  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.
