Digital signal processing assisted coherent optical receiver for high dynamic range fiber optic networks

A single fiber network transporting the multitude of signals required on an avionics platform can offer benefits of a lightweight and flexible harness, significantly reduced cabling and improved EMI immunity. In addition, the total bandwidth available and the potential for flexible routing in a wavelength division multiplexed (WDM) network further offers future growth capabilities, such as faster data and sensor routing for real time reaction to sensor information, without the need for additional cabling. Digital signals on such a military platform clearly benefits from the increased bandwidth. At present, the high dynamic range required by many of the analog RF signals of interest prevents the use of traditional WDM networks employing erbium or semiconductor optical amplification to overcome network node loss due to the noise added to the system. In this paper, the author proposed a technical direction for achieving a flexible, potentially mixed signal, fiber optic network suitable for the various signals and platforms in a coherent optical network utilizing a DSP-assisted optical I/Q demodulating and microwave downconverting receiver for the high dynamic range signal transport. Such a network would allow high fidelity transport of the most demanding analog RF signals while simultaneously transporting less demanding analog RF and digital signals.