Advanced data links (ADL) can be implemented using free-space optical channels with quantum encryption. The security features of these links are based on quantum communication protocols that rely upon the inherent properties of laser light and offer physical-layer encryption without the mathematical complexity of conventional cryptography. Traditionally, these links are organized using the point-to-point topology, but it is highly desirable to extend this approach to multi-access communication systems to service an array of ADLs connected into a hub-and-spokes network. To facilitate connectivity, the "hub" can use a single aperture to establish connections to several target platforms within its field-of-view. Multi-access high-capacity wavelength division multiplexing can be used as an enabling technology for establishing communication between hub and spatially separated spokes. The associated problem of discriminating between multiple signals arriving simultaneously from distinct spatial locations is addressed by optical circuits capable of processing non-classical features of quantum states, such as entangled photon. One of the key elements of this receiving systems is the Lyot filter that offers high selectivity while directing the signals along different optical path lengths while propagating through the quantum circuit components, which may affect their processing capabilities. In this paper, we present analysis and preliminary experimental results that demonstrate the effects of off-axis arrival on performance of the Lyot filter and the resulting limitations of this technology.

© 2018 COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

Vladimir V. Nikulin, Rushui Fang, David H. Hughes, and Stephen C. Huerster, "Off-axis performance of Lyot filters in multi-access quantum communication receivers," Proc. SPIE 10547, Advances in Photonics of Quantum Computing, Memory, and Communication XI, 105470F (Presented at SPIE OPTO: January 30, 2018; Published: 22 February 2018); https://doi.org/10.1117/12.2287073.