Nonreciprocal devices having reconfigurable nonreciprocal transfer functions through nonreciprocal coupling

A nonreciprocal device includes a waveguide through which waves at a first frequency propagate with a first wavevector and with a second wavevector in a direction opposite to the first wavevector; a frequency-dependent device that operates within a frequency range and modifies the waves through the waveguide in a way that is dependent on the first frequency; and a set of couplers to couple the waveguide and the frequency-dependent device. Coupling rates of the set of couplers are modulated to enable nonreciprocal coupling, with respect to the frequency-dependent device, of the first wavevector compared to the second wavevector.