Towards optimal capacity-achieving transceivers with photonic integrated circuits

Abstract

Optical communication systems have many advantages over communication systems that operate in the radio-frequency range, including decreased size, weight, and power consumption and increased bandwidth. As a result, optical communication systems are emerging as the ideal choice in many resource-constrained links such as those deployed on spacecraft. This thesis presents progress on development of a programmable nanophotonic processor (PNP) for implementing a high-fidelity reconfigurable optical transceiver at the telecommunications wavelength. By encoding information in multiple spatial modes and detecting jointly over the modes using a unitary transform prior to detection, one can in principle attain Holevo-limited channel capacity in the low mean photon number regime. Since the PNP offers dynamic reprogrammability, one can also, in principle, correct for wavefront distortion in the channel. We present a setup, calibration protocols, and preliminary results towards a turbulence-resistant integrated BPSK transmitter and joint detection receiver channel that achieves superadditive channel capacity in the low mean photon number regime.