RAM Photonics stands as a uniquely positioned SBIR performer, combining mechanical and optical expertise along with our latest technology, the FusionForge.  The FusionForge is a platform for automated reel to weld optical fiber processing system that can draw fiber from a reel, strip it, clean it, inspect it, align it to a glass microlens while maintaining polarization, and laser weld it in place to create a monolithic system.  This monolithic system is ideal for generating high stability expanded beam coupling. Additionally, this system is designed for close packing of aligned and welded fibers down to 300 µm spacing, putting the results of this SBIR either well on the way toward automated mass manufacturing or in position to provide a 6-in-1 compact arrayed fiber connector.