We propose a design for a free space optical communications (FSOC) receiver terminal that offers an improved field of view (FOV) in comparison to conventional FSOC receivers. The design utilizes a microlens to couple the incident optical signal into an individual fiber in a bundle routed to remote optical detectors. Each fiber in the bundle collects power from a solid angle of space; utilizing multiple fibers enhances the total FOV of the receiver over typical single-fiber designs. The microlens-to-fiber-bundle design is scalable and modular and can be replicated in an array to increase aperture size. The microlens is moved laterally with a piezoelectric transducer to optimize power coupling into a given fiber core in the bundle as the source appears to move due to relative motion between the transmitter and receiver. The optimum position of the lens array is determined via a feedback loop whose input is derived from a position sensing detector behind another lens. Light coupled into like fibers in each array cell is optically combined (in fiber) before illuminating discrete detectors.
Abstract-We describe and experimentally demonstrate automated identification of optical modulation formats exclusively from physical-layer signal characteristics. The system identifies the data encoding as on-off keyed versus binary or quadrature phase-shift keyed, as well as auxiliary modulation profiles. The symbol clock rate and optimal dispersion compensation are also determined. We have validated this system with over 1500 test cases. These are enabling functionalities for a universal optical receiver and for a cognitive optical network architecture that optimizes utilization of available optical bandwidth. We demonstrate the capabilities of the system using a wavelength division multiplexed signal consisting of 19 channels, with multiple modulation formats and widely varying dispersions, signal strengths, and optical signal-to-noise ratios.
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