Fundamental limits to signal integrity in nonlinear parametric optical circulators

TL;DR

This paper investigates the fundamental limits of signal integrity in nonlinear parametric optical circulators, revealing intermodulation distortion as the main limiting factor for their dynamic range.

Contribution

It provides a detailed characterization of nonlinear circulator response, highlighting intermodulation distortion as the key constraint even without pump depletion.

Findings

Intermodulation distortion limits maximal signal power

Maximum spur-free dynamic range is 81 dB

Limits hold even in undepleted pump regime

Abstract

We characterize the response of a parametric nonlinear optical circulator to realistic signals that have finite bandwidths. Our results show that intermodulation distortion (IMD), rather than pump depletion or compression, limits the maximal operating signal power and the dynamic range of nonlinear parametric circulators. This limitation holds even in the undepleted pump regime where nonlinear circulators are not constrained by dynamic reciprocity. With a realistic pump power, noise floor, and nonlinear waveguide, our numerical modeling demonstrates a maximally achievable spur-free dynamic range (SFDR) of 81 dB.